Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)
Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)
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DOI：
10.1130/b26417.1
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发表时间：
2010-05-01
影响因子：
4.9
通讯作者：
Diehl, T. M.
中科院分区：
文献类型：
--
作者：
Jordan, T. A.;Ferraccioli, F.;Diehl, T. M.
西南极裂谷系为上覆的西南极冰盖提供了关键的地质边界条件。以前的地球物理调查已经追踪了西南极裂谷系统，并解决了它对罗斯海海湾西南极冰盖的控制。然而，人们对阿蒙森海湾下的裂谷系统知之甚少，阿蒙森海湾是西南极冰盖的一个关键部分，今天正在显着变薄。松岛冰川地区是阿蒙森海湾内流动最快的冰川之一，新的空气重力数据为南极西部冰盖这一动态部分下的地壳结构提供了新的线索。地形去相关自由空气和布格重力异常数据的三维（3-D）反演揭示了松岛冰川集水区下方地壳显着变薄。在伯德冰下盆地和新发现的松岛裂谷下，莫霍面深度估计为19 +/- 1 km。这是在南极洲西部冰盖下观察到的最薄的地壳。根据均衡模型对岩石圈刚度（T-e）的估计，得出的T-e为5 +/- 5 km，这与现代裂谷系统（如盆岭省）的值相当。主要的地壳变薄，加上岩石圈硬度低，证明了南极西部冰盖这一部分下大陆裂谷的巨大影响。在类比与更好地了解西南极裂谷系的罗斯海部分，我们认为，阿蒙森海湾的分布白垩纪裂谷，其次是新生代窄模式裂谷的影响。松岛裂谷内的窄模式裂谷作用特别重要，因为它可以作为与松岛冰川相关的增强冰川流的地质模板。
The West Antarctic Rift System provides critical geological boundary conditions for the overlying West Antarctic Ice Sheet. Previous geophysical surveys have traced the West Antarctic Rift System and addressed the controls that it exerts on the West Antarctic Ice Sheet in the Ross Sea Embayment. However, much less is known about the rift system under the Amundsen Sea Embayment, a key sector of the West Antarctic Ice Sheet, which is thinning significantly today. New aerogravity data over the Pine Island Glacier region, one of the fastest flowing glaciers within the Amundsen Sea Embayment, sheds new light into the crustal structure under this dynamic part of the West Antarctic Ice Sheet. Three-dimensional (3-D) inversion of terrain-decorrelated free-air and Bouguer gravity anomaly data reveal significant crustal thinning beneath the catchment of Pine Island Glacier. Under the Byrd Subglacial Basin and the newly identified Pine Island Rift, Moho depth is estimated to be 19 +/- 1 km. This is the thinnest crust observed beneath the West Antarctic Ice Sheet. Estimates of lithosphere rigidity (T-e), based on isostatic models, yield a T-e of 5 +/- 5 km, which is comparable to values from modern rift systems such as the Basin and Range Province. Major crustal thinning, coupled with low lithosphere rigidity, attest to the considerable impact of continental rifting beneath this part of the West Antarctic Ice Sheet. In analogy with the better known Ross Sea segment of the West Antarctic Rift System we suggest that the Amundsen Sea Embayment was affected by distributed Cretaceous rifting, followed by Cenozoic narrow-mode rifting. Narrow-mode rifting within the Pine Island Rift is particularly important as it may serve as a geological template for enhanced glacial flow associated with Pine Island Glacier.