Reaction Infiltration Instabilities in Partially Molten Peridotite and Implications for Driving the Transport of Sulfide Liquid

Abstract

Reaction infiltration instability (RII) can cause the formation of melt channels and potentially facilitate the physical transport of sulfide liquid, which contributes to the geochemical evolution of chalcophile elements in the lithospheric mantle. This study conducted some two-layer reaction experiments to explore the feasibility of reaction-driven sulfide migration along high-velocity silicate-melt channels. With increasing duration, the formation of more silicate-melt channels and the transport of more sulfide droplets into a depleted peridotite were observed due to the increase of the local permeability. However, at a longer duration, the presence of some melt-channel relics implies that melt channels are temporary and ultimately closed when the reaction infiltration of silicate melt reached equilibrium in the depleted peridotite. Furthermore, theoretical calculations indicate that the RII of the system is suppressed, which impedes the formation of melt channels. The homogeneous distribution of silicate melt in a sulfide-free experiment implies that the Zener pinning of sulfide probably enhances the RII, thereby facilitating the formation of temporary melt channels. Therefore, this study demonstrates that sufficient silicate melt disequilibrium with solid phases in a liquid source potentially promotes the mechanical extraction of sulfides during reaction infiltration of silicate melt.