Cosmogenic nuclide exposure age scatter records glacial history and processes in McMurdo Sound, Antarctica

Abstract. The preservation of cosmogenic nuclides that accumulated during periods prior exposure but were not subsequently removed by erosion or radioactive decay complicates interpretation exposure, erosion, and burial ages used for a variety geomorphological applications. In glacial settings, cold-based, non-erosive glacier ice may fail to remove inventories inherited in glacially transported material. As result, individual can vary widely across single landform (e.g., moraine) exceed the expected true depositional age. surface processes contribute inheritance remain poorly understood, thus limiting interpretations nuclide datasets environments. Here, we present compilation new previously published multiple lithologies local Last Glacial Maximum (LGM) older Pleistocene sediments McMurdo Sound region Antarctica. Unlike most Antarctic chronologies, are able compare LGM directly against an independent radiocarbon chronology fossil algae from same sedimentary unit brackets age between 12.3 19.6 ka. Cosmogenic lithology, suggesting bedrock source to, during, after entrainment explain scatter. 10Be quartz granite, sourced base stratigraphic section Transantarctic Mountains, scattered young, clasts entrained sub-glacial plucking generate reasonable apparent ages. 3He pyroxene Ferrar Dolerite, which crops out above outlet glaciers older, suggests initially exposed on cliff faces rock fall carry nuclides. olivine basalt volcanic contain many excessively old also have bimodal distribution with peak probabilities slightly pre-date post-date LGM; this record landscape exposure. With magnitude geological contributing scatter mind, examine deposited extensive sheet inundate Pleistocene. These results underscore how operating Mountains expressed held sediments.