Study On Geology And Gensis Of The Mao Ping Lead-zinc Deposit,Zhaotong,Yunnan,China

On the basis of field work,the geological features of the Mao Ping lead zinc deposit and the genesis of the deposit are studied by using the theory and research methods of mineral deposits and mineral deposit geochemistry.The Mao Ping lead zinc mining area is located at the intersection of the North East Huize Yiliang fault zone and the NW to Kangding Yiliang water city deep fault.The lead-zinc deposits?points?in the mining area are controlled by north-east compression and torsion faults,along the north-east direction,and the lead-zinc deposits,including Maoping,the Ma Ma dam,the Luo Ze River and other lead-zinc deposits?points?,and12 lead and zinc ore points.The Mao Ping lead zinc deposit is a medium-sized lead-zinc deposit located in northeastern Yunnan.The main structure in the mining area is the stone mendan anticline.It is the main location of the known lead and zinc ore bodies.It is the NE direction and NW trending fault structure.The ore bodies mainly contain two dolomites of the Devonian Jay group,the Carboniferous lower part of the lower Carboniferous group,the limestone and the Carboniferous system.In the dolomite strata of the middle Weining formation,they are mainly bedded,columnar,and vein shaped,and yield along bedding.The ore body moves towards NE30⁷5°,tends to SE,dip 60⁸0m,extend20³40m,thickness 2.21¹6m,extend deeper than extension,and part is larger than800m.The ore structure is mainly self shaped granular-semi-self shaped granular structure?colloidal structure?metasomatism structure and metasomatism residual structure.The ore structure mainly includes block structure?lamellar structure?strip structure?disseminated structure?fine vein structure and net vein structure.There are fewer minerals in ores,including pyrite,sphalerite,galena and gangue and quartz.Wall rock alteration is relatively limited and simple,mainly dolomitization,calcite,silicification and pyrite mineralization.The study of geochemical characteristics of the deposit shows that the value of²³⁸U/²⁰⁴Pb in this area is located in 9.07⁹.72,and the lead in this area is mainly from the upper crust,but a small amount of lead in orogenic belt and mantle lead may be mixed.The pyrite?³⁴S is 12.24¹5.68‰,the sphalerite?³⁴S is 9.63¹9.31‰,and the galena?³⁴S is 7.97⁹.14‰.The sulfur isotope composition shows the characteristics of the enrichment of heavy sulfur,and the sulfur mainly comes from the sulphate in the sea water.The?D is mainly distributed in-35.3‰^-70.5‰,and the?¹⁸O_H2O range of the ore-forming fluid is 5.15‰-9.67‰.The sample mainly falls within the stable isotopic composition range of the fluid inclusions in the typical MVT lead zinc deposit of the Mississippi River,that is,mainly from the construction of water.The homogeneous temperature of the gas-liquid water inclusions in dolomite and calcite is117¹88?and 108²94?,which is mainly concentrated at 140¹80?and has the characteristics of middle and low temperature.The salinity range of fluid inclusions in the main metallogenic period is in the range of 12²1wt%NaCl,which has the characteristics of high salinity.The formation pressure of calcite is 471⁵92×10⁵Pa,which is characterized by medium pressure.The isotopic isochronous age of Rb-Sr isotopes is 321.7±5.8Ma,indicating that the main mineralization occurred in the Late Carboniferous.It is a typical epigenetic deposit and has nothing to do with the Late Permian basaltic magma activity.Based on the above research,the Mao Ping Pb Zn deposit belongs to the MVT type deposit.