Collaborative Research: Lithospheric Controls on the Behavior of the West Antarctic Ice Sheet: Corridor Aerogeophysics of Eastern Ross Transect Zone

合作研究：岩石圈对南极西部冰盖行为的控制：东罗斯横断带的走廊航空地球物理学

• 批准号: 9319854
• 负责人: Robin Bell
• 金额: $ 55.8万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9319854&HistoricalAwards=false
• 关键词: Collaborative; Research; Lithospheric; Controls; Behavior

Blankenship: 9319369 Bell: 9319854 Behrendt: 9319877 This award supports a project to conduct an integrated geophysical survey over a large portion of the West Antarctic Ice Sheet (WAIS) toward an understanding of the dynamic behavior of the ice sheet and the nature of the lithosphere beneath the ice sheet. West Antarctica is characterized by two kinds of the Earth s most dynamic systems, a continental rift (the West Antarctic Rift System) and a marine based ice sheet (the WAIS). Active continental rift systems, caused by divergent plate motions, result in thinned continental crust. Associated with the thin crust are fault-bounded sedimentary basins, active volcanism, and elevated heat flow. Marine ice sheets are characterized by rapidly moving streams of ice, penetrating and draining a slowly moving ice reservoir. Evidence left by past marine ice sheets indicates that they may have a strongly non- linear response to long-term climate change which results in massive and rapid discharges of ice. Understanding the evolution of the ice stream system and its interaction with the interior ice is the key to understanding this non-linear response. Subglacial geology and ice dynamics are generally studied in isolation, but evidence is mounting that the behavior of the West Antarctic ice streams may be closely linked to the nature of the underlying West Antarctic rift system. The fast moving ice streams appear to glide on a lubricating layer of water-saturated till. This till requires easily eroded sediment and a source of water, both of which may be controlled by the geology of the rift system; the sediments from the fault-bounded basins and the water from the elevated heat flux associated with active lithospheric extension. This project represents an interdisciplinary aerogeophysical study to characterize the lithosphere of the West Antarctic rift system beneath critical regions of the WAIS. The objective is to determine the effects of the rift architect ure, as manifested by the distribution of sedimentary basins and volcanic constructs, on the ice stream system. The research tool is a unique geophysical aircraft with laser altimetry, ice penetrating radar, aerogravity, and aeromagnetic systems integrated with a high precision kinematic GPS navigation system. It is capable of imaging both the surface and bed of the ice sheet while simultaneously measuring the gravity and magnetic signature of the subglacial lithosphere. Work to be done under this award will build on work already completed in the southern sector of central West Antarctica and it will focus on the region of the Byrd Subglacial Basin and Ice Stream D. The ice sheet in these regions is completely covered by satellite imagery and so this project will be integrated with remote sensing studies of the ice stream. The changing dynamics of Ice Stream D, as with other West Antarctic ice streams, seem to be correlated with changes in the morphological provinces of the underlying rift system. The experimental targets proceed from the divide of the interior ice, downstream through the onset of streaming to the trunk of Ice Stream D. This study will be coordinated with surface glaciological investigations of Ice Stream D and will be used to guide cooperative over-snow seismic investigations of the central West Antarctic rift system. The data will also be used to select a site for future deep ice coring along the crest of the WAIS. These data represent baseline data for long term global change monitoring work and represent crucial boundary conditions for ice sheet modeling efforts.

Blankenship：9319369 BELL：9319854 BEHRENDT：9319877该奖项支持一个项目，该项目对一项综合的地球物理调查进行了对大部分南极冰盖（WAI）（WAIS）的一体化调查，以了解对冰盖的动态行为的理解和冰期冰期的性质。 西南极洲西部的特征是两种地球的最具动态系统，大陆裂谷（西南极裂谷系统）和一个基于海洋的冰盖（WAIS）。 由发散板运动引起的活跃大陆裂谷系统导致大陆壳变薄。 与薄皮相关的是结合断层的沉积盆地，活跃的火山和升高热流。 海洋冰盖的特征是迅速移动的冰流，穿透并耗尽缓慢移动的冰库。 过去的海洋冰盖留下的证据表明，它们可能对长期气候变化具有强烈的线性反应，从而导致冰的大规模排出。 了解冰流系统的演变及其与内部冰的相互作用是理解这种非线性反应的关键。 通常孤立地研究了冰山下的地质和冰动力学，但有证据表明，南极冰流的行为可能与基础西南裂谷系统的性质紧密相关。 快速移动的冰流似乎在水饱和的润滑层上滑动。 这需要易于侵蚀的沉积物和水源，这两者都可以由裂谷系统的地质控制；来自断层盆地的沉积物和与活动岩石圈延伸相关的升高热通量的水。 该项目代表了一项跨学科的航空地质物理研究，以表征WAIS关键区域下南极裂谷系统的岩石圈。 目的是确定裂谷建筑师URE的影响，如沉积盆地和火山构建体对冰流系统的分布所表现出的。 该研究工具是一架独特的地球物理飞机，具有激光高度测定，冰渗透雷达，空气气流和航空磁系统，该系统与高精度运动学GPS导航系统集成在一起。 它能够同时测量冰片下岩石圈的重力和磁性特征，同时对冰盖的表面和床进行成像。 根据该奖项将要完成的工作将基于已经在南极中部南部已经完成的工作，它将重点放在伯德冰山亚冰川盆地和冰流D的区域上。这些地区的冰盖完全涵盖了卫星图像，因此该项目将与冰流的远程感知研究集成。 与其他西南极冰流一样，冰流D的动态变化似乎与基础裂谷系统的形态省的变化相关。 实验目标从内部冰层的鸿沟，下游到流到冰流的躯干。这项研究将与冰流D的表面冰川学协调，并将用于指导中央西方南极反隆起的合作过度的地震研究。 该数据还将用于选择一个沿WAIS冠的未来深层冰芯的地点。 这些数据代表了长期全球变更监控工作的基线数据，并代表了冰盖建模工作的关键边界条件。