Genesis and Evolution of Shoshonitic Volcanism in the Northern Mariana and Southern Volcano Arcs

该项目将继续对马里亚纳弧最北端的玄武岩岩浆进行研究，以验证马里亚纳海槽向北扩展导致交代富集地幔拆顶的假设。该项目的总体目标是更好地了解弧岩浆作用。具体而言，目标是确定：(1)通过检查来自选定火山的代表性熔岩，确定shoshontic省母熔岩的组成；(2)富弧岩浆活动源区空间分布——以交叉链海山熔岩为例；(3)对残弧和锋面弧火山岩的时间分布进行研究。研究人员从一条火山弧中获得了一组非常不寻常的样品。本项目将进行的分析应解决与弧岩浆作用有关的若干问题。其中最重要的是弧型火山的组成和早期演化。这个问题很重要，因为弧在大陆地壳的形成中可能起着作用。

This project will continue work on shoshonitic magmas from northernmost Mariana arc to test hypothesis that the enrichments result from the unroofing of metasomatically enriched mantle as a consequence of the northward propagation of the Mariana Trough. The overall objective of this project is to better understand arc magmatism. In particular, the goals are to determine: (1) the compositions of parental lavas in shoshonitic province--by examining representative lavas from selected volcanoes; (2) the spatial distribution of the source of enriched arc magmatism--by analyses of cross-chain seamount lavas; (3) the temporal distribution of shoshonites--by studying volcanic rocks from remnant and frontal arcs. %%% The investigators have obtained a very unusual suite of samples from a volcanic arc. The analyses that will be carried out in this project should address a number of question related to arc magmatism. The most important of these are the composition and early evolution of arc volcanoes. This question is important because of the possible role of arcs in the formation of continental crust.