乌兹别克斯坦Uchkulach铅锌矿流体包裹体特征及矿床成因分析

Uchkulach大型铅锌矿床位于乌兹别克斯坦南天山造山带北缘，矿体主要顺层产出于中泥盆统至上泥盆统碳酸盐岩地层中。由于赋矿地层下伏酸性火山岩，该矿床是否和岩浆活动有关仍存在争议。本次在对该矿床地质特征研究的基础上，对矿石样品中重晶石和闪锌矿的流体包裹体以及主要矿物的矿物化学进行分析。结果表明，其均一温度为71～153 ℃，峰值为93～133 ℃，冰点温度在-74～-169 ℃之间，盐度为110%～202%，属于低温中盐度流体，暗示其流体来源为盆地卤水或浓缩的海水。对矿石样品中的方铅矿、闪锌矿和重晶石的电子探针分析结果表明，闪锌矿中铁含量较低(＜6%)，指示其形成温度较低。由此推测该矿床属于与盆地流体有关的MVT型铅锌矿床，而非前苏联学者认为的与下伏火山岩有关的火山-沉积型铅锌矿床。

Fluid Inclusions and Ore Genesis Analysis of the Uchkulach Lead Zinc Ore Deposit in Nuratau Region,Uzbekistan

The Uchkulach large lead zinc deposit is located in the north margin of the South Tianshan orogenic belt, Uzbekistan. The orebodies are concordantly imbedded in the Middle Upper Devonian carbonate successions. Because the lead zinc ores are hosted over acid volcanic rocks, it still remains controversial if the formation of the Uchkulach lead zinc deposit is correlated to magmatic activity. On the basis of the geological characteristics, we determined fluid inclusions in barite and sphalerite from the ores and chemical compositions of the major minerals by EPMA. Our results show that the homogenization temperatures of the liquid rich inclusions range from 71 ℃ to 153 ℃, with the peak temperature of 93 ℃ to 133 ℃. The calculated salinities range from 110 to 202 NaCl wt% according to their determined ice temperatures of -74 to -169 ℃. Such low temperature and middle salinity fluids suggest that they were possibly derived mainly from the basin brine or evaporated seawater. The election microprobe analyses of sphalerite, galena and barite suggest that the sphalerites are characterized low Fe contents (＜6%), which also indicates low temperature fluids. Concludingly, the Uchkulach lead zinc deposit belongs to Mississippi Valley type, and cannot be classified into the one genetically related to underlying volcano sedimentary rocks.