@article {2542,
	title = {No iron fertilization in the equatorial Pacific Ocean during the last ice age},
	journal = {Nature},
	volume = {529},
	year = {2016},
	month = {Mar-01-2018},
	pages = {519 - 522},
	abstract = {The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron1. Greater atmospheric dust deposition2 could have fertilized the equatorial Pacific with iron during the last ice age{\textemdash}the Last Glacial Period (LGP){\textemdash}but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain3, 4, 5, 6. Here we present meridional transects of dust (derived from the 232Th proxy), phytoplankton productivity (using opal, 231Pa/230Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ15N) from six cores in the central equatorial Pacific for the Holocene (0{\textendash}10,000 years ago) and the LGP (17,000{\textendash}27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region7, 8. Thus, ice-age iron fertilization in the Subantarctic Zone would have ultimately worked to lower, not raise, equatorial Pacific productivity.},
	keywords = {Biogeochemistry, Palaeoceanography},
	issn = {0028-0836},
	doi = {10.1038/nature16453},
	url = {http://www.nature.com/doifinder/10.1038/nature16453},
	author = {Costa, K. M. and McManus, J. F. and Anderson, R. F. and Ren, H. and Sigman, D. M. and Winckler, G. and Fleisher, M. Q. and Marcantonio, F. and Ravelo, A. C.}
}
@article {257,
	title = {Comparing glacial and Holocene opal fluxes in the Pacific sector of the Southern Ocean},
	journal = {Paleoceanography},
	volume = {24},
	year = {2009},
	note = {id: 836; 455GX Times Cited:0 Cited References Count:97Y},
	abstract = {The silicic acid leakage hypothesis (SALH) predicts that during glacial periods excess silicic acid was transported from the Southern Ocean to lower latitudes, which favored diatom production over coccolithophorid production and caused a drawdown of atmospheric CO2. Downcore records of Th-230-normalized opal (biogenic silica) fluxes from 31 cores in the Pacific sector of the Southern Ocean were used to compare diatom productivity during the last glacial period to that of the Holocene and to examine the evidence for increased glacial Si export to the tropics. Average glacial opal fluxes south of the modern Antarctic Polar Front (APF) were less than during the Holocene, while average glacial opal fluxes north of the APF were greater than during the Holocene. However, the magnitude of the increase north of the APF was not enough to offset decreased fluxes to the south, resulting in a decrease in opal burial in the Pacific sector of the Southern Ocean during the last glacial period, equivalent to approximately 15 Gt opal ka(-1). This is consistent with the work of Chase et al. (2003a), and satisfies the primary requirement of the SALH, assuming that the upwelled supply of Si was approximately equivalent during the Holocene and the glacial period. However, previous results from the equatorial oceans are inconsistent with the other predictions of the SALH, namely that either the C-org:CaCO3 ratio or the rate of opal burial should have increased during glacial periods. We compare the magnitudes of changes in the Southern Ocean and the tropics and suggest that Si escaping the glacial Southern Ocean must have had an alternate destination, possibly the continental margins. There is currently insufficient data to test this hypothesis, but the existence of this sink and its potential impact on glacial pCO(2) remain interesting topics for future study.},
	issn = {0883-8305},
	doi = {10.1029/2008pa001693},
	author = {Bradtmiller, L. I. and Anderson, R. F. and Fleisher, M. Q. and Burckle, L. H.}
}
@article {331,
	title = {Wind-Driven Upwelling in the Southern Ocean and the Deglacial Rise in Atmospheric CO2},
	journal = {Science},
	volume = {323},
	year = {2009},
	note = {id: 835; 417TP Times Cited:18 Cited References Count:69Y},
	pages = {1443-1448},
	abstract = {Wind-driven upwelling in the ocean around Antarctica helps regulate the exchange of carbon dioxide (CO2) between the deep sea and the atmosphere, as well as the supply of dissolved silicon to the euphotic zone of the Southern Ocean. Diatom productivity south of the Antarctic Polar Front and the subsequent burial of biogenic opal in underlying sediments are limited by this silicon supply. We show that opal burial rates, and thus upwelling, were enhanced during the termination of the last ice age in each sector of the Southern Ocean. In the record with the greatest temporal resolution, we find evidence for two intervals of enhanced upwelling concurrent with the two intervals of rising atmospheric CO2 during deglaciation. These results directly link increased ventilation of deep water to the deglacial rise in atmospheric CO2.},
	issn = {0036-8075},
	doi = {10.1126/science.1167441},
	author = {Anderson, R. F. and Ali, S. and Bradtmiller, L. I. and Nielsen, S. H. H. and Fleisher, M. Q. and Anderson, B. E. and Burckle, L. H.}
}
@article {482,
	title = {Modern CaCO3 preservation in equatorial Pacific sediments in the context of late-Pleistocene glacial cycles},
	journal = {Marine Chemistry},
	volume = {111},
	year = {2008},
	note = {id: 1936; PT: J; UT: WOS:000259418600004},
	pages = {30-46},
	abstract = {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.},
	issn = {0304-4203},
	doi = {10.1016/j.marchem.2007.11.011},
	author = {Anderson, R. F. and Fleisher, M. Q. and Lao, Y. and Winckler, G.}
}
@article {2086,
	title = {Accumulation of biogenic and lithogenic material in the Pacific sector of the Southern Ocean during the past 40,000 years},
	journal = {Deep-Sea Research Part Ii-Topical Studies in Oceanography},
	volume = {50},
	year = {2003},
	note = {662agTimes Cited:82
Cited References Count:86
},
	month = {2003},
	pages = {799-832},
	abstract = {The (230)Th-normalization technique was applied to surface sediments and down-core records from the Pacific sector of the Southern Ocean between 120degreesW and 170degreesW in order to reconstruct vertical rain rates, corrected for lateral redistribution of sediment. Preserved rain rates of opal, organic carbon and biogenic Ba all indicate that biological productivity south of the Antarctic Polar Front (APF) was much lower than today during the Last Glacial Maximum (LGM), probably in response to increased ice cover. However, by analogy with modern opal fluxes south of the ACC, we show that year-round ice cover is not a prerequisite for very low rates of opal accumulation. Available records from north of the APF indicate little to no change in opal export, in contrast to records from the Indian and Atlantic sectors, which show enhanced opal export north of the APF during the LGM. Glacial records from north of 66degreesS in the Pacific all show lithogenic fluxes that were greater than today, but significantly lower than lithogenic fluxes in the glacial Atlantic and Indian sectors. Together, these new records from the Pacific sector show that during the LGM the three basins of the Southern Ocean were significantly more differentiated than today. The observed inter-basin distribution of lithogenic fluxes and opal burial, and the presumed geographical distribution of increased dust input to the Southern Ocean during the LGM, are consistent with an Atlantic-Indian-Pacific gradient in the degree of iron-stimulated diatom productivity within the zone lying between the APF and the Subantarctic Front. Previous studies, which focused primarily on the Atlantic sector, may have overestimated the glacial increase in the strength of the biological pump in the Southern Ocean. (C) 2002 Elsevier Science Ltd. All rights reserved.},
	keywords = {antarctic circumpolar current, atmospheric co2, biological productivity, Deep-sea, interglacial changes, Last glacial maximum, marine-sediments, organic-carbon, pa-231/th-230 ratio, terrigenous sediment},
	isbn = {0967-0645},
	author = {Chase, Z. and Anderson, R. F. and Fleisher, M. Q. and Kubik, P. W.}
}
@article {828,
	title = {U-Th dating of carbonate platform and slope sediments},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {65},
	year = {2001},
	note = {462zlTimes Cited:49Cited References Count:44},
	month = {Aug},
	pages = {2757-2770},
	abstract = {Absolute chronology of marine sediment beyond the C-14 age range provides a test for models of climate change and has many other applications. U-Th techniques have been used for such chronology by dating corals, but extending these techniques to marine sediment is complicated by the presence of significant initial Th-230-both in detrital material and scavenged from seawater. In this study, we investigate four methods of solving the initial Th-230 problem for a particular type of marine sediment-the aragonite-rich sediments of carbonate platforms and slopes. Bulk sediment U-Th analyses can be corrected for initial Th to yield ages with approximate to2 to 3 kyr precision for highstand periods when sediment aragonite contents are particularly high. Uncertainty on the corrections causes inadequate precision for sediment from other periods, however. Removal of scavenged Th before analysis would enable a dramatic increase in this precision but has not proved successful despite a range of chemical leach approaches. Using heavy liquids to separate the various carbonate minerals found in Bahamas sediment enables an isochron approach to correct for initial Th, but the presence of initial Th from two sources requires correction or removal of one source of initial Th before the other is deconvolved by the isochron. Quantitative removal of detrital material before isochron analysis proves a successful approach. Such isochron data demonstrate that, although sediment remains closed to U-Th on a centimetre scale, nuclides are moved from grain to grain by alpha -recoil. Such intergrain exchange is expected to be observed in all sediments containing mineral grains with different U concentrations. Measured U-234/U-238 allows the recoil movement to be corrected and results in isochron ages with precision sometimes as low as 3 kyr. The accuracy of this approach has been proved by dating samples within the 14C age range. Sediments spanning the penultimate deglaciation have also been dated. After a small correction for bioturbation, the age for this event is found to be 135.2 +/- 3.5 ka. TWs date is approximate to8 kyr before the peak in northern hemisphere insolation and suggests that deglaciation is initiated by a mechanism in the southern hemisphere or tropics. This isochron approach shows considerable promise for dating of sediments older than this event, which will provide further information about the timing and mechanisms of global climate change. Copyright (C) 2001 Elsevier Science Ltd.},
	issn = {0016-7037},
	doi = {10.1016/S0016-7037(01)00621-4},
	author = {Henderson, G. M. and Slowey, N. C. and Fleisher, M. Q.}
}
@article {833,
	title = {Radiometrically determined sedimentary fluxes in the sub-polar North Atlantic during the last 140,000 years},
	journal = {Earth and Planetary Science Letters},
	volume = {155},
	year = {1998},
	note = {Ze160Times Cited:70Cited References Count:55},
	month = {Feb 15},
	pages = {29-43},
	abstract = {We have examined the record of sediment input during the last 140000 years in a deep-sea core from 49 degrees 27{\textquoteright}N, 22 degrees 16{\textquoteright}W in the eastern North Atlantic. Using uranium-series disequilibria to constrain time, we have calculated mass fluxes of total sediment, as well as mass and particle fluxes of major sedimentary components. Sediment accumulation rates were generally lower and relatively constant during broadly defined interglacial intervals, driven primarily by the burial of biogenic material. Accumulation rates were higher and more variable during glacial intervals, and were influenced primarily by terrigenous material. Peaks in bulk mass fluxes were associated with particular episodes (Heinrich events) within the last glacial and during each of the last two deglaciations. The flux of ice-rafted debris, as uniquely identified by coarse detrital fragments, was higher during layers representing each of the glacial Heinrich events, with modest increases during events H3 and H6 and dramatic increases during the others, confirming the widespread interpretation of these layers as episodes of enhanced iceberg delivery. The burial flux of foraminifera was markedly lower during each of the glacial Heinrich events, also confirming the original identification of these layers as barren intervals. Ice-rafting events within marine isotope stage 5 left neither a large detrital nor biogenic flux imprint at our study site. Variations in the burial rates of non-carbonate sediments were largely responsible for overall changes in sediment accumulation throughout the last climate cycle. Ice-rafting was apparently an important delivery mechanism for this terrigenous material. The instantaneous chronometer established here for the last 140000 years in the subpolar North Atlantic allows the transformation of existing and subsequent data from relative values to absolute burial fluxes. (C) 1998 Elsevier Science B.V.},
	issn = {0012-821x},
	doi = {10.1016/S0012-821x(97)00201-X},
	author = {McManus, J. F. and Anderson, R. F. and Broecker, W. S. and Fleisher, M. Q. and Higgins, S. M.}
}
