S-Pb isotopic characteristics of ore sulfides and U-Pb dating of zircon from the Sankuanggou skarn-type Cu-Fe-Mo deposit in Heilongjiang Province

Abstract：The Sankuanggou skarn-type Cu-Fe-Mo deposit occurs in the Sankuanggou- Duobaoshan tectonic-metallogenic belt of the Da Hinggan Mountains, and there exists close relationship between the formation of ore bodies and the intrusion of Sankuanggou multiple tonalite. Based on an analysis of the ore-forming geological conditions, the authors studied sulfur and lead isotopic compositions and zircon U-Pb dating data of ores from this ore deposit and, on such a basis, discussed the sources of ore-forming materials and the rock-forming and ore-forming epochs. Studies have shown that the composition of sulfur isotope varies greatly and has a distributional effect of tower type, the δ34S∑S of the ore-forming hydrothermal system is about -1.5‰, suggesting that sulfur was mainly derived from deep magmatic source, with a very small amount probably derived from the strata. The lead isotopic composition of ore sulfides indicates the derivation of lead from the mixed crust-mantle materials, suggesting that the ore-forming materials came mainly from crust-mantle mixing sources and were closely related to magmatism. The 206Pb/238U weighted mean ages of zircons range from (200±1)Ma to (168.18±0.96)Ma, which represent the intrusive time of tonalite and suggest that the rock-forming and ore-forming epoch of the Sankuanggou Skarn-type Cu-Fe-Mo polymetallic deposit is Early Jurassic.