International: US-Germany Doctoral Dissertation Enhancement: High-resolution Laser Ablation ICP-MS Analysis of Metamorphic Rocks from California, Germany, and the Czech Republic

俯冲带是板块构造的主要表现之一，发生在地球的两个板块碰撞，一个板块滑到另一个板块下面。 一个板块俯冲到另一个板块之下是地球表面和内部之间物质转移的主要机制。 对俯冲带中流体驱动的化学循环的理解为我们提供了发现有价值的自然资源（如金属矿石和天然气和石油储量）的工具，以开发新的资源（如地热能），并了解俯冲带的地质灾害（如地震和火山爆发）。本文主要研究俯冲带变质作用下下行板块流体中微量元素的分布。 这些流体负责产生产生弧火山的岩浆。 特别是高压变质岩，如榴辉岩（俯冲洋壳）是研究俯冲带深部流体产生和转移的宝贵资源。为了跟踪微量元素在俯冲流体中的流动性，本研究将研究榴辉岩中发现的个别矿物的地球化学，从环山地区的方济各复杂的加州，和Erzgebirge（矿石山）地区的德国和捷克共和国。 特别是，石榴石和金红石将被详细分析，以检查稀土和高场强元素在榴辉岩中流体的生产和运输过程中的行为。分析单个矿物颗粒中广谱微量元素的首选方法是激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）。 在美国的宾夕法尼亚州立大学和德国的美因茨大学有补充的LA-ICP-MS设施。美因茨的教师开发了利用变质岩中次要矿物相编码的信息的尖端方法，如金红石中的Zr温度测定法和U-Pb地质年代学。 这些方法可用于为我们的样品开发温度-时间历史，以帮助我们解释流体传输发生的条件。宾夕法尼亚州立大学的博士生艾丽西娅·克鲁兹·乌里韦将在美因茨的LA-ICP-MS实验室度过六周，学习如何从她的主人和导师托马斯扎克博士那里实施这些专业的分析技术。 Cruz-Uribe将在顾问Maureen Feineman博士的指导下，带着她在宾夕法尼亚州立大学LA-ICP-MS设施实施的这些技术的知识返回美国。 学生将受益于直接接触到新的方法和新的思维方式，以及通过教这些方法给其他学生后，她的回报。 这两个研究所都受益于国际合作研究项目。 该项目由国际科学和工程办公室和地球科学司共同资助。

Subduction zones are one of the primary manifestations of plate tectonics, occuring where two of Earth's plates collide and one slips beneath the other. Subduction of one plate beneath another functions as the primary mechanism for mass transfer between the surface and interior of the Earth. An understanding of fluid-driven chemical cycling in subduction zones provides us with the tools to discover valuable natural resources such as metal ores and natural gas and oil reserves, to develop new resources such as geothermal energy, and to understand the geologic hazards of subduction zones such as earthquakes and volcanic eruptions. This study focuses on the distribution of trace elements in fluids produced in the down-going plate during subduction zone metamorphism. These fluids are responsible for generating the magmas that produce arc volcanoes. In particular, high-pressure metamorphic rocks such as eclogite (subducted oceanic crust) are valuable resources for studying fluid production and transfer within the deeper parts of the subduction zone. In order to track the mobility of trace elements in subduction fluids, this study will examine the geochemistry of individual minerals found in eclogite from the Ring Mountain locality of the Franciscan Complex in California, and the Erzgebirge (Ore Mountains) region of Germany and the Czech Republic. In particular, garnet and rutile will be analyzed in detail to examine the behavior of rare earth and high field strength elements during the production and transport of fluids in eclogitic rocks.The preferred method for analyzing a broad spectrum of trace elements in individual mineral grains is laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Complementary LA-ICP-MS facilities exist at Pennsylvania State University in the US and the University of Mainz in Germany. Faculty at Mainz have developed cutting edge methods that make use of information encoded in minor mineral phases in metamorphic rocks, such as Zr-in-rutile thermometry and U-Pb geochronology. Together these methods can be used to develop a temperature-time history for our samples to help us interpret the conditions under which fluid transport occurred. Penn State PhD student Alicia Cruz-Uribe will spend six weeks at the LA-ICP-MS laboratory in Mainz learning how to implement these specialized analytical techniques from her host and mentor, Dr. Thomas Zack. Cruz-Uribe will return to the US with her knowledge of these techniques to be implemented at the LA-ICP-MS facility at Penn State, under the guidance of advisor Dr. Maureen Feineman. The student will benefit both by direct exposure to new methods and new ways of thinking as well as by teaching those methods to other students upon her return. Both institutes benefit by virtue of the collaborative international research project. This project is funded jointly by the Office of International Science and Engineering and the Division of Earth Sciences.