Basal conditions on Rutford Ice Stream, West Antarctica, from seismic observations
Basal conditions on Rutford Ice Stream, West Antarctica, from seismic observations
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根据地震观测得出的南极洲西部拉特福德冰流的基础条件
DOI：
10.1029/96jb02933
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发表时间：
1997
影响因子：
--
通讯作者：
A. Smith
中科院分区：
文献类型：
--
作者：
A. Smith
在南极拉特福德冰流上获得了垂直于冰流方向的地震反射剖面。对冰床界面地震反射的振幅和相位进行了解释，以研究冰下物质的性质。解释假设声阻抗可以用来暗示冰下沉积物孔隙度。从冰床界面上的多个地震广角线的多次反射允许在床上的反射系数的校准。这使得能够从地震反射数据计算床物质的声阻抗。平均声阻抗在床的不同部分的范围从2.70×106 kg m−2 s−1到4.31×106 kg m−2 s−1。该地点几乎四分之三的冰河床似乎是饱和的变形沉积物。河床的其余部分可能也是饱和沉积物，但它们没有明显的变形。冰流可能包括冰下变形和基底滑动的组合。也可能出现支持不成比例的高基底剪切应力的局部区域。根据地震数据，不可能将相对量的约束分配给这些不同的过程。在冰流床上确定的不同部分与卫星图像或附近的表面速度数据之间似乎没有任何相关性。在地震剖面上可以看到一个被解释为冰下鼓丘的特征。
A seismic reflection profile, perpendicular to the ice flow direction has been acquired on Rutford Ice Stream, Antarctica. An interpretation of both the amplitude and phase of the seismic reflections from the ice-bed interface has been made to investigate the properties of the sub-ice material. The interpretation assumes that acoustic impedance can be used to imply subglacial sediment porosity. Multiple reflections from the ice-bed interface on a number of seismic wide-angle lines allowed a calibration of the reflection coefficient at the bed. This enabled the acoustic impedance of the bed material to be calculated from the seismic reflection data. Mean acoustic impedance in the different sections of the bed ranges from 2.70×106 kg m−2 s−1 to 4.31×106 kg m−2 s−1. Almost three quarters of the ice stream bed at this site appears to be saturated, deforming sediments. The rest of the bed is probably also saturated sediments, but they are not deforming to any significant degree. Ice flow could include a combination of subglacial deformation and basal sliding. Localized regions which support disproportionately high amounts of basal shear stress may also occur. From the seismic data, it is not possible to apportion relative amounts of restraint to these different processes. There does not appear to be any correlation between the different sections identified on the ice stream bed with either satellite images or nearby surface velocity data. A feature which is interpreted as a subglacial drumlin is seen on the seismic section.