Fault‐Controlled Thermal Convection Dolomitization and Fluid Evolution Triggered by Emeishan Large Igneous Province

ABSTRACT The Emeishan Large Igneous Province (ELIP) offers a canonical setting to examine plume–lithosphere interaction and its imprint on carbonate diagenesis on sedimentary basins. In the Sichuan Basin, Lower to Middle Permian stratiform dolomites archive ELIP‐related fluid evolution. Here we integrate petrography, stable‐isotope geochemistry (C–O–Sr), trace and rare‐earth element data and in situ U–Pb geochronology to resolve the mechanisms and timing of dolomitization. Two dolomitization stages were identified. The first stage of dolomitization was driven by seawater convection through open fault systems and porous grainstones of the Chihsia Formation during the early phase of ELIP activity (~273.2–269.1 Ma). The second stage of dolomitization took place at the peak of ELIP activity (~260–259 Ma), when intensified tectonism reactivated basement faults. Seawater mixed with minor proportions of hydrothermal fluids convected along fractures, promoting both dolomite replacement and cement precipitation. Basin‐scale comparisons of oxygen isotopes reveal a shift from localized thermal effects during the early stage to late‐stage fluid homogenization, consistent with strong magmatic–fluid coupling. Collectively, we reveal that fault‐controlled thermal convection in open‐platform settings was the dominant driver of dolomitization, with hydrothermal fluids providing a limited overprint. These findings clarify the multiphase influence of ELIP on fluid dynamics and carbonate diagenesis, and provide new insights into the regulation of Large Igneous Provinces on basin‐scale diagenetic systems.