@article {3006,
	title = {Enhanced iceberg discharge in the western North Atlantic during all Heinrich events of the last glaciation},
	journal = {Earth and Planetary Science Letters},
	volume = {564},
	year = {2021},
	month = {06/2021},
	pages = {116910},
	abstract = {A series of catastrophic iceberg and meltwater discharges to the North Atlantic, termed Heinrich events, punctuated the last ice age. During Heinrich events, coarse terrigenous debris released from the drifting icebergs was preserved in deep-sea sediments, serving as an indicator of iceberg passage. Quantifying the vertical flux of ice-rafted debris (IRD) in open-ocean settings can resolve questions regarding the timing and spatial variation in ice sheet calving intensity. In this study, 230Thxs-based IRD flux throughout the last glacial period was measured in a deep-sea sediment core from the western North Atlantic, and complemented by data spanning 0-32 ka from a sediment core in the Labrador Sea. The cores were recovered from sites downstream from Hudson Strait, a likely conduit for icebergs calving from the Laurentide ice sheet (LIS). We compare our results with equivalent existing data from the eastern North Atlantic and show that the two cores in our study have higher IRD fluxes during all Heinrich events, notably including events H3 (\~{}31 ka) and H6 (\~{}60 ka). This study demonstrates that the LIS played a role in all Heinrich events, and raises the likelihood that a single mechanism can account for the genesis of these events.},
	keywords = {Heinrich event, IRD flux, thorium normalization, western north atlantic},
	isbn = {0012-821X},
	doi = {10.1016/j.epsl.2021.116910},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X21001692},
	author = {Zhou, Yuxin and McManus, Jerry F. and Jacobel, Allison W. and Costa, Kassandra M. and Wang, Shouyi and Alvarez Caraveo, Blanca}
}
@article {2811,
	title = {Evidence for Stable Holocene Basin-Scale Overturning Circulation Despite Variable Currents Along the Deep Western Boundary of the North Atlantic Ocean},
	journal = {Geophysical Research Letters},
	volume = {45},
	year = {2018},
	month = {Apr-12-2020},
	abstract = {While substantial changes in thermohaline circulation related to deglacial climate variability are well established, the role of this circulation in Holocene climate variability remains uncertain. Here we use two dynamical proxies, 231Pa/230Th ratios and mean sortable silt size ( urn:x-wiley:00948276:media:grl58406:grl58406-math-0001), to reconstruct Holocene bottom water circulation at the intermediate-depth Carolina Slope. We find no substantial change in deep current speed or 231Pa export at this site during the Holocene, suggesting consistent 231Pa export via the Deep Western Boundary Current. urn:x-wiley:00948276:media:grl58406:grl58406-math-0002 shows increasing millennial-scale variability in the middle-late Holocene, which may reflect Labrador Sea Water contribution to current speed. We conclude that deepwater export from the North Atlantic has remained remarkably stable during the Holocene, decoupled from changing rates of specific water masses, while production of these water masses varied at millennial to centennial time scales. The persistence of the large-scale overturning may reflect the ocean{\textquoteright}s stabilizing influence on Holocene climate.},
	keywords = {chemical tracers, interglacial, Radioactivity and radioisotopes, sedimentation (1861), thermohaline},
	issn = {0094-8276},
	doi = {10.1029/2018GL080187},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GL080187},
	author = {Hoffmann, Sharon S. and McManus, Jerry F. and Swank, Emerson}
}
@article {2606,
	title = {Millennial-scale variations in dustiness recorded in Mid-Atlantic sediments from 0 to 70 ka},
	journal = {Earth and Planetary Science Letters},
	volume = {482},
	year = {2018},
	month = {Jan-01-2018},
	pages = {12 - 22},
	abstract = {Sedimentary records of dust deposition in the subtropical Atlantic provide important constraints on millennial- and orbital-scale variability in atmospheric circulation and North African aridity. Constant flux proxies, such as extraterrestrial helium-3, yield dust flux records that are independent of the biases caused by lateral sediment transport and limited resolution that may be associated with age-model-derived mass accumulation rates. However, Atlantic dust records constrained using constant flux proxies are sparsely distributed and generally limited to the past 20 ka. Here we extend the Atlantic record of North African dust deposition to 70 ka using extraterrestrial helium-3 and measurements of titanium, thorium, and terrigenous helium-4 in two sediment cores collected at 26{\textdegree}N and 29{\textdegree}N on the Mid-Atlantic Ridge and compare results to model estimates for dust deposition in the subtropical North Atlantic. Dust proxy fluxes between 26{\textdegree}N and 29{\textdegree}N are well correlated, despite variability in lateral sediment transport, and underscore the utility of extraterrestrial helium-3 for constraining millennial-scale variability in dust deposition. Similarities between Mid-Atlantic dust flux trends and those observed along the Northwest African margin corroborate previous interpretations of dust flux variability over the past 20 ka and suggest that long distance transport and depositional processes do not overly obscure the signal of North African dust emissions. The 70 ka Mid-Atlantic record reveals a slight increase in North African dustiness from Marine Isotope Stage 4 through the Last Glacial Maximum and a dramatic decrease in dustiness associated with the African Humid Period. On the millennial-scale, the new records exhibit brief dust maxima coincident with North Atlantic cold periods such as the Younger Dryas, and multiple Heinrich Stadials. The correlation between Mid-Atlantic dust fluxes and previous constraints on North African aridity is high. However, precipitation exerts less control on dust flux variability prior to the African Humid Period, when wind variability governs dust emissions from consistently dry dust source regions. Thus, the Mid-Atlantic dust record supports the hypothesis that both aridity and wind strength drive dust flux variability across changing climatic conditions.},
	keywords = {helium-3, mass accumulation rate, mineral dust, North Africa, Subtropical North Atlantic, thorium-232},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2017.10.034},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X17306027},
	author = {Middleton, Jennifer L. and Mukhopadhyay, Sujoy and Langmuir, Charles H. and McManus, Jerry F. and Huybers, Peter J.}
}
@article {2531,
	title = {Compilation of geophysical, geochronological, and geochemical evidence indicates a rapid Mediterranean-derived submergence of the Black Sea{\textquoteright}s shelf and subsequent substantial salinification in the early Holocene},
	journal = {Marine Geology},
	volume = {383},
	year = {2017},
	month = {Jan-01-2017},
	pages = {14 - 34},
	abstract = {Our knowledge of rate and processes in which semi-enclosed environments alternate from lacustrine to marine is commonly limited because of the paucity of specific proxies for sea level and salinity. Here we investigate the timing, rate, and key mechanisms involved in the transformation of the previously isolated Black Sea-Lake to the modern partly-enclosed marine sea using a suite of geophysical, geochemical, and geochronological methods.

Cores were collected in transects across shelves of Ukraine, Romania, Bulgaria, and Turkey. Biogenic carbonate from these cores was analyzed for radiocarbon and strontium, oxygen, and carbon isotopes. Strontium results indicate that the submergence of the Black Sea shelf at 9300 calendar years BP was caused by the ingress of Mediterranean water and was abrupt, taking < 40 years. The seismic reflection profiles show a uniform drape of subsequent sediment over aeolian dunes indicating a drowning with no time for erosion accompanying the submergence. Moisture measurements beneath the uniform drape indicate that the shelf was dry before submergence and the shoreline of the Preboreal lake may have regressed to beyond 120 mbsl. Mollusks colonized the newly submerged substrate of the inner shelf at the same time as they colonized the outer shelf. The succession of mollusk species with shells whose strontium isotope composition has a marine component indicates a rising salinity. The transformation of the lake to a sea is affirmed by increases in the shells{\textquoteright} strontium and oxygen isotopic ratios towards the external ocean value.

Radiocarbon years are calibrated to calendar years by tuning the oxygen and carbon isotope composition of the mollusk record to that of the U/Th dated Sofular Cave stalagmites. The match shows a reduction of the lake{\textquoteright}s prior high reservoir age accompanying the inflow of the Mediterranean water. In 900 years the salinity reached a threshold that excluded all previous Black Sea lacustrine fauna. These results imply that any substantial postglacial submergence of the Black Sea shelves did not occur prior to entry of Mediterranean water.},
	keywords = {Black Sea, Black Sea transgression, Isotope geochemistry, Lake transgression, Marine-lake connections, paleoceanography, paleosalinity, Reflection profiles},
	issn = {00253227},
	doi = {10.1016/j.margeo.2016.11.001},
	url = {https://doi.org/10.1016/j.margeo.2016.11.001},
	author = {Yanchilina, Anastasia G. and Ryan, William B.F. and McManus, Jerry F. and Dimitrov, Petko and Dimitrov, Dimitar and Slavova, Krasimira and Filipova-Marinova, Mariana}
}
@article { ISI:000378338800029,
	title = {Hydrothermal iron flux variability following rapid sea level changes},
	journal = {GEOPHYSICAL RESEARCH LETTERS},
	volume = {43},
	number = {{8}},
	year = {2016},
	month = {APR 28},
	pages = {3848-3856},
	type = {Article},
	abstract = {Sea level changes associated with Pleistocene glacial cycles have been hypothesized to modulate melt production and hydrothermal activity at ocean ridges, yet little is known about fluctuations in hydrothermal circulation on time scales longer than a few millennia. We present a high-resolution record of hydrothermal activity over the past 50 ka using elemental flux data from a new sediment core from the Mir zone of the TAG hydrothermal field at 26 degrees N on the Mid-Atlantic Ridge. Mir sediments reveal sixfold to eightfold increases in hydrothermal iron and copper deposition during the Last Glacial Maximum, followed by a rapid decline during the sea level rise associated with deglaciation. Our results, along with previous observations from Pacific and Atlantic spreading centers, indicate that rapid sea level changes influence hydrothermal output on mid-ocean ridges. Thus, climate variability may discretize volcanic processing of the solid Earth on millennial time scales and subsequently stimulate variability in biogeochemical interactions with volcanic systems.},
	issn = {0094-8276},
	doi = {10.1002/2016GL068408},
	author = {Middleton, Jennifer L. and Langmuir, Charles H. and Mukhopadhyay, Sujoy and McManus, Jerry F. and Mitrovica, Jerry X.}
}
@article {2584,
	title = {What do benthic ? <sup>13</sup>               C and ? <sup>18</sup>               O data tell us about Atlantic circulation during Heinrich Stadial 1?},
	journal = {Paleoceanography},
	volume = {30},
	year = {2015},
	month = {Jan-04-2015},
	pages = {353 - 368},
	abstract = {Approximately synchronous with the onset of Heinrich Stadial 1 (HS1), δ13C decreased throughout most of the upper (~1000{\textendash}2500 m) Atlantic, and at some deeper North Atlantic sites. This early deglacial δ13C decrease has been alternatively attributed to a reduced fraction of high-δ13C North Atlantic Deep Water (NADW) or to a decrease in the NADW δ13C source value. Here we present new benthic δ18O and δ13C records from three relatively shallow (~1450{\textendash}1650 m) subpolar Northeast Atlantic cores. With published data from other cores, these data form a depth transect (~1200{\textendash}3900 m) in the subpolar Northeast Atlantic. We compare Last Glacial Maximum (LGM) and HS1 data from this transect with data from a depth transect of cores from the Brazil Margin. The largest LGM-to-HS1 decreases in both benthic δ13C and δ18O occurred in upper waters containing the highest NADW fraction during the LGM. We show that the δ13C decrease can be explained entirely by a lower NADW δ13C source value, entirely by a decrease in the proportion of NADW relative to Southern Ocean Water, or by a combination of these mechanisms. However, building on insights from model simulations, we hypothesize that reduced ventilation due to a weakened but still active Atlantic Meridional Overturning Circulation also contributed to the low δ13C values in the upper North Atlantic. We suggest that the benthic δ18O gradients above ~2300 m at both core transects indicate the depth to which heat and North Atlantic deglacial freshwater had mixed into the subsurface ocean by early HS1.},
	doi = {10.1002/2014PA002667},
	url = {http://doi.wiley.com/10.1002/2014PA002667},
	author = {Oppo, Delia W. and Curry, William B. and McManus, Jerry F.}
}
@article {2543,
	title = {Advection and scavenging controls of Pa/Th in the northern NE Atlantic},
	journal = {Paleoceanography},
	volume = {29},
	year = {2014},
	month = {Jan-06-2014},
	pages = {668 - 679},
	abstract = {Over the last 2 decades, significant advances have been made in reconstructing past rates of ocean circulation using sedimentary proxies for the dynamics of abyssal waters. In this study we combine the use of two rate proxies, sortable silt grain size, and sedimentary 231Pa/230Th, measured on a depth transect of deep-sea sediment cores from the northern NE Atlantic, to investigate ocean circulation changes during the last deglacial. We find that at two deep sites, the core-top 231Pa/230Th ratios reflect Holocene circulation rates, while during Heinrich Stadial 1, the deglacial ratios peaked as the sortable silt grain size decreased, reflecting a general circulation slowdown. However, the peak 231Pa/230Th significantly exceeded the production ratio in both cores, indicating that 231Pa/230Th was only partially controlled by ocean circulation at these sites. This is supported by a record of 231Pa/230Th from an intermediate water depth site, where values also peaked during Heinrich Stadial 1, but were consistently above the production ratio over the last 24 ka, reflecting high scavenging below productive surface waters. At our study sites, we find that preserved sediment component fluxes cannot be used to distinguish between a scavenging or circulation control, although they are consistent with a circulation influence, since the core at intermediate depth with the highest 231Pa/230Th recorded the lowest particle fluxes. Reconstruction of advection rate using 231Pa/230Th in this region is complicated by high productivity, but the data nevertheless contain important information on past deep ocean circulation.},
	doi = {10.1002/2014PA002633},
	url = {http://doi.wiley.com/10.1002/2014PA002633},
	author = {Roberts, Natalie L. and McManus, Jerry F. and Piotrowski, Alexander M. and McCave, I. Nicholas}
}
@article {2544,
	title = {Silicon isotopes indicate enhanced carbon export efficiency in the North Atlantic during deglaciation},
	journal = {Nature Communications},
	volume = {5},
	year = {2014},
	month = {Nov-01-2015},
	abstract = {Today{\textquoteright}s Sargasso Sea is nutrient starved, except for episodic upwelling events caused by wind-driven winter mixing and eddies. Enhanced diatom opal burial in Sargasso Sea sediments indicates that silicic acid, a limiting nutrient today, may have been more available in subsurface waters during Heinrich Stadials, millennial-scale climate perturbations of the last glacial and deglaciation. Here we use the geochemistry of opal-forming organisms from different water depths to demonstrate changes in silicic acid supply and utilization during the most recent Heinrich Stadial. We suggest that during the early phase (17.5{\textendash}18 ka), wind-driven upwelling replenished silicic acid to the subsurface, resulting in low Si utilization. By 17 ka, stratification reduced the surface silicic acid supply leading to increased Si utilization efficiency. This abrupt shift in Si cycling would have contributed to high regional carbon export efficiency during the recent Heinrich Stadial, despite being a period of increasing atmospheric CO2.},
	keywords = {Biogeochemistry, Cryospheric science, Ocean sciences},
	doi = {10.1038/ncomms4107},
	url = {http://www.nature.com/doifinder/10.1038/ncomms4107},
	author = {Hendry, Katharine R. and Robinson, Laura F. and McManus, Jerry F. and Hays, James D.}
}
@article {2545,
	title = {Persistent export of 231Pa from the deep central Arctic Ocean over the past 35,000 years},
	journal = {Nature},
	volume = {497},
	year = {2013},
	month = {May-05-2015},
	pages = {603 - 606},
	abstract = {The Arctic Ocean has an important role in Earth{\textquoteright}s climate, both through surface processes1 such as sea-ice formation and transport, and through the production and export of waters at depth that contribute to the global thermohaline circulation2, 3. Deciphering the deep Arctic Ocean{\textquoteright}s palaeo-oceanographic history is a crucial part of understanding its role in climatic change. Here we show that sedimentary ratios of the radionuclides thorium-230 (230Th) and protactinium-231 (231Pa), which are produced in sea water and removed by particle scavenging on timescales of decades to centuries, respectively4, record consistent evidence for the export of 231Pa from the deep Arctic and may indicate continuous deep-water exchange between the Arctic and Atlantic oceans throughout the past 35,000 years. Seven well-dated box-core records provide a comprehensive overview of 231Pa and 230Th burial in Arctic sediments during glacial, deglacial and interglacial conditions. Sedimentary 231Pa/230Th ratios decrease nearly linearly with increasing water depth above the core sites, indicating efficient particle scavenging in the upper water column and greater influence of removal by lateral transport at depth. Although the measured 230Th burial is in balance with its production in Arctic sea water, integrated depth profiles for all time intervals reveal a deficit in 231Pa burial that can be balanced only by lateral export in the water column. Because no enhanced sink for 231Pa has yet been found in the Arctic, our records suggest that deep-water exchange through the Fram strait may export 231Pa. Such export may have continued for the past 35,000 years, suggesting a century-scale replacement time for deep waters in the Arctic Ocean since the most recent glaciation and a persistent contribution of Arctic waters to the global ocean circulation.},
	keywords = {Marine chemistry, Palaeoceanography, Palaeoclimate},
	issn = {0028-0836},
	doi = {10.1038/nature12145},
	url = {http://www.nature.com/doifinder/10.1038/nature12145},
	author = {Hoffmann, Sharon S. and McManus, Jerry F. and Curry, William B. and Brown-Leger, L. Susan}
}
@article {2546,
	title = {Transient stratification as the cause of the North Pacific productivity spike during deglaciation},
	journal = {Nature Geoscience},
	volume = {6},
	year = {2013},
	month = {Feb-07-2014},
	pages = {622 - 626},
	abstract = {During the B{\o}lling{\textendash}Aller{\o}d warm period of the last deglaciation, about 14 kyr ago, there was a strong and pervasive spike in primary productivity in the North Pacific Ocean1. It has been suggested that this productivity event was caused by an influx of the micronutrient iron from surrounding continental shelves as they were flooded by sea-level rise2. Here we test this hypothesis by comparing numerous proxies of productivity with iron flux and provenance measured from a core from the subarctic Pacific Ocean. We find no evidence for an abrupt deglacial pulse of iron from any source at the time of peak productivity. Instead, we argue that the deglacial productivity peak was caused by two stepwise events. First, deep convection during early deglaciation increased nutrient supply to the surface but also increased the depth of the mixed layer, which pushed surface production deeper in the water column and induced light limitation. A subsequent input of meltwater from northern American ice sheets then stratified the water column, which relieved light limitation while leaving the surface waters enriched in nutrients. We conclude that iron plays, at most, a secondary role in controlling productivity during the glacial and deglacial periods in the subarctic Pacific Ocean.},
	keywords = {Biogeochemistry, Marine biology, Marine chemistry, Palaeoceanography},
	issn = {1752-0894},
	doi = {10.1038/ngeo1873},
	url = {http://www.nature.com/doifinder/10.1038/ngeo1873},
	author = {Lam, Phoebe J. and Robinson, Laura F. and Blusztajn, Jerzy and Li, Camille and Cook, Mea S. and McManus, Jerry F. and Keigwin, Lloyd D.}
}
@article {2549,
	title = {Radiocarbon and 230Th data reveal rapid redistribution and temporal changes in sediment focussing at a North Atlantic drift},
	journal = {Earth and Planetary Science Letters},
	volume = {301},
	year = {2011},
	month = {Jan-01-2011},
	pages = {373 - 381},
	abstract = {In locations of rapid sediment accumulation receiving substantial amounts of laterally transported material the timescales of transport and accurate quantification of the transported material are at the focus of intense research. Here we present radiocarbon data obtained on co-occurring planktic foraminifera, marine haptophyte biomarkers (alkenones) and total organic carbon (TOC) coupled with excess Thorium-230 (230Thxs) measurements on four sediment cores retrieved in 1649{\textendash}2879m water depth from two such high accumulation drift deposits in the Northeast Atlantic, Bj{\"o}rn and Gardar Drifts. While 230Thxs inventories imply strong sediment focussing, no age offsets are observed between planktic foraminifera and alkenones, suggesting that redistribution of sediments is rapid and occurs soon after formation of marine organic matter, or that transported material contains negligible amounts of alkenones. An isotopic mass balance calculation based on radiocarbon concentrations of co-occurring sediment components leads us to estimate that transported sediment components contain up to 12\% of fossil organic matter that is free of or very poor in alkenones, but nevertheless appears to consist of a mixture of fresh and eroded fossil material. Considering all available constraints to characterize transported material, our results show that although focussing factors calculated from bulk sediment 230Thxs inventories may allow useful approximations of bulk redeposition, they do not provide a unique estimate of the amount of each laterally transported sediment component. Furthermore, our findings provide evidence that the occurrence of lateral sediment redistribution alone does not always hinder the use of multiple proxies but that individual sediment fractions are affected to variable extents by sediment focussing. 

},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2010.11.022},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0012821X1000717X},
	author = {Mollenhauer, Gesine and McManus, Jerry F. and Wagner, Thomas and McCave, I. Nick and Eglinton, Timothy I.}
}
@article { ISI:000286640400038,
	title = {Radiocarbon and Th-230 data reveal rapid redistribution and temporal changes in sediment focussing at a North Atlantic drift},
	journal = {EARTH AND PLANETARY SCIENCE LETTERS},
	volume = {301},
	number = {{1-2}},
	year = {2011},
	month = {JAN 3},
	pages = {373-381},
	type = {Article},
	abstract = {In locations of rapid sediment accumulation receiving substantial amounts of laterally transported material the timescales of transport and accurate quantification of the transported material are at the focus of intense research. Here we present radiocarbon data obtained on co-occurring planktic foraminifera, marine haptophyte biomarkers (alkenones) and total organic carbon (TOC) coupled with excess Thorium-230 (Th-230(xs)) measurements on four sediment cores retrieved in 1649-2879 m water depth from two such high accumulation drift deposits in the Northeast Atlantic, Bjorn and Gardar Drifts. While Th-230(xs), inventories imply strong sediment focussing, no age offsets are observed between planktic foraminifera and alkenones, suggesting that redistribution of sediments is rapid and occurs soon after formation of marine organic matter, or that transported material contains negligible amounts of alkenones. An isotopic mass balance calculation based on radiocarbon concentrations of co-occurring sediment components leads us to estimate that transported sediment components contain up to 12\% of fossil organic matter that is free of or very poor in alkenones, but nevertheless appears to consist of a mixture of fresh and eroded fossil material. Considering all available constraints to characterize transported material, our results show that although focussing factors calculated from bulk sediment Th-230(xs) inventories may allow useful approximations of bulk redeposition, they do not provide a unique estimate of the amount of each laterally transported sediment component. Furthermore, our findings provide evidence that the occurrence of lateral sediment redistribution alone does not always hinder the use of multiple proxies but that individual sediment fractions are affected to variable extents by sediment focussing. (C) 2010 Elsevier B.V. All rights reserved.},
	keywords = {alkenones, compound-specific radiocarbon dating, drift sediments, focussing factors, Th-230(xs)},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2010.11.022},
	author = {Mollenhauer, Gesine and McManus, Jerry F. and Wagner, Thomas and McCave, I. Nick and Eglinton, Timothy I.}
}
@article {1933,
	title = {Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Th evidence},
	journal = {Deep-Sea Research I},
	volume = {53},
	year = {2006},
	note = {id: 543},
	month = {2006},
	pages = {1224-1243},
	author = {Mollenhauer, Gesine and McManus, Jerry F. and Benthien, Albert and Muller, Peter J. and Eglinton, Timothy I.}
}
