T51 Looking to the Past to Understand the Future: Glacial Chronology and Process

Sunday, 22 October 2017
1:30 PM - 5:30 PM
Chelan 2

A MIDDLE PLEISTOCENE THROUGH MIDDLE MIOCENE MORAINE SEQUENCE IN THE CENTRAL TRANSANTARCTIC MOUNTAINS, ANTARCTICA

Paper number: T51-9
Program: Technical Sessions
Time: 3:35 PM – 3:50 PM

Authors

Abstract

Ice-free areas at high elevation in the central Transantarctic Mountains preserve extensive moraine sequences and drift deposits that comprise a geologic record of former East Antarctic Ice Sheet thickness and extent. We are applying cosmogenic-nuclide exposure dating to determine the ages of these moraine sequences at Roberts Massif and Otway Massif, at the heads of the Shackleton and Beardmore Glaciers, respectively. Moraines at these sites are for the most part openwork boulder belts characteristic of deposition by cold-based ice, which is consistent with present climate and glaciological conditions. To develop our chronology, we collected samples from ~30 distinct ice-marginal landforms and have so far measured >100 3He, 10Be, and 21Ne exposure ages. Apparent exposure ages range from 1-14 Ma, which shows that these landforms record glacial events between the middle Pleistocene and middle Miocene. These data show that the thickness of the East Antarctic Ice Sheet in this region was similar to or thicker than present for long periods between the middle Miocene and today. The time range represented by these moraine sequences indicates that they may also provide direct geologic evidence for East Antarctic Ice Sheet behavior during past periods of warmer-than-present climate, specifically the Miocene and Pliocene. As the East Antarctic Ice Sheet is the largest ice sheet on earth, understanding its sensitivity to warm-climate conditions is critical for projections of ice sheet behavior and sea-level rise in future warm climates.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-300203

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