Collaborative Research: Identification of magnetic sources in the upper mantle

合作研究：识别上地幔磁源

• 批准号: 1345071
• 负责人: Joshua Feinberg
• 金额: $ 4.5万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1345071&HistoricalAwards=false
• 关键词: Collaborative; Research; Identification; magnetic; sources

The view that the upper mantle is universally non-magnetic because it lacks ferromagnetic minerals and would be too hot to carry a magnetic remanence needs to be revisited because converging evidence suggests that some magnetic sources reside at mantle depths. This situation occurs in cold geotherm settings. We propose to carefully measure the magnetic properties of mantle xenoliths using new collections of fresh mantle rocks. The magnetic measurements will be supported by thorough petrologic investigations and by experiments in piston cylinders replicating the rapid ascent of mantle rocks to the Earth surface. The results these investigations will most likely transform the interpretation of data returned by the Swarm mission, deployed in November 2013, which will provide an unprecedented resolution of the lithospheric magnetic field.Our understanding of the internal structure of the Earth relies on geophysical approaches including for example seismology, gravimetry and magnetism. The magnetic field at the Earth's surface informs us about temperature at depth because below the Curie depth, minerals become too hot to be magnetic. Up to now, we thought that mantle rocks, at depths of about 30 kilometers, did not carry any magnetic minerals, an assumption based on measurements made in the 1980?s. The proposed research will re-evaluate this non-magnetic mantle concept and provide a far more accurate knowledge base to interpret magnetic satellite data. The information deduced from magnetic satellites provides vital information on regions of the globe where tectonic plates collide and create abundant seismicity.

认为上地幔普遍是非磁性的观点，是因为它缺乏铁磁性矿物，而且温度太高，无法携带磁性残留物，这一观点需要重新审视，因为越来越多的证据表明，一些磁性源位于地幔深处。这种情况发生在寒冷的地热环境中。我们建议利用新的地幔岩石标本仔细测量地幔捕虏体的磁性。全面的岩石学调查和在活塞缸中模拟地幔岩石迅速上升到地球表面的实验将支持磁场测量。这些调查的结果很可能会改变2013年11月部署的Swarm任务返回数据的解释，Swarm任务将提供前所未有的岩石圈磁场分辨率。我们对地球内部结构的了解依赖于地球物理方法，例如地震学、重力学和磁学。地球表面的磁场告诉我们深处的温度，因为在居里深度以下，矿物变得太热而不具有磁性。到目前为止，我们认为30公里深处的地幔岩石不携带任何磁性矿物，这是基于20世纪80年代进行的测量的假设。拟议的研究将重新评估这种非磁性地幔概念，并为解释磁性卫星数据提供更准确的知识基础。从磁卫星中推断出的信息提供了地球上构造板块碰撞并产生丰富地震活动区域的重要信息。