Peloidal Micrites in the Late Carboniferous (Moscovian) Microbial Reefs of Southern Guizhou, China: Origins and Geological Implications

Abstract The origins of peloidal micrites in reefal limestone are not yet well understood. Moscovian microbial reefs with abundant peloidal micrites from Guizhou, South China, provide an opportunity to study the peloids and their geological significance for this time interval. Three types of peloids are differentiated: microbial, lithic, and bioclastic peloids. Microbial peloids that are well‐sorted and may form in situ by microbial activities. The poorly sorted lithic peloids are derived from erosion and redeposition of the micrite matrix caused by the bottom turbulence induced by periodic storms. Bioclastic peloids are completely micritized fragments of hard parts and shells. Microbial boring and encrustations promote the processes of micritization. Microbial peloids commonly develop in zones with low or normal energy levels, and contribute to the construction and stabilization of the framework. In contrast, the occurrence of lithic peloids reflects that the reefs are destroyed by bottom turbulence during growth. It is suggested that the microbial reefs were deposited under a dynamic balance between constructional versus destructive processes. By comparative analysis, the peloids as microbial in origin play a key role in the growth and stabilization of bioconstructions during Carboniferous, which should be paid more attention in the studies of Carboniferous buildups.