Collaborative Research: Evaluating the Competing Roles of Garnet and Fluid in Controlling U-Th Disequilibria in Lavas of the Aleutian Island Arc

本项目的主要目标是了解在阿留申岛弧不同地区产生的原始镁安山岩岩浆中，残余石榴石和流体在控制U系列不平衡状态方面的竞争作用。本研究的研究对象包括以下阿留申火山：科罗温火山、小锡特金火山和皮普火山。 熔岩从这些火山演化沿着独特的地球化学趋势在不同的位置沿着弧正交俯冲率和推断的俯冲系统的热状态是不同的。在这种情况下，皮普火山特别令人感兴趣，因为它是阿留申Komandorsky地区西部相对知名的镁质安山岩。 主要的分析工作将是测量234 U/238 U、230 Th/232 Th和238 U、232 Th和226 Ra的浓度。 此外，还将收集所有样品的全岩主要和微量元素数据以及Pb、Sr、Nd和Hf同位素组成数据，这些数据尚不存在。 一些样品的制备，包括Pb、Sr、Nd和Hf的柱化学，将在南卡罗来纳州大学进行，但所有U系列化学和所有同位素测量（Hf除外）将在伍兹霍尔海洋研究所的实验室进行。 该项目将作为南卡罗来纳州大学研究生Chris Wyatt博士学位的主要基础，他将在PI的指导下工作。该项目还资助本科生的参与，其中包括学术实力强和积极性高的学生的本科生研究。

The main objective of this project is to understand the competing roles of residual garnet and fluid in controlling the state of U-series disequilibria in primitive magnesian andesite magmas produced in different parts of the Aleutian island arc. The research target for this study includes the following Aleutian volcanoes: Korovin, Little Sitkin and Piip. Lavas from each of these volcanoes have evolved along distinctive geochemical trends at different locations along the arc where orthogonal subduction rates and the inferred thermal state of the subduction system are different. In this context Piip Volcano is of particular interest because it is a relatively well-known magnesian andesite occurrence in the far western Aleutian Komandorsky area. The main analytical effort will be the measurement of 234U/238U, 230Th/232Th and 238U, 232Th and 226Ra concentrations. In addition, whole rock major and trace element data and Pb, Sr, Nd and Hf isotopic compositions will be collected for all samples where such data do not already exist. Some sample preparation, including column chemistry for Pb, Sr, Nd and Hf, will be done at the University of South Carolina, but all U-series chemistry and all isotopic measurements (except Hf) will be made in the laboratories at the Woods Hole Oceanographic Institution. This project will serve as the primary basis for the PhD degree of University of South Carolina graduate student Chris Wyatt, who will work under the direction of both PI's. The project also funds undergraduate participation, which will include undergraduate research for academically strong and well-motivated students.