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，亲石元素(Se-Te)和高度亲铁元素(HSe)在俯冲带中的行为仍然受到很少的限制，但仍然相互矛盾。该项目旨在获得爱琴海锡罗斯岛和西夫诺斯岛蓝片岩和榴辉岩古俯冲岩序列的第一个全面的Se-Te-HSe和187Os同位素数据集，以了解这些元素在洋壳与高压-低温俯冲有关的进行性脱水过程中的行为。这些目标将通过结合对全岩、硅酸盐和单个寄主矿物的Se-Te-HSE-187Os分析与活塞筒模拟典型俯冲P-T路径的压力和温度实验来实现。这一结果将有助于更好地了解Se-Te-Hse的陆地旋回和地幔中小规模和大规模187Os-186Os不均一性的来源，包括大洋岛和中洋脊玄武岩中的特征。

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.