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Paper No. 163-7
Presentation Time: 2:50 PM
LATE HOLOCENE GLACIAL ADVANCE AND ICE SHELF GROWTH IN BARILARI BAY, GRAHAM LAND, WEST ANTARCTIC PENINSULA
In the heavily glaciated Antarctic Peninsula (AP) most glaciers terminate as tide-water fronts, and thus it has been generally difficult to document fluctuations in past ice extent during later phases of the Holocene such as the Little Ice Age (LIA). In Barilari Bay, Graham Land, west AP, new multibeam swath bathymetric data and a suite of marine sediment cores afforded the unprecedented opportunity to precisely define and constrain the timing of the most recent glacial advance. All previous efforts on the topic in the AP were inferential in terms of the actual advanced position of glaciers and/or terrestrial termini with no grounding limits defined. Multi-proxy analytical results constrained by high-resolution geochronological methods (Pb-210, C-14, Cs-137) in concert with historical observations capture a record of Holocene paleoenvironmental variability. Our results suggest Early and Middle Holocene (>7022 to 2815 calibrated years before present [cal. yr BP]) 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 ~730 cal. yr BP). This climatic cooling culminated with glacial advance to maximum Holocene positions and expansion of a fjord-wide ice shelf during the LIA (~730 to 82 cal. yr BP). Seasonally open marine conditions were achieved and remnant ice shelves decayed within the context of recent rapid regional warming (82 cal. yr BP 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. Glacial advance in Barilari Bay was broadly in sync with glacial advance events in the south east Pacific and coincides with periods of intensified cooling in the Arctic, suggesting the LIA was truly global in scope.