陕西洛源金矿床标型矿物电子探针分析及矿床成因探讨

Research on Electron Probe Analysis and the Genesis of Typomorphic Minerals of Luoyuan Gold Deposit in Shanxi

在洛源金矿详细野外地质特征、室内岩矿鉴定基础上,查明研究区主要控矿韧性剪切带及围岩蚀变特征,确定与金矿化关系密切的金属矿石矿物主要为黄铁矿、闪锌矿、方铅矿,并对其进行电子探针测试。黄铁矿中Fe平均值为45.975%,S平均值为54.046%,说明洛源金矿床中的黄铁矿可能以沉积成因为主。黄铁矿中Co/Ni值大多>1,显示热液成因,部分≤1,显示沉积成因,表明成矿物质可能具有多源性、多期次供应特征,推测地层提供了部分成矿物质,成矿热液可能与花岗岩岩体有关。闪锌矿中Zn平均值为64.876%,S平均值为32.768%,相对Zn亏损,说明Fe以类质同象置换Zn较少,属于浅色闪锌矿,成矿条件为浅成,成矿温度属于低温。方铅矿中Pb平均值为86.411%,S平均值为13.490%,样品中Pb/S值多小于理论值,表现出亏损Pb、富S的特征,说明硫逸度在成矿过程中发生了变化,该变化趋势有利于成矿。综合区域金矿床,洛源地区金矿具有沉积地层,韧-脆性剪切作用与花岗岩浆热液叠加改造特征。

Based on the detailed field geological characteristics and indoor rock and mineral identification of the Luoyuan Gold deposit,the main ore-controlling ductile shear zone and wall rock alteration characteristics in the study area were identified,and the metal ore minerals closely related to gold mineralization were determined to be mainly pyrite Ore,sphalerite,galena,then do the electronic probe testing.The average value of Fe in pyrite is 45.975%and the average value of S is 54.046%,indicating that the pyrite in Luoyuan gold deposit may be mainly due to sedimentary origin.The ratio of Co/Ni in pyrite is more than 1,indicating hydrothermal origin,and some Co/Ni≤1,indicating sedimentary origin,which state that the ore-forming material may have the characteristics of multi-source and multi-phase supply.It is inferred that the formation provides Some ore-forming hydrothermal fluids,which may be related to granite intrusions.The average value of Zn in sphalerite is 64.876%,and the average value of S is 32.768%.The relative Zn loss indicates that Fe replaces less Zn with isomorphism.It belongs to light-colored sphalerite,and the mineralization condition is shallow formation.The temperature is low.The average value of Pb in galena is 86.411%,and the average value of S is 13.490%.The Pb/S value in the sample is mostly less than the theoretical value,showing the characteristics of Pb depletion and S richness,indicating that sulfur fugacity occurred in the mineralization process.This trend of change is conducive to mineralization.Comprehensively show that the Luoyuan gold deposit has the characteristics of sedimentary strata,ductile shear and granite magma hydrothermal superimposition.