Controlling factors of organic matter enrichment in lacustrine basins

Studying the organic matter (OM) enrichment mechanisms in lacustrine basins is crucial for a deeper insight into the formation and evaluation of lacustrine hydrocarbon source rocks. A review reveals that OM enrichment in lacustrine basins is primarily influenced by paleoproductivity, preservation conditions, and OM dilution. Secondary factors, including paleoclimate, paleosalinity, paleowater depth, and geological events, can affect productivity and preservation conditions by altering nutrient concentrations and redox conditions in lakes. The OM dilution is primarily influenced by the sedimentation rate (SR). Notably, the factors controlling the OM enrichment are dual-faceted, and only moderate levels of water salinity, depth, SR, and geological events are conducive to the organic-rich source rocks. Additionally, a study of the third Member of the middle Eocene Shahejie Formation in the Bohai Bay Basin (hereafter referred to as the MES shale) indicates that climatic fluctuations significantly impact the salinity. Different types of hydrocarbon-generating organisms were present under varying salinity conditions, and the abundance of algae exhibited a normal distribution pattern with changes in salinity. Future studies should focus on the varying contributions of different hydrocarbon-generating organisms to primary productivity and the effectiveness of various preservation mechanisms for OM enrichment in lacustrine basins.