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

海岛玄武岩锂同位素变化：岩浆源与地幔异质性研究

• 批准号: 0439960
• 负责人: Lui-Heung Chan
• 金额: $ 15.98万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0439960&HistoricalAwards=false
• 关键词: Lithium; Isotope; Variation; Ocean; Island

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.

同位素比率是一种相对新颖的示踪剂，它显示出跟踪地壳和地幔之间材料回收的希望。 该研究项目是一项全面的研究，旨在确定南太平洋海洋岛上的锂同位素变化，该岛屿藏有长寿的热点岩浆作用。目的是阐明产生海洋岛玄武岩锂同位素组成的源成分和过程，并评估深幔中成分异质性的程度。该方法将是研究代表地幔端构件的海洋岛中的锂同位素，如放射性同位素组成所定义。 调查将集中在三组岛屿（1）皮特凯恩岛（富集的地幔I），（2）萨摩亚链（富集的地幔II），以及（3）漫画和Tubuai（高U/PB Mantle，Himu）。通过研究组成极端，我们可能可以定义地幔的全部同位素组成。 由此产生的数据库将允许对主要地幔储层的起源进行新的工作假设进行测试，从而更好地了解地幔羽流的源材料，其与浅层储层的相互作用以及俯冲过程在地幔地球化学和进化中的作用。涉及地幔地球化学的这项研究将使对弧菌和地幔进化感兴趣的研究人员广泛关注。拟议的研究将是与S. R. Hart（Woods Hole海洋学机构）和E. Hauri（华盛顿州卡内基研究所）的合作努力，并整合了对不同同位素和化学系统的研究。