The Origin of a Polar Ice Sheet in East Antarctica

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This award supports a study to determine the sequence and chronology of events that led to the development of the Antarctic ice sheet. A continental-scale ice sheet probably first developed in East Antarctica close to the Eocene-Oligocene boundary under temperate climatic conditions. The purpose of this project is to determine, from landscape analysis (with a numerical chronology), when (and why) these early temperate conditions gave way to a polar environment in Antarctica. From previous field work and recent photographic analysis, an extensive relict landscape (older than 17 million years) with landforms and erosional features characteristic of temperate glaciation has been delineated. This relict landscape has been called the Sessrumnir erosion surface and it extends over three degrees of latitude and covers almost 10,000 km2 in three fault blocks of the Transantarctic Mountains (Convoy, Dry Valleys, Royal Society). It is on this relict land surface that data will be collected which record Middle and Early Miocene glacial history and paleoclimate. The results should allow an identification of the transition from temperate to polar conditions. This work will involve landscape analysis, stratigraphy of glacial deposits, and Argon-40/Argon-39 dating of volaanic ashfalls. Denudation rates will come from fission-track analyses and from exposure-age analyses of bedrock surfaces and erratic boulders. The overall results will elucidate the origin and stability of the polar Antarctic cryosphere.