Accessory Minerals and Crustal Processes

沃森-0073752这项研究计划涉及在高压和高温下的实验研究，这些研究涉及稀有元素矿物的性质和行为（即，（地球上的矿物）。 副矿物-例如，锆石（ZrSiO 4）、磷灰石（Ca 5 [PO 4]3F）、独居石（CePO 4）、磷钇矿（YPO 4）、钛铁矿（CaTiSiO 5）和金红石（TiO 2）-是放射性同位素（例如，U、Th、Lu、Sm）及其衰变产物（例如，Pb、Hf、Nd的同位素）以及可用于解释地球化学过程的痕量元素（例如稀土）。 该研究项目旨在了解这些矿物如何参与熔融过程和变质反应，以及它们如何有效地保留放射性年龄信息和稳定同位素比值。 进行几种类型的实验和测量以便表征：1）副矿物（例如，氧、Pb、Th和REE的含量; 2）俯冲环境中锆石在岩浆和深海沉积物熔体中的溶解度。 我们也正在探索阴极发光（CL）作为一种手段，半定量映射的微量元素分布在实验样品。 这项工作的预期长期影响是提高地球化学家理解和模拟地壳中化学元素重新分布过程的能力。

WatsonEAR-0073752This research program involves experimental investigations at high pressures and temperatures that address the properties and behavior of rare-element minerals (i.e., ac-cessory minerals) in the Earth's crust. Accessory minerals - for example, zircon (ZrSiO4), apatite (Ca5[PO4]3F), monazite (CePO4), xenotime (YPO4), titanite (CaTiSiO5), and rutile (TiO2)-are the principal hosts of radioactive isotopes (e.g., of U, Th, Lu, Sm) and their decay products (e.g., isotopes of Pb, Hf, Nd) and also of trace elements such as the rare earths that are useful in deciphering geochemical processes. The research con-ducted under this grant is aimed at learning how these minerals participate in melting processes and metamorphic reactions, and how effectively they retain radiometric age in-formation and stable isotope ratios. Several types of experiments and measurements are conducted in order to characterize: 1) ionic diffusion in accessory minerals (e.g., of oxy-gen, Pb, Th and REE); and 2) solubility of zircon in silicic magmas and pelagic sediment-derived melts in subduction environments. We are also exploring cathodoluminescence (CL) as a means of semi-quantitative mapping of trace-element distribution in experi-mental samples. The intended long-range impact of the work is to enhance the ability of geochemists to understand and model the processes that redistribute the chemical elements in the Earth's crust.