Paper No. 69-11
Presentation Time: 4:15 PM
OSL DATING OF HIGH ELEVATION FAN DEPOSITS IN THE ANTARCTIC DRY VALLEYS: CURRENT RESULTS
We have been investigating high elevation alluvial fans, above 1000 m, in the McMurdo Dry Valleys of Antarctica as storehouses for proxy records of climate change. Alluvial deposits at high elevations are small and record occasional sedimentation events indicating brief periods of increased warmth along terrestrial margins of the East Antarctic Ice Sheet. The fans are inactive in the present day based on cross-cutting permafrost wedges and well-developed desert pavements on their surfaces. Thirteen samples from five of these relic alluvial fans, as well as 11 previously collected samples were dated using Optically Stimulated Luminescence (OSL) dating to determine when deposition from aqueous transport occurred, thereby dating brief periods of warming at the glacial margins. Our results suggest clusters of fan activity occurred at 1000-3000 calendar years ago and 8000-10,000 calendar years ago. The OSL ages indicate fan activity also occurred at other times throughout the past 120,000 years, but clustering at these older time periods cannot yet be verified due to the small number of available samples. Possible reasons for increased warmth during the time periods indicated (1-3 ka and 8-10 ka) will be discussed.