Geological, Geochemical Characteristics And Genesis Of The Tabei And Tulasu Pb-Zn Deposit, Xinjiang

The basic geological research of Tabei and Tulasu Pb-Zn deposit in XinjiangWest Tianshan, Tulasu basin is in the level of low level of nearly vacancy. the authorsummarized the geological and geochemical characteristics features of these twodeposits, and further explore the genesis types. A series of neutral-intermediate-acidvolcaniclastic rock and lava is closely associated with the two lead-zinc deposits,andcontrolled by volcanic edifice and related fracture.The fifth member of Lower Carboniferous Series Dahalajunshan Group(C1d5),which the main part is acidic volcaniclastic rock, is the ore-bearing strata ofTabei lead-zinc deposit.the only NNE-trending fault in deposit is closely related to themineralization. Ore and minerals mostly is sphalerite, galena main;gangue mineral ismainly gypsum, quartz and kaolin.Based on mineral assemblages, generatingsequence, structure, and relationships. It is shows that there are three types ofinclusions in sphalerite:gas-liquid two-phase aqueous，pure liquid and pure vaporpackage inclusions.the ore fluid is belong to H2O-NaCl system. Homogenizationtemperatures of fluid inclusions mainly concentrated in the peak range100℃～150℃; salinity (mass fraction) is in the range of0.4%to6.2%; fluid density changes is0.85g/cm3～0.99g/cm3; average fluid pressure is88.9MPa; mineralization depthaverage is0.30km. the ore fluid has the characteristics of low temperature, lowsalinity, shallow mineralization.The ore-bearing strata of Tulasu lead-zinc deposit is dacite volcaniclastic of thefourth member of Lower Carboniferous Series Dahalajunshan Group(C1d4).the orebody’s surface manifestation is quartz-sulphide veins. Most of the sulphide is galena.There are two stages: quartz-sulphide phases and carbonate phases. The inclusionsin quartz are gas-liquid two-phase aqueous mostly, homogenization temperaturespeak inclusions are concentrated in140℃～210℃; salinity range of8.1%～16.9%; density changes in0.91g/cm3～1.04g/cm3, average mineralization pressureis195.7MPa; average mineralization depth is0.65km, ore-forming fluid has thequality of medium-low salinity, low density, shallow mineralization. The magmatic rocks mainly derived from remelting mantle affected by thesubduction zone, and the ascent magma, under the influence of crustal material’sassimilation. The volcanic rock of both deposit have the analogous properties on thechondrite-normalized REE and trace element primitive mantle normalized diagram,indicating that the volcanic rock of two deposits are of the same magmatic evolutionsequence. Carbon and oxygen isotope studies have shown Tabei Pb-Zn deposits orefluid may be derived from granitic magma; research of sulfur and lead isotopes inTabei and Tulasu indicate crust and mantle contamination characteristics. In summary,Tabei and Tulasu Pb-Zn are epithermal vein deposits under the joint control of magmaand tectonic.