Li Isotopic Investigations of the Crust and Mantle

地壳和地幔的锂同位素研究：Rudnick、McDonough、TomascakLi是最轻的亲石元素，具有流体流动性。锂的两种同位素之间的巨大质量差使锂同位素比率的测量成为追踪地球流体过程的有力工具。该项目将完成对来自地幔的橄榄岩和榴辉岩包体以及大陆的沉积和花岗岩的锂同位素研究。其目的是了解流体作用在大陆岩石圈增长中所起的作用，并评估主要固体地球储集层中的锂同位素清单，以约束地球系统中的锂同位素质量平衡。锂同位素测量将使用MC-ICPMS方法对岩石和矿物溶液进行。PI已经在马里兰州建立了这项技术，通常能够测量40纳克或更小的锂分数，精度为每毫升正负1(2西格玛)。新获得的数据集将提供对控制地壳和地幔锂同位素组成的过程的洞察，确定俯冲带岩浆的潜在贡献者的d7Li，并最终确定随着时间的推移，地壳再循环对地幔d7Li的影响。

Li Isotopic Investigations of the Crust and MantleEAR-0208012PIs: Rudnick, McDonough, TomascakLithium, the lightest lithophile element, is fluid mobile. The large mass difference between its two isotopes makes measurement of the Li isotopic ratio a powerful tool for tracing fluid processes in the Earth. This project will complete Li isotope investigations of peridotite and eclogite xenoliths from the mantle and sedimentary and granitic rocks from the continents. The goal is to understand the role that fluid processes play in the growth of the continental lithosphere and to evaluate the inventory of Li isotopes in major solid Earth reservoirs in order to constrain Li isotope mass balance in the Earth system. The Li isotopic measurements will be performed using MC-ICP-MS methodology on solutions of rocks and minerals. The PIs have established this technique at Maryland and are routinely able to measure 40 ng or smaller Li fractions to plus or minus1 per mil precision (2 sigma). The newly acquired data sets will provide insights into the processes that control the Li isotopic composition of the crust and mantle, define the d7Li of potential contributors to subduction zone magmas and, ultimately, the influence of crustal recycling on d7Li of the mantle over time.