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

最近的格洛丽亚调查和疏浚发现了一个大的 年轻的碱性溢流玄武岩穿过弯曲拱 位于夏威夷岛链以北 这些岩石代表了 夏威夷火山的重要和以前未知的部分 历史，并承诺大大提高我们对 热点火山作用 马奥尼和辛顿医生会监督 20-30个疏浚物样品同位素和微量元素分析 为了确定地幔来源和获得 深入了解这一大片的岩浆历史， 流场进行 前期对热点、中盘的认识 火山（如夏威夷群岛）已经确定 三个阶段：1）拉斑玄武岩的主要盾构建造阶段 组合物; 2）次要（1体积%）碱性帽;和3） 少量的硅质贫乏的、“再生”的熔岩在 几百万年的沉寂 Clague的初步研究 (USGS，一个不收费的合作者在这个请求）显示拱门 火山岩在性质上最接近这最后一种， 一套类似MORB的岩石 马奥尼和辛顿希望 更好地了解可能的性质和可变性 地幔来源，以及部分熔融的各自作用， 岩浆混合和分离结晶作用。

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.