A Window Into Deep Lithospheric Processes of the Western U.S. From Os Isotope Investigations of Mantle Xenoliths

我们建议通过研究从内华达山脉到科罗拉多高原沿东西向样带喷发的地幔捕虏体来研究发生在美国西南部深部岩石圈的构造过程。将对内华达山脉（大溪和橡树溪）、盆地和山脉（西玛火山场）和科罗拉多高原（大拇指）的几组地幔捕虏体进行岩石学、矿物和主要元素化学、热气压测定和Re-Os同位素组成测定。这条横断面采样的元古代地壳受到了不同的构造影响：弧岩浆作用（内华达山脉）、挤压构造作用（科罗拉多高原）和弧后伸展作用（盆地和山脉）。目的是绘制这些不同区域的岩石圈地幔图，以确定岩石圈目前的厚度和年龄。然后，这些数据将与岩石圈结构的地表地质和地球物理遥感相结合，以推断形成深层岩石圈的过程。

RudnickEAR-9909526We propose to investigate the tectonic processes occurring in the deep lithosphere of the SW US through studies of mantle xenoliths erupted along an E-W transect from the Sierra Nevada to the Colorado Plateau. Petrography, mineral and major element chemistry, thermobarometry and Re-Os isotopic compositions will be determined for several suites of mantle xenoliths from the Sierra Nevada mountains (Big Creek and Oak Creek), the Basin and Range (Cima volcanic field) and the Colorado Plateau (the Thumb). This traverse samples Proterozoic crust that has been subjected to diverse tectonic influences: arc magmatism (Sierra Nevada), compressional tectonism (Colorado Plateau) and back-arc extension (basin and range). The goal is to map the lithospheric mantle in these diverse regions in order to determine the present day thickness and age of the lithosphere. These data will then be integrated with surface geology and geophysical remote sensing of lithospheric structure to infer the processes that have shaped the deep lithosphere.