Collaborative Research: The Origin and Evolution of the Galapagos Lithosphere, Floreana Volcano

合作研究：加拉帕戈斯岩石圈、弗洛雷纳火山的起源和演化

• 批准号: 0207605
• 负责人: Dennis Geist
• 金额: $ 5.45万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-12-01 至 2006-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0207605&HistoricalAwards=false
• 关键词: Collaborative; Research; Origin; Evolution; Galapagos

GeistEAR-0207605Floreana Island is the most distinctive volcano of the Galapagos hotspot system. Unlike other Galapagos Islands, Floreana experienced extensive explosive activity, and its alkalic lavas are anomalously enriched in incompatible trace elements, exhibit evidence of metasomatism, have unique isotopic compositions, and contain abundant mantle xenoliths. The fundamental goal of the proposed project is to use Floreana's unique features to elucidate the magmatic processes that construct and modify the lithosphere forming the Galapagos Platform, which will be accomplished through a detailed volcanologic, petrologic, and geochemical study. Determining the volcanic history and compositional evolution of Floreana volcano will permit estimation of variations in the depths and extents of melt production through analysis of major and trace element variations and how those change with time. These results will be applied to questions about Floreana's volcanic evolution, including: a) the relationship between the different eruptive sequences; b) apparent shallow depths of melting, which may contradict a deep plume origin; c) compositional variations within single eruptive episodes; d) the relationship between Floreana lavas and the giant volcanic terraces which underlie the southern Galapagos Platform; and e) the origins of the xenoliths and their relationship to Floreana lavas and other parts of the Galapagos lithosphere. The powerful combination of high precision geochemical and petrologic analysis coupled with detailed field observations will provide a rare opportunity to gain insight into elusive questions about plume-lithosphere interaction, ocean-island magmatism, and, ultimately, mantle evolution.

弗洛里亚纳岛是加拉帕戈斯热点系统中最具特色的火山。与其他加拉帕戈斯群岛不同，弗洛里亚纳经历了广泛的爆炸活动，其碱性熔岩异常富含不相容的微量元素，显示出交代作用的证据，具有独特的同位素组成，并含有丰富的地幔包体。拟议项目的基本目标是利用弗洛里亚纳的独特功能来阐明形成加拉帕戈斯平台的岩石圈构造和改造的岩浆过程，这将通过详细的火山学、岩石学和地球化学研究来实现。通过确定弗洛里亚纳火山的火山史和成分演化，将能够通过分析主要和微量元素变化以及这些变化如何随时间变化来估计熔体产生的深度和程度的变化。这些结果将被用于有关弗洛雷亚纳火山演化的问题，包括：a)不同喷发序列之间的关系；b)明显的浅层熔融深度，这可能与深羽流起源相矛盾；c)单喷发时期的成分变化；d)弗洛里亚纳熔岩与南加拉帕戈斯地台下的巨大火山阶地之间的关系；以及e)捕虏体的起源及其与弗洛里亚纳熔岩和加拉帕戈斯岩石圈其他部分的关系。高精度的地球化学和岩石学分析与详细的野外观测相结合，将提供一个难得的机会来洞察关于烟柱-岩石圈相互作用、海洋-岛屿岩浆活动以及最终地幔演化的难以捉摸的问题。