河南栾川三道沟铅锌银矿床成矿流体地球化学特征

摘要

The Sandaogou Pb-Zn-Ag deposit is an important part of the Pb-Zn-Ag ore concentration area in Western Henan Province.The Pb-Zn-Ag mineralization shows three stages:the early stage is characterized by quartz-pyrite;the middle stage includes quartz-(Pb-Zn-Ag)sulfide;and the late stage includes quartz-calcite. Three types of fluid inclusions are trapped in quartz,which are water inclusions,gas inclusions and CO2-H2 O inclusions.The temperatures of the ore-forming fluids in the early,middle and late stages are 260 -360 ℃, 200-320℃and 160-260℃,respectively.The salinity of the ore-forming fluid is in a range of 4%-10%in the early stage,6%-12% in the middle stage,4%-8% in the late stage,and the salinity increases in the beginning and then decreases.The densities of the ore-forming fluid are between 0.58 and 1.06 g/cm3 ,with a mean value of 0.86 g/cm3 .The ore-forming fluids are high-middle temperature,low salinity and low density fluids.In the early mineralization stage,δD values are from -67.5‰to -75.1‰andδ18 Owater values are from 6.4‰ to 1 1.1‰;in the middle mineralization stage,δD value is -106.8‰ and δ18 Owater value is 5.0‰;in the late mineralization stage,δD is from -86.4‰to -100‰andδ18 Owater values are from -0.7‰to 2.2‰. The results show that the ore-forming fluids were derived from the magmatic water or the metamorphic water, and mixed with meteoric water in the major stage and the late stage.We preliminarily present that the genesis of the Sandaogou deposit was mid-temperature hydrothermal vein type Pb-Zn-Ag deposit,and it was the result of the post Yanshanian magmatic ore-bearing hydrothermal filling mineralization.%河南栾川三道沟铅锌银矿床是豫西铅锌银矿集区的重要组成部分。矿床成矿作用划分为早、中、晚3个成矿阶段，即石英-黄铁矿阶段、石英-铅锌银硫化物阶段和石英-方解石阶段。各成矿阶段石英中流体包裹体主要有液体包裹体、气体包裹体、含CO2包裹体3种类型。成矿早、中、晚阶段成矿温度依次降低，分别为260～360℃、200～320℃、160～260℃，成矿流体盐度先升高后降低，分别为4％～10％、6％～12％、4％～8％，密度为0.58～1.06 g/cm3，平均0.86 g/cm3，即成矿流体为高-中温、低盐度、低密度流体。成矿早阶段δD ＝-67.5‰～-75.1‰，δ18 O水＝6.4‰～11.1‰；成矿中阶段δD＝-106.8‰，δ18 O水＝5.0‰；成矿晚阶段δD＝-86.4‰～-100‰，δ18 O水＝-0.7‰～2.2‰，综合研究表明成矿流体为岩浆水或变质水，成矿中-晚阶段有大气降水的加入。初步认为三道沟铅锌银矿床属于中温热液脉型铅锌银矿床，是燕山期岩浆期后含矿热液充填成矿作用的产物。