Petrography and sulfur isotopic compositions of SEDEX ores in the early Cambrian Nanhua Basin, South China

•Three major mineralization stages of sulfide ores are identified.•Alternating precipitation of Mo and Ni-Zn sulfides represents a SEDEX deposition.•Sulfur sourced from both hydrothermal emissions and microbial sulfate reduction.•Presence of euxinic water column limited colonization of deep-water habitats.