The fine- grained carbonate rocks with typical characteristics and well- preserved laminations occurred at the Third Member of the Lower Triassic Jialingjiang Formation, Nanzhang—Yuan’an area. This study aims to summarize the characteristics of fine- grained carbonate laminates, and elucidate the formation mechanisms and the depositional environments of the fine- grained carbonate laminates.Methods: In this study, field observation in combination with petrographic analysis under normal light, fluorescent, and scanning electronic microscopes, as well as geochemical analysis (LA- ICP- MS mapping) were conducted to solve these problems.Results: The laminae are composed of an alternating stacking of dark laminae and light laminae, with an average thickness ranging from 0.22~0.62 mm. There are abundant organic matter, extracellular polymeric substance (EPS), automicrites, and framboidal pyrites as well as clay minerals preserved within the dark laminae, while light laminae are rich in microcrystalline- sparitic calcite crystals with a few dolomitic crystals but rare clay minerals. LA- ICP- MS mapping analysis indicates different contents of some major and trace elements within different laminae.Conclusions: The study elucidates the formation mechanisms and depositional environment of the fine- grained carbonate laminates. The formation of the dark laminae is attributed to organic matter and clay mineral adsorption, biomineralization and organomineralization of microbes. While the light laminae may precipitate in a supersaturated calcium carbonate environment. These all indicate that those fine- grained carbonate laminates deposited in a stagnant, reduced, and hypersaline tidal flat pond environment.