USING DIATOM ASSEMBLAGES FROM DEGLACIAL TO RECENT TO STUDY ICE-OCEAN INTERACTIONS OFFSHORE THE TOTTEN GLACIER, EAST ANTARCTICA

The marine based Totten Glacier system, which holds roughly 3.9 m sea-level equivalent ice, is rapidly losing ice mass at rates comparable to systems in West Antarctica. Presently, relatively warm modified Circumpolar Deep Water (mCDW) is upwelling onto the continental shelf suggesting that this glacial system is sensitive to ocean thermal forcing. To study deglacial to recent ice-ocean interaction of the Totten Glacier system, and how these interactions influenced this glacial system over longer timescales, we integrate sedimentological and diatom data from a 9-meter jumbo piston core (NBP1402 JPC43) taken from a bathymetric channel on the Sabrina Coast continental shelf. These analyses are used in conjunction with multibeam swath bathymetry and CTD data to contextualize modern observations with the sediment record. The core contains three distinct lithologic units spanning from the last Glacial Period to the recent: the basal unit is comprised of bedded muddy sands to sandy muds with low magnetic susceptibility (MS), overlain by a unit of high MS diatom-bearing muds and sands, followed by laminated diatom mud and oozes. Preliminary radiocarbon dating via ramped pyrolysis, a technique that thermochemically separates mixed pools of carbon from a bulk sediment sample, suggests that the basal unit was deposited during the last glacial period. We hypothesize that this unit records an initial period of high-velocity flow through the bathymetric channel, potentially deposited by a subglacial meltwater outburst from the Aurora Subglacial Basin. In the overlying unit, continued but lower velocity flow delivered finer-grained terrigenous debris. This unit has a high relative abundance of F. kerguelensis, a diatom species associated with the Antarctic Circumpolar Current, which points to the presence of mCDW on the continental shelf at this time, potentially a heat source for basal melting at the initiation of the last deglaciation of the Totten Glacier System. The upper 490 cm is highly biosiliceous laminated mud and ooze and records changes in oceanographic conditions through the Holocene. Ongoing work aims to provide further time constraints on sedimentologic and biological facies transitions as well as to produce a provenance record of the basal sandy section of the core to examine the origin of the sands.