Amphibole control on copper systematics in arcs: Insights from the analysis of global datasets

Copper, obtained from porphyry deposits formed in arc settings, is a critical resource, and primarily sourced magmas. However, the processes that shape copper contents of magmas are up for debate. Existing models place emphasis on different petrological agents explain large-scale trends systematics. Previous studies have noted ’Cu paradox,’ where with high Sr/Y ratios, indicative ore-forming potential, lowest concentrations. Here we compile multidimensional database volcanic whole rock compositions couple it simple to elucidate controls respect Cu. We show calc-alkaline, undergo major element modification caused by extensive amphibole and/or garnet fractionation, which promotes sulphide precipitation depletion. demonstrate importance fractionation as globally important process both calc-alkaline differentiation magmas, well its role signalling right set chemical conditions ultimately feed deposits. This work also raises possibility geochemical indicator potential porphyry-forming magma, should be readily detectable combination metrics. Despite their paucity copper, associated deposits, implying propensity form such depends factors other than magma’s bulk content.