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

Abstract

Upper Palaeozoic intracontinental massive sulphide deposits occur in both the Lower Yangtze River and the Nanling Mountain regions of South China. However, sulphide ores of these two regions are remarkably different in composition. 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 of radiogenic lead and have tight δ34S distribution patterns close to zero. Fluid inclusions are highly saline and sodium-rich. Ores of the Nanling Mountain region mainly comprise Pb, Zn, Sn and W as well as Cu with recoverable Ag, Sb, Hg, U, Bi, Tl and Mo; they usually have higher concentrations of radiogenic lead and wide-ranging δ34S values. Their fluid inclusions 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 Mountain region. The compositional contrasts between these two regions are suggested to have been controlled by differences in their basin basements and thus reflect the difference in crustal maturity during ore formation.