Extending the record of Antarctic landscape evolution into the Pliocene with neon-21 measurements

Berkeley Geochronology Center, Berkeley CA

Investigators

Abstract

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The proposal seeks limited funds to develop the capability of the Berkeley Geochronology Center to measure the stable cosmogenic nuclide 21Ne, and to use this capability to measure 21Ne concentrations in an existing set of bedrock and sediment samples from the Antarctic Dry Valleys (DV). These samples were collected during two previous Antarctic field seasons and concentrations of the cosmogenic radionuclides 26Al and 10Be was measured in order to determine whether the observed antiquity of DV surface sediments and landforms was the result of vanishingly small erosion and degradation rates or of long periods of cover by cold-based glaciers. If the former hypothesis is confirmed, measure the degradation rates of these processes. These results quantify existing stratigraphic observations that many DV landscape surfaces are very old and erode very slowly. One consequence of the results is that, unlike in most environments worldwide where relatively rapid surface erosion limits the period about which cosmogenic-nuclide measurements can provide information, surfaces in the DV are sufficiently stable that the factor governing this time scale is not surface erosion, but the radioactive decay of 26Al and 10Be. The research results will have important implications in understanding Antarctic ice sheet and climate evolution.