Fluid Characteristics And Metallogenic Process Analysis In Limei Pb-zn Deposit In Western Hunan

Limei Pb-Zn deposit is located in the transitional belt between Yangtze block and Jiangnan massif of Wuling mountain weak deformation belt,It is very important MVT type Pb-Zn deposit in Huayuan ore concentration area of the western Hunan-western Hubei Pb-Zn metallogenic belt.The strata of deposit is mainly exposed the middle?upper Cambrian Loushanguan formation(?2-3l);the middle Cambrain Gaotai formation(?2g)and lower Cambrian Qingxudong formation(?1q).Lead-zinc mine is in Qingxudong formation limestone layer,obviously controlled by the tectonic lithofacies features.I choose?Fluid characteristics and metallogenic process analysis in Limei Pb-Zn deposit in the western Hunan?as my thesis topic,is of great significance and reference value for geological prospecting.Relying on the project ?Geological research and prospecting of ore field in the Zhangjiajie-Huayuan integrated exploration area of western Hunan Province?,On the basis of field geological survey and construction measure,I make the system of interior microscopic identification?test analysis and a comprehensive study.In the mining structure and rock characteristics as the main research targets,submit the research report and dissertation.The research mainly the following progress:1.Limei lead-zinc metallogenic process is divided into four stagesAccording to the different type of mineralization with relations and distribution characteristics in field?microscopic detail ore structure?mineral crystallization condition and characteristics of combination.I divided the ore-forming process into four stages.Sphalerite along sutures crystal phases: the phase formation of the ore is mainly for sparse disseminated ores,formed in the early stages.Sphalerite-galena along the fracture and pore metasomatic filling stages: the stage of mineralization is stronger and the ore-forming material concentration.Metal minerals are mainly sphalerite,followed by galena and pyrite.The gangue minerals are mainly calcite,barite,fluorite,etc.The phase formation of the ore is mainly for web,vein and in the main metallogenic stage.Galena-calcite filling stage: the mineral composition is simple in this stage and ore-forming metals mineral galena and a small amount of sphalerite,gangue minerals found calcite.Hydrothermal calcite vein along the fissure intrusion stage: this stage of the late hydrothermal calcite vein invasion into the cracks,porosity and other crystal.This stage metallogenic have the effect of damage.2.I have completed the analysis of characteristics of Limei deposit ore-forming fluidWe found a certain amount of fluid inclusions development in the samples,mainly for the gas-liquid two phase coexistence of inclusions.Sphalerite,galena along the fracture and pore metasomatic filling stage,Gas-liquid two phase fluid inclusion salinity between 1.1%-23.1% Na Cleqv,uniform temperature is between 78-342?,the ore-forming fluid density is between 0.70-1.14 g/cm3,pressure changes in the 194.30-960.19 bar.Galena-calcite filling stage,the gas-liquid inclusion salinity ranged from 1.4%-23.1%Na Cleqv,uniform temperature is between 68-259?,the ore-forming fluid density changes in the range of 0.88-1.15g/cm3,pressure changes in the 190.99-727.13 bar.Hydrothermal calcite vein along the fissure intrusion stage,the gas-liquid inclusion salinity ranged from 3.71%-23.18%Na Cleqv.,uniform temperature is between 76-227?,the ore-forming fluid density changes in the range of 0.91-1.12g/cm3,pressure changes in the 199.46-637.29 bar.Research shows that uniform temperature are decreases,the average salinity change is weaker,the salinity peak occurred within the range of 21.0% to 23.0%in the process of mineralization in Limei deposit.3.Point out the Limei MVT type lead-zinc mine deposit environment characteristicsTo Limei lead-zinc mining area periphery Qingxudong and Gaotai formation in the different layer of carbonate as the research object,mainly adopts the main content,trace element geochemical analysis,it is concluded that the environment of carbonate sedimentary shows seawater gradually receded from Qingxudong to Gaotai period in the Limei lead-zinc mine area.In the Qingxudong to Gaotai period,carbonate deposit in study area are affected by terrigenous detritus and digenesis is limited,the ancient marine environment for oxidizing environment,the ancient sea water is warm,the ancient climate change from wet to dry,also it is because of the water environment leads to a large number of biological species breeding,and sedimentary formation of algal limestone,become major ore rock.4.Prepared the ore body contour map of Huayuan ore filed and analyzed the Limei Pb-Zn deposit metallogenic process.Based on core hole data mapping,deepen the distribution characteristics of the deep deposit,and the understanding of the tectonic evolution and mineralization.Limei MVT type Pb-Zn deposit ore rock is given priority to with algal limestone,production stage in xuefeng-jialidong tectonic movement formed the NE-NNE gently fold,fault structure zone.Ore-bearing hydrothermal from underlying formation during thermal driven by a large,upward along the fault zone migration,in algal limestone containing cracks and pore against the original survival response,displacement of lead and zinc and other elements,the enrichment.The deposit has obvious epigenetic characteristics.