Regional Variability in Aleutian Primitive Magmas and Implications for Processes in the Mantle Wedge: Proposal for an Ion Probe Study

9419240阿留申高镁硅酸盐(斑晶、包裹体、包体、玻璃包裹体、火山岩)的离子探针和同位素研究。这项研究的目的是了解各种原始阿留申熔体类型的区域重要性，并推断阿留申地幔楔体中发生的主要混合、熔融和反应过程。方法是利用大腿镁矿物的微量元素和同位素特征作为地幔楔入过程的示踪剂。最近，与俯冲有关的岩浆弧中的原生钙碱性安山岩岩浆重新受到重视，具有高的镁#‘S和高的镍、铬含量，与地幔橄榄石和尖晶石的平衡一致。这些熔岩的存在再次提出了与俯冲有关的岩浆作用形成的地壳的主体成分的问题。这项研究将通过更清楚地定义阿留申弧内代表的各种原始熔体来解决这一广泛的问题，并为识别发生在阿留申地幔楔体中的主要过程提供更好的基础。

9419240 Yogodzinski An ion microprobe and isotopic study of Aleutian high Mg# silicates (phenocrysts, xenocrysts, xenoliths, glass inclusions, volcanic rocks) is proposed here. The aim of this study is to understand the regional importance of the various primitive Aleutian melt types, and to infer the predominant mixing, melting, and reaction processes that occur in the Aleutian mantle wedge. The approach is to use the trace element and isotopic characteristics of thigh Mg# minerals as tracers of mantle wedge processes. There has been a recent re-emphasis on primary calc-alkaline andesitic magmas in subduction related magmatic arcs, with high Mg#'s, and high Ni and Cr contents, consistent with equilibration with mantle olivine and spinel. The presence of these lavas in arcs raises once again the question of the bulk composition of crust formed by subduction-related magmatism. This study will address this broad issue by defining more clearly the various primitive melts which are represented in the Aleutian arc, and by providing an improved basis for identifying the predominant processes which occur in the Aleutian mantle wedge.