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

阿留申镁质安山岩中类MORB的同位素特征和微量元素组成的极端多样性表明，这些岩石是理解阿留申弧岩浆形成过程的关键。虽然镁安山岩在阿留申山脉中部和东部很少见，但在俯冲速率较低的西部弧区，它们在体积上很重要。镁安山岩之所以令人感兴趣，是因为它们包含的成分(显然)范围从几乎纯的“地幔楔形”熔体到几乎纯的俯冲板块熔体。该项目旨在确定地幔楔体的组成，并量化俯冲板和地幔楔组分对中东部更常见的岩浆岩的贡献。矿物和全岩主量元素、微量元素和同位素(锶、钕、铅)组成的测定将足以表征熟悉的“正常”阿留申岩浆岩框架内的镁质安山岩。

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.