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CANCELLED - The multidisciplinary story of Antarctica's history as told from blue ice moraines

Associate Professor Kathy Licht, Department of Earth Sciences, IUPUI

Till in an extensive blue ice moraine in the central Transantarctic Mountains shows relatively continuous deposition by East Antarctic derived ice throughout the last glacial cycle. The well-preserved moraine consists of quasi-continuous, hummocky sediment ridges that form on top of sublimating ice. Ground-penetrating radar (GPR) imaging of the internal structure beneath the moraine’s debris cover shows that the moraine formed through the lateral accretion of basal debris-rich ice layers thrust upward over time. Pebble lithology and detrital zircon geochronology reveal distinct spatial changes between dominant sedimentary (Beacon) and igneous (Ferrar) composition at both meter and kilometer scales. The provenance changes observed in the pebble fraction are interpreted to indicate relative stability of the East Antarctic ice sheet, as the Law Glacier tapped into and eroded successively lower stratigraphic units of the Beacon Supergroup. We also analyzed stable isotope values, which indicate warm-based ice upstream of this site. Together these datasets suggest that Antarctic blue ice moraines may be repositories of sediment from the warm-based portions of ice on the polar plateau and provide valuable archives of ice sheet and geologic history around the continent.

Date Wednesday, 18 March 2020
Time 1:00pm - 2:00pm
Audience Public
Event Category Sciences
Event Type Departmental Seminar
CampusDunedin
DepartmentGeology
LocationBenson Common Room (Room Gn9, Geology)
Contact Emailchristian.ohneiser@otago.ac.nz

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