Platinum-group element geochemistry of the Paraná flood basalts – Modelling metallogenesis in rifting continental plume environments

The 135 Ma Paraná-Etendeka Large Igneous Province (PELIP) is one of the largest areas continental flood basalt (CFB) volcanism in world and widely agreed to be a product intracontinental melts related thermal anomalies from Tristan mantle plume. province rifted during break-up Gondwana, as plume transitioned into an oceanic geodynamic environment. This study reports analyses plume-derived basalts Brazilian side PELIP (the Serra Geral Group) investigate major, trace platinum-group element (PGE) abundances evolving plume-rift metallogenic setting, with aim contextualising controls alongside existing magmatic interpretations region. chalcophile geochemistry these defines three distinct groupings that fit modern multi-element magma classifications for lavas. In this scheme, Type 4 lavas have distinctive PGE-poor signature, 1 (Central-Northern) are enriched Pd, Au Cu, (Southern) Ru Rh. Our melt modelling indicates compositional variations result changes melting regime between garnet spinel stability fields, response thinning ‘unlidding’ rifting continent above. process imposes progressively shallower depths higher degrees partial melting. Accordingly, magmas formed small degree melts, reducing likelihood sulphide exhaustion/chalcophile acquisition at source. incorporated components sub-continental lithospheric (SCLM) higher-degree melts; SCLM was heterogeneously via metasomatism prior melting, produced enrichment volatile metals (Pd, Au) magmas. contrast, Ru-Rh attributed increased spinel-group mineral incorporation close rift zone. models confirm importance contributions precious metal systems within CFB provinces, reinforce role heterogeneous metasomatic underneath cratons boosting prospectivity respect ore deposits.