The world’s largest carbonate-hosted Zn-Pb deposit
image: Genesis model of carbonate-hosted Zn-Pb deposit
Credit: Xing-Wang Xu
The Huoshaoyun deposit showcases three distinct mineralization stages: exhalative smithsonite (Smt) deposition, hydrothermal cerussite (Cer) veining, and fault-controlled sulfide formation. Stratiform Smt ores dominate (85% reserves), displaying sedimentary-exhalative (SEDEX) features with feeder veins and horizontal layering. Zn-Pb-C-O isotopes and trace elements (e.g., high Li, Be, Sr) indicate magmatic-hydrothermal fluids interacting with limestone. Decoupled O isotopes between Smt and quartz suggest dual fluid sources (aqueous vs. CO2-rich), challenging supergene oxidation models.
Early-stage Smt formed via CO2-rich fluids dissolving limestone in a shallow lagoonal setting, supported by C-O isotopes mirroring host rocks. Subsequent hydrothermal Cer veins (high Sr, low Zr) and sulfides (enriched Cd) overprinted Smt, reflecting evolving fluid chemistry. Sulfide δ66Zn values (-0.09‰ to +0.04‰) and Pb isotopes point to lower crustal sources. Quartz δ18O variations (+1.14‰ to -14‰) track magmatic-to-meteoric fluid shifts, aligning with Jurassic volcanic activity (~195 Ma) driving fluid convection and metal enrichment.
The deposit formed during early Jurassic Linjitang back-arc rifting, triggered by Bangong-Nujiang Ocean subduction. Crustal extension facilitated magma ascent, releasing SO2 (acid rain) and CO2, which promoted karstification and Zn-Pb precipitation. Large-scale Smt accumulation resulted from volcanic-induced acid rain, limestone dissolution, and granitic magma-driven fluid convection. This model redefines carbonate-hosted Zn-Pb systems, emphasizing magmatic-volcanic synergism in rift settings, offering new exploration frameworks for Tethyan metallogenic belts. The work entitled “Anatomy and genesis of the world’s largest carbonate-hosted Zn-Pb deposit: New insights from ore characteristics, Zn-Pb-C-O isotopes, and trace element constraints of the Huoshaoyun deposit, Karakorum Range, Xinjiang” was published on Geoscience Frontiers (published on Jun 29, 2024).