Reconstructing the post-LGM deglacial history of Hollingsworth Glacier on Ricker Hills, Transantarctic Mountains, Antarctica

Abstract

The Transantarctic Mountains are an important corridor between the East Antarctic Ice Sheet and the Western Ross Sea, where most current ice streams and outlet glaciers arise. We investigated Ricker Hills, the largest exposed mountainous region between Southern Victoria Land and Terra Nova Bay, and dated the glacial landforms using in-situ cosmogenic-nuclide Be-10 surface exposure dating to reconstruct the paleo-glacial dynamics. The surface of the Hollingsworth glacier lowered since the middle of Marine Isotope Stage (MIS) 2 (22.1 ka); therefore, the Last Glacial Maximum (LGM) occurred before that period. Cosmogenic, geomorphic, and climatic records constrained the glacial surface slope to be between 5.4 degrees and 6.8 degrees. The ice was 270-320 m thicker at the LGM (MIS 2) than presently but did not override the top surface of the Benson Knob. Moreover, previous glacial periods such as the local LGM (MIS 4) or Penultimate Glacial Maximum (MIS 6) maintained thicker ice than the LGM (MIS 2). The Ross Ice Shelf opening during the mid-Holocene (similar to 6 ka) caused the rapid collapse of the terminal outlet glaciers and supplied notable snow accumulation upstream, which stagnated lowering. The greatest lowering and retreat occurred during the late Holocene (2.3 similar to 0.8 ka), when elephant seal colonies thrived in the Ross Embayment.