He-Ne-Ar Isotope Studies in Iceland, Heard Island and La Palma (Canaries): Identifying Mantle Plume Signatures and Crustal Contamination

冰岛、赫德岛和拉帕尔马岛（加那利群岛）的氦氖氩同位素研究：识别地幔柱特征和地壳污染

• 批准号: 9614347
• 负责人: David Hilton
• 金额: $ 13.55万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-15 至 2000-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9614347&HistoricalAwards=false
• 关键词: He; Ne; Ar; Isotope; Studies

9614347 Hilton The presence of distinct reservoirs in the mantle as indicated by the geochemical and isotopic characteristics of ocean island basalts provide key constraints on the geodynamic history of the earth. This proposal seeks to characterize the He-Ne-Ar isotopic compositions and concentrations of samples from three ocean islands previously studied for their geochemical and Sr-Nd-Pb isotope systematics that show different mantle affinities: Heard Island (EM1/EM2), Iceland (DMM-FOZO), and La Palma, Canaries (HIMU). The proposed work will search for rare gas differences between the different mantle source reservoirs and will consider the degree of coupling between rare gases and radiogenic isotopes. A specific aim will be to test the presence of a mantle component (FOZO or 'C') common to all three ocean islands. If present, an attempt will be made to characterize its rare gas and radiogenic isotope systematics. An important aspect of this work will be to compare the results obtained by measuring different sampling media (i.e. geothermal fluids, glass rims of basalts, and mafic phenocrysts) to evaluate their capabilities for preservation of features that are characteristic of the mantle source region or susceptibility to modification by upper-crustal (magma chamber) processes. Another goal of this study will be to consider the integrity of the 'low-3He' hotspot signal found in some ocean islands to evaluate if this is a mantle feature or a crustal overprint introduced immediately prior to eruption in crustal magma chambers.

希尔顿洋岛玄武岩的地球化学和同位素特征表明地幔中存在不同的储集层，这为地球动力学历史提供了关键制约。该建议旨在表征He-Ne-Ar同位素组成和浓度的样品从三个海洋岛屿以前研究的地球化学和Sr-Nd-Pb同位素系统，显示不同的地幔亲和力：赫德岛（EM 1/EM 2），冰岛（DMM-FOZO），和拉帕尔马，加那利群岛（HIMU）。 这项工作将寻找稀有气体在不同地幔源储层之间的差异，并将考虑稀有气体与放射性同位素之间的耦合程度。一个具体的目标是测试所有三个海洋岛屿共同的地幔成分（FOZO或“C”）的存在。 如果存在的话，将试图描述其稀有气体和放射性同位素系统学的特征。 这项工作的一个重要方面是比较通过测量不同取样介质（即地热流体、玄武岩玻璃边和镁铁质斑晶）获得的结果，以评估它们保存地幔源区特征或易受上地壳（岩浆房）过程修改的能力。 本研究的另一个目标将是考虑在一些海洋岛屿中发现的“低-3 He”热点信号的完整性，以评估这是否是一个地幔特征或在地壳岩浆房爆发前立即引入的地壳叠印。