The Origin of a Polar Ice Sheet in East Antarctica

南极洲东部极地冰盖的起源

• 批准号: 9527047
• 负责人: George Denton
• 金额: $ 30.59万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 2001-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9527047&HistoricalAwards=false
• 关键词: Origin; Polar; Ice; Sheet; East

This award supports a study to determine the sequence and chronology of events that led to the development of the Antarctic ice sheet. A continental-scale ice sheet probably first developed in East Antarctica close to the Eocene-Oligocene boundary under temperate climatic conditions. The purpose of this project is to determine, from landscape analysis (with a numerical chronology), when (and why) these early temperate conditions gave way to a polar environment in Antarctica. From previous field work and recent photographic analysis, an extensive relict landscape (older than 17 million years) with landforms and erosional features characteristic of temperate glaciation has been delineated. This relict landscape has been called the Sessrumnir erosion surface and it extends over three degrees of latitude and covers almost 10,000 km2 in three fault blocks of the Transantarctic Mountains (Convoy, Dry Valleys, Royal Society). It is on this relict land surface that data will be collected which record Middle and Early Miocene glacial history and paleoclimate. The results should allow an identification of the transition from temperate to polar conditions. This work will involve landscape analysis, stratigraphy of glacial deposits, and Argon-40/Argon-39 dating of volaanic ashfalls. Denudation rates will come from fission-track analyses and from exposure-age analyses of bedrock surfaces and erratic boulders. The overall results will elucidate the origin and stability of the polar Antarctic cryosphere.

该奖项支持一项研究，以确定导致南极冰盖发展的事件的顺序和年表。 大陆规模的冰盖可能首先在南极洲东部靠近始新世-渐新世边界的温带气候条件下发展起来。 该项目的目的是通过景观分析（用数字年表）确定南极洲这些早期温带条件何时（以及为什么）让位于极地环境。 从以前的实地工作和最近的摄影分析，一个广泛的残留景观（年龄超过1700万年）的地形和侵蚀特征的温带冰川已经划定。 这一残留景观被称为Sessrumnir侵蚀面，它延伸到三个纬度，覆盖了跨南极山脉（康涅兹山脉、干谷山脉、皇家学会）三个断层块中近10，000平方公里的面积。 正是在这一残留的地表上，将收集到记录中、早中新世冰川历史和古气候的资料。 结果应允许从温带到极地条件的过渡的识别。 这项工作将涉及景观分析、冰川沉积物地层学和火山灰的氩-40/氩-39定年。 剥蚀率将来自裂变径迹分析以及基岩表面和不稳定巨砾的年代分析。 总体结果将阐明南极极地冰冻圈的起源和稳定性。