Effects of Intracratonic Strike‐slip Fault on the Differentiation of Carbonate Microfacies: A Case Study of a Permian Platform Margin in the Sichuan Basin (SW China)

Abstract

AbstractIn intracratnoic basins, the effect of strike‐slip faults on sedimentary microfacies is generally underestimated due to their small scale. Based on the integration of core, well logs, and three‐dimensional seismic data, this study presents a comprehensive analysis of the Permian carbonate platform and strike‐slip faults in the southwestern Kaijiang‐Liangping trough of the Sichuan Basin. The relationship between strike‐slip faults and Permian carbonate microfacies is investigated. The results reveals the existence of a NW‐trending strike‐slip fault zone along the platform margin, exhibiting clear segmentation. The western side of the study area exhibits a rimmed platform margin characterized by type I reefs, which corresponds to the presence of a large‐scale strike‐slip fault zone. In contrast, the eastern side is characterized by a no‐rimmed and weak rimmed platform margin, accompanied by type II reefs, which align with smaller strike‐slip fault zones. It was found that the strike‐slip fault had some effects on the platform and reef‐shoal complex of the Permain Changxing Formation. First, the platform was divided by strike‐slip fault into three segments to show rimmed, week rimmed and no‐rimmed platform. Second, reef‐shoal complex devolped along the faulted high position in the strike‐slip fault zone, and separated by faulted depression. Third, strike‐slip faults can offset or migrated the reef‐shoal complex and platform margin. Additionally, the thickness of the platform margin varies across strike‐slip fault zone, which is related to the activity of strike‐slip faults. The strike‐slip faults affect the microfacies by controlling the pre‐depositional paleotopography. This case suggests that the strike‐slip faults play a crucial role in the diversity and distribution of carbonate microfacies in the intracratonic basin.