新疆维宝铅锌矿床地质、流体包裹体和同位素地球化学特征

摘要

The Weibao Pb Zn deposit is located in the western Qimantage,east Kunlun,Xinjiang Province.The stratiform ore bodies are controlled by the strata,and occur in the banded epidote diopsite skarn in middile-lower Langyashan Formation of Jixianian Period.Major Pb Zn (Cu)ore belongs to epidote diopsite skarn type.The ore minerals consist of galena,sphalerite and chalcopyrite,and the gangue minerals are composed of diopsite,epidote,calsite,chlorite and garnet.The sphalerite is characterized by higher content of Fe (2.206% 2.679%),lower content of Ga,Ge,Cd and Zn/Cd (143 150),and the content of Ag in galena is lower (0.163% 0.210%),which indicates that the metallic minerals may be formed closely with magmatic fluid.There are two types of fluid inclusions,liquid-rich two-phase and gas-rich two-phase.The average homogenization temperatures of two types of inclusions are 268.2 and 273.1 ℃,respectively.The gas components of CO2 ,CH4 ,N2 and H 2 in inclusions indicate the ore-forming fluid may be derived from magmatic fluid.In all,the initial ore-forming fluid belongs to immiscibility,characterized by middle-high temperature,high salinity and low density.The values ofδ34 S vary from 0.49‰ to 2.41‰,which indicates that sulfur in sulfides was mainly from the magma.The sulfides have 206 Pb/204 Pb values from 18.254 to 18.336,207 Pb/204 Pb values from 15.556 to 15.664,208 Pb/204 Pb values from 38.060 to 38.367,which suggests that ore-forming metals come from deep magmatic activity,with little crust mixing.In summary,the Weibao Pb Zn deposit may be a layered skarn type deposit related to Indosinian magmatic activity.%新疆维宝铅锌矿床位于东昆仑祁漫塔格地区西段，铅锌矿体受地层及岩性控制，多呈层状、似层状赋存于蓟县纪狼牙山组中下部条带状绿帘石（透辉石）矽卡岩中，矿石类型主要为绿帘石透辉石矽卡岩型铅锌（铜）矿石。矿石矿物主要为方铅矿、闪锌矿、黄铜矿等，脉石矿物主要为透辉石、绿帘石、方解石、绿泥石、石榴子石等。金属硫化物电子探针分析表明，闪锌矿中 Fe 质量分数为2．206％～2．679％，贫 Ga、Ge、Cd，Zn/Cd 为143～150，方铅矿中 Ag 质量分数较低（0．163％～0．210％），具有与岩浆热液有关的金属硫化物特征。流体包裹体以富气相两相包裹体和富液相两相包裹体为主，均一温度平均值分别为268．2和273．1℃，含有 CO2、CH4、N2、H2等成分，成矿流体可能来源于岩浆流体，具中温、高盐度、低密度的特征，成矿过程中发生了不混溶作用。金属硫化物的δ34 SV CDT 为0．49‰～2．41‰，主要来源于岩浆；金属硫化物的206 Pb/204 Pb 为18．254～18．336，207 Pb/204 Pb 为15．556～15．664，208 Pb/204 Pb 为38．060～38．367，主要来源于区内深源岩浆活动，有少量地壳铅的混染。综合分析认为维宝铅锌矿床为与印支期岩浆作用有关的层控矽卡岩型矿床。