A Petrologic, Trace Element, and Isotopic Investigation intothe Upper Mantle Xenoliths From Oahu, Hawaii

对夏威夷瓦胡岛上地幔包体的岩石学、微量元素和同位素研究

• 批准号: 8903879
• 负责人: Andrew Macfarlane
• 金额: --
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-05-15 至 1993-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8903879&HistoricalAwards=false
• 关键词: Petrologic; Trace; Element; Isotopic; Investigation

Current models of Hawaiian magma genesis postulate the involvement of at least two or more isotopically and chemically distinct end member mantle sources, one of which is a primitive hot plume and another one is the lithosphere. The relative roles of the lithosphere and the plume have been a matter of debate in these models, which are generally based on the composition of the erupted lavas. Fragments of the lithosphere occur in abundance as xenoliths in the post-erosional Honolulu lavas of Oahu, which provide a window into the Hawaiian lithosphere, and a critical examination of these rocks may help resolve some of these disputes. The present project is concerned with the second phase of an ongoing study of upper mantle xenoliths from Oahu, which includes a detailed isotopic and trace element investigation into the mineral phases of several xenoliths selected on the basis of their mineralogy and petrography (and, in some cases, trace elements). In the first phase of this research, petrographic and mineral-chemical characterization was carried out on a large number of xenoliths from number of vents that cut across the koolau shield volcano. The proposed isotopic and trace element investigation, in conjunction with the earlier petrographic- mineralogic study, is expected to offer an insight into the nature of the lithosphere and the fluids which have crystallized the hydrous phases. Comparative studies of the compositional the hydrous phases. Comparative studies of the compositional variations within and between xenoliths and the erupted Koolau (tholeiitic) and Honolulu (alkalic) lavas will help evaluate models of Hawaiian magma generation and help evaluate models of Hawaiian magmas generation and lithosphere-magma interaction processes during hot spot magmatism. //

目前夏威夷岩浆成因模型假设至少涉及两个或两个以上的同位素和化学性质不同的端元地幔源，其中之一是原始热柱，另一个是岩石圈。在这些模型中，岩石圈和地幔柱的相对作用一直是一个有争议的问题，这些模型通常基于喷发熔岩的成分。岩石圈的碎片出现在丰富的捕虏体在后侵蚀檀香山熔岩的夏威夷，这提供了一个窗口到夏威夷岩石圈，和这些岩石的关键检查可能有助于解决这些争议。本项目涉及正在进行的对奥陶洛斯上地幔捕虏体的研究的第二阶段，其中包括对根据矿物学和岩相学（以及某些情况下的微量元素）选定的几种捕虏体的矿物相进行详细的同位素和微量元素调查。在这项研究的第一阶段，岩石学和矿物化学特性进行了大量的捕虏体从数量的通风口，切断了库劳盾状火山。建议的同位素和微量元素调查，结合早期的岩石矿物学研究，预计将提供一个深入了解岩石圈的性质和流体结晶的含水相。含水相组成的比较研究。对捕虏体内部和捕虏体之间的成分变化以及库劳（拉斑玄武岩）和檀香山（碱性）熔岩的对比研究，将有助于评价夏威夷岩浆生成的模式，有助于评价夏威夷岩浆生成的模式以及热点岩浆作用期间岩石圈-岩浆相互作用过程的模式。//