河南省九仗沟金矿床金矿物特征及成矿物质来源

Characteristics and ore-forming material source of gold minerals in Jiuzhanggou Gold Deposit,Henan Province

九仗沟金矿床位于小秦岭—熊耳山金矿集区,为断裂控制的破碎蚀变带型—细脉浸染型金矿床。通过显微镜、扫描电子显微镜观测金矿物形态及粒度特征,发现矿石中的金多为自然金,形态不规则,呈角砾状、板片状、麦粒状和枝杈状,且以角砾状为主,板片状、麦粒状次之。载金矿物主要为黄铁矿、方铅矿、褐铁矿、白云石等,金的主要赋存状态为包裹金、裂隙金,以细粒金和微粒金为主。黄铁矿的w(Co)/w(Ni)值显示成矿与岩浆热液有关。根据金成色与成矿年代、成矿温度与成矿深度的关系可知:金成色越高,成矿时代就越早,成矿温度就越高,形成深度也就越大。通过电子探针测定金矿物成分,计算金成色,发现金矿物种类为自然金,金成色最低为758,最高为931,平均值为871。认为九仗沟金矿床的成矿物质来源为中深源,由岩浆热液作用形成,属于中温岩浆热液矿床。

The Jiuzhanggou Gold Deposit lies in Xiaoqinling-Xiongershan high ore concentration area in Henan Province.Its deposit type belongs to broken altered belt-veinlet disseminated gold deposit controlled by the fracture system.The morphology and particle size of gold deposits were observed by microscope and scanning electron micro-scopy,finding that the gold in ores is mostly native gold and amorphous,taking brecciform,plate-like,grainy and branched forms,dominated by brecciform forms,followed by plate-like,grainy and branched forms.Pyrite,galena,limonite and dolomite are the main gold-bearing minerals.The occurrence state of gold is wrapped gold,fissure gold,dominated by fine particle and micro particles.The w(Co)/w(Ni)value in the pyrite shows that the mineralization is related to magmatic hydrothermal fluid.The relation between gold fineness and ore-forming age,ore-forming temperature,ore-forming depth shows that the higher the gold fineness is,the more ancient the ore-forming age is,the higher the ore-forming temperature is,and the greater the ore-forming depth is.Electronic probe is used to detect gold mineral composition and calculate gold fineness,finding that the gold minerals are native gold with the lowest fineness of gold 758,the highest 931,averaging 871.Based on the above,the study thinks that the ore-forming material source is intermediate deep source in Jiuzhanggou Gold Deposit and the deposit is formed by magmatic hydrothermal fluids,belonging to a mesothermal magmatic hydrothermal fluid deposit.