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

• 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

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。形成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。本项目将研究被动边缘的深部结构，并提供对美国东海岸沿着早期构造演化、热流和沉积物积累的更好理解。了解地质历史将增进我们对自然资源和影响大陆坡的古代海底滑坡的了解。该项目支持培养一名研究生，具体而言，研究员和研究生将调查位于美国东部近海的布莱克支线磁异常的深层结构和起源。在北美东部边缘社区实验期间收集的地震数据将用于对该磁异常下的地壳和上地幔进行成像。对地震数据的初步研究表明，地震波在地幔中的传播速度在平行于磁异常方向上比垂直于磁异常方向上要快，这种形式的地震各向异性可以用来测试地幔熔体的渗透或地幔岩石的拉伸是否形成了裂谷边缘的岩石组构。