豫西南周庄铅锌银矿床是最近在豫西南铅锌银矿集区新发现的一处矿产地。矿床形成于印支期造山后板内构造-岩浆地质环境,工业矿体主要是东秦岭二郎坪群中充填于垂直造山带走向的断裂构造中的石英-铅锌银硫化物矿脉,热液成矿作用经历了石英-黄铁矿、石英-铅锌银硫化物、石英-方解石等早、中、晚3个不同阶段。矿石中以石英为主的脉石矿物捕获水溶液、CO2-H2O和含子矿物三类流体包裹体,早、中、晚成矿阶段流体温度(分别为310~270、230~200、180~150℃)逐渐降低,流体盐度先升高后降低(NaClequiv.质量分数分别为10%~6%,18%~14%、12%~8%)。估算周庄铅锌银成矿流体压力早、中、晚不同阶段分别为270~235、230~200、79.39~39.37MPa,对应成矿深度分别为10~8.7、8.5~7.4、2.9~1.5km,成矿过程中伴随地壳持续抬升。铅锌银成矿从早阶段到中阶段,成矿流体中水δDH2O V-SMOW从-59‰~-70‰降到-70‰~-82‰,δ18 OH2O V-SMOW从5.19‰~6.53‰降到2.32‰~2.46‰,成矿晚阶段流体中水的δ18 OH2O V-SMOW进一步降至-0.05‰,成矿流体主体来自深部岩浆或变质水,晚阶段有浅部大气降水的加入。研究丰富了对豫西南铅锌银成矿学的认识。
The Zhouzhuang Ag-Pb-Zn ore deposit was recently discovered in the southwestern Henan Province where there are some other Ag-Pb-Zn ore deposits.It occurred in an inter-plate tectonic-magmatic geological environment after Indosinian orogeny.The ore-body is mainly in the Erlangping Group and the veins of quartz-(Ag-Pb-Zn) sulfides filled in the fault fractures whose strike-directions are perpendicular to the orogenic belt.The Ag-Pb-Zn hydrothermal mineralization shows three stages: the early stage is characterized by quartz-pyrite;the main stage is quartz-(Ag-Pb-Zn) sulfide;and the late stage is quartz-calcite.Three types of fluid inclusions were trapped in the quartz in the Ag-Pb-Zn ores;they are the water solution,the CO2-H2O,and the daughter mineral-bearing inclusions.The ore-forming fluid temperatures of the early,the main and the late mineralization stages are 310-270 ℃,230-200 ℃,and 180-150 ℃,respectively.The ore-forming fluid salinity of the early stage is 10%-6% NaCleq.,the main stage is 18%-14% NaCleq.,and the late stage 12%-8% NaCleq..The temperature decreased,and the salinity increased first and then decreased during the mineralization.The mineralization were accompanied with the rising of the crust;the ore-forming fluid pressures in the early-,the main-and the late-mineralization stages are 270-235 MPa,230-200 MPa,and 79.39-39.37 MPa,respectively;and the corresponding depths are 10-8.7 km,8.5-7.4 km,and 2.9-1.5 km,respectively.The δDH2O V-SMOW decreased from-59‰——70‰ to-70‰——82‰ and the δ18OH2O V-SMOW also decreased from 5.19‰-6.53‰ to 2.32‰-2.46‰ when the mineralization developed from the early to the main stage,and the δ18OH2O V-SMOW further decreased to-0.05‰ in the late mineralization stage.The ore-forming fluid was mainly from the magma or the metamorphic water,and mixed by some meteoric water in the late stage.This study gives some new information for understanding the metallogeny of Ag-Pb-Zn in southwestern Henan Province.