Temporal and Geochemical Evolution of the Society Islands Hotspot Lineament

该项目将继续研究社会群岛链的时间和石化演变。收集了火山、深成岩和上地幔捕虏体，对碱性海洋岛屿的母岩浆、分异机制和火山内部的地球化学变化进行了评价。这些研究将与更为人所知的、但可能是非典型的夏威夷拉斑岩火山形成对比。这两种地貌都被认为是由太平洋板块在静止热点上的运动引起的，对比地球化学演化应揭示热点结构的复杂性和海洋岩石圈可能的熔体贡献。从塔希提岛的两座火山上收集的150多个样本已经被岩石学描述并确定了它们的年龄。这些调查现在将扩展到社会群岛的其他火山，并将涉及俄勒冈州立大学的辐射测量、地球化学和实验研究的合作项目，以及康奈尔大学的威廉·怀特的同位素分析。法国火山学家R. Brousse和H. Barsczus正在提供大量新的样品和地质图。

This project is to continue studies of the temporal and petrochemical evolution of the Society Islands chain. Volcanic and plutonic rocks and upper mantle xenoliths have been collected to evaluate the parental magmas and differentiation mechanisms for alkaline oceanic islands and geochemical variations within these volcanoes. These studies will contrast with the better known, but perhaps atypical, tholeiitic Hawaiian volcanoes. Both lineaments are thought to arise from Pacific plate motion over stationary hotspots, and the contrasting geochemical evolutions should reveal complexities in hotspot structure and possible melt contributions from the oceanic lithosphere. Over 150 samples collected from two volcanoes on the island of Tahiti have been described petrographically and their ages determined. These investigations will now be extended to other volcanoes in the Society Islands and will involve a collaborative program of radiometric, geochemical and esperimental studies at Oregon State, and isotopic analyses by William White at Cornell. A large number of new samples and geological maps are being supplied by French volcanologists R. Brousse and H. Barsczus.