Testing the Use of OSL on Cobbles From the Raised Beaches of King George Island, Antarctica

Abstract

The purpose of this thesis is to find a new method for dating raised-beach deposits in order to create more accurate sea-level curves for the Antarctic Peninsula. 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 commonly used for sediment, but the application to rocks is in its infancy. Methods were developed to isolate quartz grains from the cobbles for OSL measurement. Of the 12 samples I attempted to obtain age dates from, 8 contained enough material for OSL analysis. The OSL ages are in agreement with calibrated radiocarbon ages from the same deposits. In addition, the OSL ages are all internally consistent in that ages obtained from higher ridges are always older than lower ridges and ages obtained from the same ridges overlap one another. My results also clearly illustrate a change in rebound rates within the South Shetland Islands roughly coincident with recent glacier expansion recorded by the mapping and dating of moraines. Because of the large radiocarbon reservoir in Antarctica, OSL is shown to be a more precise method for dating raised beaches than radiocarbon techniques.