Key to formation of Jinding world-class Mississippi Valley-type lead-zinc deposit in the Tibetan-Himalayan orogen

Mississippi Valley-type (MVT) deposits are vital sources of lead and zinc, crucial for the energy transition. Giant MVT deposits often occur in fold-thrust systems within collisional orogens, but the processes driving mineralizing fluids remain unclear. Here, we investigate a deep seismic reflection profile and broadband magnetotelluric survey traversing the world-class Jinding MVT deposit in the Sanjiang belt of Tibetan-Himalayan orogen. Our results reveal an upper-crustal fold-thrust system with a deep décollement underlain by a thermal dome at a depth of ~20-40 km that is likely caused by ponding and degassing of hydrous potassic magmas. We suggest that rock dilatancy along the décollement during compressive deformation provided a pathway for the lateral migration of regional ore-forming fluids. Heat, provided by the underlying thermal dome, together with fault channels caused by a transition from regional compression to extension, drove the upward discharge of fluids from the décollement and led to mineralization in the overlying fold-thrust belt. Although MVT deposits have classically been considered unrelated to magmatic activity, our revised model of deposit genesis suggests that intra-crustal magma chambers may drive fluid circulation and make important contributions to the timing and spatial localization of MVT ores in collisional orogens.