Seismic study of mantle deformation and melt extraction during continental breakup in the ENAM primary site

ENAM 原生地大陆破裂过程中地幔变形和熔体抽出的地震研究

基本信息

批准号：
1551717
负责人：
Harm Van Avendonk
金额：
$ 23.44万
依托单位：
University of Texas at Austin
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-04-01 至 2019-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1551717&HistoricalAwards=false
关键词：
Seismic study mantle deformation melt

项目摘要

Continental drift between the eastern United States and northwest Africa about 180 million years ago was a key event in Earth's plate tectonic history. The mechanical and volcanic processes that shaped the continental margins of the eastern U.S. left a record of volcanic crust and deep sedimentary rocks beneath the coastal plain, and offshore in the Atlantic Ocean. This project will examine the deep structure of the passive margin and provide a better understanding of the early tectonic evolution, heat flow, and sediment accumulation along the east coast of the United States. Understanding the geologic history will improve our knowledge of natural resources and ancient submarine landslides that affected the continental slope. The project supports the training of a graduate student.Specifically, the researcher and graduate student will investigate the deep structure and origin of the Blake Spur Magnetic Anomaly, which lies offshore the eastern United States. Seismic data collected during the Eastern North American Margin community experiment will be used to image the crust and upper mantle beneath this magnetic anomaly. A preliminary inspection of the seismic data suggests that seismic waves here can travel through the mantle with a speed that is higher parallel to the magnetic anomaly than perpendicular to it. This form of seismic anisotropy can be used to test whether mantle melt infiltration or stretching of the mantle rock created the rock fabric of the rifted margin.

大约1.8亿年前，美国东部和非洲西北部之间的大陆漂移是地球板块构造史上的一个关键事件。塑造美国东部大陆边缘的机械和火山过程在沿海平原和大西洋近海留下了火山地壳和深层沉积岩的记录。该项目将研究被动边缘的深层结构，并更好地了解美国东海岸的早期构造演化、热流和沉积物堆积。了解地质历史将提高我们对自然资源和影响大陆坡的古代海底滑坡的了解。该项目支持研究生的培训。具体来说，研究人员和研究生将调查位于美国东部近海的布莱克马刺磁异常的深层结构和起源。在北美东部边缘群落实验期间收集的地震数据将用于对该磁异常下方的地壳和上地幔进行成像。对地震数据的初步检查表明，这里的地震波可以以平行于磁异常的速度高于垂直于磁异常的速度穿过地幔。这种形式的地震各向异性可用于测试是否是地幔熔融渗透或地幔岩石拉伸产生了裂谷边缘的岩石结构。