Geophysical Studies of the Lateral Transition Zone of an Active Antarctic Ice Stream

活跃南极冰流横向过渡带的地球物理研究

• 批准号: 9220678
• 负责人: Charles Bentley
• 金额: $ 36.57万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-05-01 至 1996-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9220678&HistoricalAwards=false
• 关键词: Geophysical; Studies; Lateral; Transition; Zone

The manner and rate of deformation of the Earth's major ice sheets depend on a complex interplay of their geographical and climatic setting, as well as their internal dynamics. In the West Antarctic Ice Sheet, it is known that rapidly moving ice streams alternate with large areas of stagnant ice, and that the transition between streaming and non-streaming flow can be be quite narrow. In these lateral shear margins it is thought that the physical controls on ice stream dynamics must show significant differences. This study will examine the geophysical differences between an ice stream and a stagnant ridge along the Siple Coast in West Antarctica. The ice will be probed with electromagnetic and seismic waves to infer the internal temperature and the crystalline structure of the ice, as well as the proportion of old (Wisconsin Ice Age) ice, since it is known that ice flow laws depend exponentially on temperature, that ice crystals are much less resistant to deformation in the plane of their hexagonal faces than in other directions, and that old ice may deform much more readily than ice of more recent geological age. Measurement of radar diffraction patterns and the analysis of the records of micro- earthquakes can be used to show whether the base of the ice sheet is frozen to the underlying bedrock.

地球主要冰盖的变形的方式和速率取决于其地理和气候环境的复杂相互作用及其内部动力学。 在南极西部的冰盖中，众所周知，快速移动的冰流与大面积停滞的冰交替出现，并且流媒体和非流动流之间的过渡可能很狭窄。 在这些侧向剪切边缘中，人们认为冰流动力学上的物理控制必须显示出显着差异。 这项研究将检查冰流和南极西部Siple海岸停滞的山脊之间的地球物理差异。 将用电磁和地震波探测冰，以推断冰的内部温度和晶体结构，以及旧的（威斯康星州冰期）冰的比例，因为众所周知，冰流量法指数依赖于温度，冰晶体对冰晶的近期冰层的抗性比其他更高的冰层更易于冰的，并且比其他更旧的冰层更易于冰，并且更旧。 可以使用雷达衍射模式的测量和微地震记录的分析来显示冰盖的底部是否将其冻结到基础基岩中。