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

该项目将确定南极洲西部干燥山谷中发现的埋藏冰的年龄、来源和气候意义。之前的研究表明，这块冰的年龄可能超过100万年，使其成为迄今为止在地球上发现的最古老的冰。另一种观点认为，这些冰代表了最近冻结的地下水。为了区分这些假说和确定冰层的特征，我们正在进行一项跨学科的研究计划，重点是：1)了解使冰得以保存的表面过程；2)测试宇宙源核素和40Ar/39Ar分析在测定冰层和与冰有关的火山灰年龄方面的有效性。我们的计划要求分析至少六个宇宙成因深度剖面，以确定冷冻扰动是否以及如何使升华作用重新发挥作用，并评估三个被碎片覆盖的冰川的平均冰升华速度。我们将通过有限元分析对至少三条被埋藏的冰川进行建模，并将流速与基于地表沉积物辐射测年的流速进行比较。还将收集10个冰芯，用于测量d18O、dd、冰组分、冰结构、总气体含量/组成。更好地了解埋藏冰层上方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。这项工作还可能增加对火星历史的有价值的洞察。在更广泛的影响方面，我们招募了三名女性博士生，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州大学的数值建模人员之间开展了跨学科的合作。

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.