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

该奖项支持一个了解科尔盖伦羽流的地球化学演化的项目。地幔热柱是从地球内部进行热量和质量转移的主要工具。它们也是重要的地球化学窗口，通过它们可以研究地球内部的物质和过程。在地幔热柱中，科尔盖伦热柱是独特的，因为它创造了一个漫长的(1.2亿年)岩浆记录，其中包括最大的海洋高原之一的科尔盖伦高原，随着印度板块向北移动到地幔热柱上方而形成的近5000公里的线性火山链，以及南极板块上的科尔盖伦群岛。这个从大约4000万年前到现在活跃的岛屿杂岩，主要由一个厚(约3公里)的玄武岩高原熔岩序列组成。该项目将对科尔盖伦群岛上的玄武岩以及玄武岩熔岩中的镁铁质和超镁铁质包体进行详细的地球化学研究。这是麻省理工学院、伍兹霍尔海洋研究所和比利时的Libre de Bruxelle大学合作的成果。本次合作研究项目分为两个项目：(1)玄武岩项目是对高原熔岩形成地层层序的研究，高原熔岩是群岛中最古老、规模最大的喷出单元。熔岩成分和锶、钕、铅同位素比值的时间变化将被用来确定地幔源组分比例、熔融过程特征、岩浆供应速率和地壳处理历史的时间变化，并对各种羽流地球化学特征模型进行评估。(2)Xenolite项目是对下地壳和地幔包体的研究。这项研究将包括岩相学、主量元素和微量元素丰度以及矿物的同位素比值。地质化学结果，包括地温、地球压力和地质年代学，将被用来了解捕虏体的来源，并推断在羽流演化过程中存在的地球动力学环境和地球化学过程。这项研究的这些结果将更好地约束克尔盖伦热柱演化的物理模型，特别是总体上的地幔热柱。

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 researah 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.