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

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。该提案寻求有限的资金，以发展伯克利地质年代学中心测量稳定的宇宙成因核素21Ne的能力，并利用这一能力测量南极干燥山谷现有的一套基岩和沉积物样本中的21Ne浓度。这些样品是在前两个南极野外季节采集的，测量了宇宙成因放射性核素26Al和10Be的浓度，以确定所观测到的DV表层沉积物和地貌的古老是微小的侵蚀和退化速度消失的结果，还是寒冷冰川长期覆盖的结果。如果前一个假设得到证实，则测量这些过程的降解率。这些结果量化了现有的地层观测结果，即许多DV景观表面非常古老，侵蚀非常缓慢。结果之一是，与世界上大多数环境不同，在世界范围内，相对快速的表面侵蚀限制了宇宙成因核素测量可以提供信息的周期，DV中的表面足够稳定，以至于支配这一时间尺度的因素不是表面侵蚀，而是26Al和10Be的放射性衰变。这一研究成果将对理解南极冰盖和气候演化具有重要意义。

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.