Geology, Geochemistry And Genesis Of The Tuokesai Lead-zinc Deposit In The Western Tianshan Mountains, Xinjiang

The Tuokesai lead-zinc deposit is located on the northern margin of the Sailimu block in the northern part of the Kazakhstan-Yili plate,Western Tianshan,Xinjiang,which adjacent to the Late Paleozoic continental margin basin in Alatau in the north,and the Boluohuoluo Paleozoic arc belt in the south.The few previous studies focused on the geological characteristics of the deposit,siliceous rock geochemistry,and genesis of the deposit,but the research on the ore-bearing surrounding rock,the source of ore-forming materials,and the metallogenic geological background is still superficial,and there is a lack of systematic study of lead-zinc ore body and ore characteristics.Through systematic field geological observation and indoor analysis,the author focuses on the ore body output characteristics,mineral composition,ore structure,ore-bearing rock series geochemistry and stable isotopes of the Tuokesai lead-zinc deposit for comprehensive analysis the genesis and metallogenic process of the deposits,and establish a metallogenic model to enrich the understanding of the metallogenic regularity of the Sailimu lead-zinc-copper belt in the West Tianshan.The occurrence of lead-zinc sulfide ore body is obviously controlled by the stratigraphic horizon,and occurs in siliceous rock?intercalated with carbonate rock?in the form of stratiform and stratoid.The ore body and stratum are in conformity,and it can be seen that there is synchronous corrugation deformation with stratum locally.The lithology of ore bearing strata of the deposit is mainly schist,gneiss,marble and siliceous rock.The recovery results of metamorphic protolith show that the protolith is felsic clastic rock with carbonate rock.The geochemical characteristics show that the rocks are formed in passive continental margin environment.The total amount of siliceous rocks Al₂O₃ and REE exposed in the mine area is relatively low,and the enrichment of HREE and Ce is negative anomaly,showing the characteristics of hot water deposition genesis and formed in the continental marginal environment.The metal mineral content in the ore is less than 5%,mainly sphalerite,containing a small amount of galena and pyrite.The non-metallic minerals are mainly calcite,followed by tremolite and quartz,containing small or trace amounts of fluorite and chlorite.The ore structure is mainly laminar-strip-like,vein-disseminated,the ore structure is mainly semi-automorphic-other-shaped granular structure and co-joined edge structure,and a small amount is self-shaped granular structure,metasomatic structure and solid solution separation structure.The grain sequence bedding,rhythmic bedding and scour surface structure indicating synsedimentary genesis can be seen in the ore.Stable isotope studies have shown that the sulfur isotope fractionation of the ore reaches equilibrium.The source of sulfur is thermochemical reduction of seawater sulfate?TSR?,and some samples are lower The?³⁴S value reflects that part of the reduced sulfur in the ore-forming fluid may come from bacterial reduction of seawater sulfate?BSR?.Comprehensive regional geological background and structural evolution,ore deposit geological characteristics and ore-forming material sources,and compared with the characteristics of typical sedimentary exhalation type deposit?SEDEX?,it is considered that the genetic type of the Tuokesai lead-zinc deposit is a remote SEDEX type deposit.