Fluid-driven auto-oxidation in magmas associated with porphyry Cu-Au deposits

Article Article scientifique Article Fluid-driven auto-oxidation in magmas associated with porphyry Cu-Au deposits eng 2025-12 author Wang Shiwei 0009-0008-3093-306X 431150 author Zhou Taofa author Chiaradia Massimo 0000-0003-4943-2480 110575 Services communs du département des sciences de la terre (DETCO) author Fan Yu author Zhang Lejun 1-8 119667 10.1016/j.epsl.2025.119667 0012-821X https://linkinghub.elsevier.com/retrieve/pii/S0012821X25004650 The exsolution of chlorine-rich fluids plays a key role in porphyry Cu-Au deposits (PCDs) formation by transferring metals from the melt to the fluid, either directly or via breakdown of pre-existing magmatic sulfides. However, the relative roles of these two mechanisms of metal transfer to the magmatic-hydrothermal fluid remain unclear. In this study, amphibole composition is employed as a proxy to reconstruct magmatic evolution and fluid exsolution conditions favorable to the formation of PCDs. Our results show that magmatic Cl and Cu contents, Mg#, and fO2 values inferred from amphiboles exhibit coupled variations during magma evolution. We interpret these correlations to be due to Cl-rich fluid exsolution from a deep-seated PCD system which triggers an increase in fO2 and the destabilization of previously formed sulfides in the middle to upper crust. This mechanism may be a key factor for the formation of Cu-rich PCDs that tend to be deeper and more oxidized than Au-rich PCDs. Our findings highlight amphibole composition as a potential indicator of magmatic-hydrothermal mineralization. Fluid-driven auto-oxidation Cl-rich fluid exsolution Porphyry Cu-Au deposit Amphibole Dewey 550 National Natural Science Foundation of China 42172078 42 Département des sciences de la Terre 154 false 663 Isotope Geochemistry, Geochronology and Thermochronology 692 Mineral Resources and Geofluids Earth and planetary science letters 671 0722591b-983a-44cf-8897-ba7d225fcea3 Article (Published version) Restricted ShiweiWang_EPSL_2025.pdf 4182754 application/pdf dadb46975508d82f6b395201832633d6104b5d95ca7a95912dfd130bcc1e4ab8 restrictedAccess Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département des sciences de la Terre

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Fluid-driven auto-oxidation in magmas associated with porphyry Cu-Au deposits	Earth and planetary science letters			2025	24	0

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Wang, Shiwei