Antarctic Glacial Chronology: New Constraints from Surface Exposure Dating
Abstract
Surface exposure dating using 3He, Ne-21 and Cl-36 combined with mapping of moraines, provide new constraints on West Antarctic Ice Sheet (WAIS) chronology. New He-3 production rates are determined from a 125 ka lava flow. Measurements of inherited He-3/He-4 in two common Antarctic lithologies allow measurement of exposure ages < 6000 years. At Mt. Waesche, a moraine band records interior WAIS elevations higher than present. Surface exposure ages indicate that the last ice highstand occurred 10 +/- 1 ka. The data constrain past WAIS behavior and ice volume. Surface exposure ages place age constraints on six Beardmore Glacier drifts. Two drifts record damming of the glacier during the last glacial maximum (10-20 ka) by an expanded WAIS. The four older drifts record similar damming by the WAIS approx. 600 ka, approx. 1 Ma, and approx. 2 Ma. Moraines of Koettlitz Glacier also record damming by the WAIS prior to the LGM. The oldest moraines are > 400 ka. Independent stratigraphic control allows evaluation of prior exposure, cover and determination of erosion rates. Taken together, the results are consistent with sea level control of WAIS extent; the WAIS probably has fluctuated synchronously with the Northern Hemisphere ice sheets for at least the last 1 million years.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2000
- Accession Number
- ADA390281
Entities
People
- Robert P. Ackert Jr
Organizations
- Massachusetts Institute of Technology