Paper No. 104-4
Presentation Time: 8:55 AM
DETRITAL THERMOCHRONOLOGY OF ANTARCTIC GLACIGENIC SEDIMENTS: INSIGHTS INTO PAST ICE SHEET BEHAVIOR AND ANTARCTICA’S HIDDEN GEOLOGY
Detrital thermochronology of sand grains in glacigenic sediments is a particularly powerful way to decipher the history of the ice sheets and the landscapes that underlie them. The Antarctic continent is a patchwork of geological terranes that has been formed disassembled and reassembled through a large part of Earth’s history. Although the landscape is currently 98% hidden by the continent-scale ice sheets, sedimentary provenance studies can help us to understand the hidden geology of Antarctica and can be particularly valuable for documenting past changes in the ice sheets. The wide range of closure temperatures of chronometers that can be applied to commonly found detrital minerals in glacial debris allows exploration of the thermal history of sediment sources. Circum-Antarctic surveys of zircon U-Pb, hornblende Ar-Ar, and biotite Ar-Ar from proximal sediment cores, coupled with radiogenic isotopes in bulk fine terrigenous sediments show that different sectors of the ice sheet are distinguishable. Down-core measurements from more distal cores can be used to diagnose which parts of the ice sheets were dynamic and producing large numbers of icebergs in the past. Analysis of terrestrial glacial deposits provides an integrated signal of the thermochronological history of unexposed upstream bedrock. Double- and triple dating of U-bearing minerals such as zircon and apatite allow estimations of the erosion history and thus constraining the landscape evolution.