Tamu lead and zinc ore deposit, located in the southwest margin of Tarim, is regarded as a carbonate-hosted Pb-Zn deposit.  Sedimentary period, diagenetic period and epigenetic period can be distinguished in Tamu ore deposit. 

Intraclast breccia and layer textures formed during the sedimentary period.  Diagenetic breccia and recrystal dolomite mainly formed during the diagenetic period.  Dislocation breccia, fall breccia and tube structure mainly formed during the epigenetic period.  Ore deposit-forming period ranging between diagenetic period and epigenetic period, can be further subdivided into two stages; Dissolving-metasomatic stage and cavity-filling stage.  Fine-grained sphalerite and galena mainly formed during the dissolving-metasomatic stage.  Huge-grained sphalerite and galena mainly formed during the cavity-filling stage.

Fifty one sulfur isotope analyses were determined on sphalerite, galena, pyrite, chalcopyrite (sedimentary period and ore deposit-forming period), and these sulfides were collected from fourteen specimens.  Sulfur isotope values display a wide variation in Tamu deposit.  The delta S-34 values of sulfides formed in the sedimentary period (- 17. 6 parts per thousand to -7. 3 parts per thousand CDT) are lower than those formed in ore deposit-forming period (-5. 7 parts per thousand to + 10. 2 parts per thousand CDT). Sulfides formed in the cavity-filling stage are rich in heavier sulfur isotope (+ 5. 1 parts per thousand to + 10. 2 parts per thousand CDT) than those formed in the dissolving-metasomatic stage (-5. 7 parts per thousand to + 9. 2 parts per thousand CDT), and at sulfur isotope equilibrium.  The geologic setting, paragenesis, ore textures, fluid inclusion microthermometry, and delta S-34 values indicate that Thermo-chemical Sulfate Reduction (TSR) was the principal HS- production mechanism in ore deposit-forming period.  Sulfur from thermal cracking of sulfur-bearing organism might have been present in the ore deposit-forming period.  Sulfur reservoir effect and sulfides' solubility product constant (Ksp) of sulfides constrained the change of delta S-34 values, especially in the dissolving-metasomatic stage. 

This study places constraints on the mineralization mechanism, the nature of sulfate reduction and the source of sulfur in Tamu ore deposit. The delta S-34 values of Tamu ore deposit support fluid mixing genetic model.

Author Keywords: Sulfur isotopes; Carbonate-hosted lead and zinc ore deposit; Tamu lead and zinc ore deposit; Southwest margin of Tarim; China
KeyWords Plus: THERMOCHEMICAL SULFATE REDUCTION; OXYGEN ISOTOPES; PRECIPITATION; GEOCHEMISTRY; RESERVOIRS; AUSTRALIA; SULFIDES; BRINES; CANADA; RIVER