Geological Features And Ore Genesis Analysis Of 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.This paper is based on other researchers' work,fieldwork,microscopic observation and petrogeochemistry method.Discussions aimed at analyzing the geological characteristics,metallogenic material,temperatures and salinity of the metallogenic inclusions.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,enargite,pyrite,chalcopyrite et al.suggest that the sphalerites are characterized low Fe contents(<6%.).What's more,we noticed the absence of silver in galena's crystal lattice,both indicates low-temperature fluids.The characteristics of the galena lead isotope and wall rock show that metallogenic lead mainly from upper crust,but there is no conclusive evidence that metallogenic lead from wall rock.Concludingly,the Uchkulach lead-zinc deposit belong to Mississippi Valley-type,and cannot be classified into the one genetically related to underlying volcano-sedimentary rocks.