A set of organic- rich shales, known as the Luzhai Formation, has developed within an inter- platform basin facies in the Dianqiangui basin, which is located in the southwestern part of the South China plate. These shales reach a thickness of approximately 300 m and exhibit a relatively high total organic carbon (TOC) content, exceeding 2%. The Luzhai Formation formed during a third- order sea- level rise spanning the Tournaisian and Visean ages of the Early Carboniferous, making it a promising target rock for shale gas exploration. The Luzhai Formation exhibits a distinctive diachronous development, characterized by a complex transition from deep- water inter- platform basin facies to shallow- water continental shelf facies, marked by a decrease in thickness and facies changes within the overlying Yingtang Formation. This diachronous development culminates in the formation of coal measure strata caused by deltaic sedimentation, highlighting a unique sedimentary succession within the Early Carboniferous (Missippissian) of the study area. This succession contrasts significantly with the depositional patterns observedon the Pangaea supercontinent, where the Pennsylvanian Subsystem is characterized by extensive coal deposits, while the Missippissian Subsystem exhibits an unusually large proportion of limestone. Organic matter accumulation within the anoxic basin facies of the Lower Carboniferous shales in the study area aligns with a comprehensive model that emphasizes the complex interaction of three primary factors: 1) enhanced productivity; 2) organic matter preservation that is associated with reducing conditions; and 3) a decreased sedimentation rate that led to reduced dilution of organic matter. These factors are directly affected by relative sea- level fluctuations. In addition to these factors, the biological carbon pump, specifically involving phytodetritus, appears to be a crucial mechanism for organic matter enrichment in this organic- rich shale. Further research is necessary to fully elucidate the details of this mechanism.