Spatiotemporal Link Between MVT Pb–Zn Mineralization and Paleo-Oil Reservoirs in the Micangshan Area, China: Implications for Fluid Migration and Metallogenic Model

The Micangshan lead–zinc deposits, located in the northern margin of the Sichuan Basin, are classified as the Mississippi Valley-type (MVT) deposits. This study investigates the genetic linkage between Pb–Zn mineralization and paleo-oil reservoirs in the region, which is distinct from separate investigations on lead–zinc deposits or paleo-oil reservoirs. Through mineralogy, isotope, and fluid inclusion analyses, it is revealed that the direction of ore-forming fluid migration and the ore-forming process are closely related to the thermal cracking of paleo-oil reservoirs. The deposits show a characteristic clustered distribution along the southern part of the Micangshan area, with high-grade mineralization concentrated in the Nanmushu and Kongxigou Pb–Zn deposits. Rb–Sr isotopic dating indicates that mineralization occurred during the Late Cambrian to Early Ordovician (Nanmushu deposit 486.7 ± 3.1 Ma; Kongxigou deposit 472 ± 6.1 Ma), coinciding with the formation of the first-stage paleo-oil reservoirs. The study concludes that the MVT Pb–Zn mineralization in the Micangshan area is genetically linked to the first-stage paleo-oil reservoirs’ hydrocarbon generation and migration events. The organic-rich hydrothermal fluids facilitated the migration and precipitation of Pb–Zn minerals.