Antiphase dynamics between cold-based glaciers in the Antarctic Dry Valleys region and ice extent in the Ross Sea during MIS 5

• Main Authors: Anderson, Jacob T. H., Fujioka, Toshiyuki, Fink, David, Hidy, Alan J., Wilson, Gary S., Wilcken, Klaus, Abramov, Andrey, Demidov, Nikita
• Format: Text
• Language: English
• Published: 2023
• Subjects: Antarctic; Pearse Valley; Ross Ice Shelf; Ross Sea; Taylor Dome; Taylor Glacier; Taylor Valley; The Antarctic; Wright Valley; Antarc*; Antarctica; Ice; Ice Shelf; permafrost; Sea ice
• Online Access: https://doi.org/10.5194/tc-2022-252; https://tc.copernicus.org/preprints/tc-2022-252/

During the interglacial and interstadials of Marine Isotope Stage 5 (MIS 5e, 5c, 5a), outlet and alpine glaciers in the Dry Valleys region, Antarctica, appear to have advanced in response to increased precipitation from enhanced open ocean conditions in the Ross Sea. We provide further evidence of this antiphase behaviour through retreat of a peripheral lobe of Taylor Glacier in Pearse Valley, a region that was glaciated during MIS 5. We measured cosmogenic 10 Be and 26 Al in three granite cobbles from thin, patchy drift (Taylor 2 Drift) in Pearse Valley to constrain the timing of retreat of Taylor Glacier. Assuming simple continuous exposure, our minimum, zero erosion, exposure ages suggest Taylor Glacier partially retreated from Pearse Valley no later than 65–74 ka. Timing of retreat after 65 ka and until the Last Glacial Maximum (LGM) when Taylor Glacier was at a minimum position, remains unresolved. The depositional history of permafrost sediments buried below Taylor 2 Drift in Pearse Valley was obtained from 10 Be and 26 Al depth profiles to ~3 metres in permafrost in proximity to the cobble sampling sites. Depth profile modelling gives a depositional age for near-surface (< 1.65 m) permafrost at Pearse Valley of 180 ka +20 / −40 ka, implying deposition of permafrost sediments predate MIS 5 advances of Taylor Glacier. Depth profile modelling of deeper permafrost sediments (> 2.09 m) indicates a depositional age of > 180 ka. The cobble and permafrost ages reveal Taylor Glacier advances during MIS 5 were non-erosive or mildly erosive, preserving the underlying permafrost sediments and peppering boulders and cobbles upon an older, relict surface. Our results are consistent with U/Th ages from central Taylor Valley, and suggest changes in moisture delivery over Taylor Dome during MIS 5e, 5c and 5a appear to be associated with the extent of the Ross Ice Shelf and sea ice in the Ross Sea. At a coastal, lower elevation site in neighbouring Lower Wright Valley, 10 Be and 26 Al depth profiles from a second ...