Lithium Isotope Variation in Ocean Island Basalts: A Study of Magma Source and Mantle Heterogeneity

锂同位素比值是一种较新的示踪剂，有望用于追踪壳幔之间的物质循环。 该研究项目是一项综合调查，以确定在南太平洋的海洋岛屿的锂同位素变化，窝藏长期热点岩浆活动。目的是阐明洋岛玄武岩锂同位素组成的来源和过程，并评估深部地幔成分的不均匀性程度。该方法将研究代表由放射性同位素组成定义的地幔端元的海洋岛屿中的锂同位素。 调查将侧重于三组岛屿：（1）皮特凯恩岛（富集地幔I）;（2）萨摩亚岛链（富集地幔II）;（3）Mangaia和Tubuai（高铀/铅地幔，HIMU）。通过研究组成的极端，我们可能会定义地幔的同位素组成的全部范围。 由此产生的数据库将允许测试新的工作假设的起源方面的主要地幔水库，导致更好地了解地幔柱的源材料，其与浅水库的相互作用，以及俯冲过程中的作用地幔地球化学和演化。这一研究涉及地幔地球化学，将引起对弧岩浆作用和地幔演化感兴趣的研究人员的广泛兴趣。拟议的研究将是一个合作的努力与S。R.哈特（伍兹霍尔海洋研究所）和E. Hauri（华盛顿卡内基研究所），并整合不同同位素和化学系统的研究。

Lithium isotope ratio is a relatively novel tracer that shows promise for tracking material recycling between crust and mantle. This research project is a comprehensive investigation to determine the lithium isotope variation in ocean islands of the south Pacific Ocean which harbors long-lived hotspot magmatism. The goal is to elucidate the source components and processes that generate the lithium isotope compositions of ocean island basalts and assess the degree of compositional heterogeneity in the deep mantle. The approach will be to study lithium isotopes in ocean islands that represent mantle end members as defined by radiogenic isotope compositions. The investigation will focus on three groups of islands (1) Pitcairn Island (Enriched Mantle I), (2) Samoan chain (Enriched Mantle II), and (3) Mangaia and Tubuai (high U/Pb mantle, HIMU). By studying the compositional extremes, we are likely to define the full range of isotopic composition of the mantle. The resulting database will permit testing of new working hypotheses in regard to the origin of the major mantle reservoirs, leading to a better understanding of the source material of the mantle plume, its interaction with shallow reservoirs, and the role of subduction process in mantle geochemistry and evolution. This study, which deals with mantle geochemistry, will be of broad interest to the researchers interested in arc magmatism and mantle evolution. The proposed research will be a collaborative effort with S. R. Hart (Woods Hole Oceanographic Institution) and E. Hauri (Carnegie Institute of Washington), and integrate research on different isotope and chemical systems.