Seismic imaging of crust-mantle interaction

壳幔相互作用的地震成像

• 批准号: 261640-2008
• 负责人: Frederiksen, Andrew
• 金额: $ 2.04万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=547836
• 关键词: Seismic; imaging; crust; mantle; interaction

The large-scale processes governing the evolution of the Earth's surface and its deep interior are fundamentally different: the crust undergoes plate tectonics, while the mantle overturns through thermal convection. My proposed research program will examine how these two processes are coupled, particularly in the case of thick continental plates. The continental lithosphere, a ca. 250 km thick layer of mantle material, participates in plate-tectonic motions, but is also eroded by thermal plumes arising from the deep mantle. I propose to examine the lithosphere beneath the Canadian Shield for both crustal and mantle influences, using passive seismic imaging techniques. These techniques involve recording seismic waves produced by earthquakes at networks of seismometers deployed over the study area, and then mathematically reconstructing the properties of the material through which the waves were transmitted. My planned field experiments will be focused on Manitoba, Saskatchewan, and western Ontario, and will target the edge of the ancient Superior continent, the former Trans-Hudson mountain belt lying beneath Saskatchewan, and a billion-year-old rift zone underlying Lake Superior. For all of these structures, I intend to examine the extent to which the geology of the crust is reflected within the lithosphere below. I will also contribute to the development of new methods for producing images of Earth structure from seismic waves: in particular, the use of seismic noise recordings in structural imaging, and the use of scattered and deflected waves travelling along the Earth's surface. This work will contribute to a better understanding of the forces acting on continental plates, along with the deformation history of these plates. I thereby expect to help establish a framework for understanding the large-scale processes that have preserved or deformed ancient continental crust, and the specific history and dynamics of the Canadian Shield. As the lithosphere beneath ancient shield regions is known to be a source region for diamonds, better images of the lithosphere beneath the Canadian Shield will also assist in future diamond exploration.

控制地球表面和内部演化的大范围过程从根本上是不同的：地壳经历板块构造，而地幔通过热对流翻转。我提议的研究计划将研究这两个过程是如何耦合的，特别是在厚大陆板块的情况下。大陆岩石圈是一层约250公里厚的地幔物质，参与了板块构造运动，但也受到来自地幔深处的热柱的侵蚀。我建议使用被动地震成像技术来检查加拿大地盾下的岩石圈，以了解地壳和地幔的影响。这些技术包括在部署在研究区域的地震仪网络上记录地震产生的地震波，然后从数学上重建波通过的材料的性质。我计划的野外实验将集中在马尼托巴省、萨斯喀彻温省和安大略省西部，目标将是古老的苏必利尔洲的边缘，位于萨斯喀彻温省下面的前哈德逊山脉地带，以及苏必利尔湖下面一个有10亿年历史的裂谷地带。对于所有这些构造，我打算检查地壳地质在下面的岩石圈中的反映程度。我还将促进开发从地震波产生地球结构图像的新方法：特别是在结构成像中使用地震噪声记录，以及使用沿地球表面传播的散射和偏转波。这项工作将有助于更好地了解作用于大陆板块的力以及这些板块的变形历史。因此，我希望帮助建立一个框架，以了解保存或变形的古代大陆地壳的大规模过程，以及加拿大地盾的具体历史和动力学。由于古盾下的岩石圈是已知的钻石来源地，更好地拍摄加拿大盾下的岩石圈图像也将有助于未来的钻石勘探。