Origin and Evolution of the Kerguelen Plume: Constraints from Studies of the Kerguelen Archipelago (Collaborative Research)

摘要该奖项支持一个项目，以了解凯尔盖朗羽的地球化学演化。 地幔柱是地球内部热量和质量转移的主要载体。 它们也是研究地球内部物质和过程的重要地球化学窗口。 在地幔柱中，凯尔盖朗地幔柱是独特的，因为它创造了一个漫长的（1.2亿年）岩浆记录，其中包括凯尔盖朗高原，最大的海洋高原之一，Ninetyeast Rdge，一个近5000公里的线性火山链，随着印度板块向北移动越过地幔柱而形成，以及南极板块上的凯尔盖朗群岛。 这个岛屿复合体，从大约4000万年前到现在都很活跃，主要由厚（约3公里）的玄武岩高原熔岩序列组成。 该项目将对凯尔盖朗群岛的玄武岩以及玄武岩熔岩中的镁铁质和超镁铁质捕虏体进行详细的地球化学研究。 这是马萨诸塞州理工学院、伍兹霍尔海洋研究所和比利时布鲁塞尔自由大学之间的合作。 该合作研究计划分为两个项目：（1）玄武岩项目是研究高原熔岩中的熔岩形成地层序列，高原熔岩是群岛中最古老和体积最大的喷出单元。熔岩成分和锶、钕和铅同位素比率的时间变化将用于确定地幔源成分比例的时间变化、熔融过程的特征、岩浆供应速率和地壳加工历史，并评价羽流地球化学特征的各种模型。 (2)捕虏体项目是一个研究下地壳和地幔捕虏体的项目。 这项研究将包括岩相学、矿物的主要和微量元素丰度和同位素比率。 地球化学的结果，包括地质测温，地质测压和地质年代学，将被用来了解捕虏体的来源，并推断地球动力学环境和地球化学过程中存在的演化过程中的羽。 这项研究的这些结果将更好地约束凯尔盖朗羽流演化的物理模型，特别是地幔羽流一般。

Abstract This award supports a project to understand the geochemical evolution of the Kerguelen plume. Mantle plumes are a major vehicle of heat and mass transfer from the Earth's interior. They are also important geochemical windows through which materials and processes of the Earth's interior can be studied. Among mantle plumes, the Kerguelen plume is distinctive because it has created a long (120 million year) magmatic record which included the Kerguelen Plateau, one of the largest oceanic plateaus, the Ninetyeast Rdge, a nearly 5000 kilometer linear chain of volcanoes which formed as the Indian Plate moved northward over the plume, and the Kerguelen Archipelago on the Antarctic plate. This island complex, active from about 40 million years ago to the present, is largely composed of a thick (about 3 kilometers) basaltic plateau lava sequence. This project will undertake detailed geochemical studies of the basaltic rocks on the Kerguelen Archipelago as well as mafic and ultramafic xenoliths occurring in the basaltic lavas. This is a collaboration between Massachusetts Institute of Technology, Woods Hole Oceanographic institution and the University Libre de Bruxelles in Belgium. This collaborative research program is divides into two projects: (1) The Basalt Project is a study of lavas forming stratigraphic sequences in the plateau lavas which are the oldest and most voluminous extrusive unit in the archipelago. The temporal variations in lava compositions and isotopic ratios of strontium, neodymium and lead will be used to determine temporal variations in proportions of mantle source components, characteristics of the melting process, magma supply rates and crustal processing history, and to evaluate various models for the geochemical characteristics of the plume. (2) The Xenolith Project is a study of lower crustal and mantle xenoliths. This research will include petrography, major and trace element abundances and isotopic ratios of minerals. Geoch emical results, including geothermometry, geobarometry, and geochronology, will be used to understand provenance of the xenoliths and to infer the geodynamic environments and geochemical processes which existed during the evolution of the plume. These results of this research will better constrain physical models of the evolution of the Kerguelen plume, specifically, and mantle plumes in general.