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Lavoie, C.,Domack, E. W.,Pettit, E. C.,Scambos, T. A.,Larter, R. D.,Schenke, H.-W.,Yoo, K. C.,Gutt, J.,Wellner, J.,Canals, M.,Anderson, J. B.,Amblas, D. Copernicus GmbH 2015 The cryosphere Vol.9 No.2
<P><p><strong>Abstract.</strong> We present a new seafloor map for the northern Antarctic Peninsula (AP), including swath multibeam data sets from five national programs. Our map allows for the examination and interpretation of Last Glacial Maximum (LGM) paleo-ice-flow paths developed on the seafloor from the preservation of mega-scale glacial lineations, drumlinized features, and selective linear erosion. We combine this with terrestrial observations of flow direction to place constraints on ice divides and ice domes on the AP continental shelf during the LGM time interval. The results show a flow bifurcation as ice exits the Larsen B embayment. Flow emanating off the Seal Nunataks (including Robertson Island) is directed toward the southeast, then eastward as the flow transits toward the Robertson Trough. A second, stronger 'streaming flow' is directed toward the southeast, then southward as ice overflowed the tip of the Jason Peninsula to reach the southern perimeter of the embayment. Our reconstruction also refines the extent of at least five other distinct paleo-ice-stream systems that, in turn, serve to delineate seven broad regions where contemporaneous ice domes must have been centered on the continental shelf at LGM. Our reconstruction is more detailed than other recent compilations because we followed specific ice-flow indicators and have kept tributary flow paths parallel.</p> </P>
Christ, Andrew J.,Talaia-Murray, Manique,Elking, Natalie,Domack, Eugene W.,Leventer, Amy,Lavoie, Caroline,Brachfeld, Stefanie,Yoo, Kyu-Cheul,Gilbert, Robert,Jeong, Sun-Mi,Petrushak, Stephen,Wellner, J Geological Society of America 2015 Geological Society of America bulletin Vol.127 No.1
<P>Three marine sediment cores were collected along the length of the fjord axis of Barilari Bay, Graham Land, west Antarctic Peninsula (65°55′S, 64°43′W). Multi-proxy analytical results constrained by high-resolution geochronological methods (<SUP>210</SUP>Pb, radiocarbon, <SUP>137</SUP>Cs) in concert with historical observations capture a record of Holocene paleoenvironmental variability. Our results suggest early and middle Holocene (>7022–2815 cal. [calibrated] yr B.P.) retreated glacial positions and seasonally open marine conditions with increased primary productivity. Climatic cooling increased sea ice coverage and decreased primary productivity during the Neoglacial (2815 to cal. 730 cal. yr B.P.). This climatic cooling culminated with glacial advance to maximum Holocene positions and expansion of a fjord-wide ice shelf during the Little Ice Age (LIA) (ca. 730–82 cal. yr B.P.). Seasonally open marine conditions were achieved and remnant ice shelves decayed within the context of recent rapid regional warming (82 cal. yr B.P. to present). Our findings agree with previously observed late Holocene cooling and glacial advance across the Antarctic Peninsula, suggesting that the LIA was a regionally significant event with few disparities in timing and magnitude. Comparison of the LIA Antarctic Peninsula record to the rest of the Southern Hemisphere demonstrates close synchronicity in the southeast Pacific and southern most Atlantic region but less coherence for the southwest Pacific and Indian Oceans. Comparisons with the Northern Hemisphere demonstrate that the LIA Antarctic Peninsula record was contemporaneous with pre-LIA cooling and sea ice expansion in the North Atlantic–Arctic, suggesting a global reach for these events.</P>
Kim, Sunghan,Yoo, Kyu-Cheul,Lee, Jae Il,Khim, Boo-Keun,Bak, Young-Suk,Lee, Min Kyung,Lee, Jongmin,Domack, Eugene W.,Christ, Andrew J.,Yoon, Ho Il Elsevier 2018 Quaternary science reviews Vol.192 No.-
<P><B>Abstract</B></P> <P>Paleoceanographic changes in response to Holocene climate variability in Bigo Bay, west Antarctic Peninsula (WAP) were reconstructed through geochemical, isotopic, sedimentological, and microfossil analysis. Core WAP13-GC47 is composed of 4 lithologic units. Unit 4 was deposited under ice shelf settings. Unit 3 represents the mid-Holocene open marine conditions. Unit 2 indicates lateral sediment transport by a glacier advance during the Neoglacial period. The chronological contrast between the timing of open marine conditions at core WAP13-GC47 (<I>ca</I>. 7060 cal. yr BP at 540 cm) and the ages of calcareous shell fragments (<I>ca</I>. 8500 cal. yr BP) in Unit 2b suggests sediment reworking during the Neoglacial period. Unit 1 was deposited during the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Surface water productivity, represented by biogenic opal and total organic carbon (TOC) concentrations, increased and bulk δ<SUP>15</SUP>N (nitrate utilization) decreased during the warmer early to middle Holocene and the MWP. In contrast, surface water productivity decreased with increased bulk δ<SUP>15</SUP>N during the colder Neoglacial period and LIA in Bigo Bay. The nitrate utilization was enhanced during cold periods in association with strong surface water stratification resulting from increased sea ice meltwater discharge or proximity to an ice shelf calving front in Bigo Bay. Reduced nitrate utilization during warm periods is related to weak stratification induced by less sea ice meltwater input and stronger Circumpolar Deep Water influence.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Enhanced stratification caused high nitrate utilization during cold periods. </LI> <LI> Low nitrate utilization is ascribed to CDW input/less sea-ice melt water during warm periods. </LI> <LI> Surface water productivity was high (low) during warm (cold) periods with opposite patterns of nitrate utilization. </LI> <LI> Surface-deep water mass exchange in the WAP fjord is influenced by ice shelf/sea-ice variation. </LI> </UL> </P>