Oxygen Isotope Studies of Crustal Recycling at Convergent Margins

9805101 Stolper洋壳俯冲是控制弧岩浆作用、地壳生长以及挥发分和其他元素向地幔再循环的主要因素。在弧下地幔的俯冲成分主要是研究使用的丰度和微量元素，高度集中到流体和硅酸盐熔体的同位素组成的变化。氧同位素的变化应提供互补的限制，由于地壳和地幔氧之间的同位素对比和简单的关系，氧同位素比值的变化和地壳成分的相对丰度地幔来源的熔岩。以前的激光拉曼光谱和离子探针氧同位素数据表明，地幔熔融俯冲带环境中的“板”衍生的含水流体的丰度是一个敏感的功能，提供了一个不寻常的和具体的联系之间的地球化学示踪剂俯冲物质和岩石成因的弧相关的熔岩。在这些结果的基础上，本研究包括以下调查：[1]来自高度亏损源的弧相关熔岩和来自具有大“板片熔体”成分的微量元素证据的弧的氧同位素变化，[2]存在高度亏损的高δ 18 O地幔橄榄岩，我们的弧熔岩数据表明存在，[3]堪察加岛弧等地地幔捕虏体中的硅质熔体。这项研究有可能产生重要的新的见解地壳循环的作用，在弧相关熔岩的成因。

9805101StolperSubduction of oceanic crust is a major factor controlling arc magmatism, crustal growth and the recycling of volatiles and other elements into the mantle. Subducted components in the sub-arc mantle have principally been studied using variations in the abundance and isotopic composition of minor and trace elements that are highly concentrated into fluids and silicate melts. Oxygen isotope variations should provide complementary constraints due to the isotopic contrast between crustal and mantle oxygen and to the simple relationship between variations in oxygen isotope ratio and the relative abundances of crustal components in the sources of mantle derived lavas. Previous laser fluorination and ion microprobe oxygen isotope data suggest that mantle melting in subduction zone environments is a sensitive function of the abundance of a 'slab' derived hydrous fluid, providing an unusual and concrete link between geochemical tracers of subducted materials and the petrogenesis of arc-related lavas. Building on these results this study includes investigations of: [1] the oxygen isotope variability in arc-related lavas from highly depleted sources and from arcs with trace element evidence for a large 'slab melt' component, [2] the existence of highly depleted, high delta 18O mantle peridotites suggested to exist by our data for arc lavas, and [3] siliceous melts in mantle xenoliths from the Kamchatka arc and elsewhere. This research has the potential to yield significant new insights into the role of crustal recycling in the genesis of arc-related lavas.