Controls since the Mid‐Pleistocene Transition on Sedimentation and Primary Productivity Downslope of Totten Glacier, East Antarctica

• Published in: Paleoceanography and Paleoclimatology
• Main Authors: Holder, L., Duffy, M., Opdyke, B., Leventer, A., Post, A., O'Brien, P., Armand, L. K.
• Format: Text
• Language: English
• Published: American Geophysical Union (AGU) 2020
• Subjects: geo; envir; Amundsen Sea; Antarctic; East Antarctica; Sabrina Coast; The Antarctic; Totten Glacier; Wilkes Land; Antarc*; Antarctica; Ice Sheet; Sea ice
• Online Access: https://doi.org/10.1029/2020PA003981; https://archimer.ifremer.fr/doc/00663/77548/79434.pdf; https://archimer.ifremer.fr/doc/00663/77548/79435.pdf; https://archimer.ifremer.fr/doc/00663/77548/

The rapidly thinning Totten Glacier on the Sabrina Coast, East Antarctica, is the primary drainage outlet for ice within the Aurora Subglacial Basin, which could destabilize under the current atmospheric warming trend. There is growing need for direct geological evidence from the Sabrina Coast to frame late 20th century Totten melting in the context of past warm climate analogues. Addressing this need, sediment archives were recovered from two sites on the Sabrina Coast slope and rise that record changes in terrigenous sedimentation and primary productivity in the region over glacial cycles since the mid‐Pleistocene Transition (MPT). This research presents physical properties, grain size, diatom abundance and assemblages and geochemical analysis from the two sites to determine how the processes that control sedimentation change between glacial and interglacial phases. The stratigraphic sequences in both cores record cyclic variations in physical properties and diatom abundances, which radiocarbon and biostratigraphic chronologies reveal as 100kyr glacial‐interglacial cyclicity. During glacials, terrigenous sediment deposition is enhanced by advanced grounded ice on the shelf, while primary productivity is restricted due to permanent summer sea‐ice extending past the continental slope. During interglacials, pelagic sedimentation suggests high surface productivity associated with contractions of regional sea‐ice cover. Comparison with post‐MPT slope records from Wilkes Land and the Amundsen Sea show this pattern is consistent in slope sediments around the margin. The higher amplitude variations in Antarctic ice volume and sea ice extent post‐MPT ensure that these signals are pervasive around the Antarctic margin. Plain Language Summary To improve predictions of future Antarctic ice sheet behaviour, knowledge of how Antarctica responded in the past, particularly when temperatures were similar to or higher than today, is required. Geological records recovered from ice proximal sediments can provide this information. ...