C024-04
On the origin and cycling of Holocene-aged carbon beneath the West Antarctic Ice Sheet

Wednesday, 9 December 2020: 05:40
Virtual
Ryan Venturelli1, Christina Davis2, Trista Vick-Majors3, Wei Li4, Matthew Siegfried5, Joel D Barker6, Amy Leventer7, David M Harwood8, Brent Christner2, Helen Amanda Fricker9, John C Priscu4, Brad E Rosenheim10 and SALSA Science Team, (1)University of South Florida, College of Marine Science, Tampa, FL, United States, (2)University of Florida, Microbiology and Cell Science, Ft Walton Beach, FL, United States, (3)Michigan Technological University, Biological Sciences, Houghton, MI, United States, (4)Montana State University, Land Resources and Environmental Science, Bozeman, MT, United States, (5)Colorado School of Mines, Geophysics, Golden, CO, United States, (6)University of Minnesota, Minneapolis, MN, United States, (7)Colgate University, Geology, Hamilton, NY, United States, (8)University of Nebraska Lincoln, Lincoln, NE, United States, (9)Scripps Institution of Oceanography, La Jolla, CA, United States, (10)University of South Florida St. Petersburg, College of Marine Science, St Petersburg, FL, United States
Abstract:
The identification of active subglacial lakes and the subsequent decade of observation has revealed that movement of water through the subglacial hydrologic system beneath the Antarctic Ice Sheet influences regional ice dynamics and coastal biogeochemical cycling. This enigmatic environment remains one of the least explored frontiers on Earth, yet our limited access to subglacial West Antarctica has already transformed the way in which we view the entire continent. Direct access to the subglacial environment using clean drilling approaches has revealed a diverse microbial ecosystem and sediments that have recorded evidence of past marine incursions. As part of the Subglacial Antarctic Lakes Scientific Access (SALSA) Project, we drilled through nearly 1100 m of a West Antarctic ice stream to sample an Antarctic subglacial lake (Mercer Subglacial Lake; SLM) and its underlying sediments. Here we characterize new isotopic measurements (δ¹³C and Δ14C) from the SLM water column and cores that captured up to 1.7 m of the sediment profile. Applying Ramped PyrOx 14C to subglacial sediments, we find evidence for Holocene grounding line retreat past the core site at SLM, which is over 150 km upstream from the modern grounding line along the modern ice flowline. Our results constrain carbon cycling for a subglacial region of West Antarctica, offer insight on the southward extent of grounding line retreat along the Siple Coast in the recent past, and provide valuable information to model future WAIS dynamics.
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