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.

该奖项支持在南极西部冰盖（WAIS）的大部分地区进行综合地球物理调查的项目，以了解冰盖的动态行为和冰盖下岩石圈的性质。南极洲西部以大陆裂谷（南极西部裂谷系统）和海洋冰原（WAIS）两种地球上最具活力的系统为特征。活跃的大陆裂谷系统是由分裂的板块运动引起的，导致大陆地壳变薄。与薄地壳相关的是断界沉积盆地、活火山活动和高热流。海洋冰盖的特点是快速移动的冰流穿透并排出缓慢移动的冰库。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有强烈的非线性反应，从而导致大量和迅速的冰排放。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响应的关键。冰下地质和冰动力学通常是单独研究的，但越来越多的证据表明，南极西部冰流的行为可能与南极西部裂谷系统的性质密切相关。快速移动的冰流似乎在水饱和的润滑层上滑动。这一过程需要容易被侵蚀的沉积物和水源，这两者都可能受到裂谷系统地质的控制；来自断界盆地的沉积物和来自岩石圈扩张活动引起的热通量升高的水。本项目是一项跨学科的航空地球物理研究，旨在表征西南极带关键区域下南极西部裂谷系统的岩石圈。目的是确定裂谷构造对冰流系统的影响，如沉积盆地和火山构造的分布所表现的那样。该研究工具是一种独特的地球物理飞机，具有激光测高、破冰雷达、航空重力和航空磁系统，并集成了高精度的运动学GPS导航系统。它能够对冰盖表面和床层进行成像，同时测量冰下岩石圈的重力和磁场特征。根据该合同进行的工作将建立在西南南极洲中部南部地区已经完成的工作的基础上，并将重点放在伯德冰下盆地和冰流d地区。这些地区的冰盖完全被卫星图像覆盖，因此该项目将与冰流的遥感研究相结合。与南极西部其他冰流一样，冰流D的动态变化似乎与下伏裂谷系统的形态变化有关。实验目标从内部冰的分裂开始，下游通过流的开始一直到D冰流的主干。这项研究将与D冰流的地表冰川学调查相协调，并将用于指导南极中西部裂谷系统的合作积雪地震调查。这些数据还将用于选择未来沿WAIS顶部进行深冰取芯的地点。这些数据代表了长期全球变化监测工作的基线数据，并代表了冰盖模拟工作的关键边界条件。