COOPERATIVE RESEARCH PROGRAM: Aleutian Magnesian Andesites:Keys to Magma Generation Processes in Island Arcs

阿留申镁质安山岩的类morb同位素特征和微量元素组成的极端多样性表明，这些岩石是了解阿留申弧岩浆生成过程的关键。虽然镁质安山岩在阿留申群岛中部和东部很少见，但在俯冲率较低的西弧地区，镁质安山岩具有重要的体积意义。镁质安山岩之所以引起人们的兴趣，是因为它们的成分（显然）从几乎纯的“地幔楔”熔体到几乎纯的俯冲板块熔体不等。本项目旨在确定地幔楔的组成，量化俯冲板块和地幔楔组成对中、东弧更常见岩浆岩的贡献。矿物和全岩主元素、微量元素和同位素（Sr、Nd、Pb）组成的测定将足以在熟悉的“正常”阿留申岩浆岩框架内表征镁质安山岩。

The MORB-like isotopic character and extreme diversity of trace element compositions within ALeutian magnesian andesites suggest that these rocks are key to the understanding of magma generation processes in the Aleutian arc. While magnesian andesites are rare in the central and eastern Aleutians, they are volumetrically important in the western arc where subduction rates are low. Magnesian andesites are of interest because they include compositions that (apparently) range from melts of nearly pure "mantle wedge" to melts of nearly pure subducting slab. This project is to determine the composition of the mantle wedge and quantify the contributions of subducting slab and mantle wedge components to more common magmatic rocks of the central and eastern arc. Determinations of mineral and whole-rock major element, trace element, and isotope (Sr, Nd, Pb) compositions will be sufficient to characterize magnesian andesites within the familiar framework of "normal" Aleutian magmatic rocks.