Collaborative Research: Evolution of the Kerguelen Plume: A Geochemical Approach

在众多的地幔柱中，克尔格伦火山柱最为突出，因为它是一个巨大的、长期存在的地幔柱，它就是世界上两个巨大的海洋高原之一——克尔格伦高原。私家侦探们建议从地球化学方面研究地幔柱的进化史。我们的工作将集中在两个单独的项目上：(1)玄武岩项目（Frey）将重点研究西北省的旧高原玄武岩熔岩。这些最古老的玄武岩的地球化学特征将提供对较年轻喷发所观察到的长期同位素变化的清晰理解。Kerguelen和夏威夷羽流之间的比较研究将为地幔羽流的不同部分是如何被挖掘的以及地幔羽流是如何地球化学演化的提供重要信息。(2)捕虏体项目（清水）将重点研究下地壳和地幔捕虏体的详细岩石学、矿物化学（主要元素和微量元素）和同位素组成。P.I.s的目的是获得关于麻粒岩是在麻粒岩相条件下重新结晶的古代大陆地壳还是年轻玄武岩地壳的明确答案。上地幔捕虏体还将用于研究板块背景、古大陆岩石圈的可能参与以及羽流衍生熔体与岩石圈/软流圈之间的相互作用。

Among many mantle plumes, the Kerguelen plume stands out as a large, long-lived plume manifesting itself as the Kerguelen Plateau, one of the two giant oceanic plateaus of the world. The P.I.s propose to investigate geochemical aspects of the evolutionary history of the plume. Our effort will be focused into two separate projects: (1) Basalt project (Frey) will focus on the old plateau basalt lavas in the northwestern province. Geochemical characterization of these oldest basalts will present clear understanding of secular isotopic variations observed on younger eruptives. Comparative studies between the Kerguelen and Hawaiian plumes will provide important information on how different parts of mantle plumes are tapped and on how mantle plumes evolve geochemically. (2) Xenolith project (Shimizu) will focus on detailed petrography, mineral chemistry (major and trace elements) and isotopic compositions of lower crustal and mantle xenoliths. The P.I.s intend to obtain definitive answers on whether granulites are pieces of ancient continental crust or young basaltic crust recrystallized in the granulite facies conditions. Upper mantle xenoliths will also be used to investigate the plate setting, a possible involvement of ancient continental lithosphere, and interaction between plume-derived melts and lithosphere/asthenosphere.