Chalcophile and highly siderophile element behaviour in subduction zones: implication for global recycling of crustal 186Os-187Os signatures.

与广泛研究的与俯冲相关的亲石元素和挥发性元素的再循环相比，亲铜元素（Se-Te）和高亲铁元素（HSE）在俯冲带的行为仍然缺乏约束，但仍然存在矛盾。本项目旨在获得爱琴海Syros岛和Sifnos岛（基克拉迪蓝片岩单元）蓝片岩和榴辉岩古俯冲岩的第一个完整的Se-Te-HSE和187Os同位素数据集，以了解这些元素在海洋地壳的进行高压-低温俯冲相关脱水过程中的行为。这些目标将通过结合Se-Te-HSE-187Os对整个岩石、硅酸盐和单个宿主矿物的分析，以及在压力和温度下模拟典型的P-T俯冲路径的活塞缸实验来实现。这些结果将有助于更好地理解Se-Te-HSE的陆地旋回，以及地幔中1870s - 1860s小尺度和大尺度非均质性的起源，包括海洋岛屿和洋中脊玄武岩的特征。

In constrast to the widely investigated subduction-related recycling of lithophile and volatile elements, the behavior of chalcophile (Se-Te) and highly siderophile elements (HSE) in subduction zones remains poorly constrained but is yet contradictory. This project aims at obtaining the first comprehensive Se-Te-HSE and 187Os isotope dataset on a coherent sequence of blueschist and eclogitic paleosubduction rocks from the Aegean islands of Syros and Sifnos (Cycladic Blueschist Unit) in order to understand how these elements behave during prograde high pressure-low temperature subduction-related dehydration of the oceanic crust. These aims will be achieved by combining Se-Te-HSE-187Os analyses on whole-rocks, silicates and individual host minerals with piston cylinder experiments at pressures and temperatures mimicing the typical P-T path of subduction. The results will contribute to a better understanding of the terrestrial cycle of Se-Te-HSE and of the origin of small and large-scale 187Os-186Os heterogeneities in the Earth mantle, including signatures in oceanic island and mid-oceanic ridge basalts.