Contribution of microbial processes to the enrichment of Middle Permian manganese deposits in northern Guizhou, South China

•New mineral-elemental-isotopic data for manganese deposits of the Permian Maokou Formation, northern Guizhou, South China.•Mn and Fe systems in biomats led to precipitated micro-laminae of microbiogenic minerals.•This manganese deposit is formed by the combination of hydrothermal and microbial activities.