Salinization mechanism of lakes and controls on organic matter enrichment: From present to deep-time records

Abstract

Saline lakes have developed worldwide throughout geological history and continue to develop, is important for understanding deep-time climate evolution, lake evolution and extinction, terrestrial ecosystem evolution, and organic carbon burial processes. The basic conditions required for the formation of saline lakes are a sufficient source of salt, an arid or semi-arid climate, and a closed or semi-closed lake environment. There are four mechanisms of lake basin salinization: (1) seawater-derived salinized lake, salt irons are provided by seawater; (2) Inland evaporative saline lakes, the land is the source of salt substances following strong evaporation; (3) Deep hydrothermal fluids-based saline lakes, high-salinity hydrothermal fluids enter the basin through faults; and (4) Any combination of the above mechanisms. During the evolution of saline lake, one or more can be the main salinization mechanism, and the primary mechanism may change with the evolution of salinization periods. Hydrological characteristics of saline lakes control biome development, biogeochemical processes, sediment deposition, and organic matter enrichment. Due to high productivity and reducing conditions, the salinized lake basin environment is conducive to the formation of organic rich source rocks and/or type I and II sapropelic organic matter with high hydrocarbon generation potential. Future studies should focus on evolutionary processes of deep-time saline lake development based on Earth System Science and interactions between spheres, ecological reconstruction and biogeochemical processes in saline lakes, sediments burial diagenesis and physico-chemical-microbiological processes.