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折返和出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。 本文利用锆石U-Pb年代学，结合稀土元素地球化学、矿物包裹体分析和热压法，研究了柴达木盆地北部和阿尔金山盆地南部超高压变质作用的年龄，以及榴辉岩相-麻粒岩相-角闪岩相的退变质作用的折返速率。 这一结果将极大地推进我们对北太平洋地质历史的认识。柴达木和S.阿尔金盆地，并将评估它们之间提出的地质年代学相关性。 此外，这项研究也将有助于我们对超高压过程的总体了解，特别是那些负责在折返过程中保存的超高压岩石和随后的暴露在地球表面的建议研究解决了变质岩石学领域的重要问题，以及中亚构造。PI，研究生Chris Mattinson，与合作者J.L.伍登，J.S.杨和马汀森的论文共同顾问J. G。Liou拥有解决所提出的问题所需的现场和实验室经验，并且所需的资源可以在斯坦福大学获得。这项研究是研究生克里斯·马汀森博士研究的一个组成部分，并将在同行评审期刊上发表多篇论文，并在国家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REE分析程序支持并增强了最先进的多用户斯坦福-USGS SHRIMP-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.