In Search of New High-Resolution Chronostratigraphic Constraints from the Sea-Level and Deglacial History of Polar Regions

Peter Kouremenos¹, Regina DeWitt², and Alexander Simms^1
1Geology, Oklahoma State University, Stillwater, OK
²Physics, Oklahoma State University, Stillwater, OK

Ice-sheets play a significant role in controlling climate during ice-house times. One of the few methods for determining ice-sheet thicknesses in areas with poorly preserved or absent trimlines is the geophysical inversion of sea-level curves. However, few high-resolution chronostratigraphic methods are available for the creation of sea-level curves from high-energy clastic coastlines, such as the Antarctic Peninsula and other glaciated coasts. The few sea-level curves that do exist are limited by radiocarbon dating of material that is difficult, if not impossible, to find and may have been reworked. This scarcity of data has resulted in a variety of ice-sheet models for Antarctica during the Last Glacial Maximum. We test the use of Optically Stimulated Luminescence (OSL) in dating cobbles from raised beaches within the South Shetland Islands of the Antarctic Peninsula. OSL is a method that measures trapped electron charges within quartz and feldspar crystals that are released upon light stimulation. The results are measured and compared against background radiation levels from the sample areas and an equivalent dose rate is calculated. It has the potential of obtaining more precise ages and dating geologically older samples than radiocarbon dating. These cobbles can be used to construct sea-level curves by determining the last exposure of their concealed side to sunlight. We compare more than 10 new OSL dates with previously published sea-level curves from the region in order to calibrate and test our methodology. These new sea-level curves may provide important information on the Antarctic Peninsula Ice Sheet thickness and retreat during the Holocene and late Pleistocene.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas