大兴安岭中南段昌图锡力银铅锌锰矿床矿物学特征及其对矿床成因的约束

Characteristics of ore minerals for the Changtuxili Ag-Pb-Zn-Mn deposit in the middle-southern segment of Da Hinggan Mountains and its constraints on the genesis of the deposit

昌图锡力银铅锌锰矿是近年在大兴安岭成矿带中南段锡林浩特-霍林郭勒多金属成矿亚带上新发现的1处银铅锌多金属矿床。矿床中的主要矿物分析结果表明:矿床中的银矿物有银黝铜矿、硫锑铜银矿、深红银矿等,主要以独立的银矿物分布于金属硫化物中;银黝铜矿的Ag含量为8.25%~13.11%,平均为10.54%,Cu含量为27.65%~31.43%,平均为29.64%,面扫描图像显示Ag以类质同像的形式赋存于银黝铜矿中。硫锑铜银矿的Ag含量较高,平均为68.99%,主要分布于方铅矿的边缘及其裂隙中。闪锌矿的Fe含量为0.30%~0.38%,平均为0.33%,属于贫铁闪锌矿,Cd与Zn具有很好的相关性,可作为寻找闪锌矿的地球化学标志。菱锰矿(MnCO)为晚期低温石英-碳酸盐阶段的产物,是主要的碳酸盐矿物;锰的氧化物主要为软锰矿及硬锰矿,软锰矿呈环带结构、胶状构造。除Mn外,同时也富集高品位Pb。综合分析昌图锡力矿床的矿物学特征及矿床地质特征,认为该矿为浅成低温热液型银铅锌锰多金属矿床。

The Changtuxili Ag-Pb-Zn-Mn deposit is a newly discovered polymetallic deposit in Xilinhaote-Huolinguole Pb-Zn-Ag-Cu-Mo polymetallic metallogenic subzone of the middle and southern Da Hinggan Mountains polymetallic metallogenic belt in recent years.In order to explore the mineral type, mineral occurrence state, and genesis of the Changtuxili deposit, the occurrence of silver minerals, sulfides and manganese minerals were studied by mineral phase observation and electron probe analysis.The silver minerals in the deposit are freibergite, polybasite, pyrargyrite, which are distributed as separate silver minerals in metal sulfides.The Ag content of freibergite ranges from 8.25% to 13.11%(10.54% on average),and the Cu content of freibergite ranges from 27.65% to 31.43%(29.64% on average).The element X-ray mappings show that Ag is present in freibergite in the form of isomorphism.The silver content of polybasite is relatively high(average 68.99%),mainly distributed in the edge of galena and its fissures, indicating that galena is an important silver-carrying mineral.The black manganese cap is a geological sign for finding Ag-Pb-Zn deposits.Sphalerite belongs to low iron sphalerite, and the content is 0.30%~0.38%,with an average value of 0.33%.Cd has a good correlation with Zn in sphalerite and can be used as a geochemical marker for sphalerite prospecting.Rhodochrosite is the product of late low-temperature quartz-carbonate stage.MnCOis the main mineral component and rhodochrosite belongs to hydrothermal genesis.Manganese oxides are mainly pyrolusite and psilomelane.Pyrolusite shows ring and colloidal structure, and it enriches high-grade Pb and Zn besides Mn.Comprehensive analysis of the mineralogical characteristics and ore geological characteristics of the Changtuxili deposit, which is considered to be a hypothermal hydrothermal Ag-Pb-Zn-Mn polymetallic deposit.