Isotopic and Trace Element Studies of the Lithospheric Mantle, Petrogenetic Processes and Magma Transport, & the Early Stages of Continental Crust Formation

这一建议建议继续和扩大我们对各种地幔和地幔衍生岩石的同位素和微量元素研究，以追踪岩石圈和上地幔的组成和演化，以及熔融和岩浆运输等成岩过程。我们的工作集中在锶、钕和铅的同位素研究以及U、Th系列同位素的研究，以及与同位素比值测定相一致的相关微量元素浓度的测量。此外，我们还讨论了利用电感耦合等离子体质谱增加一些重要的大离子半径和高场强元素的计划。我们的调查是多种多样的，既有地区性的，也有更具普遍性的目标。在最一般的意义上，所提出的工作是为了加深我们对大陆和大洋环境中岩石圈和最高地幔的组成和演化的认识，并有助于理解岩浆运移的时间和岩浆形成过程中的化学分馏机制等因素。利用同位素作为示踪剂，我们还将试图在一个不断增长的岛弧地体中追踪大陆地壳形成的最早阶段。为了实现这些目标，我们将调查的特定物质包括：来自印度Sylhet和Deccan圈闭的熔岩；来自因西亚、中国、北美西部和南太平洋岛屿的碱性玄武岩的地幔包体；来自菲律宾吕宋岛的一系列深成岩；来自阿留申的岛弧熔岩；来自太平洋和马里亚纳海槽弧后盆地的海脊玄武岩。

This a proposal to continue and expad our isotopic and trace element studies of a variety of mantle and mantle-derived rocks as tracers of the composition and evolution of the lithosphere and upper mantle, and of petrogenetic processes such as melting and magma transport. Our work is centered around isotopic studies of Sr, Nd and Pb on the one hand and U, Th series isotopes on the other, and the associated trace element concentrations which are measured in concert with the isotope ratio determinations. In addition, we discuss plans to add a number of important large ionic radius and high field strength elements to our capabilities using ICP-MS. Our investigations are varied and have both regional and more uniersal goals. In the most general sense, the work proposed is inteded to further our knowledge of the composition and evolution of the lithosphere anduppermost mantle in both continental and oceanic settings, and to help nderstand factors such as the timing of magma transport and the mechanisms of chemical fractionation during magmagenesis. Using isotopes as tracers we will also attempt to follow the earliest stages of continental crust formation in an accreting island arc terrane. Specific material we will investigate in pursuit of these goals incluse lavas from the Sylhet and Deccan Traps of India; mantle xenoliths from alkali basalts in Incia, China, Western North America and oceanic islands in the South Pacifice; a sequence of plutonic rocks from Luzon in the Philippines; island arc lavas from the Aleutians, ridge basalts from the Pacific and the Mariana Trough back arc basin.