Multi-episodic mantle upwelling overprinting drives the formation of large to giant porphyry Cu-Au deposits

The world’s most significant sources of copper and gold are large-to-giant porphyry Cu-Au deposits; however, the tectonic setting and mechanisms responsible for these abnormal Cu-Au enrichments are controversial, which restricted our in-depth research on Cu-Au mineralization and prospecting. The central‐western segment of the Bangong-Nujiang metallogenic belt (BNMB) contains regions with world-class porphyry Cu-Au enrichments, with deposits spanning various scales. The spatiotemporal coupling between magmatism and mineralization in this region provides critical insights into the tectonic drivers of metal super-enrichment in giant porphyry systems. This study conducted systematic petrographic, geochronological, geochemical, and Sr-Nd-Hf isotopic analyses for the Middle-Late Jurassic igneous rocks, and comprehensively analyzed spatial-temporal relationship between Late Mesozoic magmatic events and Cu-Au deposit distribution on Central Tibet. Our results indicate that the central-western BNMB experienced multi-episodic mantle-derived magmatic upwelling events during the Late Mesozoic, which all contributing to Cu-Au pre-enrichment. Medium- and small-scale Cu-Au deposits are primarily associated with single-phase mantle upwelling zones, whereas large- to giant-scale porphyry Cu-Au deposits are concentrated in areas where the effects of multiple mantle upwelling events are superimposed. Based on these spatial-temporal correlations and analogous records of multiple mantle upwelling episodes documented in other typical large- to giant-scale deposits worldwide, we propose that multi-episodic mantle upwelling overprinting is a critical prerequisite for the formation of giant porphyry Cu-Au deposits.