Evolution of the Antarctic Ice Sheet and Glacial Eustasy in the Cenozoic

J. B. Anderson, P. J. Bart, L. R. Bartek

From at least the late Eocene until the late Pliocene, the Antarctic Ice Sheet was the sole regulator to glacial eustasy. An understanding of the ice sheets evolution enables us to predict the magnitude and frequency of eustatic events throughout much of the Cenozoic.

Climate modeling studies indicate that separation of Antarctica from other Gondwana continents, especially Australia, resulted in increased moisture transfer to the continent, which triggered ice sheet development; Antarctica was in a polar position long before the Eocene. Since this mechanism was irreversible, the early ice sheet may have been relatively stable and not subject to short-term temperature changes caused by orbital forcing. Presently, the geological record of Eocene-Oligocene ice sheet behavior is inadequate to determine the magnitude and frequency of ice volume changes.

Seismic profiles from around the Antarctic continent indicate that by the early Miocene the ice sheet began to advance and retreat across the continental shelf, but glacial/interglacial cycles were long-lived, possibly third-order events. Beginning in the Plio-Pleistocene, the frequency of grounding events on the continental shelf increased, probably in response to high frequency sea-level changes caused by northern hemisphere glacial events that were in tune with climate cycles.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995