Collaborative Research: Seismic Traverse of the Byrd Subglacial Basin-Field Test

该合同支持在南极洲西部进行一项就地和短导线地震反射/折射和大地电磁实验。这个合作实验涉及四个机构的四个奖项。有四个目的：1)调查伯德冰川下盆地的部分地区，2)测试这项工作的技术，这些技术可以在长距离穿越中完成，3)确定大地电磁法在厚（电阻）冰盖上的可行性，4)评价折射-宽反射与反射-窄折射地震成像岩石圈的相对优势。将采用的地球物理技术能够对冰盖、大陆岩石圈和上地幔进行成像，并确定岩石圈和地幔部分的物理性质。过去三十年来对西南极洲和横贯南极山脉露头地质的研究得出了最近的解释，即地壳是由许多不同的岩石圈块组成的。地震反射工作是对地壳进行详细成像的唯一方法，折射工作是确定反射工作定义的层和块的物理性质的唯一方法。大地电磁工作在科学上是有风险的，因为在具有电阻性的冰盖上使用时，它可能无法提供有用的信息；然而，如果它成功了，它就有可能成像地壳和上地幔中的熔融岩石。在像西南极洲这样的大陆裂谷区，岩石圈中很可能存在融化，如果有文献记载，对冰盖动力学有非常重要的影响。该奖项支持的研究工作预计将为一系列地壳过程的模型提供约束，从冰盖动力学模型到岩石圈减薄和裂谷的构造和运动学模型。

This award supports an in situ and short traverse seismic reflection/refraction and magnetotelluric experiment in West Antarctica. This collaborative experiment involves four awards at four institutions. The four-fold purpose is 1) to investigate part of the Byrd Subglacial Basin, 2) to test techniques for this work that could be done in a long traverse, 3) to determine the viability of the magnetotelluric method on a thick (electrically resistive) ice sheet, and 4) to evaluate the relative merits of refraction with wide reflection versus reflection with narrow refraction seismic studies in imaging the lithosphere. The geophysical techniques that will be employed are capable of imaging the ice sheet, the continental lithosphere, and the upper mantle, as well as determining physical properties of parts of the lithosphere and mantle. Investigations of outcrop geology over the last thirty years in West Antarctica and the Transantarctic Mountains have lead to recent interpretations that the crust is made up of many different lithospheric blocks. Seismic reflection work is the only way to image the crust in detail and the refraction work is the only way to determine physical properties of the layers and blocks defined by the reflection work. The magnetotelluric work is scientifically risky because it may not yield useful information when used over the electrically resistive ice sheet; however, if it works it has the potential to image molten rock in the crust and upper mantle. In a continental rift region such as West Antarctica, the presence of melt in the lithosphere is likely and, if documented, has very important ramifications to ice sheet dynamics. Research work supported by this award is expected to provide constraints to models of a range of crustal processes from models of ice sheet dynamics to tectonic and kinematic models of lithospheric thinning and rifting.