Collaborative Research: Using Mineral Physics to Interpret Seismic Anisotropy of the Basin and Range Crust

合作研究：利用矿物物理学解释盆地和山脉地壳的地震各向异性。本研究的构造尺度目的是通过测量当地岩石的各向异性来解释盆地和山脉下地壳的各向异性。了解下地壳的各向异性对地球动力学家、测地学家、岩石学家、结构地质学家和地震学家来说是很重要的，他们试图了解下地壳各向异性在岩石圈流变学、岩浆的产生、地壳和地幔之间的地球化学循环以及整个地壳的形成和成因等各种过程中的作用。本研究的更大范围的目的是通过使用基于矿物物理学的各向异性成因知识作为预测工具，提高对下地壳各向异性成因的理解。正在研究来自盆地和山脉的两个捕虏岩管道和三个地壳剖面的岩石样本。电子后向散射衍射用于测量代表性样品中所有晶体的取向。单晶刚度数据用于计算样品的弹性。然后，将这些弹性与现场收集的岩石丰度和结构数据相结合，得出五个研究地点中每个地点的总体千米尺度弹性。利用五个研究地点的千米尺度弹性以及组成岩性的弹性，我们解释了由EarthScope的USArray测量的盆地和山脉下地壳的各向异性。对于各向异性研究，我们从离现场样品位置最近的台站的接收函数中寻找各向异性信号。最后，我们利用从特定地点研究中获得的知识来研究全省范围内的各向异性及其构造意义。

Proposal: 0745588 Collaborative Research: Using Mineral Physics to Interpret Seismic Anisotropy of the Basin and Range CrustThe tectonics-scale purpose of this research is to interpret the anisotropy of the lower crust in the Basin and Range using measurements of the anisotropy of local rocks. Understanding the anisotropy of the lower crust is important to geodynamicists, geodesists, petrologists, structural geologists and seismologists who seek to understand its role in processes as diverse as the rheology of the lithosphere, the generation of magmas, geochemical cycling between the crust and mantle, and the formation and genesis of the entire crust. The broader scale purpose of this research is to improve understanding of the causes of anisotropy of the lower crust in general by using mineral-physics based knowledge about the causes of anisotropy as a predictive tool. Rock samples are being studied from two xenolith pipes and three crustal sections in the Basin and Range. Electron-backscatter diffraction is used to measure orientations of all crystals in representative samples. Single-crystal stiffness data are used to calculate the elasticities of the samples. These elasticities are then combined with rock abundance and structure data collected in the field to yield bulk km-scale elasticities for each of the five study sites. Armed with km-scale elasticities for the five study sites plus elasticities for the constituent lithologies we interpret the anisotropy of the Basin and Range lower crust measured from EarthScope's USArray. For the anisotropy studies, we search for anisotropy signals in the receiver functions from the stations closest to the localities of the field samples. Finally, we use what we learn from the site-specific studies to investigate province-wide anisotropy and its tectonic implications.