Re-Os Isotopic Studies of Crust-Mantle Evolution on the Earth

PIs将分析太古宙马马岩和闪长岩-花岗闪长岩的Re-Os同位素系统；基性层状侵入体；地幔捕虏;最近的玄武岩来自洋中脊，海洋岛屿和岛弧。这些研究的具体目标是确定Os同位素地幔生长曲线；确定克拉通岩心岩的来源；了解火成岩体系中Re和Os的行为；研究次大陆地幔的形成，探讨上地幔内洋壳的再循环以及洋壳在岛弧火山活动中的作用。Re-Os同位素系统对地球的地球化学研究具有独特的潜力。该系统提供了与Rb-Sr、SM-Nd和U-Th-Pb系统相补充的新信息，原因如下：Re和Os均为亲铁元素，Os在地幔中相容，Re一般不相容；与地壳相比，Os在地幔中的丰度相对较高，并且形成玄武岩的熔融事件强烈地将Os从Re中分离出来。Re-Os同位素系统的使用将更好地了解对流地幔和岩石圈的衰竭和富集储层。古大陆地壳及其岩石圈根的形成和汇聚边缘俯冲板块的作用。

The PIs will analyze the Re-Os isotopic systematics of Archean komatiites and tonalites-granodiorites; mafic layered intrusions; mantle xenoliths; and recent basalts from mid-ocean ridges, ocean islands and island arcs. The specific goals of these studies are to determine the Os isotopic mantle growth curve; to determine the source of cratonic core rocks; to understand the behavior of Re and Os in igneous systems; to study the formation of the subcontinental mantle and to investigate recycling of oceanic crust within the upper mantle and the role of oceanic crust in island arc volcanism. The Re-Os isotopic system has unique potential to contribute to geochemical studies of the Earth. This system provides new information complementary to that available from the Rb-Sr, SM-Nd and U-Th-Pb systems for several reasons: both Re and Os are siderophile elements, Os is compatible in the mantle while Re generally is incompatible, Os has a relatively high abundance in the mantle compared to the crust and the melting events that form basaltic rocks strongly fractionate Os from Re. The use of the Re-Os isotopic system will provide a greater understanding of the depleted and enriched reservoirs of the convecting mantle and the lithosphere, the creation of ancient continental crust with its lithospheric roots and the role of subducted slab components at convergent margins.