Study on the types and genesis of nodules in shale

Concretion is a very common and complex sedimentary structure in shale, which composition, structure, color is completely different from the surrounding rock. Concretion is of great significance in revealing tectonic activity, ancient environment, ancient material sources, and diagenesis. Therefore, this article summarizes the concept of concretion, types, genesis, and geological significance of concretion in shale, providing reference for the study of shale genesis.