Oxidising agents in sub-arc mantle melts link slab devolatilisation and arc magmas.

ABSTRACT: Subduction zone magmas are more oxidised on eruption than those at mid-ocean ridges. This is attributed either to oxidising components, derived from subducted lithosphere (slab) and added to the mantle wedge, or to oxidation processes occurring during magma ascent via differentiation. Here we provide direct evidence for contributions of oxidising slab agents to melts trapped in the sub-arc mantle. Measurements of sulfur (S) valence state in sub-arc mantle peridotites identify sulfate, both as crystalline anhydrite (CaSO₄) and dissolved SO₄^2- in spinel-hosted glass (formerly melt) inclusions. Copper-rich sulfide precipitates in the inclusions and increased Fe³⁺/∑Fe in spinel record a S⁶⁺-Fe²⁺ redox coupling during melt percol

SUBMITTER: Benard A 

PROVIDER: S-EPMC6115406 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature