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

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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.