Microbial metallogenesis of early carboniferous manganese deposit in central Guangxi, South China

•New mineral-elemental-isotopic data for manganese deposits of the Early Carboniferous Baping Formation.•Mn and Fe systems in Mn ores are formed by biomats and precipitated micro-laminae of microbiogenic minerals.•Organic carbon in the alkalinity source of Mn-bearing carbonates.•Metallogenic model can be divided into two main stages.