Abstract:

The southern Daxing’anling, where tens polymetallic deposits lie, is one of important metallogenic zones in Northern area of China. Lead and sulfur isotope geochemistry is helpful for determining the sources of ore-forming materials. On the basis of predecessors’ research, sulfur and lead isotopic characteristics of sulfides from some polymetallic deposits have been studied in this paper. The δ³⁴S values of sphalerite, galena, arsenopyrite, chalcopyrite, and molybdenite rang from -6‰ to +4‰, with mean value of zero. The δ³⁴S values of most sulfides range from 0 to 2 ‰ with a pronounced tower effect, and without significant enrichment in the light sulfur and heavy sulfur, which suggests that the sulfur source is single and dominated by magmatic sulfur. Ratio values of lead isotope in both sulfides and related rocks range from 18.13 to 18.74 for ²⁰⁶Pb/²⁰⁴Pb, 15.38 to 15.68 for ²⁰⁷Pb/²⁰⁴Pb, and 37.1 to 38.93 for ²⁰⁸Pb/²⁰⁴Pb. Their mean values are 18.38, 15.54 and 38.09, respectively. Lead isotopic compositions also show obvious differences between the western and the eastern part in the southern Daxing’anling. In the lead isotopic compositions diagram, samples from polymetallic deposits in the western part are scattered nearby the evolution curve orogenic belts, while those from deposits in the eastern part are nearby curves of the orogenic belt and the upper mantle.

Key words: polymetallic metallogenic zone, sulfur and lead isotopic composition, geological implication, southern Daxing’anling, metal deposits