Deep sourced magma and ore-metal mobility in the D. João de Castro submarine volcano (Azores): a mineral chemistry and melt inclusion study

The D. João de Castro is a submarine volcano with known hydrothermal activity located in the Terceira ultra-slow spreading rift within Azores triple junction (ATJ). Several well-known mafic and ultramafic rock-hosted seafloor systems lay along Mid-Atlantic Ridge, to north south of platform, yet little about activity, ore-metal availability, magmatic–hydrothermal interactions ATJ. Here, we investigate multi-phase melt inclusions hosted early formed phenocrysts (olivine, clinopyroxene plagioclase), metallic precipitates found groundmass vesicles. Combining detailed petrographic observations geochemical data thermobarometry calculations, assess P–T conditions phenocrysts, pathways towards surface, timing sulfide saturation composition immiscible melts. Results show that characterized by multi-level magmatic system where primary segregated from upper mantle moved up through oceanic crust residence time. Sulfide formation liquid (Fe–Ni–Cu) occurred primitive magmas olivine crystallization continued during plagioclase crystallization. At shallower levels, degassing volatiles carrying base metals (Cu–Zn–Pb–Co) Ba have contributed element budget system. study vesicles at contributes understanding source surface processes Rift underline importance into systems.