Abstract:
Located in Karakoram of Xinjiang, the Duobaoshan lead-zinc deposit was formed in the limestones of the Cretaceous Tielongtan Formation, and was obviously controlled by structural fracture zones. The ore bodies are irregularly sac-like, vein-like, and lenticular-shape-like. It can be divided into three metallogenic stages:the early sulfide mineralization stage, the intermediate replacement mineralization stage and the late oxidation stage. The first stage is characterized by galena, sphalerite and calcite; the second stage is represented by smithsonite, iron oxide, cerussite, and gypsum; the last stage is characterized by hydrozincite. The δ
34S values of the galena in the first stage range from -14‰ to -0.6‰, which shows a feature of reduced sulfur source. The lead isotope compositions are concentrated and show a crustal source feature, and the Permian-Cretaceous sedimentary rocks may be the sources of metals. The δ
18C
PDB values of calcite are from 3.5‰ to 5.7‰ and the δ
18O
SMOW, from 22.1‰ to 27.1‰ are which indicate the dissolution of carbonate. The δ
18C
PDB and δ
18O
SMOW values of the smithsonite are from 2.9‰ to 3.8‰ and 16.9‰ to 20.3‰, respectively. The δ
18C
PDB and δ
18O
SMOW values of the cerussite are from 2.7‰ to 4.4‰ and 15.8‰ to 20.3‰, respectively. All these values indicate the mixing of atmospheric precipitation. The
3He/
4He and
40Ar/
36Ar ratios of the fluid inclusions in the calcite are from 0.72 R/Ra to 0.93 R/Ra and 302.1 to 350.7, respectively; and the
3He/
4He and
40Ar/
36Ar ratios of the fluid inclusions in the galena are 1.17 R/Ra and 298.1, respectively. The
3He/
4He and
40Ar/
36Ar ratios of fluid inclusions in the smithsonite are from 0.22R/Ra to 0.46R/Ra and 292.6 to 295.8, respectively; the
3He/
4He and
40Ar/
36Ar ratios of fluid inclusions in cerussite are from 0.40R/Ra to 0.59R/Ra and 292.9 to 295.4, respectively. Thus, the ore-forming fluid may be the crustal fluid mixed with atmospheric precipitation. In summary, the Duobaoshan zinc-lead deposit is the product of fold thrust in the edge of the basin, structural fluids and secondary replacement system. The sulfides are formed of structural fluids, and the nonsulfides are the result of direct replacement, with oxidation occurring and hydrozincites formed at the last stage.