Sulphur and Lead Isotope Compositions of the Dajiangp—ing Deposit in Western Guangdong Province¹

Abstract

The Dajiangping pyrite deposit located in the middle sector of the Yunkai uplift in western Guangdong is a stratiform sulphide deposit occurring in Sinian marine clastic and fine clastic rocks. The formation of the deposit was related to submarine exhalation and hot brine deposition. A part of it was reformed by late‐stage hydro thermal solution. The δ34S values of pyrite vary from — 25.55‰ to + 21.07‰, which are inversely proportional to the content of organic carbon in ore and pyrite. Passing from striped fine‐grained pyrite ore to massive coarse‐grained pyrite ore, i.e. from south to north, the sulphur isotopic composition changes from the light sulphur‐enriched one to the heavy sulphur‐enriched one. The lead isotopic composition of striped ore is consistent with that of the country locks of orebodies and the lead is radiogenic lead derived from the upper crust. The lead isotopic composition of massive ore is relatively homogeneous and its 206/Pb204Pb, 207/Pb204Pb and 208/Pb204Pb ratios are a bit lower than those of striped ore; the lead result from mixing of synsedimentary ore lead with that derived from basement migmatite brought by late‐stage hydrothermal solutions.