Progressive Thinning of Grounded Ice Sheet in Terra Nova Bay, Antarctica, During the Late Quaternary

Abstract

Victoria Land, along the western Ross Sea coast in Antarctica, provides critical insights into past glacial and climatic changes, which may be helpful to refine projections of future environmental shifts. This study refines estimates of ice thickness since the Last Glacial Period in Terra Nova Bay by integrating geomorphological, geological, and geochronological datasets, and delineates the formation of the “Terra Nova Ice Sheet/Shelf”, which resulted from the merging of outlet glaciers in the bay. Enhanced and thickened glacial discharge from the southwest sculpted the Drygalski Trough, forcing smaller outlet glaciers to merge and redirect northeastward as a unified ice body. The grounded ice sheet extended over Cape Washington, as evidenced by granitoid erratics deposited on the peninsula. Cosmogenic nuclide (in situ 10Be and 26Al) surface exposure dating indicates that ice thinning began before the LGM (Last Glacial Maximum), with a Local LGM occurring earlier. Subsequent rapid ice lowering took place in the mid-Holocene, driven by Marine Ice Sheet Instability and delayed by the stepwise retreat of the grounded ice in the Ross Sea. These findings underscore the complexity of Antarctic ice dynamics and highlight that regional ice shelf behavior, rather than temperature alone, is a primary driver in ice mass changes.