Evolution in upper water structure and paleoproductivity in the northern margin of the western pacific warm pool and its forcing mechanism during the last 190 ka B.P.-evidence from nannofossil, foraminifera and their isotope com position - Zhao, Jingtao; Li, Tiegang; Chang, Fengming; Jiang, Bo (Oceanologia et Limnologia Sinica, 2008)
id: 1932

Five Crescents from Cardwell: Context and Chronology of Chipped Stone Crescents at CA-SMI-679, San Miguel Island, California - Erlandson, Jon M.; Braje, Todd J. (Pacific Coast Archaeological Society Quarterly, 2008)
id: 2065

Forty years later: What have we learned about the earliest human occupations of Santa Rosa Island, California? - Reeder, Leslie A.; Rick, Torben C.; Erlandson, Jon M. (North American Archaeologist, 2008)
id: 2078

The Global Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch (Quaternary System/Period) in the NGRIP ice core RID B-5560-2008 RID F-1111-2011 - Walker, Mike; Johnsen, Sigfu's; Rasmussen, Sune Olander; Steffensen, Jorgen-Peder; Popp, Trevor; Gibbard, Philip; Hoek, Wim; Lowe, John; Andrews, John; Bjorck, Svante; Cwynar, Les; Hughen, Konrad; et al. (Episodes, 2008)
The Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record across the Pleistocene-Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs of climatic warming at the end of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high degree of precision. This climatic event is most clearly reflected in an. abrupt shaft in deuterium excess values, accompanied by more gradual changes in delta(18)O, dust concentration, a range of chemical species, and annual layer thickness. A timescale based on multi-parameter annual layer counting provides an age of 11,700 yr b2k (before AD2000) for the base of the Holocene, with, an estimated 2 sigma uncertainty of 99 yr: It is proposed that an archived core from this unique sequence should constitute the Global Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch (Quaternary System/Period).
id: 1988; PT: J; CT: 17th Congress of the International-Union-for-Quaternary-Research; CY: JUL 28-AUG 03, 2007; CL: Cairns, AUSTRALIA; SP: Int Union Quaternary Res; UT: WOS:000258669100017

Growth analysis and age validation of a deepwater Arctic fish, the Greenland halibut (Reinhardtius hippoglossoides) - Treble, M. A.; Campana, S. E.; Wastle, R. J.; Jones, C. M.; Boje, J. (Canadian Journal of Fisheries and Aquatic Sciences, 2008)
The accuracy of age interpretations on a deep-sea, Arctic fish species, the Greenland halibut (Reinhardtius hippoglossoides) was tested using several age validation methods. Consistent annual growth increments were either not formed or not visible in either whole or sectioned otoliths from three fish marked with oxytetracyline and recaptured after 2-4 years at liberty. Bomb radiocarbon assays based on a local reference chronology indicated that both whole and sectioned otoliths underestimated age by 1-15 years, with an average of 6 years. Growth rates estimated using the tag recapture model GROTAG were consistent with growth rates based on the radiocarbon assays and were less than half that of previously reported growth rates. The failure of otolith sections to provide an accurate age is unusual, but may be symptomatic of very slow-growing species with unusually shaped otoliths. Greenland halibut living in the deep-sea, Arctic environment are slower growing and longer lived than previously suspected, suggesting that the age-structured basis for current fisheries management warrants careful examination. Our results highlight the importance of using rigorous tests of ageing accuracy for exploited species and confirm that such age validation methods can be applied successfully in challenging environments such as the deep sea or the Arctic.
id: 806; 322ER Times Cited:3 Cited References Count:56Y

Holocene erosion of the Lesser Himalaya triggered by intensified summer monsoon - Clift, P. D.; Giosan, L.; Biusztajn, J.; Campbell, I. H.; Allen, C.; Pringle, M.; Tabrez, A. R.; Danish, M.; Rabbani, M. M.; Alizai, A.; Carter, A.; Lueckge, A. (Geology, 2008)
Climate is one of the principal controls setting rates of continental erosion. Here we present the results of a provenance analysis of Holocene sediments from the Indus delta in order to assess climatic controls on erosion over millennial time scales. Bulk sediment Nd isotope analysis reveals a number of changes during the late Pleistocene and early Holocene (at 14-20,11-12 and 8-9 ka) away from erosion of the Karakoram and toward more sediment flux from the Himalaya. Radiometric Ar-Ar dating of muscovite and U-Pb dating of zircon sand grains indicate that the Lesser Himalaya eroded relatively more strongly than the Greater Himalaya as global climate warmed and the summer monsoon intensified after 14 ka. Monsoon rains appear to be the primary force controlling erosion across the western Himalaya, at least over millennial time scales. This variation is preserved with no apparent lag in sediments from the delta, but not in the deep Arabian Sea, due to sediment buffering on the continental shelf.
id: 800; 247YL Times Cited:7 Cited References Count:27; YY

Holocene multidecadal- to millennial-scale hydrologic variability on the South American Altiplano - Ekdahl, E. J.; Fritz, S. C.; Baker, P. A.; Rigsby, C. A.; Coley, K. (Holocene, 2008)
Precipitation on the South American Altiplano varies at a range of temporal scales. A long-term secular increase in moisture availability from the early/mid Holocene to the present, driven by increasing summer insolation resulting from precessional changes in the Earth's orbit, has been documented in earlier studies. However, higher frequency Holocene variability is not yet understood. Here we present high-resolution diatom assemblage data from two small Altiplano lakes, Lago Lagunillas and Lago Umayo, indicating changes in effective moisture in the southern tropical Andes at decadal, centennial and millennial timescales throughout the mid to late Holocene. A strong millennial-scale component, similar in pacing to periods of increased ice-rafted debris flux in the North Atlantic, is observed in both lake records, which suggests that regional precipitation and North Atlantic climate variability are coupled at these scales. The interpretation of the higher frequency variability is hampered by the small number of high-resolution continental and marine records for comparison.
id: 842; ISI Document Delivery No.: 341ZR Times Cited: 1 Cited Reference Count: 49 Ekdahl, Erik J. Fritz, Sherilyn C. Baker, Paul A. Rigsby, Catherine A. Coley, KirstinY

A Holocene paleotemperature record based on radiolaria from the northern Okinawa Trough (East China Sea) - Chang, Fengming; Li, Tiegang; Zhuang, Lihua; Yan, Jun (Quaternary International, 2008)
Using a radiolarian-based transfer function, mean annual sea surface temperature (SST) and seasonal temperature range are reconstructed through the last 10,500yrs in the northern Okinawa Trough. Down-core SST estimates reveal that throughout the Holocene the changes of mean annual SST display a three-step trend: (i) an early Holocene continuous warming between 10,500 and 8500yr BP which ends up with a abrupt cooling at about 8200yr BP; (ii) a relatively stable middle Holocene with high SST that lasted until 3200yr BP; and (iii) a late-Holocene distinct SST decline between 3200 and 500yr BP. This pattern is in agreement with the ice core and terrestrial paleoclimatic records in the Chinese continent and other regions of the world. Five cooling events with abrupt mean annual SST drops, which occur at similar to 300-600, 1400, 3100, 4600-5100 and 8200yr BP, are recognized during the last 10,500yrs. Comparison of our results with records of GISP2 ice core and marine sediment in North Atlantic region suggests these cooling events are strongly coupled, which implies a possible significant climatic correlation between high- and low-latitude areas. (C) 2007 Elsevier Ltd and INQUA. All rights reserved.
id: 1926; PT: J; UT: WOS:000257255700009

Human impacts on ancient shellfish: a 10,000 year record from San Miguel Island, California - Erlandson, Jon M.; Rick, Torben C.; Braje, Todd J.; Steinberg, Alexis; Vellanoweth, Rene L. (Journal of Archaeological Science, 2008)
We use measurements of more than 11,000 marine shells from 41 archaeological components to construct a 10,000 year record of human impacts on ancient mussel and abalone stocks on San Miguel Island, California. General reductions in the mean size of mussel and abalone shells gathered through time are attributed to growing human population and predation pressure. Based on comparison with historically documented changes in shellfish communities caused by the local extinction of sea otters in the 19th century, changes in mean shell size and the abundance of other shellfish species may have been facilitated by Native American predation on sea otters as early as 7500 years ago. Despite having measurable impacts on local ecosystems, Native Americans on San Miguel harvested huge quantities of shellfish throughout the Holocene. Such longterm harvests appear to have been sustained by an early emphasis on fishing at lower trophic levels, by periodically shifting village locations, and by intensifying the use of finfish and sea mammals through time. This pattern of "fishing up the food web" contrasts with many modern fisheries, suggesting that the study of ancient fisheries can help us better manage our own endangered coastal ecosystems. (c) 2008 Elsevier Ltd. All rights reserved.
id: 2064; PT: J; UT: WOS:000257340000006

The impact of vegetation on sedimentary organic matter composition and PAH desorption - Nichols, Elizabeth Guthrie; Gregory, Samuel T.; Musella, Jennifer S. (Environmental Pollution, 2008)
Relationships between sedimentary organic matter (SOM) composition and PAH desorption behavior were determined for vegetated and non-vegetated refinery distillate waste sediments. Sediments were fractionated into size, density, and humin fractions and analyzed for their organic matter content. Bulk sediment and humin fractions differed more in organic matter composition than size/density fractions. Vegetated humin and bulk sediments contained more polar organic carbon, black carbon, and modern (plant) carbon than non-vegetated sediment fractions. Desorption kinetics of phenanthrene, pyrene, chrysene, and C(3)-phenanthrene/anthracenes from humin and bulk sediments were investigated using Tenax (R) beads and a two-compartment, first-order kinetic model. PAH desorption from distillate waste sediments appeared to be controlled by the slow clesorbing fractions of sediment; rate constants were similar to literature values for k(slow) and k(very) (slow). After several decades of plant colonization and growth (Phragmites australis), vegetated sediment fractions more extensively desorbed PAHs and had faster desorption kinetics than non-vegetated sediment fractions. (C) 2008 Elsevier Ltd. All rights reserved.
id: 2024; PT: J; UT: WOS:000261678700045

In situ carbonation of peridotite for CO2 storage - Kelemen, P. B.; Matter, J. (Proceedings of the National Academy of Sciences of the United States of America, 2008)
The rate of natural carbonation of tectonically exposed mantle peridotite during weathering and low-temperature alteration can be enhanced to develop a significant sink for atmospheric CO2. Natural carbonation of peridotite in the Samail ophiolite, an uplifted slice of oceanic crust and upper mantle in the Sultanate of Oman, is surprisingly rapid. Carbonate veins in mantle peridotite in Oman have an average C-14 age of approximate to 26,000 years, and are not 30-95 million years old as previously believed. These data and reconnaissance mapping show that approximate to 10(4) to 10(5) tons per year of atmospheric CO2 are converted to solid carbonate minerals via peridotite weathering in Oman. Peridotite carbonation can be accelerated via drilling, hydraulic fracture, input of purified CO2 at elevated pressure, and, in particular, increased temperature at depth. After an initial heating step, CO2 pumped at 25 or 30 degrees C can be heated by exothermic carbonation reactions that sustain high temperature and rapid reaction rates at depth with little expenditure of energy. In situ carbonation of peridotite could consume > 1 billion tons of CO2 per year in Oman alone, affording a low-cost, safe, and permanent method to capture and store atmospheric CO2.
id: 779; 373OP Times Cited:12 Cited References Count:37Y

In situ carbonation of peridotite for CO2 storage - Kelemen, P. B.; Matter, J. (Proceedings of the National Academy of Sciences, 2008)
The rate of natural carbonation of tectonically exposed mantle peridotite during weathering and low-temperature alteration can be enhanced to develop a significant sink for atmospheric CO2. Natural carbonation of peridotite in the Samail ophiolite, an uplifted slice of oceanic crust and upper mantle in the Sultanate of Oman, is surprisingly rapid. Carbonate veins in mantle peridotite in Oman have an average 14C age of ≈26,000 years, and are not 30–95 million years old as previously believed. These data and reconnaissance mapping show that ≈104 to 105 tons per year of atmospheric CO2 are converted to solid carbonate minerals via peridotite weathering in Oman. Peridotite carbonation can be accelerated via drilling, hydraulic fracture, input of purified CO2 at elevated pressure, and, in particular, increased temperature at depth. After an initial heating step, CO2 pumped at 25 or 30 °C can be heated by exothermic carbonation reactions that sustain high temperature and rapid reaction rates at depth with little expenditure of energy. In situ carbonation of peridotite could consume >1 billion tons of CO2 per year in Oman alone, affording a low-cost, safe, and permanent method to capture and store atmospheric CO2.
Keywords: alteration and weathering; carbon capture; carbon sequestration; exothermic; MINERAL

Incipient Aquaculture in Prehistoric California? Long-term productivity and sustainability vs. immediate returns for the harvest of marine invertebrates - Whitaker, Adrian R. (Journal of Archaeological Sciences, 2008)
California archaeologists have proposed two alternative methods for harvesting mussels—“stripping” and “plucking”. These two methods are modeled and compared with experimental data from central California (Jones, T.L., Richman, J.R., 1995. On Mussels: Mytilus californianus as a Prehistoric Resource, North American Archaeologist 16, 33–58) and archaeological data from the Punta Gorda Rockshelter, a well-stratified coastal shell midden in northern California. Foragers at the Punta Gorda Rockshelter appear to have practiced a “stripping” technique at approximately 24 month intervals. It is argued that, while this strategy reduced immediate foraging returns, it increased the long-term net productivity of the mussel beds. These findings are discussed in light of the broader literature regarding resource depression and resource cultivation in California prehistory. The conventional interpretation of reductions in the body size in archaeological assemblages is questioned both in terms of rates of return on these individuals and the impact of human predation on local prey populations.
id: 2097
Keywords: Conservation; Mytilus californianus; Optimal foraging theory; Resource depression

Increased terrestrial to ocean sediment and carbon fluxes in the northern chesapeake bay associated with twentieth century land alteration - Saenger, C.; Cronin, T. M.; Willard, D.; Halka, J.; Kerhin, R. (Estuaries and Coasts, 2008)
We calculated Chesapeake Bay (CB) sediment and carbon fluxes before and after major anthropogenic land clearance using robust monitoring, modeling and sedimentary data. Four distinct fluxes in the estuarine system were considered including (1) the flux of eroded material from the watershed to streams, (2) the flux of suspended sediment at river fall lines, (3) the burial flux in tributary sediments, and (4) the burial flux in main CB sediments. The sedimentary maximum in Ambrosia (ragweed) pollen marked peak land clearance (similar to 1900 A.D.). Rivers feeding CB had a total organic carbon (TOC)/total suspended solids of 0.24 +/- 0.12, and we used this observation to calculate TOC fluxes from sediment fluxes. Sediment and carbon fluxes increased by 138-269% across all four regions after land clearance. Our results demonstrate that sediment delivery to CB is subject to significant lags and that excess post-land clearance sediment loads have not reached the ocean. Post-land clearance increases in erosional flux from watersheds, and burial in estuaries are important processes that must be considered to calculate accurate global sediment and carbon budgets.
id: 812; 316CY Times Cited:1 Cited References Count:54Y

Interpreting sea surface temperature from strontium/calcium ratios in Montastrea corals: Link with growth rate and implications for proxy reconstructions - Saenger, C.; Cohen, A. L.; Oppo, D. W.; Hubbard, D. (Paleoceanography, 2008)
[1] We analyzed strontium/calcium ratios (Sr/Ca) in four colonies of the Atlantic coral genus Montastrea with growth rates ranging from 2.3 to 12.6 mm a(-1). Derived Sr/Ca-sea surface temperature (SST) calibrations exhibit significant differences among the four colonies that cannot be explained by variations in SST or seawater Sr/Ca. For a single coral Sr/Ca ratio of 8.8 mmol mol(-1), the four calibrations predict SSTs ranging from 24.0 degrees to 30.9 degrees C. We find that differences in the Sr/Ca-SST relationships are correlated systematically with the average annual extension rate (ext) of each colony such that Sr/Ca ( mmol mol(-1)) = 11.82 (+/- 0.13) - 0.058 (+/- 0.004) x ext ( mm a(-1)) - 0.092 (+/- 0.005) x SST (degrees C). This observation is consistent with previous reports of a link between coral Sr/Ca and growth rate. Verification of our growth-dependent Sr/Ca - SST calibration using a coral excluded from the calibration reconstructs the mean and seasonal amplitude of the actual recorded SST to within 0.3 degrees C. Applying a traditional, nongrowth-dependent Sr/Ca - SST calibration derived from a modern Montastrea to the Sr/Ca ratios of a conspecific coral that grew during the early Little Ice Age (LIA) ( 400 years B. P.) suggests that Caribbean SSTs were > 5 degrees C cooler than today. Conversely, application of our growth-dependent Sr/Ca - SST calibration to Sr/Ca ratios derived from the LIA coral indicates that SSTs during the 5-year period analyzed were within error (+/- 1.4 degrees C) of modern values.
id: 864; ISI Document Delivery No.: 333MS Times Cited: 3 Cited Reference Count: 49 Cited References: *DEP CONS CULT AFF, 1986, MAR WAT QUAL MEAS CH *NAT RES COUNC, 2006, SURF TEMP REC LAST 2 BEVINGTON PR, 1969, DATA REDUCTION ERROR, P56 BLACK DE, 2004, PALEOCEANOGRAPHY, V19, ARTN PA2022 BLACK DE, 2007, PALEOCEANOGRAPHY, V22, ARTN PA4204 CARDINAL D, 2001, CHEM GEOL, V176, P213 CARRICARTGANIVET JP, 2004, J EXP MAR BIOL ECOL, V302, P249, DOI 10.1016/j.jembe.2003.10.015 CHIANG JCH, 2002, J GEOPHYS RES-ATMOS, V107, ARTN 4004 COBB KM, 2003, EARTH PLANET SC LETT, V210, P91, DOI 10.1016/S0012-821X(03)00138-9 COHEN AL, 2004, GEOPHYS RES LETT, V31, ARTN L16310 COHEN AL, 2004, MAR ECOL-PROG SER, V271, P147 COHEN AL, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q12004 COHEN AL, 2007, GEOPHYS RES LETT, V34, ARTN L17706 CRONIN TM, 2003, GLOBAL PLANET CHANGE, V36, P17 DEVILLIERS S, 1995, SCIENCE, V269, P1247 DEVILLIERS S, 1999, EARTH PLANET SC LETT, V171, P623 FELIS T, 2004, NATURE, V429, P164, DOI 10.1038/nature02546 GABITOV RI, 2006, GEOCHIM COSMOCHIM S, V70, A187, DOI 10.1016/j.gca.2006.06.377 GAETANI GA, 2006, GEOCHIM COSMOCHIM AC, V70, P4617, DOI 10.1016/j.gca.2006.07.008 GOODKIN NF, 2005, PALEOCEANOGRAPHY, V20, ARTN PA4016 HAASESCHRAMM A, 2003, PALEOCEANOGRAPHY, V18, ARTN 1073 HAASESCHRAMM A, 2005, PALEOCEANOGRAPHY, V20, ARTN PA4015 HAUG GH, 2001, SCIENCE, V293, P1304 HENDY EJ, 2002, SCIENCE, V295, P1511 HERNANDEZGUERRA A, 2000, GEOPHYS RES LETT, V27, P3497 HODELL DA, 2005, QUATERNARY RES, V63, P109, DOI 10.1016/j.yqres.2004.11.004 HUBBARD DK, 2005, J SEDIMENT RES, V75, P97, DOI 10.2110/jsr.2005.009 HUGHEN KA, 2004, RADIOCARBON, V46, P1059 JONES PD, 2004, REV GEOPHYS, V42, ARTN RG2002 LEDER JJ, 1996, GEOCHIM COSMOCHIM AC, V60, P2857 LOUGH JM, 2004, PALAEOGEOGR PALAEOCL, V204, P115, DOI 10.1016/S0031-0182(03)00727-2 LUND DC, 2006, PALEOCEANOGRAPHY, V21, ARTN PA2009 MEIBOM A, 2006, GEOPHYS RES LETT, V33, ARTN L11608 MOHIUDDIN MM, 2004, DEEP-SEA RES PT I, V51, P1659, DOI 10.1016/j.dsr.2004.06.002 NYBERG J, 2002, PALAEOGEOGR PALAEOCL, V183, P25 OSTERMANN DR, 2000, PALEOCEANOGRAPHY, V15, P353 PFLAUMANN U, 2003, PALEOCEANOGRAPHY, V18, ARTN 1065 REYNAUD S, 2007, GEOCHIM COSMOCHIM AC, V71, P354, DOI 10.1016/j.gca.2006.09.009 REYNOLDS RW, 1994, J CLIMATE, V7, P929 ROSENTHAL Y, 1999, ANAL CHEM, V71, P3248 SCHMIDT MW, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q02P10 SMITH JM, 2006, PALEOCEANOGRAPHY, V21, ARTN PA1010 SWART PK, 2002, GEOCHEM GEOPHY GEOSY, V3, ARTN 8402 THUNELL RC, 1984, MICROPALEONTOLOGY, V30, P243 VELLINGA M, 2004, J CLIMATE, V17, P4498 WATANABE T, 2001, MAR GEOL, V173, P21 WEIL E, 1994, B MAR SCI, V55, P151 WINTER A, 2000, GEOPHYS RES LETT, V27, P3365 YOO JM, 1990, J PHYS OCEANOGR, V20, P831 Saenger, Casey Cohen, Anne L. Oppo, Delia W. Hubbard, Dennis Amer geophysical union Washington; YY

ITUHU SITE (32SN110) 1995 Archeological Excavations, Stutsman County, North Dakota. James River Report Number 5 - Toom, Dennis L. (James River Report, 2008)
id: 771

The last reconnection of the Marmara Sea (Turkey) to the World Ocean: A paleoceanographic and paleoclimatic perspective - McHugh, C. M. G.; Gurung, D.; Giosan, L.; Ryan, W. B. F.; Mart, Y.; Sancar, U.; Burckle, L.; Cagatay, M. N. (Marine Geology, 2008)
During the late glacial, marine isotope Stage 2, the Marmara Sea transformed into a brackish lake as global sea-level fell below the sill in the Dardanelles Strait. A record of the basin's reconnection to the global ocean is preserved in its sediments permitting the extraction of the paleoceanographic and paleoclimatic history of the region. The goal of this study is to develop a high-resolution record of the lacustrine to marine transition of Marmara Sea in order to reconstruct regional and global climatic events at a millennia] scale. For this purpose, we mapped the paleoshorelines of Marmara Sea along the northern, eastern, and southern shelves at Cekmece. Prince Islands, and Imrali, using data from multibeam bathymetry, high-resolution subbottom profiling (chirp) and ten sediment cores. Detailed sedimentologic, biostratigraphic (foraminifers, mollusk, diatoms), X-ray fluorescence geochemical scanning, and oxygen and carbon stable isotope analyses correlated to a calibrated radiocarbon chronology provided evidence for cold and city conditions prior to 15 ka BP, warm conditions of the Bolling-Allerod from similar to 15 to 13 ka BP, a rapid marine incursion at 12 ka BP, still stand of Marmara Sea and sediment reworking of the paleoshorelines during the Younger Dryas at similar to 11.5 to 10.5 ka BP, and development of strong stratification and influx of nutrients as Black Sea waters spilled into Marmara Sea at 9.2 ka BR Stable environmental conditions developed in Marmara Sea after 6.0 ka BP as sea-level reached its present shoreline and the basin floors filled with sediments achieving their present configuration. (C) 2008 Elsevier B.V. All rights reserved.
id: 801; 370ED Times Cited:4 Cited References Count:104; YY

Late Holocene marine productivity changes in Northern Patagonia-Chile inferred from a multi-proxy analysis of Jacaf channel sediments - Rebolledo, Lorena; Sepulveda, Julio; Lange, Carina B.; Pantoja, Silvio; Bertrand, Sbastien; Hughen, Konrad; Figueroae, Dante (Estuarine Coastal and Shelf Science, 2008)
A multi-proxy approach based on organic (organic carbon, alkenones, and C/N) and inorganic geochemical proxies (biogenic opal, inorganic carbon, Fe, Ti, and Ca) preserved in the sediments of the Jacaf channel (CF7-PC33; 44 degrees 21'S, 72 degrees 58'W, 510 m water depth), Chilean fjords, yields evidence of major past productivity fluctuations in accordance with climatic changes over the last similar to 1800 years. The downcore record clearly shows two productivity/climate modes. The first period, prior to 900 cal yr BP, is characterized by decreased marine productivity and a reduced continental signal, pointing to diminished precipitation and runoff. In contrast, the second period between similar to 750 cal yr BP and the late 1800s (top of core) is illustrated by elevated productivity and an increased continental signal, suggesting higher precipitation and runoff. Both time intervals are separated by a relatively abrupt transition of similar to 150 years which roughly coincides with the beginning of the Little Ice Age. The increased content of freshwater diatoms and Chrysophyte cysts that characterize the last 200 years of the latter mode coincides with a significant decrease in the carbonate content of the sediment; together they further indicate increased terrigenous contributions and decreased marine carbonate productivity at the end of the Little Ice Age. The correspondence between our record and other paleoclimate studies carried out in South America and Antarctica demonstrates that the Chilean fjord area of Northern Patagonia is not just sensitive to local climatic variability but also to regional and possibly global variability. (C) 2008 Elsevier Ltd. All rights reserved.
id: 2117; PT: J; TC: 5; J9: ESTUAR COAST SHELF S; UT: WOS:000261562600002

A late holocene pollen and charcoal record from La Selva biological station, Costa Rica - Kennedy, Lisa M.; Horn, Sally P. (Biotropica, 2008)
Pollen and charcoal analysis of a 5.9-m-long sediment profile from a swamp on an alluvial terrace on the edge of La Selva biological station, Costa Rica (10 degrees 26 ' 23 '' N, 84 degrees 00 ' 24 '' W, 36 m asl), documents three millennia of human and natural disturbance within a lowland tropical rain forest. The record indicates that the highly diverse rain forest that presently surrounds the Cantarrana swamp regrew following forest clearing and maize agriculture that ended only a few centuries ago. The first maize pollen appears in sediments deposited similar to 1070 calendar-year BP. Older sediments below the 'maize zone' contain macroscopic charcoal, abundant microscopic charcoal, and possible pollen indicators of forest clearance, perhaps signaling local cultivation of root crops that left no pollen in the sediments. Interpretation of local archaeology indicates that La Selva reserve may have been most heavily populated during the El Bosque and La Selva regional archaeological phases from 2250-950 yr BP. However, the distribution of maize pollen in the sediments is clear evidence that the reserve was also occupied during the later La Cabana phase (950-400 yr BP), from which few artifacts have yet surfaced. Natural forest disturbance from treefalls and stream dynamics, and hydrological shifts associated with late-Holocene climate variability, form a backdrop to the human land-use history preserved in the Cantarrana sediment profile.
id: 1997; PT: J; UT: WOS:000252319600004

Late Pleistocene freshwater fish (Cottidae) trackways from New England (USA) glacial lakes and a reinterpretation of the ichnogenus Broomichnium Kuhn - Benner, Jacob S.; Ridge, John C.; Taft, Natalia K. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2008)
New trace fossil material from Late Pleistocene glaciolacustrine varves of the Connecticut River Valley, New England, USA represent the first evidence of freshwater sculpin in glacial Lake Hitchcock. Paleobiogeographic data constrain the timing of the last reinhabitation of freshwater cottids from a Wisconsinan glacial refugium. Freshwater sculpin were present in the area of study by ~ 13.7 ky BP, moving approximately 400 km in 5000 yr, and following the ice margin at distances as close as 35 km. The trace fossils warrant erection of a new ichnospecies, Broomichnium flirii isp. nov. Comparison of this new ichnospecies to Broomichnium permianum reveals distinct similarities, and it is possible that the Permian examples of B. permianum also were made by fish, which would reconcile a long-running controversy. Many groups of fish are demersal and make ventral body contact with the substrate and could potentially leave similar traces. Identifying new forms of trace fossils made by fish that use alternative modes of locomotion will prove useful in paleoenvironmental interpretations.
id: 2129

Late Quaternary paleo-lake fluctuations in westernmost Tibet - Amidon, W.; Blard, P.; Avouac, J.; Schneider, T. (2008 Fall Meeting of the American Geophysical Union (AGU 2008), 2008)
id: 1913; TY: CPAPER; NO: Source type: conferencepapers&proceedings; Object type: Conference Paper; CSAUnique: CPI-5461640; AccNum: 5461640(USA)
Keywords: China, People's Rep., Xizang; Paleo studies; Quaternary

Late Quaternary vegetation reconstruction from the Eastern Arc Mountains, Tanzania - Mumbi, C. T.; Marchant, R.; Hooghiemstra, H.; Wooller, M. J. (Quaternary Research, 2008)
Pollen, spore, macrofossil and stable isotope (C and N) analyses from a 266-cm sediment core collected from a swamp on the Eastern Arc Mountains, Tanzania, are used to reconstruct vegetation and environmental history. An estimated time scale based on five C-14 ages records approximately 38,000 yr. This palaeorecord is the first from this biodiversity hotspot and importantly extends through the last glacial maximum (LGM). The altitudinal transition from montane to upper montane forest shifted from 1700-1800 in (38,000 C-14 yr BP) to 1800-1900 in (35,000-29,000 C-14 yr BP). From 29,000 to 10,000 C-14 yr BP, it shifted from 1850-1950 in across the LGM to 1750-1800 in (during 10,000-3500 C-14 yr BP), and to present-day elevations at 2000 in during the last 3500 C-14 yr BP. The relative ecosystem stability across the LGM may be explained by the Indian Ocean's influence in maintaining continuous moist forest cover during a period of East African regional climate aridity. During the late Holocene, presence of abundant coprophilous fungi and algal blooms demonstrates increasing human impact. Neurospora spores indicate frequent fires, coinciding with clear signals of decline in Podocarpus and Psychotria trees that possibly represent selective logging. (C) 2007 University of Washington. All rights reserved.
id: 1836; 285PB Times Cited:6 Cited References Count:105Y

Lateral organic carbon supply to the deep Canada Basin - Hwang, J.; Eglinton, T. I.; Krishfield, R. A.; Manganini, S. J.; Honjo, S. (Geophysical Research Letters, 2008)
Understanding the processes driving the carbon cycle in the Arctic Ocean is important for assessing the impacts of the predicted rapid and amplified climate change in this region. We analyzed settling particle samples intercepted by a time-series sediment trap deployed in the abyssal Canada Basin ( at 3067 m) in order to examine carbon export to the deep Arctic Ocean. Strikingly old radiocarbon ages ( apparent mean 14 C age = similar to 1900 years) of the organic carbon, abundant lithogenic material (similar to 80%), and mass flux variations temporally decoupled from the cycle of primary productivity in overlying surface waters together suggest that, unlike other ocean basins, the majority of the particulate organic carbon entering the deep Canada Basin is supplied from the surrounding margins.
id: 1830; 314KU Times Cited:7 Cited References Count:33Y

Life on the edge: early maritime cultures of the Pacific Coast of North America - Erlandson, Jon M.; Moss, Madonna L.; Des Lauriers, Matthew (Quaternary Science Reviews, 2008)
A variety of evidence suggests that the Americas may have been colonized, at least in part, by maritime peoples moving around the North Pacific Rim near the end of the Pleistocene. Understanding the geography of late glacial and early postglacial landscapes and the antiquity of human societies along the Pacific Coast continues to be a challenge, however, due to geological dynamics associated with glaciation, tectonism, submergence of coastal lowland landscapes by rising postglacial seas, and coastal erosion. Nonetheless, archaeological research has Pushed back the antiquity of human settlement along the Pacific Coast of North America to the terminal Pleistocene or early Holocene, providing important new data on the nature of the earliest coastal peoples in the Pacific Northwest, Alta California, and Baja California. In this paper, we summarize what is known about the earliest peoples of the Pacific Coast of North America and evaluate the Current viability of the coastal migration theory via a Pacific Rim route. Archaeological evidence now shows that Palaeocoastal peoples occupied each major region of the Pacific Coast by at least 13,000-11,500 calendar years ago (cal BP) (13-11.5 ka), essentially contemporaneous with Clovis and Folsom peoples of the interior. Although it is too early to conclude that the initial human colonization of the Americas took place via a migration by maritime or coastal peoples, it seems increasingly likely that such a migration played a role in the early peopling of the Americas. (c) 2008 Elsevier Ltd. All rights reserved.
id: 2062; PT: J; SI: SI; UT: WOS:000261715500012

Loess record of the Pleistocene-Holocene transition on the northern and central Great Plains, USA - Mason, Joseph A.; Miao, Xiaodong; Hanson, Paul R.; Johnson, William C.; Jacobs, Peter M.; Goble, Ronald J. (Quaternary Science Reviews, 2008)
Various lines of evidence support conflicting interpretations of the timing, abruptness. and nature of climate change in the Great Plains during the Pleistocene-Holocene transition. Loess deposits and paleosols on both the central and northern Great Plains provide a valuable record that can help address these issues. A synthesis of new and previously reported optical and radiocarbon ages indicates that the Brady Soil, which marks the boundary between late Pleistocene Peoria Loess and Holocene Bignell Loess, began forming after a reduction in the rate of Peoria Loess accumulation that most likely occurred between 13.5 and 15 cal ka. Brady Soil formation spanned all or part of the Bolling-Allerod episode (approximately 14.7-12.9 cal ka) and all of the Younger Dryas episode (12.9-11.5 cal ka) and extended at least 1000 years beyond the end of the Younger Dryas. The Brady Soil was buried by Bignell Loess sedimentation beginning around 10.5-9 cal ka, and continuing episodically through the Holocene. Evidence for a brief increase in loess influx during the Younger Dryas is noteworthy but very limited. Most late Quaternary loess accumulation in the central Great Plains was nonglacigenic and was under relatively direct climatic control. Thus, Brady Soil formation records climatic conditions that minimized eolian activity and allowed effective pedogenesis, probably through relatively high effective moisture. Optical dating of loess in North Dakota supports correlation of the Leonard Paleosol on the northern Great Plains with the Brady Soil. Thick loess in North Dakota was primarily derived from the Missouri River floodplain; thus, its stratigraphy may in part reflect glacial influence on the Missouri River. Nonetheless, the persistence of minimal loess accumulation and soil formation until 10 cal ka at our North Dakota study site is best explained by a prolonged interval of high effective moisture correlative with the conditions that favored Brady Soil formation. Burial of both the Brady Soil and the Leonard Paleosol by renewed loess influx probably represents eolian system response that occurred when gradual change toward a drier climate eventually crossed the threshold for eolian activity. Overall, the loess-paleosol sequences of the central and northern Great Plains record a broad peak of high effective moisture across the late Pleistocene to Holocene boundary, rather than well-defined climatic episodes corresponding to the Bolling-Allerod and Younger Dryas episodes in the North Atlantic region. (C) 2008 Elsevier Ltd. All rights reserved.
id: 1993; PT: J; UT: WOS:000260545800008

Matrix protected organic matter in a river dominated margin: A possible mechanism to sequester terrestrial organic matter? - Mead, R. N.; Goñi, M. A. (Geochimica Et Cosmochimica Acta, 2008)
The provenance of organic matter in surface sediments from the northern Gulf of Mexico was investigated by analyzing the compositions of lipid biomarkers (n-alkanes, fatty acids, sterols) liberated after a series of chemical treatments designed to remove different organo-mineral matrix associations (i.e. freely extractable, base-hydrolyzable, unhydrolyzable). Bulk analyses of the organic matter (carbon content, carbon:nitrogen ratios, stable and radiocarbon isotopic analyses) were also performed on the intact sediments and their non-hydrolyzable, demineralized residue. We found recognizable lipids from distinct sources, including terrestrial vascular plants, bacteria and marine algae and zooplankton, within each of the isolated fractions. Based on the lipid signatures and bulk compositions, the organic matter within the unhydrolyzable fractions appeared to be the most diagenetically altered, was the oldest in age, and had the highest abundance of terrigenous lipids. In contrast, the base-hydrolyzable fraction was the most diagentically unaltered, had the youngest ages and was most enriched in N and marine lipids. Our results indicate that fresh, autochthonous organic matter is the most important contributor to base-hydrolyzable lipids, whereas highly altered allochthonous sources appear to be predominant source of unhydrolyzable lipids in the surface sediments from the Atchafalaya River shelf. Overall, the lipid biomarker signatures of intact sediments were biased towards the autochthonous source because many of the organic compounds indicative of degraded, terrigenous sources were protected from extraction and saponification by organo-mineral matrices. It is only after these protective matrices were removed by treatment with HCl and HF that these compounds became evident. (C) 2008 Elsevier Ltd. All rights reserved.
id: 827; 309MK Times Cited:5 Cited References Count:71Y

Method for determining coal carbon in the reclaimed minesoils contaminated with coal - Ussiri, D. A. N.; Lai, R. (Soil Science Society of America Journal, 2008)
Minesoils are anthropic soils developed on land disturbed by mining activities. Minesoils developed on the reclaimed surface-mined sites for coal are contaminated with coal particles resulting from mining and reclamation activities. Therefore, the total organic carbon (TOC) pool in these sites is a mixture of coal and plant-derived recent soil organic carbon (SOC). Accurate estimates of SOC pools and C sequestration rates in the reclaimed minesoils (RMS) is limited by the lack of a standard and cost-effective method for determination of coal C concentrations in the RMS. The chemi-thermal method, based on the oxidative resistance of coal, was developed and validated with radiocarbon analysis using selected artificial soil-coal mixtures and minesoil samples. Radiocarbon analysis of RMS samples indicated that minesoils from the top 10-cm depth developing from topsoil applied during reclamation was coal C free. The contribution of coal C and the radiocarbon age of TOC increased with increasing soil depth. The coal C fraction accounted for 0 to 92% of TOC in the RMS samples. The coal C fraction was highly correlated with delta C-13 (r(2) = 0.84), suggesting that stable isotope composition could estimate the coal C concentration in RMS samples. Analysis of coal and artificial soil and coal mixtures indicated that chemi-thermal treatment was effective in removing recent SOC with minimum effect on coal. Analysis of RMS samples indicated that both radiocarbon activity and the chemi-thermal method were effective in estimating coal C concentration in RMS of southeast Ohio. The coal C concentrations for both methods were highly correlated (r(2) = 0.95), suggesting that the chemi-thermal method was as effective as radiocarbon activity measurement in estimating coal C concentration in these soils.
24
Keywords: BLACK CARBON; C-14; FOREST; GENESIS; MATTER; MINING DISTRICT; RICH MINE SOILS; sediments; SITES; SOIL ORGANIC-CARBON

Micropaleontologic record of late pliocene and quaternary paleoenvironments in the northern Albemarle embayment, North Carolina, USA - Culver, S. J.; Farrell, K. M.; Mallinson, D. J.; Horton, B. P.; Willard, D. A.; Thieler, E. R.; Riggs, S. R.; Snyder, S. W.; Wehmiller, J. F.; Bernhardt, C. E.; Hillier, C. (Palaeogeography Palaeoclimatology Palaeoecology, 2008)
Micropaleontological data provide a strong actualistic basis for detailed interpretations of Quaternary paleoenvironmental change. The 90 m-thick Quaternary record of the Albemarle Embayment in the mid-Atlantic coastal plain of the USA provides an excellent opportunity to use such an approach in a region where the details of Quaternary environmental change are poorly known. The foraminiferal record in nine cores from the northern Outer Banks, east of Albemarle Sound, North Carolina, indicates the deposition of subhorizontal, mostly open-marine early to late Pleistocene units unconformably upon a basement of late Pliocene reduced-oxygen, fine-grained, shelf-basin deposits. Pollen data record several warm-cool fluctuations within the early to mid-Pleistocene deposits. Diatom data indicate that some fresh and brackish-water units occur within the generally open-marine Pleistocene succession. A channel cut by the paleo-Roanoke River during the last glacial sea-level lowstand occurs in the northern part of the study area. Pollen indicates that the basal fluvial valley fill accumulated in cooler than modern climate conditions in the latest Pleistocene. Overlying silts and muds accumulated under cool climatic, estuarine conditions according to diatom and pollen data. Radiocarbon ages from the estuarine deposits indicate that the bulk of these sediments accumulated during the latest Pleistocene. The estuarine channel-fill deposits are overlain by Holocene open-marine sands deposited as the rising sea transgressed into the estuary approximately 8.5 to 9.0 kyr BR Within the barrier island drill cores of this study, fully marine sedimentation occurred throughout the Holocene. However, immediately west of the present barrier island, mid- to late Holocene estuarine deposits underlie the modern Albemarle Sound. The islands that currently form a continuous barrier across the mouth of Albemarle Sound have a complex history of Holocene construction and destruction and large portions of them may be less than 3 kyr old. The barrier island sands overlie open-marine sands of Colington Shoal in the north and to the south overlie fluvial and marine sand filling paleo-Roanoke tributary valleys. The Pleistocene sediments underlying the northern Outer Banks study area are mainly of open inner to midshelf origin. If, as is likely, sea level continues to rise, a return to such environmental conditions is likely in the near future. (c) 2008 Elsevier B.V. All rights reserved.
id: 815; 331MZ Times Cited:2 Cited References Count:79Y

Mineralization of ancient carbon i the subsurface of riparian forests - Gurwick, Noel P.; McCorkle, Daniel M.; Groffman, Peter M.; Gold, Arthur J.; Kellogg, D. Q.; Seitz-Rundlett, Peter (Journal of Geophysical Research, 2008)
id: 1193

Modern CaCO3 preservation in equatorial Pacific sediments in the context of late-Pleistocene glacial cycles - Anderson, R. F.; Fleisher, M. Q.; Lao, Y.; Winckler, G. (Marine Chemistry, 2008)
The CaCO3 content of marine sediments in many regions of the ocean has varied systematically with climate throughout the late-Pleistocene glacial cycles. Both biological productivity and carbonate preservation have been proposed to be the master variable regulating this variability. We have evaluated the preserved flux of CaCO3 in cores from the central equatorial Pacific Ocean (similar to 140 degrees W) using the Th-230-normalization technique. Neither barite fluxes nor Be-10/Th-230 ratios, both geochemical proxies for export production, correlate with CaCO3 fluxes, indicating that productivity is not the principal factor controlling CaCO3 accumulation in these sediments. Preserved fluxes of CaCO3 in central equatorial Pacific sediments correlate in time with the benchmark CaCO3 record from the Cape Basin (South Atlantic Ocean), supporting the view that changes in ocean chemistry (carbonate ion concentration) have controlled the pattern of CaCO3 preservation and accumulation at these sites. Modem CaCO3 preservation in equatorial Pacific sediments has dropped to levels nearly as low as those experienced at any time in the late Pleistocene. Similar changes occurred at the end of each of the late-Pleistocene interglacial periods, from which we infer that ocean carbonate chemistry has already undergone changes that are expected to precede the transition into the next ice age. However, during the late Pleistocene, the time interval between the decrease in CaCO3 preservation and the end of the interglacial has varied substantially from one interglacial to another (from similar to 2000 to similar to 15,000 years), so the late-Holocene decrease in CaCO3 preservation cannot be used to predict the end of the Holocene interglacial period. (C) 2007 Elsevier B.V. All rights reserved.
id: 1936; PT: J; UT: WOS:000259418600004

The most extensive Holocene advance in the Stauning Alper, East Greenland, occurred in the Little Ice Age - Hall, B. L.; Baroni, C.; Denton, G. H. (Polar Research, 2008)
We present glacial geologic and chronologic data concerning the Holocene ice extent in the Stauning Alper of East Greenland. The retreat of ice from the late-glacial position back into the mountains was accomplished by at least 11 000 cal years B.P. The only recorded advance after this time occurred during the past few centuries (the Little Ice Age). Therefore, we postulate that the Little Ice Age event represents the maximum Holocene ice extent in this part of East Greenland.
id: 823; 327VY Times Cited:1 Cited References Count:45Y

Mutation and evolutionary rates in adelie penguins from the antarctic - Millar, C. D.; Dodd, A.; Anderson, J.; Gibb, G. C.; Ritchie, P. A.; Baroni, C.; Woodhams, M. D.; Hendy, M. D.; Lambert, D. M. (Plos Genetics, 2008)
Precise estimations of molecular rates are fundamental to our understanding of the processes of evolution. In principle, mutation and evolutionary rates for neutral regions of the same species are expected to be equal. However, a number of recent studies have shown that mutation rates estimated from pedigree material are much faster than evolutionary rates measured over longer time periods. To resolve this apparent contradiction, we have examined the hypervariable region (HVR I) of the mitochondrial genome using families of Adelie penguins (Pygoscelis adeliae) from the Antarctic. We sequenced 344 bps of the HVR I from penguins comprising 508 families with 915 chicks, together with both their parents. All of the 62 germline heteroplasmies that we detected in mothers were also detected in their offspring, consistent with maternal inheritance. These data give an estimated mutation rate (micro) of 0.55 mutations/site/Myrs (HPD 95% confidence interval of 0.29-0.88 mutations/site/Myrs) after accounting for the persistence of these heteroplasmies and the sensitivity of current detection methods. In comparison, the rate of evolution (k) of the same HVR I region, determined using DNA sequences from 162 known age sub-fossil bones spanning a 37,000-year period, was 0.86 substitutions/site/Myrs (HPD 95% confidence interval of 0.53 and 1.17). Importantly, the latter rate is not statistically different from our estimate of the mutation rate. These results are in contrast to the view that molecular rates are time dependent.
id: 1195; Millar, Craig D Dodd, Andrew Anderson, Jennifer Gibb, Gillian C Ritchie, Peter A Baroni, Carlo Woodhams, Michael D Hendy, Michael D Lambert, David M PLoS Genet. 2008 Oct 3;4(10):e1000209.2546446

Natural Abundance Radiocarbon Studies of Dissolved Organic Carbon (DOC) in the Marine Environment - de Jesus, Roman P. (University of California, San Diego, 2008)
Marine dissolved organic carbon (DOC), an active reservoir in the global carbon cycle, has an average age of 6000 years and is comprised of biochemicals which may or may not cycle on different time scales. The primary objective of this thesis is to investigate the relationship between radiocarbon (14C) signature and chemical composition of various fractions within DOC. Specifically, this thesis was designed to provide an analytical framework to explicitly explore the relationship between DOC molecular weight, chemical composition, and reactivity. Chapter 2 describes spatial and temporal total organic carbon (TOC) concentration gradients in 2005 from the California Cooperative Fisheries Oceanic Cooperative (CalCOFI) region, which is the main study area for this thesis. Chapter 3 describes a novel solid phase extraction (SPE) method and reports the chemical and isotopic characteristics of fractionated DOC components based on their solubility. These fractions are compared to DOC isolated by the widely applied UF techniques and the results indicate that chemical composition and 14C content were related. Using compound specific isotope analysis (CSIA) of sugars and lipids, Chapter 4 shows that both SPE DOC and UDOC contain specific compounds with similar chemical and isotopic characteristics and residence times. In Chapter 5, CSIA was applied to SPE samples collected from the Delaware River and Estuary and the terrestrially influenced Eel River Margin to examine whether riverine DOC inputs contribute specific compounds or common components to the coastal ocean. Finally, the final chapter discusses the implications and significance of these results for marine DOC cycling.

Near constancy of the Pacific Ocean surface to mid-depth radiocarbon-age difference over the last 20 kyr - Broecker, W.; Clark, E.; Barker, S. (Earth and Planetary Science Letters, 2008)
Although C-13 to C-12 and cadmium to calcium ratios provide information regarding the distribution of deep water masses during late glacial time and during the period of deglaciation, our knowledge of the rate at which these water masses were ventilated comes mainly from the difference in radiocarbon-age between coexisting bottom- and surface-dwelling foraminifera. Paired benthic/planktonic foraminiferal radiocarbonage differences covering last 20 kyr in a high-deposition-rate western equatorial Pacific core, MD01-2386, from a water depth of 2.8 km show no significant climate-related variations over this period. This result is surprising for we would have expected a change in this age difference between the last glacial maximum (LGM) and the Holocene and also during the Mystery Interval (17.5-14.5 kyr ago) when the waters in a radiocarbon-depleted abyssal reservoir were presumably being mixed back into the remainder of the ocean. (C) 2008 Elsevier B.V. All rights reserved.
id: 770; 390GV Times Cited:2 Cited References Count:27Y

A New Look at Perishable Technologies from the Ozark Plateau: Focus - Horton, Elizabeth T. (31st Annual Conference of the Society of Ethnobiology, 2008)
id: 777

Northern hemisphere controls on tropical southeast African climate during the past 60,000 years - Tierney, Jessica E.; Russell, James M.; Huang, Yongsong; Damste, Jaap S. Sinninghe; Hopmans, Ellen C.; Cohen, Andrew S. (Science, 2008)
The processes that control climate in the tropics are poorly understood. We applied compound-specific hydrogen isotopes (delta D) and the TEX(86) (tetraether index of 86 carbon atoms) temperature proxy to sediment cores from Lake Tanganyika to independently reconstruct precipitation and temperature variations during the past 60,000 years. Tanganyika temperatures follow Northern Hemisphere insolation and indicate that warming in tropical southeast Africa during the last glacial termination began to increase similar to 3000 years before atmospheric carbon dioxide concentrations. delta D data show that this region experienced abrupt changes in hydrology coeval with orbital and millennial-scale events recorded in Northern Hemisphere monsoonal climate records. This implies that precipitation in tropical southeast Africa is more strongly controlled by changes in Indian Ocean sea surface temperatures and the winter Indian monsoon than by migration of the Intertropical Convergence Zone.
id: 2047; PT: J; UT: WOS:000259902300046

Origins of archaeal tetraether lipids in sediments: Insights from radiocarbon analysis RID A-6723-2009 - Shah, Sunita R.; Mollenhauer, Gesine; Ohkouchi, Naohiko; Eglinton, Timothy I.; Pearson, Ann (Geochimica et Cosmochimica Acta, 2008)
Understanding the supply and preservation of glycerol dibiphytanyl glycerol tetraethers (GDGTs) in marine sediments helps inform their use in paleoceanography. Compound-specific radiocarbon measurements of sedimentary alkenones from multiple environments have been used to gain insight into processes that affect U-37(K') paleotemperature reconstructions. Similar analyses are warranted to investigate how analogous processes affecting GDGTs impact TEX86 paleotemperatures. Here we present radiocarbon measurements on individual GDGTs from Bermuda Rise and Santa Monica Basin sediments and discuss the results in the context of previous studies of co-depositional alkenones and foraminifera. The C-14 contents of GDGTs and planktonic foraminifera in Bermuda Rise are very similar, suggesting a local source; and TEX86-derived temperatures agree more closely with foraminiferal temperatures than do U-37(K') temperatures. In contrast, GDGTs in Santa Monica Basin are depleted in C-14 relative to both alkenones and foraminifera, and TEX86 temperatures agree poorly with known surface water values. We propose three possible factors that could explain these results: (i) GDGTs may be labile relative to alkenones during advective transport through oxic waters; (ii) archaeal production deep in the water column may contribute C-14-depleted GDGTs to sediments; and (iii) some GDGTs also may derive from sedimentary archaeal communities. Each of these three processes is likely to occur with varying relative importance depending on geographic location. The latter two may help to explain why TEX86 temperature reconstructions from Santa Monica Basin do not appear to reflect actual sea surface temperatures. Terrigenous GDGTs are unlikely to be major contributors to Bermuda Rise or Santa Monica Basin sediments, based on values of the BIT index. The results also indicate that the crenarchaeol regioisomer is governed by processes different from other GDGTs. Individual measurements of the crenarchaeol regioisomer are significantly depleted in C-14 relative to co-occurring GDGTs, indicating an alternative origin for this compound that presently remains unknown. Re-examination of the contribution of crenarchaeol regioisomer to the TEX86 index shows that it is a significant influence on the sensitivity of temperature reconstructions. (C) 2008 Elsevier Ltd. All rights reserved.
id: 2051; PT: J; UT: WOS:000259107700010

Oxygen and carbon isotope records of calcareous nannofossils from the west Philippine Sea during the last 190ka - Jingtao, Zhao; Li, Tiegang; Chang, Fengming; Li, Jun (Earth Science.Journal of China University of Geoscience, 2008)
The piston core Ph05-5 recovered from the West Philippine Sea(16.049 degrees N, 124.344 degrees E, water depth 3382m) was used to study the delta (super 18) O and delta (super 13) C variations of calcareous nannofossils. The delta (super 18) O values of calcareous nannofossils were obviously lower in Holocene and the last interglaciation than those in the last and the penultimate glaciation. During the last 190 ka the nannofossil delta (super 18) O values were positively correlated with those of planktonic and benthic foraminifera from the same core. But the average delta (super 18) O value of nannofossils was 0.431X10 (super -3) , higher than that of planktonic foraminifera Globigerinoides rubber, and was 0.410X10 (super -3) , lower than that of planktonic foraminifera Neogloboquadrina dutertrei. All the above three average delta (super 18) O values were much lower than those of benthic foraminifera Cibicides wullerstorfi. The change of nannofossil delta (super 13) C values showed similar trends with the absolute abundance of calcareous nannofossils in core Ph05-5, which also indicates the primary productivity variations in the West Philippine Sea. The primary productivity stayed at a stable but relatively low level at MIS 6 and MIS 5e.There was an abrupt rise at the beginning of MIS 5d for the primary productivity which retained high value until 25 ka BP. The primary productivity showed a slight decline during MIS 2 and MIS 1, but still higher than that of MIS 6 and MIS 5e.
id: 1933; NO: Source type: scholarlyjournals; Object type: Article; Copyright: GeoRef in Process, Copyright 2011, American Geosciences Institute. After editing and indexing, this record will be added to Georef.; CSAUnique: 570969-5; AccNum: 570969-5; ISSN: 1000-2383; Peer Reviewed: true
Keywords: 02D; 24; algae; biochemistry; C-13/C-12; carbon; Cenozoic; Foraminifera; Geochemistry; Holocene; Invertebrata; Isotope geochemistry; isotope ratios; isotopes; Last glacial maximum; microfossils; nannofossils; north pacific; Northwest Pacific; O-18/O-16; oxygen; Pacific Ocean; paleo-oceanography; Philippine Sea; Plantae; Pleistocene; productivity; Protista; Quaternary; Quaternary geology; Stable isotopes; upper Pleistocene; West Pacific

Palaeoclimate - Tree rings floating on ice cores - Reimer, Paula J.; Hughen, Konrad A. (Nature Geoscience, 2008)
id: 1984; PT: J; UT: WOS:000256433500013

PALEOPRODUCTIVITY VARIATION AND ITS CORRELATION WITH CLIMATE CHANGES:AN APPROACH OF LONG-CHAIN ALKENONE - Nan, Q.; Li, T.; Chen, Jinxia; Yu, X.; Li, Q. (Quaternary Sciences, 2008)
The accurate reconstruction of paleoproductivity is critical for understanding the carbon cycle in the past and for predicting the fate of anthropogenic carbon in the future.Biomarkers in marine sediments are useful tools for paleoenvirionment study and have been used as proxies for total and specific phytoplankton group paleoproductivity.Based on 17 AMS14C age controlling points,we report here molecular abundance data for alkenone and organic carbon isotopic data for bulk samples from a giant piston core MD05-2908(24°48.04'N,122°29.35'E).The aim is to evaluate the paleoproductivity and interpret the climatic-induced controlling factors for the past 7000aB.P.The results showed that the paleoproductivity in the South Okinawa Trough(SOT)fluctuated frequently in the past 7000aB.P.By correlating with the Titanium records from Huguang Marr and Cariaco Basin,we found out that the paleoproductivity was largely controlled by the latitude migration of ITCZ.The rapid southward shift of the ITCZ might have caused longer staying of the rainfall front in the source supply area,thus,led to intensified erosion,brought increased terrigenous material into the ECS and SOT by fluvial the terrigenous materil delivers to the SOT.Terrigenous input on the one hand might have fertilized the sea surface of SOT and stimulated the production,but on the other hand might have diluted the signal of marine derived input to the sediments.The lower production periods in the SOT correlated well with those ice-drift episodes recorded in the high latitude Atlantic Ocean,suggesting the strong relationships between high and low latitude climate.
id: 1968
Keywords: Alkenone; ITCZ; paleoproductivity; SOT; the last 7000aB.P.

Paleotsunami History Recorded in Holocene Coastal Lagoon Sediments, Southeastern Sri Lanka - Jackson, Kelly (Marine Geology and Geophysics (Marine), 2008)
Tsunamis are low amplitude, large wavelength waves that can significantly impact coastal regions. Although their destructive impacts are clear from recent events, the frequency with which tsunamis occur is less well constrained. To better understand the tsunami history and coastal impacts in Sri Lanka, this study compares sediments deposited by the December 26, 2004, tsunami to older lagoon sediments in search of evidence for paleotsunami deposits. Results from this study illustrate that the coastal lagoons in Sri Lanka preserve tsunami deposits and can provide the first steps towards constraining the paleotsunami history of the Indian Ocean. Because Sri Lanka is a far field location relative to the Sumatra-Andaman subduction zone, the preserved tsunami deposits are likely mega-tsunami events similar in size and destruction to the December 26, 2004, tsunami. The December 26, 2004, M 9.1?9.3 Sumatra-Andaman earthquake generated a massive tsunami that propagated throughout the Indian Ocean, causing extreme coastal inundation and destruction. The southeastern coastline of Sri Lanka was impacted by the 2004 tsunami where between one and three waves inundated coastal villages, lagoons, and lowlands, killing more than 35,000 people. Karagan Lagoon, located on the southeastern coast of Sri Lanka, was impacted by two waves from this tsunami. Although the lagoon commonly is dominated by organic-rich, siliciclastic clays, silts, and fine sands, the 2004 tsunami deposited a distinct layer of coarse quartz-dominated sand between 1 and 22 cm thick. The base of the 2004 deposit is sharp and erosional and some layers feature faint subparallel laminations. The 2004 tsunami deposit is generally continuous, fines landward, and is confined to the eastern portion of Karagan Lagoon, in the direction from which the tsunami arrived. Sri Lankan lore, in conjunction with reconstructed historical earthquake data, suggests that other tsunamis likely affected Sri Lanka in the past. To test this, twenty-two 1?4 m sediment cores were collected from Karagan Lagoon, providing key information for unraveling the pre-2004 tsunami history of southeastern Sri Lanka. At depth, sixteen cores from Karagan Lagoon contain as many as ten distinct sand layers, including the deposit from the 2004 tsunami. These cores feature siliciclastic clays, silts, and fine sands that dominate the background lagoonal sedimentation that are punctuated by coarse sand layers. These sand-rich layers feature sharp, erosional bases, coarsen and fine upwards, vary in thickness from 1 to 22 cm, and include varying percentages of fine to very coarse sand, with a low-abundance of silt and clay. In the best constrained interval, three coarse sand layers include composition, grain size, grading, and sedimentary structures similar to the sediments deposited by the December 26, 2004, tsunami. The layers are identified in five of the twenty-two cores, although the thicknesses vary. Six additional less well constrained sand layers are present in four of the twenty-two cores. Cores located closer to the lagoon mouth and the eastern coastline (the direction from which the 2004 tsunami arrived) contain more sand layers than cores farther away from the tsunami wave entry point. On the basis of their sedimentary structures, geometry, and extent, these sandy layers are interpreted to represent paleotsunami deposits. AMS radiocarbon dating was used to date the bulk organic sediment from above, between, and below the ten paleotsunami layers in sediment cores from Karagan Lagoon to constrain the timing of events in southeastern Sri Lanka. Material from within the deposit was not dated because it was likely transported from various sources during the event and thus does not represent the age of the tsunami. AMS radiocarbon dates from above and below the paleotsunami layers were calibrated from radiocarbon years before present to calendar years before present (Cal YBP) using OxCal v. 4.0 (Bronk Ramsey, 1995; Bronk Ramsey, 2001) with calibration curve IntCal04 (Reimer et al., 2004). The constraining time intervals of tsunami deposits II?VI were averaged to yield deposits of ages 226, 1641, 4198, 4457, 4924 Cal YBP. Tsunamis VII?X only had sediment dated immediately below the deposit and therefore were deposited prior to 6249, 6455, 6665, and 6840 Cal YBP. In total, ten tsunami deposits, including the 2004 event, are preserved in Karagan Lagoon on the southeastern coast of Sri Lanka. The Karagan Lagoon paleotsunami deposits provide constraints on the recurrence interval of tsunamis similar in magnitude to the 2004 event. The uppermost paleotsunami units were deposited 226, 1641, 4198, 4457, and 4924 Cal YBP, based on AMS radiocarbon dating. Thus, including the 2004 event, six tsunamis affected Karagan Lagoon in the past 5500 years, yielding a recurrence interval of approximately 916 years. Three of the six events, however, occur between ~4000 and 5500 years yielding a recurrence interval of approximately 500 years for this 1500 year period. Four additional older paleotsunami deposits occur in the deeper sections of the cores and were deposited prior to 6249, 6455, 6665, and 6840 Cal YBP, yielding a recurrence interval of approximately 200 years for this time period. Assuming that Karagan Lagoon contains a complete record of tsunami events, the recurrence of tsunamis similar in magnitude to the December 26, 2004, event can occur as often as 200 years. This ?recurrence interval? is illustrated by our data for the time period with increased tsunami activity from ~4000 to 7000 Cal YBP. Tsunamis may potentially affect Sri Lanka at relatively high frequency during certain time intervals though the overall recurrence pattern of these events displays a highly irregular distribution. This extreme variability needs to be taken into consideration when such events are related to earthquake recurrence intervals. Prior to the December 26, 2004, tsunami, paleotsunami deposits in the Indian Ocean were largely unstudied and consequently, Holocene tsunami chronology was incompletely understood for the Indian Ocean. The results from this study represents the first geologic evidence of paleotsunami deposits in Sri Lanka generated by tsunamis during the past 7000 years. The identification of these paleotsunami deposits illustrates that the 2004 tsunami was not a ?one-time event,? but in fact has ancient counterparts.
Keywords: Coastal Lagoons; Holocene; Paleotsunamis; Sri Lanka; Tsunami Deposits; Tsunami Sediments; Tsunamis

Pan-Arctic patterns in black carbon sources and fluvial discharges deduced from radiocarbon and PAH source apportionment markers in estuarine surface sediments - Elmquist, M.; Semiletov, I.; Guo, L. D.; Gustafsson, O. (Global Biogeochemical Cycles, 2008)
A pan-arctic geospatial picture of black carbon (BC) characteristics was obtained from the seven largest arctic rivers by combining with molecular combustion markers (polycyclic aromatic hydrocarbons) and radiocarbon (C-14) analysis. The results suggested that the contribution from modern biomass burning to BC ranged from low in the Yukon (8%) and Lena (5%) Rivers to high in the Yenisey River (88%). The Mackenzie River contributed almost half of the total arctic fluvial BC export of 202 kton a(-1) (kton = 10(9) g), with the five Russian-Arctic rivers contributing 10-36 kton a(-1) each. The C-14-based source estimate of fluvially exported BC to the Arctic Ocean, weighted by the riverine BC fluxes, amount to about 20% from vegetation/biofuel burning and 80% from C-14-extinct sources such as fossil fuel combustion and relict BC in uplifted source rocks. Combining these pan-arctic data with available estimates of BC export from other rivers gave a revised estimate of global riverine BC export flux of 26 x 10(3) kton a(-1). This is twice higher than a single previous estimate and confirms that river export of BC is a more important pathway of BC to the oceans than direct atmospheric deposition.
id: 820; 307ZP Times Cited:3 Cited References Count:89Y

Quaternary paleoceanography of the central arctic based on Integrated Ocean Drilling Program Arctic Coring Expedition 302 foraminiferal assemblages - Cronin, T. M.; Smith, S. A.; Eynaud, F.; O'Regan, M.; King, J. (Paleoceanography, 2008)
The Integrated Ocean Drilling Program (IODP) Arctic Coring Expedition (ACEX) Hole 4C from the Lomonosov Ridge in the central Arctic Ocean recovered a continuous 18 m record of Quaternary foraminifera yielding evidence for seasonally ice-free interglacials during the Matuyama, progressive development of large glacials during the mid-Pleistocene transition (MPT) similar to 1.2-0.9 Ma, and the onset of high-amplitude 100-ka orbital cycles similar to 500 ka. Foraminiferal preservation in sediments from the Arctic is influenced by primary (sea ice, organic input, and other environmental conditions) and secondary factors (syndepositional, long-term pore water dissolution). Taking these into account, the ACEX 4C record shows distinct maxima in agglutinated foraminiferal abundance corresponding to several interglacials and deglacials between marine isotope stages (MIS) 13-37, and although less precise dating is available for older sediments, these trends appear to continue through the Matuyama. The MPT is characterized by nearly barren intervals during major glacials (MIS 12, 16, and 22-24) and faunal turnover (MIS 12-24). Abundant calcareous planktonic (mainly Neogloboquadrina pachyderma sin.) and benthic foraminifers occur mainly in interglacial intervals during the Brunhes and very rarely in the Matuyama. A distinct faunal transition from calcareous to agglutinated foraminifers 200-300 ka in ACEX 4C is comparable to that found in Arctic sediments from the Lomonosov, Alpha, and Northwind ridges and the Morris Jesup Rise. Down-core disappearance of calcareous taxa is probably related to either reduced sea ice cover prior to the last few 100-ka cycles, pore water dissolution, or both.
id: 813; 281VR Times Cited:10 Cited References Count:84Y

Radiocarbon ages on deep water corals from the Ross Sea - Burt, T. (Hamilton College, 2008)

Radiocarbon evidence for the importance of surface vegetation on fermentation and methanogenesis in contrasting types of boreal peatlands - Chanton, J. P.; Glaser, P. H.; Chasar, L. S.; Burdige, D. J.; Hines, M. E.; Siegel, D. I.; Tremblay, L. B.; Cooper, W. T. (Global Biogeochemical Cycles, 2008)
We found a consistent distribution pattern for radiocarbon in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and methane replicated across spatial and temporal scales in northern peatlands from Minnesota to Alaska. The (14)C content of DOC is relatively modern throughout the peat column, to depths of 3 m. In sedge-dominated peatlands, the (14)C contents of the products of respiration, CH(4) and DIC, are essentially the same and are similar to that of DOC. In Sphagnum- and woody plant-dominated peatlands with few sedges, however, the respiration products are similar but intermediate between the (14)C contents of the solid phase peat and the DOC. Preliminary data indicates qualitative differences in the pore water DOC, depending on the extent of sedge cover, consistent with the hypothesis that the DOC in sedge-dominated peatlands is more reactive than DOC in peatlands where Sphagnum or other vascular plants dominate. These data are supported by molecular level analysis of DOC by ultrahigh-resolution mass spectrometry that suggests more dramatic changes with depth in the composition of DOC in the sedge-dominated peatland pore waters relative to changes observed in DOC where Sphagnum dominates. The higher reactivity of DOC from sedge-dominated peatlands may be a function of either different source materials or environmental factors that are related to the abundance of sedges in peatlands.
id: 1949; PT: J; UT: WOS:000262041000002

Radiocarbon-based assessment of fossil fuel-derived contaminant associations in sediments - White, H. K.; Reddy, C. M.; Eclinton, T. I. (Environmental Science & Technology, 2008)
Hydrophobic organic contaminants (HOCs) are associated with natural organic matter (OM) in the environment via mechanisms such as sorption or chemical binding. The latter interactions are difficult to quantitatively constrain, as HOCs can reside in different OM pools outside of conventional analytical windows. Here, we exploited natural abundance variations in radiocarbon (C-14) to trace various fossil fuel-derived HOCs (C-14- free) within chemically defined fractions of contemporary OM (modern C-14 content) in 13 samples including marine and freshwater sediments and one dust and one soil sample. Samples were sequentially treated by solvent extraction followed by saponification. Radiocarbon analysis of the bulk sample and resulting residues was then performed. Fossil fuel-derived HOCs released by these treatments were quantified from an isotope mass balance approach as well as by gas chromatography-mass spectrometry. For the majority of samples (n = 13), 98-100% of the total HOC pool was solvent extractable. Nonextracted HOCs are only significant (29% of total HOC pool) in one sample containing pp-2,2-bis(chlorophenyl)1,1,1-trichloroethane and its metabolites. The infrequency of significant incorporation of HOCs into nonextracted OM residues suggests that most HOCs are mobile and bioavailable in the environment and, as such, have a greater potential to exert adverse effects.
id: 881; 332HW Times Cited:1 Cited References Count:43Y

A radiocarbon-based assessment of the preservation characteristics of crenarchaeol and alkenones from continental margin sediments - Mollenhauer, G.; Eglinton, T. I.; HopmanSd, E. C.; Damste, J. S. S. (Organic Geochemistry, 2008)
Crenarchaeotal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids and alkenones are two types of biomarkers, derived from planktonic marine microorganisms, which are used for reconstruction of sea surface temperature. We determined the radiocarbon contents of the archaeal GDGT crenarchaeol and of alkenones isolated from continental margin sediments. Systematic differences were found between the two biomarkers, with higher radiocarbon content in crenarchaeol than in the phytoplankton-derived alkenones. These differences can be explained by variable contributions of pre-aged, laterally-advected material to the core sites. Crenarchaeol appears to be more efficiently degraded during transport in oxygen-replete environments than alkenones. Whether this reflects the influence of chemical structure or mode of protection (e.g., particle association) is not known. (C) 2008 Elsevier Ltd. All rights reserved.
id: 883; 344AQ Times Cited:11 Cited References Count:33Y

Radiocarbon-derived sedimentation rates in the Gulf of Mexico - Santschi, P. H.; Rowe, G. T. (Deep-Sea Research Part Ii-Topical Studies in Oceanography, 2008)
Sedimentation rates were determined for the northern Gulf of Mexico margin sediments at water depths ranging from 770 to 3560m, using radiocarbon determinations of organic matter. Resulting sedimentation rates ranged from 3 to 15 cm/kyr, decreasing with increasing water depth. These rates agree with long-term sedimentation rates estimated previously using stratigraphic methods, and with estimates of sediment delivery rates by the Mississippi River to the northern Gulf of Mexico, but are generally higher by 1-2 orders of magnitude than those estimated by (210)Pb(xs) methods. Near-surface slope sediments from 2737 to water depth in the Mississippi River fan were much older than the rest. They had minimum (14)C ages of 16-27 kyr and delta(13)C values ranging from -24 parts per thousand to -26.59 parts per thousand, indicating a terrestrial origin of organic matter. The sediments from this site were thus likely deposited by episodic mass wasting of slope sediment through the canyon, delineating the previously suggested main pathway of sediment and clay movement to abyssal Gulf sediments. (C) 2008 Published by Elsevier Ltd.
United States Mineral Management Service [1435-01-99-CT-30991]
Keywords: accumulation; ATCHAFALAYA RIVER; cores; Gulf of Mexico; ice-sheet; Mass; Meltwater; MISSISSIPPI RIVER DELTA; Nepheloid layer transport; Organic carbon burial rates; radiocarbon; Sedimentation rates; TERRIGENOUS ORGANIC-MATTER; wasting

Reconstructing relative flooding intensities responsible for hurricane-induced deposits from Laguna Playa Grande, Vieques, Puerto Rico - Woodruff, J. D.; Donnelly, J. P.; Mohrig, D.; Geyer, W. R. (Geology, 2008)
Extreme coastal flooding, primarily during hurricane strikes, has deposited sand-rich layers in Laguna Playa Grande, a back-barrier lagoon located on the island of Vieques, Puerto Rico. Silici-clastic grain-size distributions within these overwash deposits fine landward (away from the barrier and toward the mainland). A simple advective-settling model can explain this pattern of lateral sorting and is used to constrain the relative magnitude of past flooding events. A deposit associated with the A.D. 1928 San Felipe hurricane is used as a modern analogue to test the technique, which produces reasonable estimates for wave heights that exceed the barrier during the event. A 5000 yr reconstruction of local flooding intensity is developed that provides a measure of the competence for each overwash event to transport coarser-grained sediment a fixed distance into the lagoon. This reconstruction indicates that although the Laguna Playa Grande record exhibits large-scale changes in hurricane frequency on centennial to millennial time scales, the magnitude of these events has stayed relatively constant. Over the last 5000 yr, no evidence exists for an anomalously large hurricane or tsunami event with a competence for sediment transport greater than historical hurricane events.
id: 865; ISI Document Delivery No.: 300VM Times Cited: 3 Cited Reference Count: 19 Cited References: BALDOCK TE, 2005, COAST ENG, V52, P633, DOI 10.1016/j.coastaleng.2005.04.002 BOOSE ER, 2004, ECOL MONOGR, V74, P335 DONNELLY C, 2006, J COASTAL RES, V22, P965, DOI 10.2112/04-0431.1 DONNELLY JP, 2001, GEOLOGY, V29, P615 DONNELLY JP, 2007, NATURE, V447, P465, DOI 10.1038/nature05834 FERGUSON RI, 2004, J SEDIMENT RES, V74, P933 HAUG GH, 2001, SCIENCE, V293, P1304 HOLLAND TK, 2001, COASTAL SEDIMENTS 91, P489 JAFFE BE, 2007, SEDIMENT GEOL, V200, P347, DOI 10.1016/j.sedgeo.2007.01.013 LIU KB, 1993, GEOLOGY, V21, P793 MERCADO A, 1994, NAT HAZARDS, V10, P235, DOI 10.1007/BF00596144 MEYERPETER E, 1948, 2ND P C IAHR STOCKH, V2, P39 MOORE AL, 2007, SEDIMENT GEOL, V200, P336, DOI 10.1016/j.sedgeo.2007.01.012 NOTT J, 2004, ENVIRON INT, V30, P433, DOI 10.1016/j.cnvint.2003.09.010 NYBERG J, 2001, QUATERNARY RES, V56, P87, DOI 10.1006/qres.2001.2249 RUESSINK BG, 1998, J GEOPHYS RES-OCEANS, V103, P3111 SOLA EM, 1995, HISTORIA HURACANES P STOCKDON HF, 2006, COAST ENG, V53, P573, DOI 10.1016/j.coastaleng.2005.12.005 VISSER PJ, 1998, BREACH GROWTH SAND D Woodruff, Jonathan D. Donnelly, Jeffrey P. Mohrig, David Geyer, Wayne R. Geological soc amer, inc Boulder; YY

Recycling of graphite during Himalayan erosion: a geological stabilization of carbon in the crust - Galy, V.; Beyssac, O.; France-Lanord, C.; Eglinton, T. (Science, 2008)
At geological time scales, the role of continental erosion in the organic carbon (OC) cycle is determined by the balance between recent OC burial and petrogenic OC oxidation. Evaluating its net effect on the concentration of carbon dioxide and dioxygen in the atmosphere requires the fate of petrogenic OC to be assessed. Here, we report a multiscale (nanometer to micrometer) structural characterization of petrogenic OC in the Himalayan system. We show that graphitic carbon is preserved and buried in marine sediments, while the less graphitized forms are oxidized during fluvial transport. Radiocarbon dating indicates that 30 to 50% of the carbon initially present in the Himalayan rocks is conserved during the erosion cycle. Graphitization during metamorphism thus stabilizes carbon in the crust over geological time scales.
id: 1876; Galy, Valier Beyssac, Olivier France-Lanord, Christian Eglinton, Timothy New York, N.Y. Science. 2008 Nov 7;322(5903):943-5.; YY

Relative sea-level change, Kjove Land, Scoresby Sund, East Greenland: implications for seasonality in Younger Dryas time - Hall, B.; Baroni, C.; Denton, G.; Kelly, M. A.; Lowell, T. (Quaternary Science Reviews, 2008)
The age of the Milne Land Stade (MLS) moraines in the Scoresby Sund region of East Greenland is key for testing the hypothesis that strong seasonality marked abrupt cooling events, such as the Younger Dryas, registered in Greenland ice cores. The relevant chronology is based on 69 radiocarbon dates of shells from raised beaches and deltas related to marine inundation and isostatic rebound that accompanied glacier retreat from the moraines. Taken together, these dates form the basis for a relative sea-level curve that shows very high rates of emergence typical of recently deglaciated regions. Upward extrapolation of this curve suggests that the marine limit (134 m a.s.l.) dates to about 12,400 cal yr B.R The shorelines that mark the marine limit lie within areas that were ice-covered when the glaciers were at the outer limit of the MLS advance; hence, the moraines that form the outer limit must antedate 12,400 cal yr B.R and probably are from earliest Younger Dryas or Allerod time. At Holger Danskes Briller, an inner moraine grades to a massive ice-contact delta, now at 101 m a.s.l., which is dated to 11,000-11,300 cal yr B.P. The age of the outer MLS moraines, along with constraints on the maximum possible Younger Dryas ice extent and snowline lowering are consistent with the idea that East Greenland climate experienced strong seasonality during Younger Dryas time. (C) 2008 Elsevier Ltd. All rights reserved.
id: 824; 389XX Times Cited:3 Cited References Count:43Y

Reply to Comment on "The timing and evolution of the post-glacial transgression across the Sea of Marmara shelf south of Istanbul" by Hiscott et al., Marine Geology 248, 228-236 - Eris, K. K.; Ryan, W. B. F.; Cagatay, M. N.; Lericolais, G.; Sancar, U.; Menot, G.; Bard, E. (Marine Geology, 2008)
In their comment Hiscott and co-authors adhere rigidly to ages and sources for sedimentary units in the subsurface of the Marmara shelf that they have previously reported in their publications from 2002 through 2007. This adherence is in spite of a superior age-depth model from our 13 m-long sediment core that penetrated deeply into the deposits under consideration and in disregard to the results of subsequent more-detailed and full-coverage mapping of the region under scrutiny. The age revisions are dismissed by the authors of the comment as representing sediments severely disturbed during coring. We rebut this criticism. The Bosporus source attributed by them to the sedimentary units sampled and dated by us appears to be driven by their conception that the Black Sea had a persistent outflow prior to its two-way connection with Marmara. Irrespective of whether the outflow was persistent, our reply shows that the drawing of the isopachs of the sedimentary units by Hiscott and coauthors was accomplished in a fashion to promote the Bosporus source hypothesis regardless of the geographic limits of their survey. The ages assigned to the units are equally indeterminate because the cores used by them have missing core tops of unknown lengths that are not discussed in their publications. Furthermore, the sub-bottom reflectors at the sites where the reflectors were calibrated to their only core without a missing top are actually hidden by the finite width of the bottom reflecting wavelet. (C) 2008 Elsevier B.V. All rights reserved.
id: 784; 377ZE Times Cited:0 Cited References Count:33Y

Research focus - Tempestuous highs and lows in the Gulf of Mexico - Donnelly, J. P.; Giosan, L. (Geology, 2008)
id: 863; ISI Document Delivery No.: 344QW Times Cited: 3 Cited Reference Count: 25 Cited References: BLUM MD, 2003, T GULF COAST ASS GEO, V53, P64 BLUM MD, 2008, GEOLOGY, V36, P675, DOI 10.1130/G24728A.1 DONNELLY JP, 2007, NATURE, V447, P465, DOI 10.1038/nature05834 GIOSAN L, 2006, GEOLOGY, V34, P757, DOI 10.1130/G22587.1 HUTTON EWH, 2008, COMPUT GEOSCI-UK, V34, P1319, DOI 10.1016/j.cageo.2008.02.013 IVINS ER, 2007, GEOPHYS RES LETT, V34, ARTN L16303 JURKOWSKI G, 1984, J GEOPHYS RES, V89, P6247 KOMAR PD, 2008, J COASTAL RES, V24, P479, DOI 10.2112/07-0894.1 LAMBERT WJ, 2003, T GULF COAST ASS GEO, V53, P433 LIU KB, 2004, HURRICANES TYPHOONS, P13 LOPEZ GI, 2008, J COASTAL RES, P49 MILLIKEN KT, 2008, GEOL S AM S, V443, P1, DOI 10.1130/2008.2443(01) MORTON RA, 2000, J SEDIMENT RES A, V70, P478 OTVOS EG, 1995, J COASTAL RES, V11, P984 OTVOS EG, 1999, J COASTAL RES, V15, P438 OTVOS EG, 2000, GEOMORPHOLOGY, V32, P83 OTVOS EG, 2002, QUATERNARY RES, V57, P425 RODRIGUEZ AB, 2004, J SEDIMENT RES, V74, P405 RODRIGUEZ AB, 2006, J SEDIMENT RES, V76, P257, DOI 10.2110/jsr.2006.018 SHEPARD FP, 1964, SCIENCE, V143, P574 STAPOR FW, 1991, J COASTAL RES, V7, P815 TANNER WF, 1992, B AM METEOROL SOC, V73, P297 TANNER WF, 1995, MAR GEOL, V129, P149 TORNQVIST TE, 2006, GEOLOGY, V34, P697, DOI 10.1130/G22624.1 WRIGHT EE, 2005, J SEDIMENT RES, V75, P621 Donnelly, Jeffrey P. Giosan, Liviu Geological soc amer, inc Boulder; YY

Robust deterministic model describing the bomb radiocarbon signal for use in fish age validation - Hamel, O. S.; Piner, K. R.; Wallace, J. R. (Transactions of the American Fisheries Society, 2008)
The bomb radiocarbon chronometer has become a standard tool for assessing the accuracy of otolith-based fish age estimates. Use of the chronometer depends upon the increase in C-14 that occurred due to the atmospheric testing of nuclear weapons in the middle of the 20th century. In previous analyses, a variety of ad hoc methods have been used to compare test chronologies with reference chronologies. This paper proposes a deterministic coupled-functions model that describes bomb radiocarbon chronologies and standardizes and facilitates comparisons within and across species. In this model, a Gaussian pulse of radiocarbon over time is assumed, and dispersion and dilution are described by continuous exponential decay. The model simplifies to the product of a cumulative normal function and an exponential function; despite its simplicity, the model approximates the observed changes in oceanic radiocarbon quite well. It also allows for statistical testing of the timing of increase between different time series and thus permits quantitative aging validation as well as analysis of geographical differences in the timing of the bomb radiocarbon signal. Estimated model parameters describe the timing of the onset and temporal midpoint of the bomb-related increase in C-14 and the rate of C-14 dispersion or dilution, which corresponds to the observed rate of decline during the postbomb period. Nine published chronologies are used to demonstrate the model and compare it with other published methods of summarizing bomb radiocarbon data for age validation purposes.
id: 775; 306ZU Times Cited:2 Cited References Count:21Y

Rock magnetic and geochemical record in a sediment core from the eastern Arabian Sea: Diagenetic and environmental implications during the late Quaternary - Rao, Venigalla Purnachandra; Kessarkar, Pratima Mohan; Patil, Shiva Kumar; Ahmad, Syed Masood (Palaeogeography, Palaeoclimatology, Palaeoecology, 2008)
Rock magnetic concentration, grain size and mineralogy parameters together with organic carbon, calcium carbonate, redox-sensitive elements, δ18O of Globigerinoides ruber and radiocarbon dating were carried out on a 445 cm long sediment core collected at 1380 m depth off Mangalore, southwestern margin of India. The top 290 cm sediments of the core correspond to the last 18 kaBP. The δ18O and magnetic records exhibit major events at ∼ 16 kaBP, 14.5 kaBP, 11.5 kaBP and 9.8/8.6 kaBP related to start and intensity of the summer monsoon and climate change, and are synchronous with that of the western Arabian Sea and North Atlantic. The sediments with high magnetic susceptibility correlate with high sedimentation rates. The sediments are dominated by fine-grained magnetite, but intervals of 1.2–3.8 kaBP and 10–13.5 kaBP were subjected to diagenetic changes, resulting in the dissolution of fine-grained magnetites and enrichment of redox-sensitive trace elements (Cu, Ni, Zn, V, Mo and U). The sediments between 290 cm and 445 cm correspond to 18–27 kaBP and are characterized by distinct decrease in magnetic concentration, grain size and mineralogy parameters, high organic carbon, low concentrations of redox-sensitive trace elements and abundant pyritized tubules. The reductive diagenetic conditions indicated by rock magnetic properties are in contrast with the weak sub-oxic conditions revealed by low concentrations of trace elements in the sediments. The seasonal organic matter flux produced during the winter monsoon and moderate sedimentation rates favoured reductive diagenesis in the sediments at and below the last glacial maximum (LGM). Intermittent bioturbation, however, allowed oxidants to penetrate into the sediments, remobilized redox-sensitive trace elements into the water column and modified the primary geochemical signal of the sedimentary environment.

The sedimentary record of glacial retreat, Marinelli Fjord, Patagonia: Regional correlations and climate ties - Boyd, B.L.; Anderson, J.B.; Wellner, J.S.; ández, R.A. (Marine Geology, 2008)
The Inland Passage of Chile comprises the most continuous latitudinal transect of ice fields, ice caps, and alpine glaciers in the Southern Hemisphere, providing an excellent natural laboratory for the study of glacial response to climate change during the Holocene. Here we report results from a marine geological investigation of Marinelli Fjord, Tierra del Fuego (54°25 S, 69°35 W) and Ainsworth Fjord, which merges with Marinelli Fjord. Data acquired during July 2005 onboard the RV/IB Nathaniel B. Palmer include high-resolution seismic data, multibeam swath bathymetry data and sediment cores. Post-cruise analyses include detailed seismic facies and lithofacies analysis and radiocarbon dating. The results indicate that a major transition in the glacimarine record from ice-proximal facies to ice-distal facies occurred in the outer basins of the fjord at 15.5 kyr to 12.5 kyr. The ice-proximal facies consists of pebbly mud with abundant laminations and is characterized by high average sedimentation rates (28 mm/yr). In contrast, an ice-distal facies is dominantly bioturbated mud with low average sedimentation rates (0.56 mm/yr). This transition marks the retreat of Marinelli Glacier from the outer basins with no evidence for glacial re-advance. Subsequently, during the mid to late-Holocene, Ainsworth Glacier retreated and exposed Ainsworth Fjord. Our results are consistent with the climatic trends for southern South America where the final deglaciation of the region ended at ~ 12.5 ka. During the Holocene, stable ice conditions persisted until the mid-1960s when Marinelli Glacier began rapidly retreating to its modern day position.

Sex and Symbolism: A Middle Holocene Phallic Artifact from Santa Rosa Island, California - Rick, Torben C.; Erlandson, Jon M.; Wolff, Christopher B. (Pacific Coast Archaeological Society Quarterly, 2008)
id: 2066

Shell and Bone Artifacts from Two Middle Holocene Red Abalone Middens on San Miguel Island - Braje, Todd J.; Erlandson, Jon M. (Pacific Coast Archaeological Society Quarterly, 2008)
id: 2067

Software development for continuous-gas-flow AMS - von Reden, K. F.; Roberts, M. L.; W. J. Jenkins; Rosenheim, B. E.; McNichol, A. P.; Schneider, R. J. (Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 2008)
The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility at Woods Hole Oceanographic institution is presently completing installation of a novel continuous-flow AMS system. A multi-year development of an AMS microwave gas ion source in collaboration with Atomic Energy Canada Limited (AECL), Chalk River, has preceded this final step of an implementation that is expected to add a new dimension to (14)C AMS. National Instruments, NIM, and CAMAC modules have been programmed with Lab-VIEW on a Windows XP platform to form the basis for data acquisition. In this paper we discuss possible applications and include simulations of expected data acquisition scenarios like real-time AMS analysis of chromatograms. Particular attention will have to be given to issues of synchronization between rapidly changing input amplitudes and signal processing cycles in hardware and software. (C) 2008 Elsevier B.V. All rights reserved.
id: 2091; PT: J; CT: 9th European Conference on Accelerators in Applied Research and Technology; CY: SEP 03-07, 2007; CL: Florence, ITALY; SP: Univ Florence, Dept Phys, Ist Nazl Fis Nucl; UT: WOS:000257185600033

Source and composition of organic matter in the Bari canyon (Italy): Dense water cascading versus particulate export from the upper ocean - Tesi, T.; Langone, L.; Goñi, M. A.; Turchetto, M.; Miserocchi, S.; Boldrin, A. (Deep-Sea Research Part I-Oceanographic Research Papers, 2008)
Recent studies in the southern Adriatic Sea have shown that dense water cascading is an effective off-shelf transport mechanism. In order to evaluate the relative importance of different processes affecting the down-slope transfer of organic matter (OM), a multi-proxy biogeochemical study was carried out in the southern Adriatic. Three sediment traps were deployed on the southern slope in March 2004 for 1 year at 35 m above the seabed. Surficial sediments were collected on the shelf and slope along a shore-normal transect. Suspended material in the water column at different water depths was collected along nine shore-normal transects. Organic carbon (OC), total nitrogen (TN), carbon isotopic composition (delta C-13 and Delta C-14) and CuO reaction products were used to identify the OM sources and to asses the relative importance of vertical and lateral particulate fluxes. Both sinking particulates from the euphotic zone and advected material from the seafloor were collected by the moored instrumentations. During low-mass fluxes, the trapped material exhibited the highest Delta C-14 values (from -162.0 parts per thousand to +42.3 parts per thousand) and OC contents (from 1.13% to 2.17%) while the lignin displayed the lowest content (from 0.160 to 0.285 mg 100 mg(-1) OC). However, during dense water cascading events, the down-slope particulate flux showed different compositional features. In this period the trapped material displayed the most depleted Delta C-14 values (from -275.3 parts per thousand to -171.3 parts per thousand.), the lowest OC content (from 0.87% to 1.31%), and the highest lignin content (from 0.230 to 379 mg 100 mg(-1) OC). Holocene sea-level rise has drastically reduced sediment availability to the Bari canyon, and this in turn has affected the OC composition of the material funneled toward the deep Adriatic Sea. Parameters based on lignin CuO products suggest that the terrestrial material exported down the slope is very different from riverine inputs and inner shelf sediments. This indicates that neither river floods nor sediment resuspension from the inner shelf contributes directly to the down-slope flux. Rather, the material collected in the sediment traps exhibits an OM composition comparable to the surface sediments collected in the southern outer shelf. This correspondence suggests that resuspension of sediments by bottom currents in the southern outer shelf significantly contribute to down-slope OM transfer. Finally, the presence of lignin phenols in all cups indicates that lateral fluxes were constantly active on the slope throughout the deployment. (C) 2008 Elsevier Ltd. All rights reserved.
id: 828; 330FL Times Cited:4 Cited References Count:87Y

Stratigraphy, pollen history and geochronology of tidal marshes in a Gulf of Maine estuarine system: Climatic and relative sea level impacts - Ward, Larry G.; Zaprowski, Brent J.; Trainer, Kevin D.; Davis, P. Thompson (MARINE GEOLOGY, 2008)
Sedimentologic and stratigraphic characteristics of five tidal marshes in Great Bay Estuary, New Hampshire, which is located on the western boundary of the Gulf of Maine, were assessed from 20 vibracores. detailed descriptions of surficial environments, pollen analyses, and radiocarbon dating. Modern marsh sequences in Great Bay Estuary initiated with a time-transgressive basal peat that formed at the upland-brackish marsh boundary. The oldest basal peat deposit sampled during this study was dated at similar to 4560 cal yr B.P (based on an age of 4060 +/- 40 C-14 yr B.P.). The original tidal marshes that formed in Great Bay Estuary apparently were unable to accrete at a high enough rate to allow seaward expansion, resulting in a transgressive sequence of low marsh or mudflat sediments overlying the basal peat. The transgressive tidal marsh sequence is capped by high marsh sediments that corresponded to a slowing of relative sea-level (RSL) rise in the region and regressive seaward expansion of the tidal marshes. However, significant variations from these transgressive-regressive sequences occur in the Great Bay tidal marshes as a result of more recent marsh expansion and tidal channel migrations. Detailed pollen analyses of a vibracore taken in a tidal marsh along Squamscott River with a sedimentary record spanning the last similar to 3900 cal yr B.P exhibit five well-documented marker horizons including: 1) an increase of Tsuga (hemlock); 2) the appearance of Picea (spruce); 3) Tsuga and Fagus (beech) declines; 4) an increase in Ambrosia (ragweed) coupled with a sudden decrease in Quercus (oak); and 5) the Castanea (chestnut) decline. Using published ages for these pollen horizons and a calibrated 14C age obtained during this study for a basal peat, accretion rates for this marsh system over five time intervals were calculated: 1) 0.4 to 0.5 mm yr(-1) from similar to 3900 to 2850 cal yr B.P.; 2) 0.6 mm yr(-1) from similar to 2850 to similar to 1960 cal yr B.P.; 3) 0.8 mm yr(-1) from similar to 1960 to similar to 580 cal yr B.P.; 4) 0.7 to 0.8 mm yr(-1) from similar to 580 to similar to 210 cal yr B.P.: and 5) 0.8 to 0.9 mm yr(-1) over the last 210 years. The long-term accretion rate for the entire sequence based on the calibrated C-14 age of the basal peat was 0.6 to 0.7 mm yr(-1). This result agrees with accretion rates determined from calibrated C-14 ages from two other tidal marsh systems in Great Bay Estuary with accretion rates between similar to 0.6 to similar to 0.8 mm yr(-1). Higher accretion rates were obtained at a nearby tidal marsh with 1.2 mm yr(-1) for just the marsh and 1.3 mm yr(-1) for the marsh and underlying subtidal sediment. The results of this study indicate that the sedimentology and stratigraphy of moderate-size tidal marshes in rocky, glaciated coasts are highly variable and are strongly influenced by complex interactions among RSL, climatic variations, and anthropogenic influences. For instance, the early development of many of the marshes in the Great Bay Estuary area were likely driven by changes in rates of RSL resulting in transgressive onlap boundaries, subsequently overlain by regressive intertidal marsh sequences. However, more recent changes in tidal marsh sediment composition deposited during a relatively slow, steady RSL rise likely result from other forcings. such as changes in minerogenic and orogenic sediment inputs due to anthropogenic effects, tidal channel migrations, major storms causing erosion of the marsh, or climatic changes causing shifts in sediment delivery or vegetation. (C) 2008 Elsevier B.V. All rights reserved.
Keywords: accretion; climate effects; pollen; relative sea level; salt marshes; sedimentology; stratigraphy

Subdecadally resolved paleoceanography of the Peru margin during the last two millennia - Agnihotri, R.; Altabet, M. A.; Herbert, T. D.; Tierney, J. E. (Geochemistry Geophysics Geosystems, 2008)
Using multiproxy sediment core data from the El Nino-Southern Oscillation (ENSO)-sensitive Peru margin, subdecadally resolved (down to similar to 0.6 year) surface productivity and subsurface denitrification are reconstructed for the last similar to 2300 years. Scanning XRF generated major elemental data (Ti, Fe, Si) correlate well with discrete inductively coupled plasma-atomic emission spectometry (ICP-AES) analyses and together with X-radiography (core density) are used as productivity indices. As surface productivity in this marine region is strongly impacted by ENSO, higher (lower) periods of surface productivity are inferred to represent a persistent normal/La Nina (El Nino)-like state. Surface productivity and subsurface denitrification appear to have remained intimately coupled during this period due to direct stimulation of requisite subsurface suboxia and/or hydrographic restructuring. The late Holocene Peru margin is characterized by persistent moderate productivity and subsurface denitrification punctuated at centennial scale by shorter-duration periods of high production and intense denitrification. These centennial-scale events are likely analogous to modern observations of decadal-scale "regime shifts'' but of higher amplitude and provide a background history for future natural changes to this system. Solar (irradiance) variability is suggested to have influenced Peru productivity as evidenced in numerous high-resolution paleorecords from the northern hemisphere.
id: 780; 303SA Times Cited:7 Cited References Count:54Y

Subtropical Atlantic salinity variability and Atlantic meridional circulation during the last deglaciation - Carlson, A. E.; Oppo, D. W.; Came, R. E.; LeGrande, A. N.; Keigwin, L. D.; Curry, W. B. (Geology, 2008)
During the last deglaciation (ca. 21-10 ka), freshening of the North Atlantic surface likely caused reductions in Atlantic meridional overturning circulation (AMOC); the mechanisms related to AMOC recovery remain poorly understood. Here we present three new deglacial surface temperature and delta O-18(seawater) (delta O-18(sw)) reconstructions from the western subtropical North and South Atlantic. Similarities to tropical Caribbean and western Atlantic delta O-18(sw) records suggest that a salty surface water mass accumulated in the western Atlantic from 27 degrees S to 33 degrees N during periods of reduced AMOC. However, delta O-18(sw) decreases led deep AMOC resumption by hundreds of years. We suggest that the northward export of salt previously trapped in the western Atlantic resulted in the early establishment of a shallow overturning circulation that eventually culminated in deep AMOC resumption, implying that AMOC may constitute a self-limiting system.
id: 862; ISI Document Delivery No.: 381WN Times Cited: 5 Cited Reference Count: 32 Cited References: *CLIMAP PROJ MEMB, 1981, GEOL SOC AM MAP CHAR ANAND P, 2003, PALEOCEANOGRAPHY, V18, ARTN 1050 BENWAY HM, 2006, PALEOCEANOGRAPHY, V21, ARTN PA3008 BEVINGTON P, 2002, DATA REDUCTION ERROR BOYLE EA, 1987, NATURE, V330, P35 BROECKER WS, 1990, PALEOCEANOGRAPHY, V5, P469 CARLSON AE, 2007, P NATL ACAD SCI USA, V104, P6556, DOI 10.1073/pnas.0611313104 CLARK PU, 2004, SCIENCE, V304, P1141 GRIMM EC, 2006, QUATERNARY SCI REV, V25, P2197, DOI 10.1016/j.quascirev.2006.04.008 GROOTES PM, 1993, NATURE, V366, P552 KASPI Y, 2004, PALEOCEANOGRAPHY, V19, ARTN PA3004 KNORR G, 2003, NATURE, V424, P532, DOI 10.1038/nature01855 LEA DW, 2003, SCIENCE, V301, P1361 LEDUC G, 2007, NATURE, V445, P908, DOI 10.1038/nature05578 LEGRANDE AN, 2006, GEOPHYS RES LETT, V33, ARTN L12604 LEGRANDE AN, 2008, PALEOCEANOGRAPHY, V23, DOI 10.1029/2008PA001610 MCMANUS JF, 2004, NATURE, V428, P834, DOI 10.1038/nature02494 OPPO DW, 2007, GEOPHYS RES LETT, V34, ARTN L13701 PEETERS FJC, 2004, NATURE, V430, P661, DOI 10.1038/nature02785 PETERSON LC, 2000, SCIENCE, V290, P1947 ROBINSON LF, 2005, SCIENCE, V310, P1469, DOI 10.1126/science.1114832 RUHLEMANN C, 1999, NATURE, V402, P511 SCHMIDT GA, 2007, J GEOPHYS RES-ATMOS, V112, ARTN D10103 SCHMIDT MW, 2004, NATURE, V428, P160, DOI 10.1038/nature02346 SCHMIDT MW, 2006, NATURE, V443, P561, DOI 10.1038/nature05121 SCHMITZ WJ, 1995, REV GEOPHYS, V33, P151 SKINNER LC, 2006, QUATERNARY SCI REV, V25, P3312, DOI 10.1016/j.quascirev.2006.07.005 STOUFFER RJ, 2006, J CLIMATE, V19, P1365 THOMAS AL, 2006, EARTH PLANET SC LETT, V241, P493, DOI 10.1016/j.epsl.2005.11.031 WANG XF, 2004, NATURE, V432, P740, DOI 10.1038/nature03067 WEAVER AJ, 2003, SCIENCE, V299, P1709 WELDEAB S, 2006, EARTH PLANET SC LETT, V241, P699, DOI 10.1016/j.epsl.2005.11.012 Carlson, Anders E. Oppo, Delia W. Came, Rosemarie E. LeGrande, Allegra N. Keigwin, Lloyd D. Curry, William B. Geological soc amer, inc Boulder; YY

Taphonomy and ages of bivalve shells from San Salvador Island, Bahamas - Pruss, Sara B. (Geological Society of America (GSA), Boulder, CO, United States (USA), 2008)
Paleontological interpretations of taphonomic processes can be complimented by examining abrasion and age of shells in modern settings. A preliminary analysis of the ages of bivalves from Haitian Boat Beach (just east of Barkers Point, northwest coast of San Salvador Island, Bahamas) provides a range of ages of shell material exposed on modern beaches of San Salvador Island and provides estimates of the timing of beach rock lithification. At Haitian Boat Beach Beach, bivalves and gastropods were collected from shell accumulations preserved on the beach as well as within a single 3 to 5-cm thick horizon of beach rock. The ages of 2 valves (Genus Chione) from the beach and 4 valves (Genus Chione and Genus Glycymeris) from the beach rock were analyzed. Two of the most abraded shells were selected for analysis from the beach in an attempt to get a maximum age of beach shell material. These shells were radiocarbon dated by measuring carbon-14 at NOSAMS and converted to calendar years using the CALIB program of Stuiver and Reimer (1993). Two abraded valves collected from the beach yielded calendar year ages BP of 512 and 549 years. The beach rock valves yielded calendar year ages BP of 143, 129, and 1628. These results suggest lithification of beach rock was initiated
id: 2219; Source type: conferencepapers&proceedings; Object type: Article; Object type: Conference Paper; Copyright: GeoRef, Copyright 2008, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States; CSAUnique: 2010-024085; AccNum: 2010-024085; ISSN: 0016-7592; CODEN: GAAPBC
Keywords: 10; abrasion; absolute age; Bahamas; beachrock; Bivalvia; C-14; carbon; carbonate rocks; Caribbean region; Cenozoic; Chione; dates; Gastropoda; Glycymeris; Heterodonta; Holocene; interpretation; Invertebrata; Invertebrate paleontology; isotopes; lithification; living taxa; Mollusca; Quaternary; radioactive isotopes; San Salvador; sedimentary rocks; sediments; shells; taphonomy; upper Holocene; Veneridae; Veneroida; West Indies

Terrigenous organic matter in sediments from the Fly River delta-clinoform system (Papua New Guinea) - Goñi, M. A.; Monacci, N.; Gisewhite, R.; Crockett, J.; Nittrouer, C.; Ogston, A.; Alin, S. R.; Aalto, R. (Journal of Geophysical Research-Earth Surface, 2008)
Although an inordinate fraction of the global sediment flux to the ocean occurs in tropical mountainous river margins, little is known regarding the sources and fate of organic matter in these systems. To address these knowledge gaps, the distribution and composition of organic matter in sediments from the Fly River delta-clinoform were examined in the context of the source-to-sink study of the Papuan Continuum. The significant contrasts in the texture of seabed sediments measured across the study area coincided with stark contrasts in concentration and composition of the sedimentary organic matter. Coarser sediments displayed significantly lower organic carbon and nitrogen contents, more enriched stable carbon and nitrogen compositions, lower lignin product yields, and distinctly different lignin and nonlignin product compositions than their fine-textured counterparts. Compositional differences were also measured between high-and low-density fractions of selected sediment samples. Subsurface sediments showed marked compositional variations that were predominantly associated with changes in the texture of the deposits. Most sediments were characterized by moderate carbon loadings (0.5-1.0 mg C m(-2)), although several samples from the outer topset region, an area of sediment bypass, were characterized by lower carbon loadings indicative of enhanced carbon losses. Overall, the organic matter in both surface and subsurface sediments appeared to have predominantly a terrigenous origin, with no evidence for dilution and/or replacement by marine carbon. The measured compositions were consistent with contributions from modern vascular plant detritus, aged soil organic matter, and very old or fossil organic matter devoid of recognizable biochemicals.
id: 826; 257VD Times Cited:8 Cited References Count:78Y

TRACING PAST CIRCULATION CHANGES IN THE WESTERN SOUTH ATLANTIC BASED ON PLANKTONIC FORAMINIFERA - Toledo, F. A. L.; Costa, K. B.; Pivel, M. A. G.; Campos, E. (Revista Brasileira de Paleontologia, 2008)
In this study, we traced past oceanographic changes in the southeastern Brazilian Continental Margin based on the ratio between two planktonic foraminifera species (Globigerina bulloides and Globigerinoides ruber), along a core located close to the transition between the tropical and subtropical biogeographic provinces. Each species is representative of a biogeographic province and has excluding ecological preferences. According to our interpretation, periods of low G. bulloides/G. ruber values would characterize a stronger influence of the warm, oligotrophic tropical water and, conversely, periods of high G. bulloides/G. ruber values correspond to a stronger influence of colder and nutrient-richer waters. Changes in the relative influence of the different water masses are strongly dependent on the regional wind field which affects the upper-level circulation mostly by the latitudinal displacement of the bifurcation of the South Equatorial Current which, in turn, has strong impacts on the Brazil Current’s strength and on the intensity of the upwelling regime in the study area. The analysis of the last 30 kyr record, suggests that productivity was highly increased both around the Last Glacial Maximum and the Younger Dryas event. In between these events, the record suggests that productivity was severely decreased during deglaciation. Also, our record suggests a gradual decrease in productivity from 11 kyr BP through the Holocene which can be explained by a progressively stronger Brazil Current resulting from a southward displacement of the Intertropical Convergence Zone. Our results are consistent with other studies providing estimates of changes in trade wind strength and in the extent of the climatic belts through time.
id: 1973

A validated description of age and growth of western Atlantic bluefin tuna (Thunnus thynnus) - Neilson, J. D.; Campana, S. E. (Canadian Journal of Fisheries and Aquatic Sciences, 2008)
Current stock assessments of western Atlantic bluefin tuna (Thunnus thymus) use age-structured population analyses, but the age assignment in the population model is made using all age-length relationship derived from mark and recapture studies largely completed during the 1970s. In our study, the deposition of bomb radiocarbon was used as a dated mark to validate age inferences of bluefin tuna and to compare the validated ages with those predicted from the age-length relationship. The results support the view that the age-length relationship currently in use for the assessment overestimates growth rate and the ultimate size of the fish. These findings have implications for the estimation of stock productivity and may negatively impact the rebuilding schedules established by fisheries managers.
id: 805; 348EN Times Cited:4 Cited References Count:12Y

Very high-resolution seismo-acoustic imaging of seagrass meadows (Mediterranean Sea): Implications for carbon sink estimates - Lo Iacono, C.; Mateo, M. A.; Gracia, E.; Guasch, L.; Carbonell, R.; Serrano, L.; Serrano, O.; Danobeitia, J. (Geophysical Research Letters, 2008)
Posidonia oceanica is a widespread coastal Mediterranean seagrass which accumulates in its subsurface large quantities of organic material derived from its roots, rhizomes and leaf sheaths embedded in sandy sediments. These organic deposits may be up to several meters thick as they accumulate over thousands of years forming the matte, whose high content in organic carbon plays a major role in the global ocean carbon cycle. In this study, very highresolution seismo-acoustic methods were applied to image the subsurface features of a P. oceanica seagrass meadow at Portlligat (Cadaque's, Girona, Spain), in the NW-Mediterranean Sea. Our findings yield fresh insights into the settling of the P. oceanica meadow in the study area, and define with unprecedented detail the potential volume occupied by the matte. A strong reflector, located from 4.3 to 11.7 m depth, was recognized in several seismo-acoustic profiles as the substratum on which P. oceanica first settled in the study area. A 3D bathymetric model of this substratum allowed us to reconstruct the Portlligat palaeo-environment prior to the settling of P. oceanica, which corresponded to a shallow coastal setting protected from the open sea. A core drilled in the meadow at Portlligat revealed the presence of a 6 m thick dense matte composed of medium to coarse sandy sediments mixed with plant debris and bioclasts. Radiocarbon datings revealed a constant accretion rate of the matte of about 1.1 m/kyr. Gravelly bioclastic deposits observed at the base of the core correspond to the base of the matte and gave a date of 5616 +/- 46 Cal yr BP. For the first time, very high-resolution marine geophysical techniques allowed us to accurately define the volume occupied by P. oceanica matte, which in the study area reaches up to almost 220,000 +/- 17,400 m(3). This result is an important step forward in our efforts to estimate the size of the carbon sink represented by P. oceanica meadows along the Mediterranean coasts significantly contributing to the biosphere carbon cycle.
id: 896; 351AE Times Cited:1 Cited References Count:14
Keywords: cycle

14C and 13C isotopic characterization of organic carbon in surface waters of the South Atlantic Bight - De Alteris, J. A.; Bauer, J. E.; Perkey, D. W.; Keesee, E. J.; Cai, W. J. (ASLO Aquatic Sciences Meeting, 2007)
id: 1026

14C Groundwater age and the importance of chemical fluxes across aquifer boundaries in confined Cretaceous aquifers of North Carolina, USA - Kennedy, C. D.; Genereux, D. P. (Radiocarbon, 2007)
id: 1192

A 1,500-year record of North Atlantic storm activity based on optically dated relict beach scarps - Buynevich, I. V.; FitzGerald, D. M.; Goble, R. J. (Geology, 2007)
Understanding of long-term dynamics of intense coastal storms is important for determining the frequency and impact of these events on sandy coasts. We use optically stimulated luminescence (OSL) dates on relict scarps within a prograded barrier sequence to reconstruct the chronology of large-magnitude erosional events in the western Gulf of Maine. OSL dates obtained on quartz-rich sediments immediately overlying relict scarps indicate severe beach erosion and retreat due to erosional events ca. 1550, 390, 290, and 150 cal yr B.P. Our data provide new evidence of increased storm activity (most likely frequency and/or intensity of extratropical storms) during the past 500 yr, which was preceded by a relatively calm period lasting ∼1000 yr. The width of the coastal sequence preserved between successive paleoscarps shows strong correlation with the time interval elapsed between storms. Our findings indicate that diagnostic geophysical and sedimentological signatures of severe erosional events offer new opportunities for assessing the impact and timing of major storms along sandy coasts.
id: 1083
Keywords: barrier; erosion; ground-penetrating radar; heavy minerals; Maine; OSL dating

A 190% drop in atmosphere's Delta(14) C during the "Mystery Interval" (17.5 to 14.5 kyr) - Broecker, Wallace; Barker, Stephen (Earth and Planetary Science Letters, 2007)
Reconstructions of atmospheric Delta(14)C for the deglacial period reveal a 190 +/- 10%. drop between 17.5 and 14.5 kyr before present, during the 'mystery interval'. While it appears that the major contributor must be the mixing between an isolated low radiocarbon abyssal reservoir and the remainder of the ocean, a combination of (14)C measurements on coexisting benthic and planktic foraminifera shells and (13)C/(12)C measurements on benthic foraminifera make it difficult to identify a sufficiently large volume for this reservoir. An alternative scenario, based on higher (14)C production rates between about 38 and 18 kyr ago, would escape the need for a large, isolated reservoir prior to the mystery interval but instead would call for a better ventilated ocean afterwards. The addition of (14) C-deficient sedimentary carbon appears not to be an important contributor. While the unlikely explanation that the half-life of (14)C is 15% greater than the accepted value (5730 yr) would eliminate the steady decrease in the (14)C/C over the last 40 kyr, it would not explain the steep drop which occurred between 17.5 and 14.5 kyr. (c) 2007 Elsevier B.V. All rights reserved.
id: 1921; PT: J; UT: WOS:000246051000009

A 28-ka history of sea surface temperature, primary productivity and planktonic community variability in the western Arabian Sea - Pourmand, Ali; Marcantonio, Franco; Bianchi, Thomas S.; Canuel, Elizabeth A.; Waterson, Elizabeth J. (Paleoceanography, 2007)
Uranium series radionuclides and organic biomarkers, which represent major groups of planktonic organisms, were measured in western Arabian Sea sediments that span the past 28 ka. Variability in the past strength of the southwest and northeast monsoons and its influence on primary productivity, sea surface temperature (SST), and planktonic community structure were investigated. The average alkenone-derived SST for the last glacial period was ∼3°C lower than that measured for the Holocene. Prior to the deglacial, the lowest SSTs coincide with the highest measured fluxes of organic biomarkers, which represent primarily a planktonic suite of diatoms, coccolithophorids, dinoflagellates, and zooplankton. We propose that intensification of winter northeast monsoon winds during the last glacial period resulted in deep convective mixing, cold SSTs and enhanced primary productivity. In contrast, postdeglacial (<17 ka) SSTs are warmer during times in which biomarker fluxes are high. Associated with this transition is a planktonic community structure change, in which the ratio of the average cumulative flux of diatom biomarkers to the cumulative flux of coccolithophorid biomarkers is twice as high during the deglacial and Holocene than the average ratio during the last glacial period. We suggest that this temporal transition represents a shift from a winter northeast monsoon-dominated (pre-17 ka) to a summer southwest monsoon-dominated (post-17 ka) wind system.

Abrupt climate change in southeast tropical Africa influenced by Indian monsoon variability and ITCZ migration - Tierney, J. E.; Russell, J. M. (Geophysical Research Letters, 2007)
The timing and magnitude of abrupt climate change in tropical Africa during the last glacial termination remains poorly understood. High-resolution paleolimnological data from Lake Tanganyika, Southeast Africa show that wind-driven seasonal mixing in the lake was reduced during the Younger Dryas, Inter-Allerod Cool Period, Older Dryas, and Heinrich Event 1, suggesting a weakened southwest Indian monsoon and a more southerly position of the Inter-Tropical Convergence Zone over Africa during these intervals. These events in Lake Tanganyika, coeval with millennial and centennial-scale climate shifts in the high latitudes, suggest that changes in ITCZ location and Indian monsoon strength are important components of abrupt global climate change and that their effects are felt south of the equator in Africa. However, we observe additional events in Lake Tanganyika of equal magnitude that are not correlated with high-latitude changes, indicating the potential for abrupt climate change to originate from within tropical systems.
id: 1851; 201ZV Times Cited:4 Cited References Count:31Y

Age under-estimation in New Zealand porbeagle sharks (Lamna nasus): is there an upper limit to ages that can be determined from shark vertebrae? - Francis, M. P.; Campana, S. E.; Jones, C. M. (Marine and Freshwater Research, 2007)
Annual deposition of growth bands in vertebrae has been validated for many shark species, and is now widely regarded as the norm. However, vertebrae are part of the shark's axial skeleton, and band deposition may stop in old sharks when somatic growth ceases. We aged vertebral sections from New Zealand porbeagle sharks (Lamna nasus) under reflected white light and using X-radiographs. Bomb radiocarbon assays supported vertebral age estimates up to similar to 20 years, but not at older ages. The results suggest that older porbeagles were under-aged by as much as 50% from vertebral band counts, presumably because band width declined to a point where it became unresolvable. This has important implications for growth studies on other long-lived sharks. Estimated ages at sexual maturity were 8-11 years for males and 15-18 years for females, and longevity may be similar to 65 years. New Zealand and North Atlantic porbeagles differ in these parameters, and in length at maturity and maximum length, suggesting genetic isolation of the two populations.
id: 1857; 131AF Times Cited:5 Cited References Count:60Y

Aging of marine organic matter during cross-shelf lateral transport in the Benguela upwelling system revealed by compound-specific radiocarbon dating - Mollenhauer, G.; Inthorn, M.; Vogt, T.; Zabel, M.; Damste, J. S. S.; Eglinton, T. I. (Geochemistry Geophysics Geosystems, 2007)
Organic matter accumulation and burial on the Namibian shelf and upper slope are spatially heterogeneous and strongly controlled by lateral transport in subsurface nepheloid layers. Much of the material deposited in depo-centers on the slope ultimately derives from the shelf. Supply of organic matter from the shelf involves selective transport of organic matter. We studied these selective transport processes by analyzing the radiocarbon content of co-occurring sediment fractions. Here we present radiocarbon data for total organic carbon as well as three tracers of surface ocean productivity (phytoplankton-derived alkenones, membrane lipids of pelagic crenarchaeota (crenarchaeol), and calcareous microfossils of planktic foraminifera) in core-top and near-surface sediment samples. The samples were collected on the Namibian margin along a shelf-slope transect (85 to 1040 m) at 24 degrees S and from the upper slope depo-center at 25.5 degrees S. In core-top sediments, alkenone ages gradually increased from modern to 3490 radiocarbon years with distance from shore and with water depth. Crenarchaeol, while younger than alkenones, also increased in age with distance offshore. It was concluded that the observed ages were a consequence of cross-shelf transport and associated aging of organic matter. Radiocarbon ages of preserved lipid biomarkers in sediments thus at least partially depend on the relative amount of laterally supplied, pre-aged material present in a sample, highlighting the importance of nepheloid transport for the sedimentation of organic matter over the Namibian margin.
213qvTimes Cited:3 Cited References Count:60
Keywords: alkenones; atlantic-ocean; burial; carbon accumulation; coastal; compound-specific radiocarbon dating; continental-margin; ionization mass-spectrometry; membrane-lipids; namibia; sea sediments; Sediment transport

Amplitude and timing of temperature and salinity variability in the subpolar North Atlantic over the past 10 k.y. - Came, R. E.; Oppo, D. W.; McManus, J. F. (Geology, 2007)
Paired planktic foraminiferal δ18O and Mg/Ca data reveal trends of increasing temperatures (∼3 °C) and salinities in the subpolar North Atlantic over the course of the Holocene, which were punctuated by abrupt events. The trends likely reflect an insolation-forced northward retreat of the boundary between polar and North Atlantic subsurface waters. The superimposed variability does not appear to be periodic, but tends to recur within a broad millennial band. The records provide convincing evidence of open-ocean cooling (nearly 2 °C) and freshening during the 8.2 ka event, and suggest similar conditions at 9.3 ka. However, the two largest temperature oscillations in our record (∼2 °C) occurred during the past 4 k.y., suggesting a recent increase in temperature variability relative to the mid-Holocene, perhaps in response to neoglaciation, which began at about this time.
id: 983
Keywords: Björn Drift; Mg/Ca; Neogloboquadrina pachyderma dextral; Ocean Drilling Program Site 984; paleotemperature

THE ANALYSIS OF STABLE ISOTOPES FROM CALIFORNIA COASTAL ARCHAEOLOGICAL SITES: IMPLICATIONS FOR UNDERSTANDING HUMAN CULTURAL DEVELOPMENTS AND ENVIRONMENTAL CHANGE - Robbins, John A.; Rick, Torben C. (Proceedings of the Society for California Archaeology, 2007)
id: 2079

Archaeological investigations in Jedediah Smith Campground and Hiouchi Flat - Tushingham, Shannon (Redwood National and State Park, 2007)
id: 1158

The Archaeology and Historical Ecology of Late Holocene San Miguel Island - Rick, Torben C. (Cotsen Institute of Archaeology, University of California, 2007)
id: 1086

Are tsunamis always sedimentologically important events? A case study of sedimentological and geochemical analyses of coastal lagoons, Sri Lanka - Jackson, K. L.; Rankey, E. C.; Eberli, G. P.; Amelung, F.; Andres, M. S.; Peterson, L. P.; Swart, P. K.; Jayasena, H. A. H.; Kehelpannala, K. V. W. (American Association of Petroleum Geologists Abstracts with Programs, 2007)
id: 1144; Annual Meeting

Assessing environmental factors associated with changes in the growth rate of a bivalve mollusk species through the Holocene - Krause R.A, Jr.; Huntley, J. W.; Kowalewski, M.; Romanek, C. R.; Kaufmann, D. S.; Simoes, M. G. (First International Sclerochronology Conference, 2007)
id: 1169

Atlantic meridional overturning circulation during the Last Glacial Maximum - Lynch-Stieglitz, J.; Adkins, J. F.; Curry, W. B.; Dokken, T.; Hall, I. R.; Herguera, J. C.; Hirschi, J. J. M.; Ivanova, E. V.; Kissel, C.; Marchal, O.; Marchitto, T. M.; McCave, I. N.; et al. (Science, 2007)
The circulation of the deep Atlantic Ocean during the height of the last ice age appears to have been quite different from today. We review observations implying that Atlantic meridional overturning circulation during the Last Glacial Maximum was neither extremely sluggish nor an enhanced version of present-day circulation. The distribution of the decay products of uranium in sediments is consistent with a residence time for deep waters in the Atlantic only slightly greater than today. However, evidence from multiple water-mass tracers supports a different distribution of deep-water properties, including density, which is dynamically linked to circulation.
id: 1897; ISI Document Delivery No.: 153XD Times Cited: 46 Cited Reference Count: 61 Cited References: ADKINS JF, 1997, NATURE, V390, P154 ADKINS JF, 1999, RECONSTRUCTING OCEAN, P103 ADKINS JF, 2003, EARTH PLANET SC LETT, V216, P109, DOI 10.1016/S0012-821X(03)00502-8 BACON MP, 1982, J GEOPHYS RES, V87, P2045 BICKERT T, 2004, S ATLANTIC LATE QUAT, P671 BOYLE EA, 1982, SCIENCE, V218, P784 BROECKER W, 1988, RADIOCARBON, V30, P261 CHASE Z, 2002, EARTH PLANET SC LETT, V204, P215 CLARK PU, 2002, NATURE, V415, P863 CONKRIGHT ME, 2002, WORLD OCEAN ATLAS 20 CURRY WB, 1982, QUATERNARY RES, V18, P218 CURRY WB, 2005, PALEOCEANOGRAPHY, V20, ARTN PA1017 DUPIESSY JC, 1980, NATURE, V286, P479 DUPLESSY JC, 1988, PALEOCEANOGRAPHY, V3, P343 DUPLESSY JC, 1989, RADIOCARBON, V31, P493 ELDERFIELD H, 2006, EARTH PLANET SC LETT, V250, P633, DOI 10.1016/j.epsl.2006.07.041 EMILIANI C, 1955, J GEOL, V63, P538 GANACHAUD A, 2000, NATURE, V408, P453 GEBBIE G, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q11N07 GHERARDI JM, 2005, EARTH PLANET SC LETT, V240, P710, DOI 10.1016/j.epsl.2005.09.061 HALL IR, 2006, GEOPHYS RES LETT, V33, ARTN L16616 HALL MM, 1982, DEEP-SEA RES, V29, P339 HEWITT CD, 2003, CLIM DYNAM, V20, P203, DOI 10.1007/s00382-002-0272-6 HIRSCHI JJM, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q10N04 HUYBERS P, 2007, J PHYS OCEANOGR, V37, P394, DOI 10.1175/JPO3018.1 KEIGWIN LD, 2004, PALEOCEANOGRAPHY, V19, ARTN PA4012 KISSEL C, 1999, EARTH PLANET SC LETT, V171, P489 KITOH A, 2001, GEOPHYS RES LETT, V28, P2221 KUCERA M, 2005, QUATERNARY SCI REV, V24, P951, DOI 10.1016/j.quascirev.2004.07.014 KUMAR N, 1993, NATURE, V362, P45 LEGRAND P, 1995, PALEOCEANOGRAPHY, V10, P1011 LEGRANDE AN, 2006, P NATL ACAD SCI USA, V103, P837 LYNCHSTIEGLITZ J, 1999, PALEOCEANOGRAPHY, V14, P360 LYNCHSTIEGLITZ J, 2001, GEOCHEM GEOPHY GEOSY, V2, DOI 10.1029/2001GC000208 LYNCHSTIEGLITZ J, 2003, TREATISE GEOCHEMISTR, V6, P433 LYNCHSTIEGLITZ J, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q10N03 MANABE S, 1988, J CLIMATOL, V1, P841 MANGINI A, 1998, NATURE, V392, P347 MARCHAL O, 2000, PALEOCEANOGRAPHY, V15, P625 MARCHITTO TM, 2000, PALEOCEANOGRAPHY, V15, P299 MARCHITTO TM, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q12003 MAROTZKE J, 1999, J GEOPHYS RES-OCEANS, V104, P29529 MATSUMOTO K, 1999, PALEOCEANOGRAPHY, V14, P149 MCCAVE IN, 2006, GEOCHEM GEOPHY GEOSY, V7, ARTN Q10N05 MCMANUS JF, 2004, NATURE, V428, P834, DOI 10.1038/nature02494 MIX AC, 2001, QUATERNARY SCI REV, V20, P627 OTTOBLIESNER BL, 2006, J CLIMATE, V19, P2526 PAUL A, 2003, PALEOCEANOGRAPHY, V18, ARTN 1058 PIOTROWSKI AM, 2005, SCIENCE, V307, P1933, DOI 10.1126/science.1104883 ROBINSON LF, 2005, SCIENCE, V310, P1469, DOI 10.1126/science.1114832 ROEMMICH D, 1985, DEEP-SEA RES, V32, P619 SARNTHEIN M, 1994, PALEOCEANOGRAPHY, V9, P209 SCHMITTNER A, 2005, GLOBAL BIOGEOCHEM CY, V19, ARTN GB3004 SHACKLETON NJ, 1988, NATURE, V335, P708 SHIN SI, 2003, CLIM DYNAM, V20, P127, DOI 10.1007/s00382-002-0260-x STOMMEL H, 1961, TELLUS, V13, P224 STREETER SS, 1979, SCIENCE, V203, P168 VELLINGA M, 2002, CLIMATIC CHANGE, V54, P251 WUNSCH C, 2003, QUATERNARY SCI REV, V22, P371 YU EF, 1996, NATURE, V379, P689 ZHANG R, 2005, J CLIMATE, V18, P1853 Lynch-Stieglitz, Jean Adkins, Jess F. Curry, William B. Dokken, Trond Hall, Ian R. Herguera, Juan Carlos Hirschi, Joel J. -M. Ivanova, Elena V. Kissel, Catherine Marchal, Olivier Marchitto, Thomas M. McCave, I. Nicholas McManus, Jerry F. Mulitza, Stefan Ninnemann, Ulysses Peeters, Frank Yu, Ein-Fen Zahn, Rainer Amer assoc advancement science Washington; YY

Biomarker evidence for the co-occurrence of three races (A, B and L) of Botryococcus braunii in El Junco Lake, Galapagos - Zhang, Z. H.; Metzger, P.; Sachs, J. P. (Organic Geochemistry, 2007)
In spite of the fact that individual races of Botryococcus braunii are widely distributed in lakes, reports of the co-existence of different chemical races are rare. Here we report biomarker evidence for the co-occurrence of three different races of B. braunii (A, B and L) in the water column and sediments of El Junco Lake, a freshwater crater lake at 700 m elevation on San Cristobal Island, Galapagos. We also show the existence of lycopadienes and lycopatrienes in suspended particles and sediments. Biomarker indicators of the three races were: cis and trans C-25-C-31 n-alkadienes and a C-29 triene for race A, a series of C34H58 botryococcenes for race B, and a C40H78 hydrocarbon, trans, trans-lycopadiene accompanied by minor amounts of isomers for race L. Epoxides derived from n-alkadienes and trans, trans-lycopadiene, specific to races A and L respectively, were also detected. Several previously unreported lycopadienes and lycopatrienes were identified in both the water column and sediment, and are believed to represent by-products and intermediates, respectively, of trans, trans-lycopadiene synthesis. Botryococcene and lycopadiene concentrations reached 16.7 and 0.8 mg/g dry sediment in near-surface sediments, and varied over more than three orders of magnitude, while n-alkadienes were present in trace quantities. Pyrolysates from the kerogen fraction of sediment contained lycopadiene and alkadiene related lipids along with chemically resistant polymers of R braunii cell walls. Apparently n-alkadienes, botryococcenes and lycopadienes and -trienes can survive in oxic sediments for several decades, and the down core variation in these lipids likely reflects changes in lake hydrology, alternately favoring the bloom or near-extinction of R braunii race B. (C). 2007 Elsevier Ltd. All rights reserved.
id: 590; 218MC Times Cited:7 Cited References Count:72

Calcification in sclersoponges: implications for reconstructing CO2 fluxes in the tropics - Grottoli, A. G. (ASLO, 2007)
id: 1132

Carbon, chlorine, and oxygen isotopes as tracers of interbasin groundwater flow at La Selva Biological Station, Costa Rica - Webb, Mathew (North Carolina State University, 2007)

Carbon export and cycling by the York, Tanana and Porcupine Rivers, Alaska, 2001-2005 - Striegl, R. G.; Dornblaser, M. M.; Aiken, G. R.; Wickland, K. P.; Raymond, P. A. (Water Resources Res., 2007)
id: 1162

Carbon in riparian subsurface ecosystems: Sources, lability, and spatial patterns - Gurwick, N. P. (Cornell University, 2007)

Carbon isotope variation in modern soils of the tallgrass prairie: Analogues for the interpretation of isotopic records derived from paleosols - Johnson, W. C.; Willey, K. L.; Macpherson, G. L. (Quaternary International, 2007)
Use of stable carbon isotope data from paleosols to reconstruct past plant community structure (C-3 vs. C-4) has become commonplace. In an effort to improve our ability to make isotope-based reconstructions and to better appreciate the pitfalls, investigations were conducted on both modern soils and paleosols in the Kansas grasslands.Stable carbon isotope data were derived from soils and vegetation on the near-pristine, C-4-dominated grassland of the Konza Tallgrass Prairie Long-Term Ecological Research (LTER) site in northeastern Kansas. In order to evaluate variation of delta C-13 within the landscape, two levels of sampling were employed: 2 m-deep upland cores extracted to assess variation with depth in the soil profile, and, to assess variability across the landscape, surface samples along two transects and from within a 660 x 690 m grid. For transect and grid points, both the upper 2cm of sediment and the aboveground biomass were collected. Core samples taken at Konza reveal that soil organic carbon was depleted in C-13 within the upper 10-20cm relative to the remainder of the soil solum below, a phenomenon previously reported. In transects and the sample grid, soil organic carbon from soil surfaces was consistently more depleted in C-13 than aboveground tissue of associated vegetation samples. Slope, azimuth, and insolation were computed from field data and a highresolution DEM of the sample grid, but these variables offered no significant explanation of the spatial variability in delta C-13 data from soil organic carbon. The observation that modern landscape position has little effect on delta C-13 over short distances, at least in a C4-dominated community, lends support to the application of delta C-13 analysis to buried soils for paleoenvironmental reconstruction where paleolandscape position is often unknown.Stable carbon isotope data were derived from paleosols at from the Beisel-Steinle site located to the west of Konza in central Kansas. Three soils were examined: the interstadial paleosol within the Gilman Canyon Formation (c. 38-27k cal yr BP), the Late Pleistocene-Holocene Brady Soil, and the modern surface soil. With the exception of isotopic depletion at the top of the surface soil, all three soils exhibited similar delta C-13 values of about14 parts per thousand, the same value realized in the soil cores from Konza, suggesting close similarity among the plant communities of the interstade, the Late Pleistocene-Early Holocene transition, and pristine prairie of today.This investigation emphasizes the need for additional research into the variation in stable carbon isotope signals vertically within the profile and across the landscape. Issues include the source of the near-surface depletion zone, the relationship between isotopic values in the soil versus those of the vegetation, and variation in Soil delta 13C values delta 13C throughout the landscape. (c) 2006 Elsevier Ltd and INQUA. All rights reserved.
158nkTimes Cited:9Cited References Count:144

Carbon nanotube foils for electron stripping in tandem accelerators - von Reden, K.; Zhang, M.; Meigs, M.; Sichel, E.; Fang, S.; Baughman, R. (Nucl. Inst. & Meth. in Physics Research B., 2007)
id: 690

Caribbean sclerosponge radiocarbon measurements re-interpreted in terms of U/Th age models - Rosenheim, B. E.; Swart, P. K. (Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 2007)
Previously unpublished AMS radiocarbon measurements of a sclerosponge from tongue of the ocean (TOTO), Bahamas, as well as preliminary data from an investigation of the radiocarbon records of sclerosponges living at different depths in the adjacent Bahamas basin, Exuma Sound, are interpreted in terms of U-series age models. The data are compared to an existing Caribbean sclerosponge radiocarbon bomb curve measured using standard gas proportional beta counting and used to interpret a Pb-210 age model. The Delta C-14 records from the sclerosponges illustrate a potential for use of radiocarbon both as a tracer of subsurface water masses or as an additional age constraint on recently sampled sclerosponges. By using an independent age model, this study lays the framework for utilizing sclerosponges from different locations in the tropics and subtropics and different depths within their wide depth range (0-250 m) to constrain changes in production of subtropical underwater in the Atlantic Ocean. This framework is significant because the proxy approach is necessary to supplement the short and coarse time series being used to constrain variability in the formation of Caribbean subtropical underwater, the return flow of a shallow circulation cell responsible for nearly 10% of the heat transported poleward in the N. Atlantic. (c) 2007 Elsevier B.V. All rights reserved.
id: 785; 182WV Times Cited:2 Cited References Count:30Y

Century-to-millennial scale climatic variability in Lake Malawi revealed by isotope records - Barker, P. A.; Leng, M. J.; Gasse, F.; Huang, Y. (Earth and Planetary Science Letters, 2007)
Diatom-based oxygen isotope data ( delta super(1) super(8)O sub(d) sub(i) sub(a) sub(t) sub(o) sub(m)) from Lake Malawi show multi-centennial scale wet-dry intervals spaced approximately every 2.3 ka throughout a 25 ka sequence. The delta super(1) super(8)O sub(d) sub(i) sub(a) sub(t) sub(o) sub(m) record is supported by a lower resolution deuterium ( delta D sub(p) sub(a))isotope curve derived from palmitic acid. We interpret these isotope data in terms of major shifts in precipitation and evaporation moderated by seasonal controls on the host organisms. Dry periods marked by relatively positive isotope values, represent the extension of abrupt Holocene events noted from northern and equatorial Africa to 10-15 super(o)S. These events in Lake Malawi correspond to cool episodes in Greenland, thereby demonstrating teleconnections generated by meridional temperature gradients. Sea surface temperatures are likely to be the primary transmitter of deglacial climate changes, although trade wind strength and direction is critical in controlling precipitation patterns in tropical regions. Conversely, the global hydrological cycle, driven by low latitude regions represents an important positive feedback amplifying deglacial processes.
id: 2222; Source type: scholarlyjournals; Object type: Article; Object type: Feature; CSAUnique: OB-MD-0006626237; AccNum: 7631572; DOI: 10.1016/j.epsl.2007.06.010; ISSN: 0012-821X; Peer Reviewed: true

Chapter B--Field Trip Day 2: Quaternary Geology of Lake Alamosa and the Costilla Plain, southern Colorado - Machette, M. N.; Marchetti, D. W.; Thompson, R. A.; Kirkham, R. M. (Quaternary geology of the San Luis Basis, southern Colorado and Northern New Mexico--Rocky Mountain Section Friends of the Pleistocene Guidebook: U. S. Geological Survey Open-File Report 2007-1193, 2007)
id: 626

Chapter E--Holocene sand deposits in the San Luis Basin, east of Alamosa Colorado - Machette, M. N.; Puseman, K. (Quaternary geology of the San Luis Basis, southern Colorado and Northern New Mexico--Rocky Mountain Section Friends of the Pleistocene Guidebook: U. S. Geological Survey Open-File Report 2007-1193, 2007)
id: 627

Chapter F--Late Pleistocene to early Holocene paleoecology of the "Mr. Peat" wetland deposit, Alamosa County, Colorado - Schumann, R. R.; Machette, M. N. (Quaternary geology of the San Luis Basin, southern Colorado and Northern New Mexico--Rocky Mountain Section Friends of the Pleistocene Guidebook: U. S. Geological Survey Open-File Report 2007-1193, 2007)
id: 628

Climate change impact research in U.S. national parks - Ironside, Kirsten (NAU Environmental Sciences Program, 5/7, 2007)

Coastal subsistence and landscape evolution on Eastern Santa Rosa Island, California: perspectives from CA-SRI-667 - Wolff, Christopher B.; Aland, Amanda; Rick, Torben C. (Proceedings of the Society for California Archaeology, 2007)
id: 2080

Comment on "Anomalous radiocarbon ages for foraminifera shells" by W. Broecker et al.: A correction to the western tropical Pacific MD9821-81 record - Stott, Lowell D. (Paleoceanography, 2007)
id: 2017; PT: J; UT: WOS:000244478900001

Computer simulation of MC-SNICS for performance improvements - Han, B. X.; Southon, J. R.; Roberts, M. L.; von Reden, K. F. (Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 2007)
Increasing ion source current output while keeping the beam emittance small is a key for improving measurement throughput and quality of an accelerator mass spectrometry (AMS) system. The NEC MC-SNICS ion sources have widely been used for AMS around the world. In this work, a computer simulation study on MC-SNICS ion source was carried out using the code PBGUNS. The primary Cs+ beam is simulated as space-charge limited emission from the ionizer surface. The secondary negative ion beam is simulated in the presence of the space-charge induced by both the primary and the secondary beam. Two different configurations of the MC-SNICS have been studied: the original factory version and the UC Irvine modified version. The latter has a 0.668 in. radius spherical ionizer and an immersion lens at cathode potential with the original Cs focus lens removed. Simulation showed that the modified version provides more intense and better focused Cs+ beam at the cathode target, hence higher negative ion production from the sample by sputtering. The new arrangement of Einzel-preacceleration section of the MC-SNICS at UC Irvine was also simulated and discussed. Simulation results are in good agreement with the experimental observations made at UC Irvine. Hints for selection of an immersion lens geometry have been obtained. (c) 2007 Elsevier B.V. All rights reserved.
200swTimes Cited:8Cited References Count:8

Constraining global air-sea gas exchange for CO2 with recent bomb 14C measurements - Sweeney, C.; Gloor, E.; Jacobson, A. J.; Key, R. M.; McKinley, G.; Sarmiento, J. L.; Wanninkhof, R. (Global Biogeochemical Cycles, 2007)
id: 1052

Constraints on the origin of sedimentary organic carbon in the Beaufort Sea from coupled molecular 13C and 14C measurements - Drenzek, Nicholas J.; Montluçon, Daniel B.; Yunker, Mark B.; Macdonald, Robie W.; Eglinton, Timothy I. (Marine Chemistry, 2007)
id: 1030

Contributions of toluene and alpha-pinene to SOA formed in an irradiated toluene/alpha-pinene/NOx/air mixture: Comparison of results using C-14 content and SOA organic tracer methods - Offenberg, J. H.; Lewis, C. W.; Lewandowski, M.; Jaoui, M.; Kleindienst, T. E.; Edney, E. O. (Environmental Science & Technology, 2007)
An organic tracer method, recently proposed for estimating individual contributions of toluene and alpha-pinene to secondary organic aerosol (SOA) formation, was evaluated by conducting a laboratory study where a binary hydrocarbon mixture, containing the anthropogenic aromatic hydrocarbon, toluene, and the biogenic monoterpene, alpha-pinene, was irradiated in air in the presence of NOx to form SOA. The contributions of toluene and alpha-pinene to the total SOA concentration, calculated using the organic tracer method, were compared with those obtained with a more direct C-14 content method. In the study, SOA to SOC ratios of 2.07 +/- 0.08 and 1.41 +/- 0.04 were measured for toluene and alpha-pinene SOA, respectively. The individual tracer-based SOA contributions of 156 mu g m(-3) for toluene and 198 mu g m(-3) for alpha-pinene, which together accounted for 82% of the gravimetrically determined total SOA concentration, compared well with the C-14 values of 182 and 230 mu g m(-3) measured for the respective SOA precursors. While there are uncertainties associated with the organic tracer method, largely due to the chemical complexity of SOA forming chemical mechanisms, the results of this study suggest the organic tracer method may serve as a useful tool for determining whether a precursor hydrocarbon is a major SOA contributor.
id: 1882; 172ZM Times Cited:13 Cited References Count:19Y

Cooling of Northwest Atlantic slope waters during the Holocene - Sachs, J. P. (Geophysical Research Letters, 2007)
[1] Climate of the last 11,000 years, the Holocene, is usually described as warm and stable. Benchmark temperature records from central Greenland ice cores show none of the large, abrupt variations that characterized the prior 100,000 years of glacial climate. Nor do they show any substantial trend, indicating at most 1 degrees-3 degrees C of cooling. Here we show that the slope waters east of the United States and Canada cooled 4 degrees-10 degrees C during the Holocene. Declining insolation, increasing convection in the Labrador Sea, and equatorward shifting of the Gulf Stream path may have caused the cooling.
136deTimes Cited:35 Cited References Count:33
Keywords: circulation; deposition; ice; labrador sea; ocean; oscillation; sea-surface; stratigraphy; Temperature; variability

Demise of a submarine canyon? Evidence for highstand infilling on the Waipaoa River continental margin, New Zealand - Walsh, J. P.; Alexander, C. R.; Gerber, T.; Orpin, A. R.; Sumners, B. W. (Geophysical Research Letters, 2007)
Submarine canyons are major geomorphologic features on the Earth's surface. Their formation has received considerable debate, but their demise has received less attention. Research of modern canyons with cores and moorings has documented active sediment transport and deposition, but extrapolation of these local observations over larger areas is precluded by complex canyon geomorphology. High-resolution multibeam and chirp data presented here provide convincing evidence of an infilling canyon head on the Waipaoa River margin of New Zealand. Tens of meters of Holocene sediment have accumulated on the outer shelf and in Lachlan canyon as a result of off-shelf sediment transport. Regardless of the ultimate fate of this system over geological time scales, this research demonstrates highstand sedimentation as a possible mechanism for canyon burial and cause of canyon demise, which has important implications for the evolution of canyons globally.
id: 791; 228BW Times Cited:4 Cited References Count:42Y

Deposition and reactivity of aerosol-derived organic carbon in temperate watersheds - Wozniak, A. W.; Bauer, J. E.; Dickhut, R. M.; Keesee, E. J. (ASLO Aquatic Sciences Meeting, 2007)
id: 1029

Detection of silica-mediated dissolution of magnetic grains in sediments using FORC diagrams - Wetter, L.; Verosub, K.; Russell, J. (Geophysical Research Letters, 2007)
Recently silica-mediated dissolution has been recognized as a potentially important factor influencing magnetic studies of marine and lacustrine sediments. Although direct evidence for the dissolution of magnetic particles in silica-rich environments is lacking, the process is expected to produce changes in the magnetic grain-size distribution, a hypothesis that is tested in this study on sediments from Lake Tanganyika, East Africa, using First Order Reversal Curves (FORCs). Results from different magnetic intensity zones within the studied samples clearly show changes in the grain-size distribution of magnetic minerals. In particular, zones with high biogenic silica content (BSi) correlated with depletion in fine-grained magnetic material, whereas zones with lower BSi showed no depletion. These results are consistent with the idea that silica-mediated dissolution results in the preferential removal of fine-grained magnetic material, and indicate that FORC diagrams are effective in characterizing silica-mediated dissolution in sediments.
182vvTimes Cited:3Cited References Count:8
Keywords: dissolution; FORC

Diagenetic and sedimentological controls on the composition of organic matter preserved in California Borderland Basin sediments - Mollenhauer, G.; Eglinton, T. I. (Limnology and Oceanography, 2007)
Compound-specific radiocarbon (C-14) contents, stable carbon isotopes, and abundances of phytoplankton and vascular plant derived lipid biomarkers (alkenones and fatty acids) were obtained from Santa Barbara Basin and Santa Monica Basin sediments, along with radiocarbon contents of planktic foraminifera and total organic carbon. We investigated core-top and prebomb sediment intervals at sites from the flanks and depocenters of the basins deposited under contrasting bottom water oxygen concentrations. Bulk organic matter generally has the lowest radiocarbon levels of all sediment constituents measured, whereas planktic foraminifera tend to be the most radiocarbon enriched. Alkenones are systematically depleted in radiocarbon with respect to foraminifera. Short-chain (C-14, C-16, C-18) fatty acids decrease rapidly in absolute abundance and relative to longer-chain (> C-24) homologues from core-top to prebomb samples. The loss of short-chain fatty acids with depth is associated with C-13 depletion of short-chain fatty acids, indicating preferential preservation of terrestrially derived fatty acids. Short-chain fatty acids tend to be more C-14-enriched relative to alkenones in core-top sediments, whereas longer-chain homologues are generally the most radiocarbon depleted of the lipids studied here. Less refractory compounds (e.g., short-chain fatty acids) are thus enriched in radiocarbon with respect to more recalcitrant biomarkers (alkenones, long-chain fatty acids). The lower C-14 content of more refractory compounds reflects a larger proportion of laterally supplied, preaged material. Greater preservation of labile organic compounds observed at the depocenters than in flank sediments results in the presence of "younger" biomarkers, underlining the important influence of selective degradation of labile compounds on their radiocarbon ages.
149kgTimes Cited:43 Cited References Count:67
Keywords: c-14 measurements; compound-specific radiocarbon; continental-margin; fatty-acids; marine-sediments; monica basin; oxic degradation; oxygen exposure time; santa-barbara basin; surface sediments

Distribution and sub-bottom features of Holocene oyster deposits in the York River, Virginia and the rate of degradations of oyster shell - Stackhouse, B. L.; Lockwood, R. (Geological Society of America Abstracts with Programs, 2007)
id: 587

Distribution and turnover of carbon in natural and constructed wetlands in the Florida Everglades - Stern, J.; Wang, Y.; Gu, B.; Newman, J. (Applied Geochemistry, 2007)
Stable and radiocarbon isotopic contents of dissolved organic C (DOC), dissolved inorganic C (DIC), particulate organic C (POC) and plants were used to examine the source and turnover rate of C in natural and constructed wetlands in the Florida Everglades. DOC concentrations decreased, with P concentrations, along a water quality gradient from the agriculturally impacted areas in the northern Everglades to the more pristine Everglades National Park. delta C-13 values of DOC in the area reflect contributions of both wetland vegetation and sugarcane from agriculture. Radiocarbon ages of DOC, POC and DIC in the Everglades ranged from 2.01 ka BP to ">modern". The old C-14 ages of DOC and POC were found in impacted areas near the Everglades Agricultural Area (EAA) in the northern Everglades. In contrast, DOC and POC in pristine marsh areas had near modern or ">modern" C-14 ages. These data indicate that a major source of POC and DOC in impacted areas is the degradation of historic peat deposits in the EAA. In the pristine areas of the marsh, DOC represents a mix of modern and historic C sources, whereas POC comes from modern primary production as indicated by positive A C-14 values, suggesting that DOC is transported farther away from its source than POC. High A C-14 values of DIC indicate that dissolution of limestone bedrock is not a significant source of DIC in the Everglades wetlands. As a restored wetland moves towards its "original" or "natural" state, the C-14 signatures of DOC should approach that of modern atmosphere. In addition, measurements of concentration and C isotopic composition of DOC in two small constructed wetlands (i.e., test cells) indicate that these freshwater wetland systems contain a labile DOC pool with rapid turnover times of 26-39 days and that the test cells are overall net sinks of DOC. (C) 2007 Elsevier Ltd. All rights reserved.
216vhTimes Cited:23Cited References Count:36

Early Maritime Technology on California’s San Miguel Island: Arena Points from - Erlandson, Jon M.; Braje, Todd (Current Research in the Pleistocene, 2007)
id: 2071

Electromagnetic field modeling and ion optics calculations for a continuous-flow AMS system - Han, B. X.; von Reden, K. F.; Roberts, M. L.; Schneider, R. J.; Hayes, J. M.; W. J. Jenkins (Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 2007)
A continuous-flow C-14 AMS (CFAMS) system is under construction at the NOSAMS facility. This system is based on a NEC Model 1.5SDH-10.5 MV Pelletron accelerator and will utilize a combination of a microwave ion source (MIS) and a charge exchange canal (CXC) to produce negative carbon ions from a continuously flowing stream Of CO2 gas. For high-efficiency transmission of the large emittance, large energy-spread beam from the ion source unit, a large-acceptance and energy-achromatic injector consisting of a 45 degrees electrostatic spherical analyzer (ESA) and a 90 degrees double-focusing magnet has been designed. The 45 degrees ESA is rotatable to accommodate a 134-sample MC-SNICS as a second ion source. The high-energy achromat (90 degrees double focusing magnet and 90 degrees ESA) has also been customized for large acceptance. Electromagnetic field modeling and ion optics calculations of the beamline were done with Infolytica MagNet, ElecNet, and Trajectory Evaluator. PBGUNS and SIMION were used for the modeling of ion source unit. (c) 2007 Elsevier B.V. All rights reserved.
id: 1698; 182WV Times Cited:6 Cited References Count:14

The Environmental Anomalies in the Northeastern East China Sea during the Last 3000 Years: Implications for El Nino Activity in the Holocene - Chang, F.; Zhuang, L.; Li, T.; Yan, J.; Li, Q. (9th International Conference on Paleoceanography (ICP 9), 2007)
id: 1935; TY: CPAPER; NO: Source type: conferencepapers&proceedings; Object type: Conference Paper; CSAUnique: CPI-4728602; AccNum: 4728602(China)
Keywords: Donghai Sea; Holocene; Multidisciplinary; Paleo studies; Paleoenvironments; U 7000

Evaluation of gas chromatographic isotope fractionation and process contamination by carbon in compound-specific radiocarbon analysis - Zencak, Z.; Reddy, C. M.; Teuten, E. L.; Xu, L.; McNichol, A. P.; Gustafsson, O. (Analytical Chemistry, 2007)
The relevance of both modern and fossil carbon contamination as well as isotope fractionation during preparative gas chromatography for compound-specific radiocarbon analysis (CSRA) was evaluated. Two independent laboratories investigated the influence of modern carbon contamination in the sample cleanup procedure and preparative capillary gas chromatography (pcGC) of a radiocarbon-dead 3,3',4,4',5,5'-hexachlorobiphenyl (PCB 169) reference. The isolated samples were analyzed for their C-14/C-12 ratio by accelerator mass spectrometry. Sample Delta C-14 values of -996 +/- 20 and -985 +/- 20% agreed with a Delta C-14 of -995 +/- 20% for the unprocessed PCB 169, suggesting that no significant contamination by nonfossil carbon was introduced during the sample preparation process at either laboratory. A reference compound containing a modern C-14/C-12 ratio (vanillin) was employed to evaluate process contamination from fossil C. No negative bias due to fossil C was observed (sample Delta C-14 value of 165 +/- 20% agreed with Delta C-14 of 155 +/- 12% for the unprocessed vanillin). The extent of isotopic fractionation that can be induced during pcGC was evaluated by partially collecting the vanillin model compound of modern C-14/C-12 abundance. A significant change in the delta C-13 and delta C-14 values was observed when only parts of the eluting peak were collected (delta C-13 values ranged from -15.75 to -49.91% and delta C-14 values from -82.4 to +4.71%). Delta C-14 values, which are normalized to a delta C-13 of -25%, did not deviate significantly (-58.9 to -5.8%, considering the uncertainty of similar to +/- 20%). This means that normalization of radiocarbon results to a delta C-13 of -25%, normally performed to remove effects of environmental isotope fractionation on C-14-based age determinations, also cor-rects sufficiently for putative isotopic fractionation that may occur during pcGC isolation of individual compounds for CSRA.
id: 615; 140ID Times Cited:11 Cited References Count:32

Evolution and latitudinal diversity gradient: Speciation, extinction, and biogeography - Mittelbach, G. G.; Schemske, D. W.; Cornell, H. V.; Allen, A. P.; Brown, J. M.; Bush, M. B. (Ecology Letters, 2007)
id: 456

Exploring relationships between watershed properties and holocene loss-on-ignition records in high-elevation lakes, southern uinta mountains, Utah, USA - Munroe, Jeffrey S. (Arctic Antarctic and Alpine Research, 2007)
Sediment cores were retrieved from 12 lakes in the southern Uinta Mountains ranging in elevation from 2960 to 3475 m. Organic content was determined by loss-on-ignition (LOI) at 1-cm intervals (n = 2850), corresponding to 20 to similar to 100 yrs per sample. This data set was used to explore relationships between watershed variables and LOI records. Average LOI values are strongly correlated with lake elevation, elevation of the watershed, extent of late-lying snow and bare rock in the watershed, and the area of upstream lakes. Average LOI values are not significantly correlated with lake depth, or with lake or watershed area. The 12 LOI records can be visually divided into 3 groups with contrasting patterns: Steady, Trending, and Rising. Steady lakes have the lowest average LOI values, and are located in watersheds with the highest maximum elevations and the largest area of upstream lakes and late-lying snow. The most significant determinant on average LOI and LOI pattern is hydrologic through-flow as revealed by the configuration and number of inlets and outlets. The repetition of Steady, Trending, and Rising LOI patterns in different parts of the range, combined with contrasting LOI patterns in adjacent lakes, suggests that watershed characteristics strongly influence organic sedimentation.
id: 2014; PT: J; CT: Uinta Interdisciplinary Assessment Symposium (UINTAS 2006); CY: MAY , 2006; CL: Snowbird, UT; UT: WOS:000250962500006

Field and laboratory data from an earthquake history study of scarps of the Lake Creek-Boundary Creek fault between the Elwha River and Siebert Creek, Clallam County, Washington - Nelson, A. R.; Personius, S. F.; Buck, Jason; Bradley, L. A.; Wells, R. E.; Schermer, E. R. (U. S. Geological Survey Scientific Investigations Report 2004, 2007)
id: 433

Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers RID C-4087-2009 RID C-5396-2008 - Raymond, Peter A.; McClelland, J. W.; Holmes, R. M.; Zhulidov, A. V.; Mull, K.; Peterson, B. J.; Striegl, R. G.; Aiken, G. R.; Gurtovaya, T. Y. (Global Biogeochemical Cycles, 2007)
The export and Delta C-14-age of dissolved organic carbon (DOC) was determined for the Yenisey, Lena, Ob', Mackenzie, and Yukon rivers for 2004 - 2005. Concentrations of DOC elevate significantly with increasing discharge in these rivers, causing approximately 60% of the annual export to occur during a 2-month period following spring ice breakup. We present a total annual flux from the five rivers of similar to 16 teragrams (Tg), and conservatively estimate that the total input of DOC to the Arctic Ocean is 25 - 36 Tg, which is similar to 5-20% greater than previous fluxes. These fluxes are also similar to 2.5 x greater than temperate rivers with similar watershed sizes and water discharge. Delta C-14-DOC shows a clear relationship with hydrology. A small pool of DOC slightly depleted in Delta C-14 is exported with base flow. The large pool exported with spring thaw is enriched in D14C with respect to current-day atmospheric Delta C-14-CO2 values. A simple model predicts that similar to 50% of DOC exported during the arctic spring thaw is 1 - 5 years old, similar to 25% is 6 - 10 years in age, and 15% is 11 - 20 years old. The dominant spring melt period, a historically undersampled period, exports a large amount of young and presumably semilabile DOC to the Arctic Ocean.
id: 2033; PT: J; UT: WOS:000250704000002

Flux and fate of Yangtze river sediment delivered to the East China Sea - Liu, J. P.; Xu, K. H.; Li, A. C.; Milliman, J. D.; Velozzi, D. M.; Xiao, S. B.; Yang, Z. S. (Geomorphology, 2007)
Numerous cores and dating show the Yangtze River has accumulated about 1.16 x 10(12) t sediment in its delta plain and proximal subaqueous delta during Holocene. High-resolution seismic profiling and coring in the southern East China Sea during 2003 and 2004 cruises has revealed an elongated (similar to 800 km) distal subaqueous mud wedge extending from the Yangtze River mouth southward off the Zhejiang and Fujian coasts into the Taiwan Strait. Overlying what appears to be a transgressive sand layer, this distal clinoform thins offshore, from similar to 40 in thickness between the 20 and 30 m water depth to < 1-2 in between 60 and 90 m water depth, corresponding to an across shelf distance of less than 100 km. Total volume of this distal mud wedge is about 4.5 x 10(11) m(3), equivalent to similar to 5.4 x 10(11) t of sediment. Most of the sediment in this mud wedge comes from the Yangtze River, with some input presumably coming from local smaller rivers. Thus, the total Yangtze-derived sediments accumulated in its deltaic system and East China Sea inner shelf have amounted to about 1.7 x 10(12) t. Preliminary analyses suggest this longshore and across-shelf transported clinoform mainly formed in the past 7000 yrs after postglacial sea level reached its mid-Holocene highstand, and after re-intensification of the Chinese longshore current system. Sedimentation accumulation apparently increased around 2000 yrs BP, reflecting the evolution of the Yangtze estuary and increased land erosion due to human activities, such as fanning and deforestation. The southward-flowing China Coastal Current, the northward-flowing Taiwan Warm Current, and the Kuroshio Current appear to have played critical roles in transporting and trapping most of Yangtze-derived materials in the inner shelf, and hence preventing the sediment escape into the deep ocean. (c) 2006 Elsevier B.V. All rights reserved.
244vyTimes Cited:286Cited References Count:84

The Geographic, Geological and Oceanographic Setting of the Indus River - Inam, A.; Clift, P. D.; Giosan, L. (Large Rivers, 2007)
id: 867; Y

Global human impacts or climate change? : explaining the Sooty Shearwater decline at the Minard site, Washington State, USA - Bovy, K. M. (Journal of Archaeological Science, 2007)
Sooty Shearwater (Puffinus griseus) remains decrease throughout the occupation (AD 1000-1600) of the Minard site (45-GH-15) on the southern Washington coast, USA. Given that New Zealand is one of the major breeding locations for this long-distant migrant, the decline at the Minard site may be due to human impacts on a global scale. In particular, the Maori practice of muttonbirding, the killing and preparation of fledgling shearwaters for storage, may have affected the number of summer migrants reaching the Pacific Northwest Coast. A second hypothesis attributes the decline in Sooty Shearwaters at the site to increasing sea surface temperatures and/or increased frequency of ENSO events during this period. Understanding how Sooty Shearwaters responded to human hunting and/or climate events in the past may be useful for the current management of this species, which has faced dramatic declines in recent decades. (c) 2006 Elsevier Ltd. All rights reserved.
id: 445; 170KG Times Cited:4 Cited References Count:104

High-resolution proxy record of Holocene climate from a loess section in Southwestern Nebraska, USA - Miao, Xiaodong; Mason, Joseph A.; Johnson, William C.; Wang, Hong (Palaeogeography Palaeoclimatology Palaeoecology, 2007)
Multi-proxy analysis was used to produce a high-resolution paleoclimatic record from an exceptionally thick section of the Holocene Bignell Loess near Wauneta, Southwestern Nebraska, in the central Great Plains. The Wauneta section has excellent age control, based on optically stimulated luminescence (OSL) and radiocarbon dating, and records multiple episodes of rapid loess deposition alternating with slower deposition and soil formation. The lowermost and uppermost OSL ages obtained from the Bignell Loess are 10,250 +/- 610 years (5.9 in depth) and 100 +/- 10 years (0.1 in depth), respectively. As a result, the Holocene has been temporally confined. Stratigraphically, the Bignell Loess overlies the Late Pleistocene Peoria Loess (deposited similar to 21-14 ka), and the two units are separated by the Brady Soil which is distinguished by its color and other pedogenic features. L*a*b* color parameters and organic carbon content of Bignell Loess are sensitive proxies to differentiate drought-induced aeolian sediment layers from the intercalated soil horizons. Soil organic carbon-derived delta(13)C data suggest that the C(3)-dominated floral environment during Peoria Loess deposition shifted dramatically to a C(4)-dominated environment during Brady Soil formation in response to a warming trend. Even greater C(4) abundance characterized the late Holocene. High-resolution delta(13)C data support the contention that C(3) vs. C(4) vegetation change in the Holocene reflects ecosystem response to frequent vegetation disturbance under and conditions. Time series analysis reveals that delta(13)C and color parameters display high frequency variation with periodicities of 103-118 years and 103 years, respectively. Similar periodicities were also reported in studies of North Dakota takes, though the physical mechanism responsible is uncertain. Comparison of Bignell Loess color and tropical Pacific sea surface temperatures (SSTs) allows evaluation of a proposed teleconnection between drought in the Great Plains and La Nina-like conditions in the tropical Pacific. The loess color index and eastern tropical Pacific SST display broad similarities through the late Pleistocene and Holocene that are consistent with this teleconnection. On the other hand, drought centered at 3800 years ago is not consistent with the teleconnection, and the end of early Holocene aridity at the Wauneta section, around 6500 years ago, is much earlier than the corresponding rise in SST and increase in El Nino frequency in the eastern tropical Pacific. (c) 2006 Elsevier B.V. All rights reserved.
id: 1994; PT: J; UT: WOS:000245026900004

Historical ecology and human impacts on coastal ecosystems of the Santa Barbara Channel region, California - Rick, Torben C.; Erlandson, Jon M.; Braje, Todd J.; Estes, James; Graham, Michael; Vellanoweth, Rene (Ancient Human Impacts on Marine Environments: A Global Perspective, 2007)
id: 577

Holocene fire and occupation in Amazonia: Records from two lake districts - Bush, M. B.; Silman, M. R.; de Toledo, M. B.; Listopad, C. R. S.; Gosling, W. D.; Williams, C.; De Oliveira, P. E.; Krisel, C. (Philosophical Transactions of the Royal Society of London, 2007)
id: 454

Holocene Reworking of a Sand Sheet in the Merrimack Embayment, Western Gulf of Maine - Hein, C. J.; FitzGerald, D. M.; Barnhardt, W. (Journal of Coastal Research, 2007)
Recent bathymetric, backscatter, and seafloor sediment samples demonstrate that a large sand sheet was formed in the inner shelf by the reworking of the Merrimack River lowstand delta (deposited 12 kya; currently at 45 m depth) and braid plain during the Holocene transgression. Asymmetric bedforms and distinct grain size distributions suggest the sand sheet is actively being reworked by inner-shelf processes.Bottom sediments range from silty sand at the submerged delta to coarse sand and fine gravel in the innermost shelf (depth: 10-50 m). Coarse-grained sand comprises an expansive (32 km(2)) featureless sand sheet centered off the Merrimack River. Fine-grained sand discontinuously overlies this sand sheet in many locations and forms long wavelength (100 - 800 m), low amplitude (1-2 m), asymmetrical bedforms. Sets of these bedforms are oriented from slightly oblique offshore to onshore; several bedform sets are located within I km and oriented orthogonally to one another. Along the paleo-delta front north-northwest oriented bedforms are dominant. Inshore of these features, the bedforms become more closely spaced and have orientations to the west and west-southwest. Preliminary data suggest that the combined forces of instantaneous storm-wave generated shear stress and storm-induced currents associated with high energy northeast storm events may be responsible for sand sheet reworking and bedform development.
Sp. Iss. 50V16hi Times Cited:2 Cited References Count:22
Keywords: backscatter; bedforms; shallow seismic; shelf sediment transport

Holocene sea-level oscillations and environmental changes on the Eastern Black Sea shelf - Ivanova, E. V.; Murdmaa, I. O.; Chepalyga, A. L.; Cronin, T. M.; Pasechnik, I. V.; Levchenko, O. V.; Howe, S. S.; Manushkina, A. V.; Platonova, E. A. (Palaeogeography Palaeoclimatology Palaeoecology, 2007)
A multi-proxy study of four sediment cores from the Eastern (Caucasian) Black Sea shelf revealed five transgressive-regressive cycles overprinted on the general trend of glacioeustatic sea-level rise during the last 11,000 C-14 yr. These cycles are well represented in micro-and macrofossil assemblages, sedimentation rates, and gain size variations. The oldest recovered sediments were deposited in the Neoeuxinian semi-freshwater basin (similar to 10,500-9000 C-14 yr BP) and contain a Caspian-type mollusk fauna dominated by Dreissena rostriformis. Low delta O-18 and delta C-13 values are measured on this species. The first appearance of marine mollusks and ostracodes from the Mediterranean is established in this part of the Black Sea at similar to 8200 C-14 yr BP, i.e., about 1000-2000 yr later than the appearance of marine microfossils in the deeper part of the sea. The Early Holocene (Bugazian to Vityazevian) condensed section of shell and shelly mud sediments with at least two hiatuses represent a high-energy shelf-edge facies. It contains a transitional assemblage representing a mixture of Caspian and Mediterranean fauna. This pattern suggests a dual-flow regime via the Bosphorus after 8200 C-14 yr BR Caspian species disappear and oligolialine species decrease in abundance during the Vityazevian-Prekalamitian cycle. Later, during the Middle to Late Holocene, low sea-level stands are characterized by shell layers, whereas silty mud with various mollusk and ostracode assemblages rapidly accumulated during transgressions. Restricted mud accumulation, as well as benthic faunal composition and abundance, suggest high-energy and well-ventilated bottom water during low sea-level stands. A trend of O-18 enrichment in mollusk shells points to an increase in bottom-water salinity during the Vityazevian to Kalamitian transgressions (similar to 7000 to 5700 C-14 yr BP) due to a more open connection with the Mediterranean, while a pronounced increase in polyhaline species abundance is established during the Kalamitian to Djemetean transgressions (similar to 6400 to 2700 C-14 yr BP). However, the composition of the faunal assemblage indicates that bottom-water salinity never exceeded modem values of 18-20 psu. (c) 2006 Elsevier B.V. All rights reserved.
156gzTimes Cited:22Cited References Count:51

Holocene sedimentation in a kettle lpond breached by rising sea level on Cape Cod - Bratton, John F. (Northeast Section Meeting, Geological Society of America, 2007)
id: 1065; 1

Household and Community Archaeology at the Chumash Village of Niaqla, Santa Rosa Island, California - Rick, Torben C. (Journal of Field Archaeology, 2007)
id: 2072

Human responses to Middle Holocene climate change on California's Channel Islands - Kennett, D. J.; Kennettb, J. P.; Erlandson, J. M.; Cannariato, K. G. (Quaternary Science Reviews, 2007)
High-resolution archaeological and paleoenvironmental records from California's Channel Islands provide a unique opportunity to examine potential relationships between climatically induced environmental changes and prehistoric human behavioral responses. Available climate records in western North America (7-3.8 ka) indicate a severe dry interval between 6.3 and 4.8 ka embedded within a generally warm and dry Middle Holocene. Very dry conditions in western North America between 6.3 and 4.8 ka correlate with cold to moderate sea-surface temperatures (SST) along the southern California Coast evident in Ocean Drilling Program (ODP) Core 893A/B (Santa Barbara Basin). An episode of inferred high marine productivity between 6.3 and 5.8 ka corresponds with the coldest estimated SSTs of the Middle Holocene, otherwise marked by warm/low productivity marine conditions (7.5-3.8 ka). The impact of this severe aridity on humans was different between the northern and southern Channel Islands, apparently related to degree of island isolation, size and productivity of islands relative to population, fresh water availability, and on-going social relationships between island and continental populations. Northern Channel Islanders seem to have been largely unaffected by this severe and phase. In contrast, cultural changes on the southern Channel Islands were likely influenced by the climatically induced environmental changes. We suggest that productive marine conditions coupled with a dry terrestrial climate between 6.3 and 5.8 ka stimulated early village development and intensified fishing on the more remote southern islands. Contact with people on the adjacent southern California Coast increased during this time with increased participation in a down-the-line trade network extending into the western Great Basin and central Oregon. Genetic similarities between Middle Holocene burial populations on the southern Channel Islands and modern California Uto-Aztecan populations suggest Middle Holocene movement of people at this time from southern California desert environs westward to the southern islands, a migration perhaps stimulated by increased continental aridity. (c) 2006 Elsevier Ltd. All rights reserved.
158ghTimes Cited:49Cited References Count:167

Intense hurricane activity over the past 5,000 years controlled by El Nino and the West African monsoon - Donnelly, J. P.; Woodruff, J. D. (Nature, 2007)
The processes that control the formation, intensity and track of hurricanes are poorly understood. It has been proposed that an increase in sea surface temperatures caused by anthropogenic climate change has led to an increase in the frequency of intense tropical cyclones, but this proposal has been challenged on the basis that the instrumental record is too short and unreliable to reveal trends in intense tropical cyclone activity. Storm-induced deposits preserved in the sediments of coastal lagoons offer the opportunity to study the links between climatic conditions and hurricane activity on longer timescales, because they provide centennial- to millennial-scale records of past hurricane landfalls. Here we present a record of intense hurricane activity in the western North Atlantic Ocean over the past 5,000 years based on sediment cores from a Caribbean lagoon that contain coarse-grained deposits associated with intense hurricane landfalls. The record indicates that the frequency of intense hurricane landfalls has varied on centennial to millennial scales over this interval. Comparison of the sediment record with palaeo-climate records indicates that this variability was probably modulated by atmospheric dynamics associated with variations in the El Nino/Southern Oscillation and the strength of the West African monsoon, and suggests that sea surface temperatures as high as at present are not necessary to support intervals of frequent intense hurricanes. To accurately predict changes in intense hurricane activity, it is therefore important to understand how the El Nino/Southern Oscillation and the West African monsoon will respond to future climate change.
Donnelly, Jeffrey PWoodruff, Jonathan DengResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.England2007/05/25 09:00Nature. 2007 May 24;447(7143):465-8.

Last millennia sedimentary record on a micro-tidal, low-accumulation prodelta (Tet NW Mediterranean) - Bourrin, F.; Monaco, A.; Aloisi, J. C.; Sanchez-Cabeza, J. A.; Lofi, J.; Heussner, S.; de Madron, X. D.; Jeanty, G.; Buscail, R.; Saragoni, G. (Marine Geology, 2007)
Statistical sequential analysis was performed on a series of sediment cores collected from the Tet prodelta in the Gulf of Lions, northwestern Mediterranean Sea, between October 2003 and October 2004. Seabed changes during that period were correlated to hydrodynamic conditions (waves and currents) and river discharge. Low sediment supply prevents full preservation of new sediment strata on this low-accumulation prodelta located on a microtidal, storm-dorninated inner shelf. Severe meteorological events caused a rapid succession of erosion and deposition phases. For example, the December 2003 flood and storm produced a flood layer deposit that persisted for 2 months with only slight transformations due to early diagenesis and/or bioturbation, until a new, storm event eroded this layer. A typical sedimentary sequence was observed for the secular deposits composed of a 10-cm-thick sandy layer overlaying siltyclayey layers. These characteristic features were used to analyse the last millennia sedimentary record of the Tet prodelta. The low preservation of freshly deposited sediments and variable sedimentation rates during the last millennia period yield a sedimentary sequence formed by the outcropping of muddy prodeltaic units intersected by heterogeneous siltysandy units similar to those formed under present day hydrodynamic conditions. No flood layer was found related to catastrophic flooding of the last century in the sedimentary record. The Little lee Age (similar to 1550-1850 AD) probably favoured the formation of a well-developed muddy prodelta in the mouth of the Tet River. Later on, the decrease of sediment supply by rivers due to climate change and/or human activities (damming, irrigation), and the increase of the number of high-energy storms reaching the coast, induced a coarsening of the top sediment layer on this prodelta. This modem change of the substrate is also observed in the composition of benthic biota found in the substrate. (c) 2007 Elsevier B.V All rights reserved.
id: 1904; 210TU Times Cited:8 Cited References Count:68Y

Late Holocene barrier island collapse; Outer Banks, North Carolina, USA - Culver, Stephen J.; Grand Pre, Candace A.; Mallinson, David J.; Riggs, Stanley R.; Corbett, D. Reide; Foley, Jennifer; Hale, Michael; Metger, Lauren; Ricardo, John; Rosenberger, Jeb; Smith, Christopher G.; Smith, Curtis W.; et al. (The Sedimentary Record, 2007)
We document here the threat of large scale destruction (collapse) of barrier islands based on the study of many cores taken along the Outer Banks and in Pamlico Sound, North Carolina.Around 1,100 cal yr BP, probably as the result of hurricane activity, portions of the southern Outer Banks must have collapsed to allow normal salinity waters to bathe southern Pamlico Sound for several hundred years. Such collapse could occur again during our current regime of global warming, rising sea level and increased tropical cyclone activity. The economic effect of barrier island break collapse on Outer Banks communities would be devastating.
id: 1887; ISSN: 1543-8740 Language: English References: 16; illus. incl. strat. col., geol. sketch map United States (USA) Latitude:N350000,N353000 Longitude:W0753000,W0760000
Keywords: 24, Quaternary geology; algae; assemblages; barrier islands; Cenozoic; changes; clastic sediments; cores; diatoms; erosion; Foraminifera; geologic hazards; Holocene; hurricanes; Invertebrata; landform evolution; lithofacies; littoral; microfossils; North Carolina; Outer Banks; Pamlico Sound; Plantae; preservation; Protista; Quaternary; salinity; sand; sea-level; sediments; United States; upper Holocene; Vibroseis

Late Holocene fine-grained sediments of the Balearic Abyssal Plain, Western Mediterranean Sea - Zuniga, D.; Garcia-Orellana, J.; Calafat, A.; Price, N. B.; Adatte, T.; Sanchez-Vidal, A.; Canals, M.; Sanchex-Cabeza, J. A.; Masque, P.; Fabres, J. (Marine Geology, 2007)
The Late Holocene fine-grained sedimentation in the deep central Balearic Abyssal Plain, Western Mediterranean Sea, has been studied after the analysis of high quality sediment cores from three multicoring stations, named A, B and C. The coring stations are 25 km apart from each other and form a triangle that is at the greatest distance from the nearest landmasses. The sediments consist of foraminifer-pteropod oozes (layers U1 and U4 from bottom to top), two pteropod oozes (U2 and U5) and a turbidite layer (U3). The same sequence has been identified in the three cores. The turbidite layer U3 that lies on top of U2 (C-14 AMS dated at 1814 cal yrs BP) ranges from 5 to I I cm thick and is clearly distinguished from the dominating hemipelagic sediments by colour variations, higher water content and the absence of planktonic foraminifer shells. Rather uniform values of organic carbon and nitrogen are also characteristic of the U3 turbidite unit, likely because of homogenisation during transport and emplacement. In addition, U3 unit shows higher contents of terrigenous elements such as K and Fe. Otherwise, the presence of zeolites in the turbidite layer supports the hypothesis of the Sardinian continental margin, where pyroclastic deposits are known, as the most likely source area for U3. Our results demonstrate the ability of turbidity currents originating on the margins surrounding the Balearic Abyssal Plain to reach the very centre of the basin during high sea level still stands as the present one. (c) 2006 Elsevier B.V. All rights reserved.
id: 624; 139VA Times Cited:6 Cited References Count:57

Late Quaternary environmental and human events at En Gedi, reflected by the geology and archaeology of the Moringa Cave (Dead Sea area, Israel) - Lisker, S.; Porat, R.; Davidovich, U.; Eshel, H.; Lauritzen, S. E.; Frumkin, A. (Quaternary Research, 2007)
The Moringa Cave within Pleistocene sediments in the En Gedi area of the Dead Sea Fault Escarpment contains a sequence of various Pleistocene lacustrine deposits associated with higher-than-today lake levels at the Dead Sea basin. In addition it contains Chalcolithic remains and 5th century BC burials attributed to the Persian period, cemented and covered by Late Holocene travertine flowstone. These deposits represent a chain of Late Pleistocene and Holocene interconnected environmental and human events, echoing broader scale regional and global climate events. A major shift between depositional environments is associated with the rapid fall of Lake Lisan level during the latest Pleistocene. This exposed the sediments, providing for cave formation processes sometime between the latest Pleistocene (ca. 15 ka) and the Middle Holocene (ca. 4500 BC), eventually leading to human use of the cave. The Chalcolithic use of the cave can be related to a relatively moist desert environment, probably related to a shift in the location of the northern boundary of the Saharo-Arabian desert belt. The travertine layer was U-Th dated 2.46 +/- 0.10 to 2.10 +/- 0.04 ka, in agreement with the archaeological finds from the Persian period. Together with the inner consistency of the dating results, this strongly supports the reliability of the radiometric ages. The 2.46-2.10 ka travertine deposition within the presently dry cave suggests a higher recharge of the Judean Desert aquifer, correlative to a rising Dead Sea towards the end of the 1 st millennium BC. This suggests a relatively moist local and regional climate facilitating human habitation of the desert. (c) 2007 University of Washington. All rights reserved.
207wkTimes Cited:3Cited References Count:55

Late quaternary lake and swamp sediments: records of climate and environment - Horn, S. P. (Central America: Geology, Resources, Hazards, 2007)
id: 622

Late quaternary paleoseismology of the southern Steens fault zone, northern Nevada - Personius, Stephen F.; Crone, Anthony J.; Machette, Michael N.; Mahan, Shannon A.; Kyung, Jai Bok; Cisneros, Hector; Lidke, David J. (Bulletin of the Seismological Society of America, 2007)
The 192-km-long Steens fault zone is the most prominent normal fault system in the northern Basin and Range province of western North America. We use trench mapping and radiometric dating to estimate displacements and timing of the last three surface-rupturing earthquakes (E1-E3) on the southern part of the fault south of Denio, Nevada. Coseismic displacements range from 1.1 to 2.2 +/- 0.5 m, and radiometric ages indicate earthquake times of 11.5 +/- 2.0 ka (E3), 6.1 +/- 0.5 ka (E2), and 4.6 +/- 1.0 ka (E1). These data yield recurrence intervals of 5.4 +/- 2.1 k.y. between E3 and E2, 1.5 +/- 1.1 k.y. between E2 and E1, and an elapsed time of 4.6 +/- 1.0 k.y. since El. The recurrence data yield variable interval slip rates (between 0.2 +/- 0.22 and 1.5 +/- 2.3 mm/yr), but slip rates averaged over the past similar to 18 k.y. (0.24 +/- 0.06 mm/year) are similar to long-term (8.5-12.5 Ma) slip rates (0.2 +/- 0.1 mm/yr) measured a few kilometers to the north. We infer from the lack of significant topographic relief across the fault in Bog Hot Valley that the fault zone is propagating southward and may now be connected with a fault at the northwestern end of the Pine Forest Range. Displacements documented in the trench and a rupture length of 37 km indicate a history of three latest Quaternary earthquakes with magnitudes of M 6.6-7.1 on the southern part of the Steens fault zone.
id: 2022; PT: J; UT: WOS:000249930900021

Late-glacial through Holocene stratigraphy and lake-level record ofRangeley Lake, Western Maine - Metcalfe, Elisabet (University of Maine, 2007)

A late-glacial transition from Picea glauca to Picea mariana in southern New England - Lindbladh, M.; Oswald, W. W.; Foster, D. R.; Faison, E. K.; Hou, J. Z.; Huang, Y. S. (Quaternary Research, 2007)
Picea is an important taxon in late-glacial pollen records from eastern North America, but little is known about which species of Picea were present. We apply a recently developed palynological method for discriminating the three Picea species in eastern North America to three records from New England. Picea glauca was dominant at similar to 14,500-14,000 cal yr BP, followed by a transition to Picea mariana between similar to 14,000 and 13,500 cal yr BP. Comparison of the pollen data with hydrogen isotope data shows clearly that this transition began before the beginning of the Younger Dryas Chronozone. The ecological changes of the late-glacial interval were not a simple oscillation in the position of a single species' range, but rather major changes in vegetation structure and composition occurring during an interval of variations in several environmental factors, including climate, edaphic conditions, and atmospheric CO2 levels. (c) 2007 University of Washington. All rights reserved.
id: 1841; 160RU Times Cited:5 Cited References Count:61Y

Linking lithology and land use to sources of dissolved and particulate organic matter in headwaters of a temperate, passive-margin river system - Longworth, B. E.; Petsch, S. T.; Raymond, P. A.; Bauer, J. E. (Geochimica Et Cosmochimica Acta, 2007)
A number of rivers have been found to transport highly aged organic matter [OM]; however, the sources of this aged material remain a matter of debate. One potential source may be erosion and weathering of headwater lithologies rich in ancient sedimentary OM. In this study, waters, suspended particulates, streambed sediments, rocks and soils from fourteen small headwater watersheds of a mid-size, temperate, passive margin river were sampled and characterized by Delta C-14, delta C-13, and POC/TPN ratios to identify sources of particulate and dissolved OM delivered to the river mainstem. These headwater sites encompass a range in lithology (OM-rich shales, OM-lean carbonate/mudstone facies, and OM-free crystalline rocks) and land use types (forested and agricultural), and allow investigation of the influence of agriculture and bedrock types on stream OM characteristics. Streams draining large areas of both agricultural land use and OM-rich lithology contain particulate OM [POM] that is more C-14-depleted than streams draining forested, shale-free watersheds. However, this is not sufficient to account for the significantly lower Delta C-14-POC measured in the river mainstern. Dissolved OM [DOM] Delta C-14 are in all cases enriched compared to POM from the same stream, but are otherwise highly variable and unrelated to either land use or lithology. POC/TPN ratios were likewise highly variable. POC and DOC delta C-13 signatures were similar across all watersheds. Based on isotope mass balance, C-14-free fossil OM sources contribute 0-12% of total stream POM. Although these results do not unequivocally separate the influences of land use and lithology, watershed coverage by shale and agriculture are both important controls on stream A Delta C-14-POC. Thus export of aged, particle-associated OM may be a feature of river systems along both passive and active continental margins. (C) 2007 Elsevier Ltd. All rights reserved.
30
Keywords: ATCHAFALAYA RIVER; ATMOSPHERIC O-2; BLACK SHALE; continental-shelf; GULF-OF-MEXICO; marine-sediments; MINERAL; SPACE-TIME CLIMATE; STABLE-ISOTOPES; surface sediments; SURFACES

Lithological anomalies in a relict coastal dune: Geophysical and paleoenvironmental markers - Buynevich, I. V.; Bitinas, A.; Pupienis, D. (Geophysical Research Letters, 2007)
Ground exposures of migration surfaces (slipfaces) of a relict Holocene coastal dune along the southeastern Baltic Sea coast provide an ideal opportunity for establishing the causes of prominent reflections on geophysical profiles. High-amplitude reflections on high-resolution ground-penetrating radar (GPR) images correlate well with two major lithological anomalies: 1) paleosols developed on dune slipfaces, and 2) slipfaces consisting of heavy-mineral concentrations (HMCs). Paleosols serve as indicators of dune stability, represent datable chronostratigraphic surfaces, and help reconstruct dune paleo-morphology. HMCs have substantially higher magnetic susceptibility values than background quartz-rich sands and, where they are well-developed, can be also used for spatial correlation. Based on their occurrence at the study site, these enriched horizons likely represent periods of increased wind activity ( storminess). Multiple HMCs upwind of paleosol P1 ( 800 670 cal years BP) likely reflect periods of intensified wind activity along the southeast Baltic region during the Medieval Warm Period.
168ajTimes Cited:18Cited References Count:38

Little Ice Age drought in equatorial Africa: Intertropical Convergence Zone migrations and El Nino-Southern Oscillation variability RID C-1423-2010 - Russell, J. M.; Johnson, T. C. (Geology, 2007)
High-resolution analyses of the Mg concentration in authigenic calcite in five cores from Lake Edward provide a water balance history of central equatorial Africa spanning the past 1400 yr. A high ratio of Mg to Ca (%Mg) indicates strong droughts in central Africa during the Little Ice Age (A.D. 1400-1750), in contrast to records from Lake Naivasha, Kenya, which suggest a wet Little Ice Age. This spatial pattern in Africa likely arose due to coupled changes in the high latitudes, the position of the Intertropical Convergence Zone, and the Ell Ni (n) over tildeo-Southern Oscillation (ENSO) system. Our results further suggest that the patterns and variability of twentieth-century rainfall in central Africa have been unusually conducive to human welfare in the context of the past 1400 yr.
id: 2049; PT: J; UT: WOS:000243483800006

Little Ice Age drought in quatorial Africa: ITCZ migrations and ENSO variability - Russell, J. M.; Johnson, T. C. (geology, 2007)
id: 1005

Long-term settlement, mobility, and landscape formation of Eastern Eurasian pastoralists from 2500 CAL B.C - Frachetti, M. D.; Mar’yashev, A. N. (Journal of Field Archaeology, 2007)
id: 1881

Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise - Marchitto, T. M.; Lehman, S. J.; Ortiz, J. D.; Fluckiger, J.; van Geen, A. (Science, 2007)
We reconstructed the radiocarbon activity of intermediate waters in the eastern North Pacific over the past 38,000 years. Radiocarbon activity paralleled that of the atmosphere, except during deglaciation, when intermediate-water values fell by more than 300 per mil. Such a large decrease requires a deglacial injection of very old waters from a deep-ocean carbon reservoir that was previously well isolated from the atmosphere. The timing of intermediate-water radiocarbon depletion closely matches that of atmospheric carbon dioxide rise and effectively traces the redistribution of carbon from the deep ocean to the atmosphere during deglaciation.
Marchitto, Thomas MLehman, Scott JOrtiz, Joseph DFluckiger, Jacquelinevan Geen, AlexanderengResearch Support, U.S. Gov't, Non-P.H.S.2007/05/15 09:00Science. 2007 Jun 8;316(5830):1456-9. Epub 2007 May 10.

Middle Holocene subsistence and land use on Southeast Anchorage, Santa Rosa Island, California - Wolff, Christopher B.; Rick, Torben C.; Aland, Amanda (Journal of California and Great Basin Anthropology, 2007)
California's Channel Islands have a lengthy archaeological record, spanning roughly 13,000 calendar years. However, relatively little is known about cultural developments during the Middle Holocene, resulting in a substantial gap in our understanding of the prehistory of California. Our research at CA-SRI-667, a large dune site with three components dated between about 6,200 and 4,300 cal B.P., demonstrates significant environmental changes occurred through time. Faunal remains and artifacts from the site document the decline of a local estuary, intensive dune building episodes, and the presence of relatively mobile human settlement systems. These data illustrate the dynamic nature of Middle Holocene human settlement and subsistence strategies, and associated environmental changes on California's Channel Islands.
id: 2082

A Mid-Holocene environmental change in Amazonian savannas - de Toledo, M. B.; Bush, M. B. (Journal of Biogeography, 2007)
id: 455

Mobilization pathways of organic carbon from permafrost to arctic rivers in a changing climate - Guo, L. D.; Ping, C. L.; Macdonald, R. W. (Geophysical Research Letters, 2007)
[1] Arctic warming may cause the release of vast amounts of soil organic carbon (SOC) from permafrost, which will manifest itself in the fluxes and composition of organic carbon in northern rivers and Arctic coastal regions. To elucidate the transport pathways of SOC, radiocarbon composition was measured for dissolved organic carbon (DOC), particulate organic carbon (POC), sediments and SOC from the Mackenzie, Sagavanirktok, and Yukon river basins, and soil leaching experiments were conducted. The radiocarbon ages of riverine suspended POC and sediments ranged from 4430 to similar to 7970 yr BP, while DOC was much younger (390-1440 yr BP) except samples from the Sag River. Soil leaching experiments released
id: 773; 187WS Times Cited:23 Cited References Count:29Y

A multiproxy peat record of Holocene mangrove palaeoecology from Twin Cays, Belize - Wooller, Matthew J.; Morgan, Rebecca; Fowell, Sarah; Behling, Hermann; Fogel, Marilyn (The HoloceneThe Holocene, 2007)
The extent and function of coastal mangrove ecosystems are likely to be influenced by future changes in sea level. Multiple proxies of past mangrove ecosystems preserved in a 780 cm long peat core (TCC2) taken from Twin Cays, Belize, record palaeoecological changes since ~8000 cal. yr BP. The proxies included pollen and the stable-isotope (C, N and O) compositions of mangrove leaf fragments. Rhizophora mangle (red mangrove) has been dominant at this site on Twin Cays for over ~8000 years. Variations in δ13 C and δ15N suggest past changes in stand structure between dwarf, transition and tall R. mangle through the Holocene. Marked changes in the δ18O (up to ~4?) of mangrove leaf fragments throughout TCC2 most likely record variations in the proportion of seawater versus precipitation taken up by past mangroves, reflecting the degree of inundation of the site with seawater resulting from changes in the rate of Holocene sea-level rise. Notably, a decline in peat accumulation rate at ~7200 cal. yr BP correlates with a decrease in the rate of rise in sea level. This was not accompanied by a marked change in the pollen assemblages. However, changes in assemblage composition began to occur ~6300 cal. yr BP, with an increase in Myrsine-type and Avicennia germinans (black mangrove) pollen. An increase in the δ18O between 6100 and 5300 cal. yr BP, which correlates with other records from Central America, indicates a significant increase in the rate of rise in sea level.The extent and function of coastal mangrove ecosystems are likely to be influenced by future changes in sea level. Multiple proxies of past mangrove ecosystems preserved in a 780 cm long peat core (TCC2) taken from Twin Cays, Belize, record palaeoecological changes since ~8000 cal. yr BP. The proxies included pollen and the stable-isotope (C, N and O) compositions of mangrove leaf fragments. Rhizophora mangle (red mangrove) has been dominant at this site on Twin Cays for over ~8000 years. Variations in δ13 C and δ15N suggest past changes in stand structure between dwarf, transition and tall R. mangle through the Holocene. Marked changes in the δ18O (up to ~4?) of mangrove leaf fragments throughout TCC2 most likely record variations in the proportion of seawater versus precipitation taken up by past mangroves, reflecting the degree of inundation of the site with seawater resulting from changes in the rate of Holocene sea-level rise. Notably, a decline in peat accumulation rate at ~7200 cal. yr BP correlates with a decrease in the rate of rise in sea level. This was not accompanied by a marked change in the pollen assemblages. However, changes in assemblage composition began to occur ~6300 cal. yr BP, with an increase in Myrsine-type and Avicennia germinans (black mangrove) pollen. An increase in the δ18O between 6100 and 5300 cal. yr BP, which correlates with other records from Central America, indicates a significant increase in the rate of rise in sea level.

Naze Site (32SN246) 1994 Archeological Excavations Stutsman County, North Dakota. James River Report Number 4 - Toom, Dennis L. (University of North Dakota, 2007)
id: 296

The nitrogen isotope biogeochemistry of Long Island Sound; insights into mechanisms of 15N enrichment in eutrophication-impacted estuaries - Altabet, M. A.; Varekamp, J. C. (ASLO Meeting, 2007)
id: 752

North Atlantic intermediate depth variability during the Younger Dryas; evidence from benthic foraminiferal Mg/Ca and the GFDL R30 coupled climate model - Came, Rosemarie E.; Curry, William B.; Oppo, Delia W.; Broccoli, Anthony J.; Stouffer, Ronald J.; Lynch-Stieglitz, Jean (Geophysical Monograph, vol. 173, 2007)
id: 857; American Geophysical Union 2005 fall meeting, San Francisco, CA, United States, Dec 5-9, 2005 NSF grants OCE-0096495, ATM-0502428, OCE-0096472, OCE-0220776 and ATM-0501351 References: 72; illus.; Y
Keywords: 24, Quaternary geology; Atlantic Ocean; benthic environment; Cenozoic; chemical ratios; Foraminifera; Glaciation; Gulf of Mexico; ice cores; Invertebrata; isotope ratios; isotopes; Little Bahama Bank; Mg/Ca; microfossils; North Atlantic; O-18/O-16; oxygen; paleo-oceanography; paleobathymetry; paleosalinity; paleotemperature; Pleistocene; Protista; Quaternary; Stable isotopes; Straits of Florida; upper; upper Weichselian; Weichselian; Younger Dryas

Oceanic dispersal and accumulation of river sediment - Sommerfield, C. K.; Agston, A. S.; Mullenbach, B. L.; Drake, D. E.; Alexander, C. R.; Nittrouer, C. A.; Borgeld, J. C.; Wheatcroft, R. A.; Leithold, E. L. (Continental-Margin Sedimentation: from Sediment Transport to Sequence Stratigraphy, 2007)
id: 1119

One if by land, two if by sea: who were the first Californians? - Erlandson, Jon M.; Rick, Torben C.; Jones, Terry L.; Porcasi, Judith (California Prehistory:Colonization, Culture and Complexity, 2007)
id: 2081

Organic matter origin and distribution in suspended particulate materials and surficial sediments from the western Adriatic Sea (Italy) - Tesi, T.; Miserocchi, S.; Goñi, M. A.; Langone, L.; Boldrin, A.; Turchetto, M. (Estuarine Coastal and Shelf Science, 2007)
In this study, organic carbon (OC), total nitrogen (TN), stable carbon isotopic (delta C-13(OC)) and CuO reaction product compositions were used to identify the sources of organic matter (OM) and to quantify the relative importance of allochthonous and autochthonous contributions to the western Adriatic Sea, Italy. Suspended particulate material (195 samples) and surficial sediments (0- 1 cm, 70 samples) from shallow cross-shelf transects were collected in February and May 2003, respectively. Vertical water column profiles were acquired along the same transects. Data include depth, potential temperature, salinity, density and chlorophyll fluorimetry. Along the western Adriatic shelf in the near-shore region, the phytoplankton growth was influenced by dynamics of the buoyant plumes from the Po and Appennine rivers. A small amount of very fine terrigenous material remained suspended within the coastal current and was exported southward along the shelf to the slope. High variability in the bulk composition was detected in the Po prodelta surficial sediments, whereas the western Adriatic shelf, although a larger area, exhibited a narrower range of values. A significant decoupling was observed between suspended particles in the water column and surficial deposits. The organic material collected in the water column was compositionally heterogeneous, with contributions from marine phytoplankton, riverine-estuarine phytoplankton and soil-derived OM. Frequent physical reworking of surficial sediments likely leads to the efficient oxidation of marine OC, resulting in the observed accumulation and preservation of refractory soil-derived OC delivered by the Po and Appennine rivers. (c) 2007 Elsevier Ltd. All rights reserved.
id: 1869; 179HX Times Cited:12 Cited References Count:61Y

Paleoecology and ecosystem restoration: case studies from Chesapeake Bay and the Florida Everglades - Willard, D. A.; Cronin, T. M. (Frontiers in Ecology and the Environment, 2007)
Climate extremes that cause droughts, floods, or large temperature fluctuations can complicate ecosystem restoration efforts focused on local and regional human disturbance. Restoration targets are often based primarily on monitoring data and modeling simulations, which provide information on species' short-term response to disturbance and environmental variables. Consequently, the targets may be unsustainable under the spectrum of natural variability inherent in the system or under future climate change. Increasingly, ecologists and restoration planners recognize the value of the long temporal perspective provided by paleoecological data. Advances in paleoclimatology, including better climate proxy methods and temporal resolution, contribute to our understanding of ecosystem response to anthropogenic and climatic forcing at all time scales. We highlight paleoecological research in the Chesapeake Bay and the Florida Everglades and summarize the resulting contributions to restoration planning. Integration of paleoecological, historic, monitoring, and modeling efforts will lead to the development of sustainable, adaptive management strategies for ecosystem restoration.
id: 811; 227MD Times Cited:5 Cited References Count:51Y

Paleoenvironmental change in the middle Okinawa Trough since the last deglaciation: Evidence from the sedimentation rate and planktonic foraminiferal record - Xiang, R.; Sun, Y. B.; Li, T. G.; Oppo, D. W.; Chen, M. H.; Zheng, F. (Palaeogeography Palaeoclimatology Palaeoecology, 2007)
Well-dated, high-resolution records of planktonic foraminifera and oxygen isotopes from two sediment cores, A7 and E017, in the middle Okinawa Trough reveal strong and rapid millennial-scale climate changes since similar to 18 to 17 thousand years before present (kyr B.P.). Sedimentation rate shows a sudden drop at similar to 11.2 cal. kyr B.P. due to a rapid rise of sea level after the Younger Dryas (YD) and consequently submergence of the large continental shelf on the East China Sea (ECS) and the retreat of the estuary providing sediment to the basin. During the last deglaciation, the relative abundance of warm and cold species of planktonic foraminifera fluctuates strongly, consistent with the timing of sea surface temperature (SST) variations determined from Mg/Ca measurements of planktonic foraminifera from one of the two cores. These fluctuations are coeval with climate variation recorded in the Greenland ice cores and North Atlantic sediments, namely Heinrich event 1 (H1), Bolling-Allerod (B/A) and YD events. At about 9.4 kyr B.P., a sudden change in the relative abundance of shallow to deep planktonic species probably indicates a sudden strengthening of the Kuroshio Current in the Okinawa Trough, which was synchronous with a rapid sea-level rise at 9.5-9.2 kyr B.P. in the ECS, Yellow Sea (YS) and South China Sea (SCS). The abundance of planktonic foraminiferal species, together with Mg/Ca based SST, exhibits millennial-scale oscillations during the Holocene, with 7 cold events (at about 1.7, 2.3-4.6, 6.2, 7.3, 8.2, 9.6, 10.6 cal. kyr BP) superimposed on a Holocene warming trend. This Holocene trend, together with centennial-scale SST variations superimposed on the last deglacial trend, suggests that both high and low latitude influences affected the climatology of the Okinawa Trough. (c) 2006 Elsevier B.V. All rights reserved.
134kzTimes Cited:48Cited References Count:62

Paleoenvironmental proxy records from Lake Hovsgol, Mongolia, and a synthesis of Holocene climate change in the Lake Baikal watershed - Prokopenko, A. A.; Khursevich, G. K.; Bezrukova, E. V.; Kuzmin, M. I.; Boes, X.; Williams, D. F.; Fedenya, S. A.; Kulagina, N. V.; Letunova, P. P.; Abzaeva, A. A. (Quaternary Research, 2007)
Here we discuss palcoenvironmental evolution in the Baikal region during the Holocene using new records of aquatic (diatom) and terrestrial vegetation changes from Hovsgol, Mongolia's largest and deepest lake. We reconcile previous contradictory Baikal timescales by constraining reservoir corrections of AMS dates on bulk sedimentary organic carbon. Synthesis of the Holocene records in the Baikal watershed reveals a northward progression in landscape/vegetation changes and an anti-phase behavior of diatom and biogenic silica proxies in neighboring rift lakes. In Lake Baikal, these proxies appear to be responsive to annual temperature increases after 6 ka, whereas in Lake Hovsgol they respond to higher precipitation/runoff from 11 to 7 ka. Unlike around Lake Baikal, warmer summers between 6 and 3.5 ka resulted in the decline, not expansion, of forest vegetation around Lake Hovsgol, apparently as a result of higher soil temperatures and lower moisture availability. The regional climatic proxy data are consistent with a series of 500-yr time slice Holocene GCM simulations for continental Eurasia. Our results allow reevaluation of the concepts of 'the Holocene optimum' and a 'maximum of the Asian summer monsoon', as applied to palcoclimate records from continental Asia. (c) 2007 University of Washington. All rights reserved.
187enTimes Cited:71Cited References Count:58

Paleoenvironmental significance of the eastern mud snail, Ilyanassa obsolete (Say, 1822), from a microtidal coastal sequence of southern New England - Buynevich, I. V. (The Nautilus, 2007)
id: 1082

Paleoseismology of the Nephi segment of the Wasatch fault zone, Juab County, Utah--Preliminary results from two large exploratory trenches at Willow Creek - Machette, M. N.; Crone, A. J.; Personius, S. F.; Dart, R. L.; Lidke, D. J.; Mahan, S. A.; Olig, S. S. (U. S. Geological Survey, 2007)
id: 1116; Investigations Map 2966, 2 oversize plates

Placing late Neanderthals in a climatic context RID A-5197-2008 - Tzedakis, P. C.; Hughen, K. A.; Cacho, I.; Harvati, K. (Nature, 2007)
Attempts to place Palaeolithic finds within a precise climatic framework are complicated by both uncertainty over the radiocarbon calibration beyond about 21,500 (14)C years BP(1) and the absence of a master calendar chronology for climate events from reference archives such as Greenland ice cores or speleothems(2). Here we present an alternative approach, in which (14)C dates of interest are mapped directly onto the palaeoclimate record of the Cariaco Basin by means of its (14)C series(3), circumventing calendar age model and correlation uncertainties, and placing dated events in the millennial-scale climate context of the last glacial period. This is applied to different sets of dates from levels with Mousterian artefacts, presumably produced by late Neanderthals, from Gorham's Cave in Gibraltar: first, generally accepted estimates of about 32,000 (14)C years BP for the upper-most Mousterian levels(4,5); second, a possible extended Middle Palaeolithic occupation until about 28,000 (14)C years BP(6); and third, more contentious evidence for persistence until about 24,000 (14)C years BP(6). This study shows that the three sets translate to different scenarios on the role of climate in Neanderthal extinction. The first two correspond to intervals of general climatic instability between stadials and interstadials that characterized most of the Middle Pleniglacial and are not coeval with Heinrich Events. In contrast, if accepted, the youngest date indicates that late Neanderthals may have persisted up to the onset of a major environmental shift, which included an expansion in global ice volume and an increased latitudinal temperature gradient. More generally, our radiocarbon climatostratigraphic approach can be applied to any 'snapshot' date from discontinuous records in a variety of deposits and can become a powerful tool in evaluating the climatic signature of critical intervals in Late Pleistocene human evolution.
id: 1991; PT: J; UT: WOS:000249394500047

Planktonic foraminifera, calcareous nannoplankton and ascidian variations during the last 25 kyr in the Southwestern Atlantic: A paleoproductivity signature? - Toledo, Filipe A. L.; Chachao, Mario; Costa, Karen B.; Pivel, Maria A. G. (Marine Micropaleontology, 2007)
id: 1061

Population dynamics, structure and per-recruit analysis of yellowedge grouper, Epinephelus flavolimbatus, from the northern Gulf of Mexico - Cook, M. (University of Southern Mississippi, 2007)

Post-glacial changes in spatial patterns of vegetation across southern New England - Oswald, W. W.; Faison, E. K.; Foster, D. R.; Doughty, E. D.; Hall, B. R.; Hansen, B. C. S. (Journal of Biogeography, 2007)
Aim We analysed lake-sediment pollen records from eight sites in southern New England to address: (1) regional variation in ecological responses to post-glacial climatic changes, (2) landscape-scale vegetational heterogeneity at different times in the past, and (3) environmental and ecological controls on spatial patterns of vegetation. Location The eight study sites are located in southern New England in the states of Massachusetts and Connecticut. The sites span a climatic and vegetational gradient from the lowland areas of eastern Massachusetts and Connecticut to the uplands of north-central and western Massachusetts. Tsuga canadensis and Fagus grandifolia are abundant in the upland area, while Quercus, Carya and Pinus species have higher abundances in the lowlands. Methods We collected sediment cores from three lakes in eastern and north-central Massachusetts (Berry East, Blood and Little Royalston Ponds). Pollen records from those sites were compared with previously published pollen data from five other sites. Multivariate data analysis (non-metric multi-dimensional scaling) was used to compare the pollen spectra of these sites through time. Results Our analyses revealed a sequence of vegetational responses to climate changes occurring across southern New England during the past 14,000 calibrated radiocarbon years before present (cal yr BP). Pollen assemblages at all sites were dominated by Picea and Pinus banksiana between 14,000 and 11,500 cal yr BP; by Pinus strobus from 11,500 to 10,500 cal yr BP; and by P. strobus and Tsuga between 10,500 and 9500 cal yr BP. At 9500-8000 cal yr BP, however, vegetation composition began to differentiate between lowland and upland sites. Lowland sites had higher percentages of Quercus pollen, whereas Tsuga abundance was higher at the upland sites. This spatial heterogeneity strengthened between 8000 and 5500 cal yr BP, when Fagus became abundant in the uplands and Quercus pollen percentages increased further in the lowland records. The differentiation of upland and lowland vegetation zones remained strong during the mid-Holocene Tsuga decline (5500-3500 cal yr BP), but the pattern weakened during the late-Holocene (3500-300 cal yr BP) and European-settlement intervals. Within-group similarity declined in response to the uneven late-Holocene expansion of Castanea, while between-group similarity increased due to homogenization of the regional vegetation by forest clearance and ongoing disturbances. Main conclusions The regional gradient of vegetation composition across southern New England was first established between 9500 and 8000 cal yr BP. The spatial heterogeneity of the vegetation may have arisen at that time in response to the development or strengthening of the regional climatic gradient. Alternatively, the differentiation of upland and lowland vegetation types may have occurred as the climate ameliorated and an increasing number of species arrived in the region, arranging themselves in progressively more complex vegetation patterns across relatively stationary environmental gradients. The emergence of a regional vegetational gradient in southern New England may be a manifestation of the increasing number of species and more finely divided resource gradient.
id: 1840; 157BN Times Cited:5 Cited References Count:70Y

The power of radiocarbon in biogeochemical studies of the marine carbon cycle: insights from studies of dissolved and particulate organic carbon (DOC and POC) - McNichol, A. P.; Aluwihare, L. I. (Chem Rev, 2007)
McNichol, Ann PAluwihare, Lihini IengResearch Support, U.S. Gov't, Non-P.H.S.Review2007/02/16 09:00Chem Rev. 2007 Feb;107(2):443-66.

Preliminary geologic map of the north-central part of the Alamosa 1/2 degree x 1 degree quadrangle, Alamosa and Conejos Counties, Colorado - Machette, M. N.; Thompson, R. A. (U. S. Geological Survey Open-File Report, 2007)
id: 629; 1 sheet, 1:50,000 scale

Preservation of black carbon in the shelf sediments of the East China Sea - Wang, X. C.; Li, A. C. (Chinese Science Bulletin, 2007)
Concentrations and carbon isotopic (C-14, C-13) compositions of black carbon (BC) were measured for three sediment cores collected from the Changjiang River estuary and the shelf of the East China Sea. BC concentrations ranged from 0.02 to 0.14 mg/g (dry weight), and accounted for 5% to 26% of the sedimentary total organic carbon (TOC) pool. Among the three sediment cores collected at each site, sediment from the Changjiang River estuary had relatively high BC contents compared with the sediments from the East China Sea shelf, suggesting that the Changjiang River discharge played an important role in the delivery of BC to the coastal region. Radiocarbon measurements indicate that the ages of BC are in the range of 6910 to 12250 years old B. P. (before present), that is in general, 3700 to 9000 years older than the C-14 ages of TOC in the sediments. These variable radiocarbon ages suggest that the BC preserved in the sediments was derived from the products of both biomass fire and fossil fuel combustion, as well as from ancient rock weathering. Based on an isotopic mass balance model, we calculated that fossil fuel combustion contributed most (60%. 80%) of the BC preserved in these sediments and varied with depth and locations. The deposition and burial of this "slow-cycling" BC in the sediments of the East China Sea shelf represent a significant pool of carbon sink and could greatly influence carbon cycling in the region.
232knTimes Cited:13Cited References Count:28

Progress on a gas-accepting ion source for continuous-flow accelerator mass spectrometry - Roberts, M. L.; Schneider, R. J.; von Reden, K. F.; Wills, J. S. C.; Han, B. X.; Hayes, J. M.; Rosenheim, B. E.; W. J. Jenkins (Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 2007)
A gas-accepting microwave-plasma ion source is being developed for continuous-flow accelerator mass spectrometry (AMS). Characteristics of the ion source will be presented. Schemes for connecting a gas or liquid chromatograph to the ion source will also be discussed. (c) 2007 Ellsevier B.V. All rights reserved.
182wvTimes Cited:24Cited References Count:12

Quantification and radiocarbon source apportionment of black carbon in atmospheric aerosols using the CTO-375 method - Zencak, Z.; Elmquist, M.; Gustafsson, O. (Atmospheric Environment, 2007)
To make progress towards linking the atmosphere and biogeosphere parts of the black carbon (BC) cycle, a chemothermal oxidation method (CTO-375), commonly applied for isolating BC from complex geomatrices such as soils, sediments and aquatic particles, was applied to investigate the BC also in atmospheric particles. Concentrations and C-14-based source apportionment of CTO-375 based BC was established for a reference aerosol (NIST RM-8785) and for wintertime aerosols collected in Stockholm and in a Swedish background area. The results were compared with thermal-optical (OC/EC) measurements. For NIST RM-8785, a good agreement was found between the BCCTO-375 concentration and the reported elemental carbon (EC) concentration measured by the "Speciation Trends Network - National Institute of Occupational Safety and Health" method (ECNIOSH) with BCCTO-375 of 0.054+/-0.002gg(-1) and ECNIOSH of 0.067+/-0.008gg(-1). In contrast, there was an average factor of ca. 20 difference between BC(CTO-37)5 and ECNIOSH for the ambient Scandinavian wintertime aerosols, presumably reflecting a combination of BCCTO-375 isolating only the recalcitrant soot-BC portion of the BC continuum and the ECNIOSH metric inadvertently including some intrinsically non-pyrogenic organic matter. Isolation of BCCTO-375 with subsequent off-line radiocarbon analysis yielded fraction modern values (fM) for total organic carbon (TOC) of 0.93 (aerosols from a Swedish background area), and 0.58 (aerosols collected in Stockholm); whereas the fM for BCCTO-375 isolates were 1.08 (aerosols from a Swedish background area), and 0.87 (aerosols collected in Stockholm). This radiocarbon-based source apportionment suggests that contribution from biomass combustion to cold-season atmospheric BCCTO-375 in Stockholm was 70% and in the background area 88%. (C) 2007 Elsevier Ltd. All rights reserved.
id: 818; 243XB Times Cited:8 Cited References Count:58Y

Quantity, C-14 age and lability of desorbed soil organic carbon in fresh water and seawater - Butman, D.; Raymond, P. A.; Oh, N. H.; Mull, K. (Organic Geochemistry, 2007)
Soil organic carbon (OC) resulting from terrestrial photosynthesis is one of the largest reactive pools of sequestered atmospheric CO2. As an intermediate storage mechanism for organic material through time, the vertical distribution of carbon in a soil profile generally shows an age continuum with depth. Aged soil carbon is often the result of sorptive preservation, a physical mechanism that protects organic matter (OM) from microbial decay. Sorptive preservation is, however, a reversible process. Upon desorption, previously protected OM could be available for decomposition. Here we present simple fresh and salt water desorption experiments designed to determine the amount, 14C age and lability of “reversible” OM. Results suggest that 1.1–3.9% and 1.5–6.7% of OC, and 0.7–3% and 0.6–5% of total soil nitrogen can be desorbed using fresh and salt water, respectively. Radiocarbon data suggest this desorbed carbon is Δ14C-enriched compared to the bulk soil, with Δ14C values close to modern atmospheric Δ14CO2 at the soil surface, and aging with depth. Of this extractable aged carbon, upwards of 23–56% is labile across all treatments and with depth. Additional carbon is extracted with salt water compared to fresh water and this surplus is non-labile and younger than the labile component. Radiocarbon dating shows that the 14C age of soil carbon increases with depth and that there is a pool of Δ14C-depleted OC that is readily remineralized upon entering an aquatic/marine environment. These results indicate that eroded soil particles can release OC and organic N when entering rivers and oceans and that up to 50% of this carbon is available for aquatic metabolism.
id: 1161

Quaternary depositional patterns and sea-level fluctuations, northeastern North Carolina - Parham, P. R.; Riggs, S. R.; Culver, S. J.; Mallinson, D. J.; Wehmiller, J. F. (Quaternary Research, 2007)
A detailed record of late Quaternary sea-level oscillations is preserved within the upper 45 in of deposits along an eight kin transect across Croatan Sound, a drowned tributary of the Roanoke/Albemarle drainage system, northeastern North Carolina. Drill-hole and seismic data reveal nine relatively complete sequences filling an antecedent valley comprised of discontinuous middle and early Pleistocene deposits. On interfluves, lithologically similar marine deposits of different sequences occur stacked in vertical succession and separated by ravinement surfaces. Within the paleo-drainage, marine deposits are separated by fluvial and/or estuarine sediments deposited during periods of lowered sea level. Foraminiferal and molluscan fossil assemblages indicate that marine facies were deposited in a shallow-marine embayment with open connection to shelf waters. Each sequence modifies or truncates portions of the preceding sequence or sequences. Sequence boundaries are the product of a combination of fluvial, estuarine, and marine erosional processes. Stratigraphic and age analyses constrain the ages of sequences to late Marine Isotope Stage (MIS) 6 and younger (similar to 140 ka to present), indicating multiple sea-level oscillations during this interval. Elevations of highstand deposits associated with late MIS 5 and MIS 3 imply that sea level was either similar to present during those times, or that the region may have been influenced by glacio-isostatic uplift and Subsidence. (c) 2006 University of Washington. All rights reserved.
131tvTimes Cited:18Cited References Count:56

Quaternary geology of the San Luis Basin, southern Colorado and Northern New Mexico--Rocky Mountain Section Friends of the Pleistocene Guidebook - Machette, M. N.; Coates, M. M.; Johnson, M. J. (U. S. Geological Survey Open-File Report 2007-1193, 2007)
id: 625

Quaternary glaciation and hydrologic variation in the South American tropics as reconstructed from the Lake Titicaca drilling project - Fritz, S. C.; Baker, P. A.; Seltzer, G. O.; Ballantyne, A.; Tapia, P.; Cheng, H.; Edwards, R. L. (Quaternary Research, 2007)
A 136-m-long drill core of sediments was recovered from tropical high-attitude Lake Titicaca, Bolivia-Peru, enabling a reconstruction of past climate that spans four cycles of regional glacial advance and retreat and that is estimated to extend continuously over the last 370,000 yr. Within the errors of the age model, the periods of regional glacial advance and retreat are concordant respectively with global glacial and interglacial stages. Periods of ice advance in the southern tropical Andes generally were periods of positive water balance, as evidenced by deeper and fresher conditions in Lake Titicaca. Conversely, reduced glaciation occurred during periods of negative water balance and shallow closed-basin conditions in the lake. The apparent coincidence of positive water balance of Lake Titicaca and glacial growth in the adjacent Andes with Northern Hemisphere ice sheet expansion implies that regional water balance and glacial mass balance are strongly influenced by global-scale temperature changes, as well as by precessional forcing of the South American summer monsoon. (c) 2007 University of Washington. All rights reserved.
id: 841; 227AJ Times Cited:9 Cited References Count:63Y

Radiocarbon age of late glacial deep water from the equatorial Pacific - Broecker, W.; Clark, E.; Barker, S.; Hajdas, I.; Bonani, G.; Moreno, E. (Paleoceanography, 2007)
Radiocarbon age differences for pairs of coexisting late glacial age benthic and planktic foraminifera shells handpicked from 10 sediment samples from a core from a depth of 2.8 km in the western equatorial Pacific are not significantly different from that of 1600 years calculated from measurements on prenuclear seawater. This places a lower limit on the depth of the interface for the hypothetical radiocarbon-depleted glacial age seawater reservoir required to explain the 190% drop in the (14)C/C for atmospheric CO(2), which occurred during the mystery interval (17.5 to 14.5 calendar years ago). These measurements restrict the volume of this reservoir to be no more than 35% that of the ocean. Further, (14)C measurements on a single Last Glacial Maximum age sample from a central equatorial Pacific core from a depth of 4.4 km water fail to reveal evidence for the required 5- to 7-kyr age difference between benthic and planktic foraminifera shells if the isolated reservoir occupied only one third of the ocean. Nor does the (13)C record for benthic forams from this abyssal core yield any evidence for the excess respiration CO(2) expected to be produced during thousands of years of isolation. Nor, as indicated by the presence of benthic foraminifera, was the dissolved oxygen used up in this abyssal water.
id: 413; 165MC Times Cited:10 Cited References Count:18

Radiocarbon age offsets of foraminifera resulting from differential dissolution and fragmentation within the sedimentary bioturbated zone - Barker, Stephen; Broecker, Wallace; Clark, Elizabeth; Hajdas, Irka (Paleoceanography, 2007)
Shells of coexisting species of planktonic foraminifera from the Ontong Java Plateau reveal radiocarbon age offsets of up to 2200 years. Similar offsets are found between fragments and whole shells of single species. Steady state modelling of dissolution and bioturbation within the sedimentary mixed layer predicts age differences of up to several kiloyears due to the interplay between differential dissolution and fragmentation of foraminifer shells and bioturbation. The observation that fragile foraminiferal shells are systematically older than those of more robust species is more difficult to explain. Mechanisms of chemical erosion, interface dissolution, and sediment redistribution are all apparently unable to explain this phenomenon. A possible solution is presented in which a particular species may be represented by two distinct classes of shells which are more or less robust. In this case, differential dissolution and fragmentation causes an increase in the mean age as the fragile class contributes less to the remaining intact shells. This study highlights the vulnerability of low sedimentation rate cores to the effects of dissolution and bioturbation.
id: 1920; PT: J; UT: WOS:000246308600002

Radiocarbon analysis confirms the annual nature of sagebrush growth rings - Biondi, F.; Strachan, S. D. J.; Mensing, S.; Piovesan, G. (Radiocarbon, 2007)
In the Great Basin of North America, big sagebrush (Artemisia tridentata Nutt.) growth rings can be used to reconstruct environmental changes with annual resolution in areas where there is otherwise little such information available. We tested the annual nature of big sagebrush wood layers using accelerator mass spectrometry (AMS) radiocarbon dating. Four cross-sections from 3 sagebrush plants were collected near Ely, Nevada, USA, and analyzed using dendrochronological methods. Ten C-14 measurements were then used to trace the location of the 1963-64 "bomb spike." Although the number of rings on each section did not exceed 60, crossdating was possible within a section and between sections. Years assigned to individual wood layers by means of crossdating aligned with their expected C-14 values, matching the location of the C-14 peak. This result confirmed the annual nature of growth rings formed by big sagebrush, and will facilitate the development of spatially explicit, well-replicated proxy records of environmental change, such as wildfire regimes, in Great Basin valleys.
258usTimes Cited:9Cited References Count:48

Radiocarbon and stable isotope geochemistry of organic matter in the Amazon headwaters, Peruvian Andes - Townsend-Small, A.; Noguera, J. L.; McClain, M. E.; Brandes, J. A. (Global Biogeochemical Cycles, 2007)
[1] We used delta C-13, delta N-15, and Delta C-14 to determine the sources of riverine organic matter in the Pozuzo River, a tributary of the Pachitea River located in the mountainous headwaters of the Amazon. Particulate organic matter (POM) Delta C-14 decreased downstream, suggesting that young organic matter (OM) introduced in small headwaters is respired preferentially in rivers or is diluted downstream with older material. The delta C-13 and delta N-15 of POM in headwater rivers were heterogeneous and also isotopically distinct from the main stem, suggesting that differences in landscape processes in small catchments impact the concentration and composition of POM in streams. The delta C-13 of dissolved organic matter (DOM) closely mirrored that of POM in the headwaters, with an apparent decoupling of dissolved and particulate OM in the river main stem. The delta C-13 of POM sampled in 2004 had a much different relationship with altitude than observed during previous years: In 2004, a very dry year, we observed enrichment from the headwaters to the main stem, and the opposite pattern in 2002, when rain fell heavily throughout the sampling campaign. This suggests that during dry conditions, in-stream processes ( such as resuspension or photosynthesis) may control riverine POM composition as opposed to terrestrial processes, which dominate during high runoff. Thus a decrease in runoff in Andean headwaters could result in less terrestrial POM transfer to rivers in the Andes foothills and lowland Amazon with a corresponding decrease in aquatic CO2 evasion.
185aaTimes Cited:12 Cited References Count:37
Keywords: amino-acids; atlantic-ocean; carbon; drainage-basin; land-use; nitrogen; particulate; river system; sediments; streams

Radiocarbon and Th-230 data reveal temperal changes in sediment focusing at ODP site 984, Poster - Mollenhauer, Gesine; McManus, J. F.; Wagner, T.; McCave, I. N.; Eglinton, T. I. (EGU General Assembly, 2007)
id: 547

Radiocarbon dating of a very large African baobab - Patrut, A.; von Reden, K. F.; Pohlman, J. W.; Wittmann, R.; Mitchell, C. S.; Lowy, D. A.; Alberts, A. H.; Gerlach, D.; Xu, L. (Tree Physiology, 2007)
In late 2004, Grootboom, probably the largest known African baobab (Adansonia digitata L.), collapsed unexpectedly in northeastern Namibia. Ten wood samples collected from different areas of the trunk were processed and investigated by accelerator mass spectrometry radiocarbon dating. The radiocarbon dates of three samples were greater than 1000 years BP (radiocarbon years before present, i.e., before AD 1950). The corresponding calibrated calendar age of the oldest sample was 1275 +/- 50 years, making Grootboom the oldest known angiosperm tree with reliable dating results. Variations in radiocarbon dates among the wood samples indicated that, morphologically, Grootboom was a quintuple tree, whereas genetically, it was a single individual. Ages of extreme lateral samples revealed that, over the past 500-600 years, Grootbooom had almost ceased growing, providing information about climate changes in central southern Africa. The sudden demise of Grootboom coincided with the spread of the poorly studied baobab disease, which has become epidemic in Namibia.
230afTimes Cited:35 Cited References Count:43
Keywords: Adansonia digitata; Age; Age determination; amazonia; c-14 content; cal kyr bp; Calibration; dendrochronology; dendroclimatology; holocene logs; location-dependent differences; southern-hemisphere; tasmanian conifers; Trees; tropical trees

Radiocarbon dating of deep-sea sediments - Hughen, K. A. (Paleoceanography of the Late Cenozoic, 2007)
id: 552

Rapid sea level rise and ice sheet response to 8,200-year climate event - Cronin, T. M.; Vogt, P. R.; Willard, D. A.; Thunell, R.; Halka, J.; Berke, M.; Pohlman, J. (Geophysical Research Letters, 2007)
The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6 - 8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz-Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sea level rise during this event. Sea level rose similar to 14 m between 9.5 to 7.5 ka, a pattern consistent with coral records and the ICE- 5G glacio-isostatic adjustment model. There were two distinct periods at similar to 8.9 - 8.8 and similar to 8.2 - 7.6 ka when Chesapeake marshes were drown as sea level rose rapidly at least similar to 12 mm yr(-1). The latter event occurred after the 8.6 - 8.2 ka cooling event, coincided with extreme warming and vigorous AMOC centered on 7.9 ka, and may have been due to Antarctic Ice Sheet decay.
id: 810; 225MA Times Cited:4 Cited References Count:32Y

Reactivation of Coastal Dunes Documented by Subsurface Imaging of the Great Dune Ridge, Lithuania - Buynevich, I.; Bitinas, A.; Pupienis, D. (Journal of Coastal Research, 2007)
Large coastal and inland dunefields often consist of multiple generations defined by periods of stability and reactivation. Where earlier phases of aeolian activity are masked by subsequent deposition, continuous high-resolution geophysical images help to reconstruct the history of landscape change. Ground-penetrating radar (GPR) profiles from relict Holocene dunes on the northern Curonian Spit, Lithuania reveal distinct contacts between older deposits (barrier-spit facies, older aeolian strata, paleosols) and overlying dune sands. Early stages of dune migration began prior to 6,000 years B.P. followed by several periods of stabilisation and subsequent reactivation. Parabolic and transverse dunes, some attaining heights of 40-60 m, have migrated to the east in response to westerly winds from the Baltic Sea. In several places, similar to a number of sites in Northern Europe, the upper sections of large dunes have been deflated leaving near-horizontal exposures where subsurface imaging extends the continuity of key stratigraphic horizons. Within dune sequences, oblique lateral accretion surfaces indicate the direction of earlier migration phases and exhibit distinct meso-scale geometries. In GPR images and shallow trenches, buried slipfaces have dip angles varying from 10-15 degrees to 31-34 degrees, the latter being similar to the angle of repose maintained by modem unvegetated dunes. A series of cores taken through sequences of stacked buried slipfaces show little visible variation in sediment properties with depth, suggesting that minor changes in texture, mineralogy and grain packing may be responsible for individual reflections in geophysical records. Occasionally, laterally extensive horizons enriched in heavy minerals produce prominent subsurface reflections and are indicative of periods of increased wind activity.
Sp. Iss. 50V16hi Times Cited:10 Cited References Count:30
Keywords: curonian spit; gpr; medieval; reflection geometry; slipface; truncation

A regional study of Holocene climate change and human occupation in Peruvian Amazonia - Bush, M. B.; Listopad, M. C. S.; Silman, M. R. (Journal of Biogeography, 2007)
id: 453

Regional variability in the ages and reactivities of riverine dissolved and particulate organic matter exported to a temperate ocean margin - Bauer, J. E.; Raymond, P. A.; Cole, J. J.; Petsch, S. T.; Longworth, B. E.; Caraco, N. F.; Keesee, E. J. (ASLO Aquatic Sciences Meeting, 2007)
id: 477

Relationships between carbon isotopic composition and mode of binding of natural organic matter in selected marine sediments - White, Helen K.; Reddy, Christopher M.; Eglinton, Timothy I. (2007)
We have investigated the relationships between radiocarbon (14C) and stable carbon (13C) isotopic composition and the different modes of binding of organic matter (OM) in surficial sediments selected from near-shore and continental margin sites that vary in terms of input and depositional conditions. To improve our understanding of the entire OM pool, isotopic analysis of sedimentary sub-fractions, as opposed to individual compounds, was performed. This was achieved by sequentially treating sediments via solvent extraction to examine unbound compounds, followed by saponification to cleave ester linked moieties. Isotopic analysis was performed on the bulk sediment and resulting residues. The molecular composition of the extracts was examined using gas chromatography/mass spectrometry (GC/MS) and the relative contributions of terrestrial and marine biomarkers were assessed. Radiocarbon abundances (Δ14C) of the bulk sediment reflect a mixture of modern, pre-aged and fossil carbon. Offsets in Δ14C between the bulk sediment and sediment residues demonstrate varying associations of these carbon pools. For the majority of sites, a negative offset between extracted (EX-RES) and saponified (SA-RES) sediment residues results from the removal of relatively 14C-rich material during saponification. Saponification extracts (SAEs) are mainly composed of short chain (n-C12 to n-C24) alkanoic acids with an even/odd dominance, indicating a predominantly marine algal or microbial source. This provides evidence for the protection of labile marine carbon by chemical binding. This study bridges the gap between molecular level and bulk OM analysis of marine sediments.

Reply to comment by L. D. Stott on "Anomalous radiocarbon ages for foraminifera shells": A correction to the western tropical Pacific MD9821-81 record - Broecker, W. S.; Barker, S. (Paleoceanography, 2007)
id: 2015; PT: J; UT: WOS:000244478900002

Report of archaeological field research in 2006, including geological descriptions of archaeological locales - Fitzhugh, B.; Etnier, M.; MacInnes, B.; Phillips, S. C.; Taylor, J. W. (Kuril Biocomplexity Project (NSF 0508109, PI: Fitzhugh), 2007)
id: 833Unpublished project report

Response of vegetation and fire to Little Ice Age climate change: regional continuity and landscape heterogeneity - Hotchkiss, S. C.; Calcote, R.; Lynch, E. A. (Landscape Ecology, 2007)
Late-Holocene climatic conditions in the upper Great Lakes region have changed sufficiently to produce significant changes in vegetation and fire regimes. The objective of this study was to determine how the vegetation mosaic and fire regimes on an oak (Quercus spp.)- and pine (Pines spp.)-dominated sand plain in northwestern Wisconsin responded to climatic changes of the past 1,200 years. We used pollen and charcoal records from a network of sites to investigate the range of natural variability of vegetation on a 1,500-km(2) landscape on the southern part of the sand plain. A major vegetation shift from jack pine (Pines banksiana) and red pine (P. resinosa) to increased abundance of white pine (P. strobus) occurred between 700 and 600 calendar years before present (cal yr BP), apparently corresponding to more mesic conditions regionally. A decrease in charcoal accumulation rate also occurred at most sites but was not synchronous with the vegetation change. At some sites there were further changes in vegetation and fire regimes occurring similar to 500-300 cal yr BP, but these changes were not as strong or unidirectional as those that occurred 700-600 cal yr BP. Our results suggest that both the composition and the distribution of vegetation of the southern part of the sand plain have been sensitive to relatively small climatic changes, and that the vegetation at the time of European settlement was a transitory phenomenon, rather than a long-term stable condition.
Suppl. 1239unTimes Cited:25Cited References Count:92

A review of modern coral delta18O and Delta14C proxy records - Grottoli, Andrea G.; Eakin, C. Mark (Earth-Science Reviews, 2007)
id: 653

Salinity changes in the western tropical South Atlantic during the last 30 kyr - Toledo, F. A. L.; Costa, K. B.; Pivel, M. A. G. (Global and Planetary Change, 2007)
The hydrographic changes in the western tropical South Atlantic during the last 30 kyr were reconstructed based in the faunal and isotopic analyses of planktonic foraminifera of three cores taken along the Brazilian Continental Margin between 14 degrees S and 25 degrees S. The application of the SIMMAX-MAT method on faunal counts data provided the sea surface temperature estimates. Sea surface salinity estimates were based on the oxygen isotope composition of Globigerinoides ruber (white). Additionally, the abundance record of the planktonic foraminifera Globorotalia truncatulinoides (right) was used as a proxy for vertical mixing of surface waters. Sea surface temperature estimates suggest a relative stability of the area during the last 30 kyr. However, significant changes in the isotopic composition of G. ruber (white) suggest that the isotopic signal is dominated by the influence of sea surface salinity changes. The observed salinity changes are related to both the local hydrological balance and global circulation. Orbital forcing and sea surface salinity changes were responsible for considerable changes in the stability of the upper water column and consequently in the depth of the mixed layer, as indicated by the abundance record of G. truncatulinoides (right). (c) 2007 Elsevier B.V All rights reserved.
181bjTimes Cited:28Cited References Count:59

Sea level rise in Tampa Bay - Cronin, Thomas M.; Edgar, N. Terence; Brooks, Gregg; Hastings, David; Larson, Rebekka; Hine, Albert; Locker, Stanley; Suthard, Beau; Flower, Benjamin; Hollander, David; Wehmiller, John; Willard, Debra A.; et al. (Eos, Transactions, American Geophysical Union, 2007)
id: 1899; References: 14; illus. incl. geol. sketch map Latitude:N272700,N280200 Longitude:W0822200,W0825100Y

Sea-level history of the Gulf of Mexico since the Last Glacial Maximum with implications for the melting history of the Laurentide Ice Sheet - Simms, Alexander R.; Lambeck, Kurt; Purcell, Anthony; Anderson, John B.; Rodriguez, Antonio B. (Quaternary Science Reviews, 2007)
Sea-level records from the Gulf of Mexico at the Last Glacial Maximum, 20 ka, are up to 35 m higher than time-equivalent sea-level records from equatorial regions. The most popular hypothesis for explaining this disparity has been uplift due to the forebulge created by loading from Mississippi River sediments. Using over 50 new radiocarbon dates as well as existing published data obtained from shallowmarine deposits within the northern Gulf of Mexico and numerical models simulating the impact of loading due to the Mississippi Fan and glacio-hydro-isostasy, we test several possible explanations for this sea-level disparity.. We find that neither a large radiocarbon reservoir, sedimentary loading due to the Mississippi Fan, nor large-scale regional uplift can explain this disparity. We do find that with an appropriate model for the Laurentide Ice Sheet, the observations from the Gulf of Mexico can be explained by the process of glaciohydro-isostasy. Our analysis suggests that in order to explain this disparity one must consider a Laurentide Ice Sheet reconstruction with less ice from 15 ka to its disappearance 6 ka and more ice from the Last Glacial Maximum to 15 ka than some earlier models have suggested. This supports a Laurentide contribution to meltwater pulse 1-A, which could not have come entirely from its southern sector. (c) 2007 Elsevier Ltd. All rights reserved.
id: 2038; PT: J; UT: WOS:000248732200007

Searching for a suitable gas ion source for C-14 accelerator mass spectrometry - von Reden, K.; Roberts, M.; Han, B.; Schneider, R.; Wills, J. (Preceeding of PNNIB-11 (9/2006), 2007)
id: 689

Seaward-branching coastal-plain and Piedmont incised-valley systems through multiple sea-level cycles: Late Quaternary examples from Mobile Bay and Mississippi Sound, USA - Greene, D. Lawrence, Jr.; Rodriguez, Antonio B.; Anderson, John B. (Journal of Sedimentary Research, 2007)
Most incised valleys become more organized seaward through tributaries merging with the main trunk valley. Late Quaternary incised valleys on the Mississippi and Alabama inner continental shelf branch seaward, although they do coalesce towards the shelf break where they feed shelf-edge deltas. To link fluvial systems with their associated previously mapped incised valleys on the shelf, and evaluate the contribution of small coastal-plain valley systems to the lowstand systems tract, high-resolution seismic data and cores were collected from Mobile Bay, eastern Mississippi Sound, and the Mobile bay-head delta. These data show four unconformity-bounded stacked units, and this study focuses on the upper two regionally mappable units. The upper two unconformities were sampled in core as exposure surfaces, and, on the basis of stratigraphic position, depth of incision, and C-14 dates, are interpreted as sequence boundaries. The shallowest sequence boundary (A) formed in response to the Oxygen Isotope Stage 2 sea-level lowstand, while the underlying sequence boundary (B) formed in response to an earlier lowstand (Stage 6?). A map of Sequence Boundary B shows a network of seaward-branching valleys, 20-35 m deep and 0.6-7.7 km wide, that extend across Mobile Bay and Mississippi Sound. These valleys, which are bounded by well-developed terraces, are extensions of the piedmont Mobile fluvial system and the coastal-plain Fowl and La Batre fluvial systems. A map of the Stage 2 Sequence Boundary shows that all systems generally reoccupied their previous valley positions and are separated by interfluve plateaus. Valley fill between Sequence Boundary B and the Stage 2 Sequence Boundary is generally composed of a basal unit of alluvial sediments overlain by bay-head delta deposits; however, Stage 2 to 1 valley fill is composed entirely (if central-basin sediments. The presence of bay-head delta deposits on the inner shelf indicates this depositional environment backstepped across the estuaries to modern positions. Backstepping likely occurred as the low-gradient paleovalleys were inundated, resulting in rapid rates of transgression. Fluvial gradients measured on Sequence Boundary B and the Stage 2 Sequence Boundary, below the modern Mobile bay-head delta plain and the estuaries, are very low (1.3-0.3 m/km). The Mobile bay-head delta and upper Mobile Bay are confined by steep topography, which opens basinward into the low-gradient shorelines surrounding lower Mobile Bay and Mississippi Sound. During falling sea level, channel branching likely occurred as the low-gradient fluvial systems extended basinward beyond the confined topography. These channels incised as sea level fell below the steeper shelf break during the lowstand. Stage 2 valley morphology is partially influenced by the position of the underlying Stage 6 valleys. Both coastal-plain and piedmont valley systems exhibit compound fill, indicating that differentiation between these types of incised valleys cannot be based on valley-fill architecture alone.
id: 2039; PT: J; UT: WOS:000246987600011

Sedimentary evidence of hurricane strikes in western Long Island, New York - Scileppi, E.; Donnelly, J. P. (Geochemistry Geophysics Geosystems, 2007)
[1] Evidence of historical landfalling hurricanes and prehistoric storms has been recovered from backbarrier environments in the New York City area. Overwash deposits correlate with landfalls of the most intense documented hurricanes in the area, including the hurricanes of 1893, 1821, 1788, and 1693 A. D. There is little evidence of intense hurricane landfalls in the region for several hundred years prior to the late 17th century A. D. The apparent increase in intense hurricane landfalls around 300 years ago occurs during the latter half of the Little Ice Age, a time of lower tropical sea surface temperatures. Multiple washovers laid down between similar to 2200 and 900 cal yr B. P. suggest an interval of frequent intense hurricane landfalls in the region. Our results provide preliminary evidence that fluctuations in intense hurricane landfall in the northeastern United States were roughly synchronous with hurricane landfall fluctuations observed for the Caribbean and Gulf Coast, suggesting North Atlantic - wide changes in hurricane activity.
182vrTimes Cited:48 Cited References Count:59
Keywords: barrier-island; climate; Coastal geology; fire-island; global change : climate variability; hurricane; hydrology : extreme events; hydrology : hydroclimatology; ice-age; New York; new-england; new-jersey; past 5,000 years; Salt marsh; salt-marsh; sea-level rise; sedimentation; tidal marsh; tropical cyclones

Sedimentary iron cycling and the origin and preservation of magnetization in platform carbonate muds, Andros Island, Bahamas - Maloof, A. C.; Kopp, R. E.; Grotzinger, J. P.; Fike, D. A.; Bosak, T.; Vali, H.; Poussart, P. M.; Weiss, B. P.; Kirschvink, J. L. (Earth and Planetary Science Letters, 2007)
Carbonate muds deposited on continental shelves are abundant and well-preserved throughout the geologic record because shelf strata are difficult to subduct and peritidal carbonate units often form thick, theologically strong units that resist penetrative deformation. Much of what we know about pre-Mesozoic ocean chemistry, carbon cycling, and global change is derived from isotope and trace element geochemistry of platform carbonates. Paleomagnetic data from the same sediments would be invaluable, placing records of paleolatitude, paleogeography, and perturbations to the geomagnetic field in the context and relative chronology of chemostratigraphy. To investigate the depositional and early diagenetic processes that contribute to magneitzation in carbonates, we surveyed over 500 core and surface samples of peritidal, often microbially bound carbonate muds spanning the last similar to 1000 yr and deposited on top of Pleistocene aeolianites in the Triple Goose Creek region of northwest Andros Island, Bahamas. Sedimentological, geochemical, magnetic and ferromagnetic resonance properties divide the sediment columns into three biogeochemical zones. In the upper sediments, the dominant magnetic mineral is magnetite, produced by magnetotactic bacteria and dissimiliatory microbial iron metabolism. At lower depths, above or near mean tide level, microbial iron reduction dissolves most of the magnetic particles in the sediment. In some cores, magnetic iron sulfides precipitate in a bottom zone of sulfate reduction, likely coupled to the oxidation of decaying mangrove roots. The remanent magnetization preserved in all oriented samples appears indistinguishable from the modem local geomagnetic field, which reflects the post-depositional origin of magnetic particles in the lower zone of the parasequence. While we cannot comment on the effects of late-stage diagenesis or metamorphism on remanence in carbonates, we postulate that early-cemented, thin-laminated parasequence tops in ancient peritidal carbonates are mostly likely to preserve syn-depositional paleomagnetic directions and magnetofossil stratigraphies. (c) 2007 Published by Elsevier B.V.
id: 787; 197DX Times Cited:9 Cited References Count:47Y

Selective degradation of organic compounds in sediments from the California Borderland Basins: evidence from compound specific Delta 14C and delta 13C analyses - Mollenhauer, Gesine; Eglinton, Timothy I. (Limnology and Oceanography, 2007)
id: 544

Source apportionment of atmospheric PAHs in the western Balkans by natural abundance radiocarbon analysis - Zencak, Zdenek; Klanova, Jana; Holoubek, Ivan; Gustafsson, Örjan (Environmental Science and Technology, 2007)
id: 519

Source, transport and fate of terrestrial organic carbon on the western Mediterranean Sea, Gulf of Lions, France - Tesi, T.; Miserocchi, S.; Goñi, M. A.; Langone, L. (Marine Chemistry, 2007)
As part of the EuroSTRATAFORM project, a multi-proxy study was conducted in order to investigate origin, transport and deposition of riverine organic matter in the Gulf of Lions. Surface sediments (0-1 cm) from the Rhone prodelta area and along the sediment dispersal system were collected in September 2004 and in April 2005. Lignin, elemental and stable carbon isotopic analyses were carried out to characterize the source of sedimentary organic material and to facilitate evaluation of temporal and spatial variability. Large contrasts in the organic matter composition of prodelta sediments were observed as a result of the preferential transport of the finest material. In our hypothesis, woody debris, rich in organic matter, hydraulically behaves like very fine sand and is retained within the prodelta area. In contrast, the organic matter adsorbed onto finer particles is selectively transported away from the prodelta along the sediment dispersal system, explaining the distinct organic matter composition observed in the offshore regions. (c) 2007 Elsevier B.V. All rights reserved.
id: 825; 176SJ Times Cited:15 Cited References Count:70Y

Spatial complexity of 'Little Ice Age' climate in East Africa: sedimentary records from two crater lake basins in western Uganda - Russell, J. M.; Verschuren, D.; Eggermont, H. (Holocene, 2007)
Lithostratigraphic analyses of the sedimentary record from two contrasting crater lake basins in western Uganda, Africa, provide evidence for three major century-scale and intervals during the last 2000 year. Variations in sedimentation and salt mineralogy of hypersaline Lake Kitagata, and a succession of fine-grained lake sediments and peat in the freshwater Lake Kibengo, suggest century-scale droughts centred on AD 0, similar to 1100, similar to 1550 and 1750. These results broadly support data from nearby Lake Edward on the timing of drought in western Uganda, but contrast with lake sediment records from eastern equatorial Africa. In particular, our results suggest regional variability of East African climate during the main phase of the 'Little Ice Age' (AD similar to 1500 to 1800), with westernmost East Africa experiencing drought while areas farther east were wet. This spatial pattern highlights the strongly regional nature of century-scale climate changes over the African continent, and holds implications for the mechanisms governing African rainfall during the 'Little Ice Age'.
144ztTimes Cited:36Cited References Count:55

Stable carbon isotope compositions of Eastern Beringian grasses and sedges: Investigating their potential as paleoenvironmental indicators - Wooller, M. J.; Zazula, G. D.; Edwards, M.; Froese, D. G.; Boone, R. D.; Parker, C.; Bennett, B. (Arctic Antarctic and Alpine Research, 2007)
The nature of vegetation cover present in Beringia during the last glaciation remains unclear. Uncertainty rests partly with the limitations of conventional paleoecological methods. A lack of sufficient taxonomic resolution most notably associated with the grasses and sedges restricts the paleoccological inferences that can be made. Stable isotope measurements of subfossil plants are frequently used to enhance paleoenvironmental reconstructions. We present an investigation of the stable carbon isotope composition (delta C-13) of modern and subfossil grasses and sedges (graminoids) from Eastern Beringia. Modern grasses from wet habitats had a mean delta C-13 of -29.1 parts per thousand. (standard deviation [SD] = 2.1 parts per thousand, n = 75), while those from dry habitats had a mean of -26.9 parts per thousand (SD = 1.19, n = 27). Sedges (n = -50) from dry, wet, marsh, and sand dune habitats had specific habitat ranges. Four modern C-4 grasses had delta C-13 values typical Of C4 plants. Analyses were also conducted using subfossil graminoid remains from several sedimentary paleoecological contexts (e.g., arctic ground squirrel nests, loess, permafrost, and paleosols) in Eastern Beringia. Results from these subfossil samples, ranging in age from > 40,000 to ca. 11,000 cal. yr BP, illustrate that the delta C-13 of graminoid remains has altered during the past. The range of variation in the subfossil samples is within the range from modern graminoid specimens from dry and wet habitats. The results indicate that stable isotopes could contribute to a comprehensive and multiproxy reconstruction of Beringian paleoenvironments.
170fwTimes Cited:20Cited References Count:73

Stable-and radiocarbon isotopes in corals and adjacent natural waters: reconstructing land-use change and the land-ocean carbon cycle - Moyer, R. P.; Grottoli, A. G. (ASLO, 2007)
id: 654