Collaborative Research: Volcanic Evolution in the Galapagos: A Geological, Petrological, and Geochemical Investigation of Volcan Ecuador

9612110 Geist本项目是对加拉帕戈斯群岛伊莎贝拉岛厄瓜多尔火山进行综合野外、岩石学和地球化学研究。本研究的直接目的如下：1。通过野外研究和K-Ar测年确定火山的喷发和构造历史。2. 获得一套足够完整的化学数据，以便确定液体下降线，并限制母岩浆的性质。3. 通过分析地层和K-Ar测年限制的样品组，确定成分的时间趋势。为此，将从断层陡坡和破火山口壁上暴露的地层剖面中采集样本。确定厄瓜多尔明显的断层对岩浆组成有什么影响，如果有的话？基于实验室的工作将包括主要元素分析、岩石学研究、矿物相的电子探针分析、Sr、Nd、Pb和Hf同位素分析以及微量元素分析。所得结果将与岩浆的热力学模型一起用于模拟岩浆的产生和演化。这些结果将与加拉帕戈斯群岛其他火山的研究结果进行比较。这反过来将用于解决加拉帕戈斯群岛地幔柱如何与岩石圈和软流圈在加拉帕戈斯群岛下地幔的浅层相互作用的问题。这项拟议中的研究是一项法美联合项目，涉及里昂高等师范学院的弗朗西斯·阿尔巴雷德、爱达荷大学的丹尼斯·盖斯特和康奈尔大学的威廉·怀特的合作。

9612110 Geist This project is an integrated field, petrological, and geochemical study of Volcan Ecuador, Isla Isabela, Galapagos. The immediate objectives of this study are as follows: 1. Determine the eruptive and structural history of the volcano through field studies and K-Ar dating. 2. Obtain a sufficiently complete suite of chemical data so that the liquid line of descent can be determined and the nature of the parental magmas constrained. 3. Identify any temporal trends in composition, through analysis of suites of samples whose ages are constrained by a combination of stratigraphy and K-Ar dating. For this purpose, samples will be taken from stratigraphic sections exposed in fault scarps and caldera walls. Determine what, if any, effect has the apparent faulting on Ecuador had on magma composition? Laboratory based work will include major element analyses, petrographic studies, electron microprobe analyses of mineral phases, Sr, Nd, Pb, and Hf isotopic analyses, and trace element analyses. The results obtained will be used, along with thermodynamic models of magmas, to model magma generation and evolution. These will be compared with the results of studies of other volcanoes in the Galapagos. This in turn will be used to address the problem of how the Galapagos mantle plume interacts with lithosphere and asthenosphere at shallow levels in the mantle beneath the Galapagos. The proposed study is a joint Franco-American project involving a collaboration between Francis Albarede of the Ecole Normale Superieure de Lyon, Dennis Geist of the University of Idaho, and William White of Cornell University.