Geochemical Study of Lavas from the North Hawaiian Arch Flood Basalt Province

北夏威夷拱洪玄武岩省熔岩的地球化学研究

• 批准号: 8915832
• 负责人: John Mahoney
• 金额: $ 4.93万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-01-01 至 1991-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8915832&HistoricalAwards=false
• 关键词: Geochemical; Study; Lavas; North; Hawaiian

Recent GLORIA surveys and dredging have discovered a large field of young alkalic flood basalts across the flexural arch north of the Hawaiian island chain. These rocks represent a significant and previously unknown part of Hawaiian volcanic history, and promise to advance greatly our understanding of hot-spot volcanism. Drs. Mahoney and Sinton will oversee isotopic and trace element analyses on 20-30 dredge samples from this region in order to determine mantle sources and gain insight into the magmatic history of this largery of this large flow field. Previous understanding of hotspot, mid-plate volcanic (like those of the Hawaiian islands) have identified three phases: 1) the major shield building episode of tholeitic composition; 2) a minor (1% by volume) alkalic cap; and 3) a small outpouring of silica-poor, " rejuvenated" lavas after a few million years of quiesence. Initial studies by Clague (USGS, a not-cost collaborator on this request) show the arch volcanics are closest in character to this last, "rejuvenated" suite of MORB-like rocks. Mahoney and Sinton hope to gain better understanding of the nature and variability of probable mantle sources, and the respective roles of partial melting, magma mixing and fractional crystallization.

最近的 GLORIA 勘测和疏浚工作在夏威夷岛链北部的弯曲拱上发现了一大片年轻的碱性溢流玄武岩。 这些岩石代表了夏威夷火山历史上一个重要且先前未知的部分，并有望极大地增进我们对热点火山活动的理解。 博士。 Mahoney 和 Sinton 将监督对该地区 20-30 个挖泥样品的同位素和微量元素分析，以确定地幔来源并深入了解这个大流场的岩浆历史。 先前对热点、中板火山（如夏威夷群岛的火山）的了解已经确定了三个阶段：1）拉斑岩成分的主要盾构形成阶段； 2) 少量（1%体积）碱帽； 3）在几百万年的静止之后，少量的硅含量低、“恢复活力”的熔岩涌出。 Clague（美国地质勘探局，该请求的免费合作者）的初步研究表明，拱形火山的特征最接近最后一套“焕发活力”的 MORB 状岩石。 马奥尼和辛顿希望更好地了解可能的地幔来源的性质和变化，以及部分熔融、岩浆混合和分异结晶各自的作用。