Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)
The proposed work will investigate changes in the compositional variation of glacial tills over time across two concentric sequences of Pleistocene moraines located adjacent to the heads of East Antarctic outlet glaciers in the Transantarctic Mountains (TAM). The chronologic framework for this work will be generated from cosmogenic exposure ages of boulders on prominent morainal ridges. The PIs hypothesize that variations in till composition may indicate a change in ice flow direction or a change in the composition of the original source area, while ages of the moraines provide a long-term terrestrial perspective on ice sheet dynamics. Both results are vital for modeling experiments that aim to reconstruct the East Antarctic Ice Sheet and assess its role in the global climate system and its potential impact on global sea level rise. The variation of till compositions through time also allows for a more accurate interpretation of sediment cores from the Ross Sea and the Southern Ocean.
OUTCOMES: Found that the sites contain pre-LGM landforms. Also found that the moraine ages increase towards the back of the moraine sequence (towards the headwall) and away from the EAIS at both Howe and Achernar glaciers. Samples do not show a complex history of burial and re-exposure.