Regional variations in ore composition and fluid features of massive sulphide deposits in South China: Implications for genetic modelling

Upper Palaeozoic intracontinental massive sulphide deposits occur in both t he Lower Yangtze River and the Nanling Mountain regions of South China. How ever sulphide ores of these two regions are remarkably different in composi tion. Ores of the Lower Yangtze region are copper-rich with minor Pb and Zn and recoverable Au, Ag, Co and Mo; they usually, have low concentrations o f radiogenic lead and have tight delta(34)S distribution patterns close to zero. Fluid inclusions are highly saline and sodium-rich. Ores of the Nanli ng Mountain region mainly comprise Pb, Zn, Sn and W as well as Cu with reco verable Ag, Sb, Hg, U, Bi, Tl and Mo; they usually have higher concentratio ns of radiogenic lead and wide-ranging delta(34)S values. Their fluid inclu sions have low salinities and are potassium-rich. There is evidence to indicate that the Upper Palaeozic continental crust in the Lower Yangtze region has lower maturity than that of the Nanling Mount ain region. The compositional contrasts between these two regions are sugge sted to have been controlled by differences in their basin basements and th us reflect the difference in crustal maturity during ore formation.