The process of formation of manganese carbonate deposits hosted in black shale series

The two most important types of manganese deposits in China are sedimentary and super-gene, which account for 71 and 15 percent of the total manganese r serves, respectively. According to the host-rock associations, sedimentary manganese d posits can be classified into (1) a mud-rock type, (2) a black shale series type, (3) a carbonate rock type, and (4) a chert-limestone-mudstone yp. The black shale series-type manganese d posits account for 48 percent of the total manganese r serves and are large- or medium-sized deposits. The black shale series or dark-colored sedimentary association consists of dark-colored mudrock-chert-carbonate rocks rich in sulfides and organic matter (CoF-anic> • 1%). The term, black shale series-type manganese deposits, i a general name for air manganese deposits hosted in black shale, black chert, black siliceous shale, dark gray limestone, etc. Black shale series-type manganese deposits are distributed in 13 stratigraphic horizons from middle Proteozoic to Early Triassic. They can be divided into three subtypes: (1) a black shale subtype, (2) a black chert-siliceous shale subtype, and (3) a dark gray limestone sub-type. Subtype i consists mainly of primary Mn carbonate ores; subtypes 2 and 3 consist