Collaborative Proposal: Age, Origin and Climatic Significance of Buried Ice in the Western Dry Valleys, Antarctica

该项目将确定在南极洲西部干谷发现的埋藏冰的年龄、起源和气候意义。先前的研究表明，这些冰的年龄可能超过一百万年，使其成为迄今为止地球上发现的最古老的冰。另一种观点是，这些冰代表了最近冻结的地下水。为了区分这些假设和表征冰，我们正在开展一个跨学科的研究项目，重点是：1)了解允许冰保存的表面过程；2)测试宇宙形成核素和40Ar/39Ar分析在确定与冰有关的山丘和火山灰年代方面的有效性。我们的计划要求对至少6个宇宙成因深度剖面进行分析，以确定低温扰动是否以及如何改变升华过程，并评估3个被碎片覆盖的冰川的冰升华平均速率。我们将通过有限元分析建立至少三个埋藏冰川的模型，并将流速与基于地表沉积物放射性测年的流速进行比较。还将收集10个冰芯，用于测量d18O， dD，冰结构，冰质地，总气体含量/组成。更好地了解埋在地下冰层之上的地表过程，将使研究人员能够获得大气和气候变化的记录，这些记录很可能涵盖第四纪之前的时间间隔。这项工作还可能为了解火星历史提供有价值的见解。在更广泛的影响方面，我们招募了三名女博士生，并在哥伦比亚大学的地球化学家、布朗大学的行星地质学家、波士顿大学的地貌学家和缅因大学的数值建模师之间开展了跨学科合作。

This project will determine the age, origin, and climatic significance of buried ice found in the western Dry Valleys of Antarctica. Previous studies indicate that this ice may be over a million years in age, making it by far the oldest ice yet discovered on Earth. An alternative view is that this ice is represents recently frozen groundwater. To distinguish between these hypotheses and characterize the ice, we are undertaking an interdisciplinary research program focused on: 1) understanding the surface processes that permit ice preservation; and 2) testing the efficacy of cosmogenic nuclides and 40Ar/39Ar analyses in dating both tills and volcanic ash associated with the ice. Our plan calls for the analysis of a minimum of six cosmogenic depth profiles to determine if and how cryoturbation reworks sublimation tills and assess the average rate of ice sublimation for three debris-covered glaciers. We will model through finite- element analyses at least three buried glaciers and compare flow rates with those based on radiometric dating of surface deposits. Ten ice cores will also be collected for measurement of d18O, dD, ice fabric, ice texture, total gas content/composition. Better understanding of surface processes above buried ice will permit researchers to gain access to a record of atmospheric and climate change that could well cover intervals that predate Quaternary time. The work may also add valuable insight into Martian history. In terms of broader impacts, we have recruited three female PhD students and developed interdisciplinary collaborations among geochemists at Columbia University, planetary geologists at Brown University, geomorphologists at Boston University, and numerical modelers at the University of Maine.