Behaviour of Chalcogens and Highly Siderophile Elements in subduction zones: The mantle wedge perspective

俯冲带在地幔和地壳储集层的岩石学和化学演化中起着重要作用。虽然亲石元素及其同位素特征在这些构造环境中的行为已被很好地了解，但硫族(S-硒-碲)和高度亲铁元素(HSe)的系统学很难受到约束，而且仍然相互矛盾。该项目的目的是提供(I)第一个综合性的HSE-187Os-S-Se-Te数据集，并(Ii)首次对堪察加半岛和加拿大科迪勒拉地幔楔状橄榄岩包体中的硫化物和HSe寄主矿物进行详细的岩石学和地球化学研究，以便了解来自俯冲板块的流体和熔体的渗流如何改变地幔楔体的HSe-187Os-S-Se-Te系统学。通过将这些结果与古俯冲岩石的HSE-187Os-S-Se-Te特征相结合，目的是(1)评估这些元素从俯冲板块到地幔楔、从地幔楔到弧状熔岩的循环方式和程度，从而更好地理解HSe-187Os-S-Se-Te的全球陆地旋回，以及(2)更好地理解地幔中小规模和大规模的187Os-186Os不均质性的起源，包括洋岛和中洋脊玄武岩中的特征。

Subduction zones play a major role in the petrological and chemical evolution of the Earth mantle and crustal reservoirs. While the behaviour of lithophile elements and their isotopic signatures in these tectonic settings is well-understood, the systematics of the chalcogens (S-Se-Te) and highly siderophile elements (HSE) is poorly constrained and still contradictory. The aim of this project is to provide (i) the first comprehensive HSE-187Os-S-Se-Te dataset in combination with (ii) the first detailed petrographic and geochemical study of the chalcogens and HSE host minerals in mantle wedge peridotite xenoliths from the Kamchatka Peninsula and the Canadian Cordillera in order to understand how the percolations of fluids and melts, derived from the subducted slab, may modify the HSE-187Os-S-Se-Te systematics of the mantle wedge. By integrating these results with the HSE-187Os-S-Se-Te signatures of paleo-subduction rocks, the goals are (1) to evaluate how and to which extent the recycling of these elements occurs from the subducted slab to the mantle wedge and from the mantle wedge to the arc lavas and consequently provide a better understanding of the global terrestrial cycle of HSE-187Os-S-Se-Te, and (2) to better understand the origin of small and large-scale 187Os-186Os heterogeneities in the Earth mantle, including signatures in oceanic island and mid-oceanic ridge basalts.