Controls Since the mid-Pleistocene Transition on Sedimentation and Primary Productivity Downslope of Totten Glacier, East Antarctica

Abstract

The rapidly thinning Totten Glacier on the Sabrina Coast, East Antarctica, is the primarydrainage outlet for ice within the Aurora Subglacial Basin, which could destabilize under the currentatmospheric warming trend. There is growing need for direct geological evidence from the Sabrina Coast toframe late twentieth century Totten melting in the context of past warm climate analogs. Addressingthis need, sediment archives were recovered from two sites on the Sabrina Coast slope and rise that recordchanges in terrigenous sedimentation and primary productivity in the region over glacial cycles since themid‐Pleistocene transition (MPT). This research presents physical properties, grain size, diatom abundanceand assemblages, and geochemical analysis from the two sites to determine how the processes thatcontrol sedimentation change between glacial and interglacial phases. The stratigraphic sequences in bothcores record cyclic variations in physical properties and diatom abundances, which radiocarbon andbiostratigraphic chronologies reveal as 100 Kyr glacial‐interglacial cyclicity. During glacials, terrigenoussediment deposition is enhanced by advanced grounded ice on the shelf, while primary productivity isrestricted 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 icecover. Comparison with post‐MPT slope records from Wilkes Land and the Amundsen Sea shows thatthis pattern is consistent in slope sediments around the margin. The higher‐amplitude variations inAntarctic ice volume and sea ice extent post‐MPT ensure that these signals are pervasive around theAntarctic margin