Zircon Geochronology and REE Geochemistry of High- and Ultrahigh-Pressure Metamorphic Rocks: North Qaidam and South Altun Terranes, Northwest China

超高压（UHP）变质作用（深度80公里）是大陆俯冲和碰撞的产物。对超高压变质岩及其在地球表面的挖掘和暴露过程的研究有助于我们对大陆演化和壳幔地球化学过程的理解。本研究将利用锆石U-Pb年代学，结合压力、温度和矿物共生作用，通过稀土地球化学、矿物包裹体分析和热气压测量，研究中国西北柴达木北缘和阿尔金南缘UHP地体的变质作用年龄，以及与榴辉岩-麻粒岩和角闪岩相减压相关的挖掘速率。研究结果将有助于进一步认识柴达木盆地和阿尔金盆地的地质历史，并对它们之间的年代学对比进行评价。此外，这项研究还将有助于我们对超高压过程的一般理解，特别是那些在挖掘和随后暴露在地球表面期间负责保存超高压岩石的过程。提出的研究解决了变质岩石学和中亚构造学领域的重要问题。项目负责人、研究生克里斯·马汀森（Chris Mattinson）、合作者J.L. Wooden、J.S. Yang和马汀森的论文联合导师J.G. Liou都有解决所提出问题所需的现场和实验室经验，斯坦福大学也有所需的资源。这项研究是研究生Chris Mattinson博士研究的一个组成部分，并将在同行评审的期刊上发表多篇论文，并在国内和国际会议上发表演讲。这项研究的核心是与中国同事合作，从而加强国际科学交流与合作。在初步研究期间开发的稀土元素分析程序支持并增强了最先进的多用户斯坦福大学-美国地质调查局虾- rg设施，从而增强了研究和教育的基础设施。

Ultra-high pressure (UHP) metamorphism (at depths 80 km) is a product of continental subduction and collision. Investigation of UHP metamorphic rocks and the processes responsible for their exhumation and exposure at the Earth's surface aids our understanding of continental evolution and crust/mantle geochemical processes. This study will employ zircon U-Pb geochronology, linked to pressure, temperature, and mineral paragenesis by REE geochemistry, mineral inclusion analysis, and thermobarometry, to study the ages of metamorphism in the North Qaidam and South Altun UHP terranes in northwest China, as well as the exhumation rates associated with their eclogite- to granulite- and amphibolite-facies decompression. The results will significantly advance our knowledge of the geologic history of the N. Qaidam and S. Altun terranes, and will evaluate the geochronological correlation proposed between them. In addition, this study will also aid our general understanding of UHP processes, especially those responsible for the preservation of UHP rocks during exhumation and subsequent exposure at the Earth's surface.The proposed research addresses significant questions both in the field of metamorphic petrology, as well as central Asian tectonics. The PI, graduate student Chris Mattinson, together with collaborators J.L. Wooden, J.S. Yang, and Mattinson's thesis co-advisor J.G. Liou have both the field and laboratory experience necessary to address the questions posed, and the required resources are available at Stanford University. This research is an integral part of graduate student Chris Mattinson's doctoral research, and will result in multiple publications in peer-reviewed journals and presentations at national and international meetings. Central to this research is collaboration with Chinese colleagues, thereby enhancing international scientific exchange and cooperation. The REE analysis routine developed during the preliminary study supports and enhances the state-of-the-art, multi-user Stanford-USGS SHRIMP-RG facility, thereby enhancing the infrastructure for research and education.