Crustal Formation and Assembly in the NW Pacific: Aleutians and Kamchatka

9406195凯在整个第三纪，堪察加收集了大陆地壳(地体)的碎片，这些碎片在白令海和太平洋形成了海洋岛弧和高原。碎片的堆积形成了一个次大陆质量。这一过程被许多人认为是当今大陆增长的主要机制。堪察加是研究这种类型大陆增长的一个特别好的地点，因为它年轻，由于可以获得类似但尚未融合的海洋碎片(特别是阿留申群岛)的信息，以及广泛的吸积后岩浆活动，记录了深部的条件。这项研究的重点是起源于堪察加地体下地幔的碱性玄武岩岩浆。现有的这些岩浆的微量元素数据缺乏典型的特征(如高的Ba/La、La/Ta比值)，并支持要求地幔岩石圈被下伏的大洋岛玄武岩(OIB)状软流圈整体取代的拆沉模型。同位素分析(铅、锶、钕)以及其他微量元素分析将有助于确定与地壳生长和巩固的基本过程有关的物质储集层和物质通量的数量。

9406195 Kay Throughout Tertiary time, Kamchatka has collected fragments of continental crust (terranes) that formed as oceanic island arcs and plateaus in the Bering Sea and the Pacific Ocean. Accretion of the fragments has resulted in a subcontinental mass. The process is thought by many to be the main mechanism of present day continental growth. Kamchatka is a particularly good site to study this type of continental growth due to its youth, due to the availability of information on similar but as yet unaccreted oceanic fragments (especially, the Aleutian islands) and due to widespread post-accretion magmatism that records conditions at depth. This investigation focuses on alkaline basaltic magmas that originate in mantle that lies under the Kamchatka terranes. Existing trace element data on these magmas lack typical signatures (e.g. high Ba/La, La/Ta ratios), and support delamination models that call fro wholesale replacement of mantle lithosphere by underlying Oceanic Island Basalt (OIB)-like asthenosphere. Isotope analyses (Pb, Sr, Nd) as well as additional trace element analyses will permit identification of mas reservoirs and quantification of mas fluxes related to fundamental processes of crustal growth and consolidation.