Plume vs. Lithosphere Controls on Intraplate Volcanism: A Geochemical Study of the Austral Islands

羽流与岩石圈对板内火山活动的控制：南方群岛的地球化学研究

• 批准号: 9725351
• 负责人: Erik Hauri
• 金额: $ 11万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 1999-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725351&HistoricalAwards=false
• 关键词: Plume; vs.; Lithosphere; Controls; Intraplate

9725351 Hauri This is a geochemical and geochronological study of volcanic islands and seamounts comprising the Austral Islands chain of French Polynesia. This chain is being studied in order to determine whether the Hawaiian model of a focused, narrow mantle plume is an adequate one for describing all aspects of the actively convecting part of the Earth's mantle. The Austral Islands are differ in almost every aspect from the Hawaiian islands. New Ar-Ar dating of lavas and seamounts will be combined with plate-motion reconstructions using Pacific pole of rotation fixed by the Hawaiian and Louisville hotspots to determine if the size of the Austral anomaly is consistent with a narrow plume, a sheet, or a leaky plate over a diffuse warm-spot. Combined geochemical studies on lavas, xenoliths, and melt inclusion will address several key questions regarding the coupled morphologic and geochemical variation across the Austral Fracture Zone including what role the oceanic lithosphere plays in the style and composition of the Austral volcanism. The combined Os, O and He isotope studies will help determine if the chemical characteristics of the Austral HIMU and EM sources are more consistent with crustal recycling or intra-mantle metasomatism.

9725351豪里这是一项关于火山岛和海山的地球化学和地质年代学研究，这些岛屿和海山构成了法属波利尼西亚的南岛链。人们正在研究这一链，以确定夏威夷的聚焦、狭窄的地幔热柱模型是否足以描述地球地幔活跃对流部分的所有方面。南方群岛几乎在各个方面都与夏威夷群岛不同。新的熔岩和海山Ar-Ar测年将与板块运动重建相结合，利用夏威夷和路易斯维尔热点固定的太平洋自转极来确定南方异常的大小是否与扩散暖点上的窄羽流、席状物或泄漏板块一致。熔岩、包体和熔体包裹体的联合地球化学研究将解决有关南洋断裂带的地貌和地球化学耦合变化的几个关键问题，包括大洋岩石圈在南洋火山活动的类型和组成中所起的作用。结合Os、O和He同位素研究将有助于确定南方HIMU和EM源的化学特征是否更符合地壳再循环或地幔内交代作用。