The Pb-Zn-Ag Mineralization In The Metallogenic Region Of Northern Neixiang, Henan, China

As a important Pb-Zn-Ag ore concentration area in east part of northern Qinling,the northern Neixiang country region is paid much attention. Based on regionalgeology and mine geology, the Pb-Zn-Ag mineralization by mineralography, fluidgeochemistry, stable isotopes geochemistry of Pb-Zn-Ag deposits are studied in thispaper.（1）Pb-Zn-Ag deposits in northern Neixiang country，Henan province，occur inan inter-plate tectonic-magmatic geological environment after Indosinian orogeny.The ore-body is mainly in the Erlangping Grounp and the veins of quartz-（Ag-Pb-Zn）sulfides filled in the fault fractures whose strike-directions are vertical with that of theorogenic belt. The Ag-Pb-Zn hydrothermal mineralization shows three stages from theearly to the late, the early stage is characterized by quartz-pyrite, the main stage isquartz-（Ag-Pb-Zn） sulfide and the late stage is quartz-calcite.（2）Studying on the petrography of fluid inclusions find out three types trappedin the quartz in the Ag-Pb-Zn ores。Type Ⅰ：the water solution. This type solutionswould be found in the three stages（early stage，middle stage and late stage），especially in the middle stage and the late stage.Type Ⅱ：the CO₂-H2O solution.Thistype solutions always be in the early stage and few in the middle stage.Type Ⅲ：thedaughter mineral-bearing inclusions.This type solutions only be found in the middlestage of Zhouzhuang deposit，and the component of mineral-bearing is calcite.（3）The analysis of the microthermometry and Laser Raman spectroscopyshows that the ore-forming fluid of northern Neixiang region Pb-Zn-Ag deposits is amid-low temperature，mid-low salinity，mid-shallow depth，CO₂-content system.（4）Studying on C-、H-、O-isotopic composition of northern Neixiang regionPb-Zn-Ag deposits show that the ore-forming in the early stage and the middle stageis mainly from the magma or the metamorphic water.Few other style water whatfrom the water interacted with the surrounding rock may join in；And mixed by somemeteoric water in the late stage.（5）Studying on S-isotopic composition shows that sulfur is mainly from the Thermo-chemical Sulfate Reduction of Paleozoic Marine Host Strate；Pb-isotoniccomposition shows that metal ore sources from Paleozoic metamorphicvolcano-sedimentary host strata. Studies show that the ore sources of Ag-Pb-Zndeposits in the northern Neixiang County, may comes from the Qinling Group andErlangping Terrain.（6）To sum up, the northern Neixiang metallogenic region is a mid-lowtemperature metallogenic system in terms of their ore-forming fluid， metal sourceand geologic characteristics.The ore-forming process took place under the continentalcollision setting between Yangtze Block and North China Block in Mesozoic.Theplunging movement of Qinling stratum induced the developing of mineralizing fluidin Northern Neixiang，during the collision transformed from compression to extend，because of the intense water-rock reciprocity， mineralizing substance in theErlangping Group was extracted and transferred to advantaged lodging space（secondary fault of Zhuxia fault） and then deposit.