TY - JOUR T1 - Oceanographic and climatologic controls on the compositions and fluxes of biogenic materials in the water column and sediments of the Cariaco Basin over the Late Holocene JF - Deep-Sea Research Part I-Oceanographic Research Papers Y1 - 2009 A1 - Goñi, M. A. A1 - Aceves, H. A1 - Benitez-Nelson, B. A1 - Tappa, E. A1 - Thunell, R. A1 - Black, D. E. A1 - Muller-Karger, F. A1 - Astor, Y. A1 - Varela, R. AB - Materials collected by sediment traps over a 3-y period and sedimentary horizons from a gravity core covering the last 6000y were used to investigate the effects of climate-related processes such as wind-driven upwelling and regional rainfall on the production, export and burial of particulate organic matter in the Cariaco Basin. A variety of chemical analyses, including organic carbon and nitrogen, biogenic opal, calcite, lithogenic contents, stable carbon isotopic ratios of organic matter and the yields of CuO reaction products derived from distinct biochemicals such as amino acids, fatty acids and lignins, were carried out for this purpose. Principal component analyses were used to investigate the trends in this multivariate data set. These analyses reveal marked temporal differences in the composition of the materials sinking through the water column, which were related to distinct oceanographic and climatic forcings. For example, autorchthonous fluxes, characterized by elevated contents of organic carbon and opal as well as high yields of amino acid and fatty acid reaction products, displayed peaks during periods of intense wind-driven upwelling. In contrast, allochthonous materials, characterized by elevated lithogenic contents and elevated yields of lignin-derived products, were more important during periods of high rainfall, low wind and enhanced stratification. In addition to the strong seasonal contrasts, there was significant temporal variability at both shorter (monthly) and longer (inter-annual) time scales. Hence, other factors, such as zooplankton grazing and El Nino effects on local climatology, may also be important. Examination of the gravity core record yielded several significant trends. For example, there was a marked increase in sediment accumulation rates from 5000 to ca. 700 y before present with concomitant increases in the concentrations of organic carbon, opal and most biomarkers. These results suggest that the Cariaco Basin experienced a marked increase in primary productivity and particle flux to the underlying sediments since the Holocene Thermal Maximum. Also within the sedimentary record, we observed distinct variations in the relative contributions of autochthonous and allochthonous organic matter. The frequency of these variations is roughly 1500y and appears to match ice-rafted debris records from the North Atlantic. Such coincidence indicates cold periods within the Holocene, which are related to minima in insolation, may have led to the southern migration of the inter-tropical convergence zone and the enhancement of wind-driven upwelling, primary productivity and autochthonous organic matter flux to the seabed in the Cariaco Basin. Alternatively, during warm periods, the opposite climatic conditions would have increased both the thermal stratification of the water column and average rainfall in the Cariaco Basin, leading to elevated inputs of allochthonous materials. (C) 2008 Elsevier Ltd. All rights reserved. VL - 56 IS - 4 N1 - id: 1871; 430SK Times Cited:0 Cited References Count:69Y JO - Oceanographic and climatologic controls on the compositions and fluxes of biogenic materials in the water column and sediments of the Cariaco Basin over the Late Holocene ER - TY - JOUR T1 - Rapid sea level rise and ice sheet response to 8,200-year climate event JF - Geophysical Research Letters Y1 - 2007 A1 - Cronin, T. M. A1 - Vogt, P. R. A1 - Willard, D. A. A1 - Thunell, R. A1 - Halka, J. A1 - Berke, M. A1 - Pohlman, J. AB - 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. VL - 34 IS - 20 N1 - id: 810; 225MA Times Cited:4 Cited References Count:32Y JO - Rapid sea level rise and ice sheet response to 8,200-year climate event ER - TY - JOUR T1 - Decline of surface temperature and salinity in the western tropical Pacific Ocean in the Holocene epoch JF - Nature Y1 - 2004 A1 - Stott, L. A1 - Cannariato, K. A1 - Thunell, R. A1 - Haug, G. H. A1 - Koutavas, A. A1 - Lund, S. AB - In the present-day climate, surface water salinities are low in the western tropical Pacific Ocean and increase towards the eastern part of the basin. The salinity of surface waters in the tropical Pacific Ocean is thought to be controlled by a combination of atmospheric convection, precipitation, evaporation and ocean dynamics, and on interannual timescales significant variability is associated with the El Nino/Southern Oscillation cycles. However, little is known about the variability of the coupled ocean-atmosphere system on timescales of centuries to millennia. Here we combine oxygen isotope and Mg/Ca data from foraminifers retrieved from three sediment cores in the western tropical Pacific Ocean to reconstruct Holocene sea surface temperatures and salinities in the region. We find a decrease in sea surface temperatures of approximately 0.5 degrees C over the past 10,000 yr, whereas sea surface salinities decreased by approximately 1.5 practical salinity units. Our data imply either that the Pacific basin as a whole has become progressively less salty or that the present salinity gradient along the Equator has developed relatively recently. VL - 431 IS - 7004 N1 - Stott, LowellCannariato, KevinThunell, RobertHaug, Gerald HKoutavas, AthanasiosLund, SteveengResearch Support, U.S. Gov't, Non-P.H.S.England2004/09/03 05:00Nature. 2004 Sep 2;431(7004):56-9. JO - Decline of surface temperature and salinity in the western tropical Pacific Ocean in the Holocene epoch ER - TY - JOUR T1 - Super ENSO and global climate oscillations at millennial time scales JF - Science Y1 - 2002 A1 - Stott, L. A1 - Poulsen, C. A1 - Lund, S. A1 - Thunell, R. AB - The late Pleistocene history of seawater temperature and salinity variability in the western tropical Pacific warm pool is reconstructed from oxygen isotope (delta18O) and magnesium/calcium composition of planktonic foraminifera. Differentiating the calcite delta18O record into components of temperature and local water delta18O reveals a dominant salinity signal that varied in accord with Dansgaard/Oeschger cycles over Greenland. Salinities were higher at times of high-latitude cooling and were lower during interstadials. The pattern and magnitude of the salinity variations imply shifts in the tropical Pacific ocean/atmosphere system analogous to modern El Nino-Southern Oscillation (ENSO). El Nino conditions correlate with stadials at high latitudes, whereas La Nina conditions correlate with interstadials. Millennial-scale shifts in atmospheric convection away from the western tropical Pacific may explain many paleo-observations, including lower atmospheric CO2, N2O, and CH4 during stadials and patterns of extratropical ocean variability that have tropical source functions that are negatively correlated with El Nino. VL - 297 IS - 5579 N1 - Stott, LowellPoulsen, ChristopherLund, SteveThunell, Roberteng2002/07/13 10:00Science. 2002 Jul 12;297(5579):222-6. JO - Super ENSO and global climate oscillations at millennial time scales ER - TY - JOUR T1 - Glacial/interglacial slope sedimentation changes on the Pleistocene NJ margin, ODP Site 904A JF - Eos, Transactions, American Geophysical Union Y1 - 1994 A1 - Christensen, B. A. A1 - Thunell, R. A1 - Miller, K. G. A1 - Smith, N. A1 - Cockrell, K. VL - 75 IS - 16 N1 - id: 54 ER -