Collaborative Research: Mantle Dynamics and Magmatism Across the Basin and Range

合作研究：整个盆地和山脉的地幔动力学和岩浆作用

• 批准号: 0745972
• 负责人: Donald Forsyth
• 金额: $ 29.32万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745972&HistoricalAwards=false
• 关键词: Collaborative; Research; Mantle; Dynamics; Magmatism

This project is exploring the link between mantle dynamics and magmatism through an integrated seismic and petrologic study across the Basin and Range of the Western US. Many hypotheses exist for what drives melting during lithosphere extension, hydration, heating and convective removal, but there is as yet no consensus on which of these processes is dominant in the western US, nor even where melting occurs. New seismic data emerging from Earthscope/USArray are providing an unprecedented view of upper mantle structure. Developments in the inversion of Rayleigh waves are allowing the best resolution of lateral and vertical variations in phase velocities to depths of ~ 200 km. The interpretation of seismic velocity and attenuation, however, is still debated as to the relative importance of mantle temperature, water and melt content. The best approach to resolving these variables is to obtain independent constraints from young mantle-derived magmas and xenoliths from the region. Preliminary data show for the first time large variations in the water content of magmas and xenoliths derived from the mantle of the western US. By integrating such observations with other petrologic and seismic predictions of mantle temperature and melting depth, our goals are to determine 1) the lithosphere/asthenosphere boundary, 2) the shape of the melting region, and 3) the water content of the continental lithospheric mantle and underlying asthenosphere beneath the B&R. This project involves three integrated activities: 1) inversion of surface waves for velocity, attenuation and anisotropy, 2) measurement of the water content of magmas from melt inclusion studies, and 3) study of mantle xenoliths, including thermobarometry, seismic velocities, and water content. Results from this project will be shared with the EarthScope and GeoSwath communities, the NavDat database, and the interested public with a web interface.

该项目正在通过整个盆地和美国西部范围进行的综合地震和岩石学研究来探索地幔动力学与岩浆主义之间的联系。在岩石圈扩展，水合，加热和对流去除过程中驱动熔化的趋势存在许多假设，但尚无共识在美国西部占主导地位，甚至在熔融发生的位置。从Earthscope/USArray中出现的新的地震数据提供了上层地幔结构前所未有的视图。雷利波反转的发展使得相位速度的横向变化和垂直变化的最佳分辨率达到了〜200 km的深度。然而，关于地震速度和衰减的解释仍然是关于地幔温度，水和熔体含量的相对重要性的争论。解决这些变量的最佳方法是从该地区的年轻地幔衍生的岩浆和异种石中获得独立的约束。初步数据首次显示了岩浆和异种石的水含量的巨大变化，这些变化来自美国西部的地幔。通过将这种观察结果与地幔温度和熔化深度的其他岩石学和地震预测相结合，我们的目标是确定1）岩石圈/运动层边界，2）熔化区域的形状，以及3）大陆岩石层地幔和在B＆r下的大陆岩石圈地壁和下层下的水含量。 该项目涉及三个集成活动：1）速度，衰减和各向异性的表面波反转，2）测量熔融融合研究的岩浆水含量，3）研究地幔异义石的研究，包括热疗法，包括热疗法，地震速度和水含量。该项目的结果将与Earthscope和Geoswath社区，NAVDAT数据库以及感兴趣的公众通过Web界面共享。