Research On Metallogenic Regularity And Prognosis Of Lead-Zinc Deposits In Tongren Area,Western Margin Of Xuefeng Mountain

The research area is located in Tongren,eastern Guizhou Province,which is geotectonically located in the southeast margin of the Yangtze block,the western segment of the Jiangnan orogenic belt.The research area and Western Hunan Xuefeng mountain on the east side is important of manganese,lead and zinc,gold and polymetallic metallogenic belt,in recent years,the Xuefeng mountain is located in Huayuan area of Western Hunan through found super-large pb-zn deposit and aroused people’s great attention,Guizhou Tongren lead-zinc metallogenic province east as Sichuan,Yunnan and Guizhou metallogenic belt and the western Hubei intersection part of metallogenic belt,and adjacent to the west to spend through lead-zinc deposit concentration area,has been found to have rhinencephalon,generation understand,Ba Ba village,pond,house,groundwater field deposits（points）,but these generally small scale,low grade of ore mining,economic value is smaller.Lead-zinc mineralization in the study area are mainly controlled by what factors,layer control is given priority to,or structure is given priority to,the source of the minerals,ore-forming fluid characteristics,metallogenic epoch,but also how to gather the mineralization,and so on,although some scholars have studied the one kind of problem,but for the entire area of the ore-forming geological background,ore deposit geological characteristics and geochemical characteristics of less comprehensive research work.Based on the theory and method of regional metallogeny,ore deposit science,geochemistry and tectonic geology,the basic geological characteristics,orebody characteristics,ore mineral characteristics and surrounding rock alteration characteristics of the lead-zinc deposits in the west margin of Xuefeng area in eastern Guizhou province have been found out by the anatomical study of the typical lead-zinc deposits in the area.The fluid geology,isotope geochemistry,trace elements,rock and ore identification and other aspects of the test analysis,a systematic study of the nature of ore-forming fluids,the source of ore-forming materials,the determination of the Cambrian Qingxudong Pb-Zn deposit occurred in the area of the metallogenic age.Finally,the metallogenic regularity of lead-zinc deposit in this area is summarized systematically,the metallogenic model is established,and the prospecting prediction（prospect）area is delineated by using the metallogenic prediction method of comprehensive information,and the potential resources in the predicted area are estimated.The Pb-Zn deposits in the study area mainly occur in the algal limestone strata of the Cambrian Qingxudong Formation with obvious strata-controlled characteristics.The orebodies are mainly stratified,stratified and lenticular,some orebodies are cystic,and generally occur along beds.The mineral assemblage is simple,the main minerals are sphalerite,galena and calcite,followed by pyrite,limonite,dolomite and barite.The ore is dominated by Zn with Zn grade of 0.86～3.13%and Pb grade of 0.62～1.23%,accompanied by Ag,Ga,Ge and other elements.The main alteration of surrounding rock is quadrifaction,followed by dolomitization,firefytization,asphaltenization and bleaching.Fractures,interlayer fissures,other structural fissures,paleokarst,organic reef,breccia beds and so on are favorable ore-holding Spaces.Theδ34S ranges from 22.8 to35.8‰,and the sulfur is derived from seawater sulfate TSR（thermochemical reduction reaction mechanism）.The lead isotope has the characteristics of lead in the upper crust.The(⁸⁷Sr/⁸⁶Sr)_i value of sphalerite is 0.70918±0.00002,which is higher than that of the host rock and close to that of the Early Cambrian seawater(⁸⁷Sr/⁸⁶Sr).Combined with the analysis of the ore-bearing property of the regional strata,it is speculated that the ore-forming materials may come from the black rock series of the Niutitang Formation of the Lower Cambrian.The ore-forming fluid was formed by hot brine with medium temperature（homogenization temperature 106～433℃,average 277℃）and medium high salinity（8～20wt.%Na Cl）.The Pb and Zn elements migrated in the ore-forming fluid in the form of chloride.The metallogenic age is mainly 466～486Ma,which is obviously later than the surrounding rock.The metallogenic age is from the end of Late Cambrian to the beginning of Early Ordovician,which is related to the basin fluid migration caused by Caledonian Yunan movement.It is a typical epigenetic deposit.By comparing with the typical MVT type lead-zinc deposits in the world and the geological characteristics of the lead-zinc deposits in western Hunan,the lead-zinc deposits in this area basically belong to the typical MVT type lead-zinc deposits.The formation of lead-zinc deposits in the study area is closely related to the temporal and spatial evolution and migration of the Early Cambrian algal stucco mound facies belt on the southeastern margin of the Upper Yangtze craton.The ore-forming and enrichment of lead-zinc strata-controlled minerals are all controlled by the basin,phase and position in tectonic cycle,and the deposits have obvious strata-controlled and stratified properties.The ore-bearing beds are separated by non-bearing beds above and below the ore-bearing beds,and the ore bodies occur in the ore-bearing beds on both sides of the fault breakage zone of the ore-bearing beds through the secondary faults near the regional synsedimentary large faults（integrated ore bodies）,which shows a reservoir and seal combination favorable for mineralization.The Pb-Zn deposits（points）in the area are characterized by many points,wide area,many types and widespread mineralization,and are locally concentrated in the favorable structural positions such as tensile joints,fractures and interbedded voids,etc.,which are particularly controlled by stratigraphic lithology（algal limestone）and lithofacies（algal reef or algal mound）.Through the typical ore deposit geological characteristics,metallogenic regularity and metallogenic model of the comprehensive research and analysis,in Tongren region of Eastern Guizhou,established the regional Pb-Zn deposit regional metallogenic model and prospecting model,and using characteristic analysis on GIS platform to carry out the comprehensive information of metallogenic prediction,selects the two class B prospecting prediction（vision）and one C prospecting prediction（vision）.Based on the ore-bearing geological volume method,the total amount of Pb+Zn in this area is predicted to be 728,700 tons,among which the total amount of identified resources is39,400 tons,and the total amount of potential resources is 689,300 tons.