【摘要】 位于西秦岭川、陕、甘地区的大水金矿床是具有卡林特型的金矿床。矿床赋存于下三叠统马热松多组 (T1m)灰岩和印支期花岗闪长岩脉中 ,矿化受到NWW向和近SN向断裂严格控制 ,矿石矿物以赤铁矿、自然金和黄铁矿为主 ,蚀变以硅化、绢云母化和褐 (赤 )铁矿化为特征。成矿作用可以分为原生成矿期和表生氧化 次生富集期。矿床成矿温度为 10 0～ 4 0 0℃ ,盐度为 2 .70 %～ 9.10 % ,密度为 0 .875～ 970g/cm3 ,成矿深度为 1.4 2 2～ 3.5 5 5km。早期成矿流体来源于岩浆水 ,晚期成矿流体为改造的大气降水。硫同位素组成特征表明 ,该矿床成矿物质与矿区内花岗闪长岩有关 ,同时也有深部物质的参与。该矿床为多次构造 岩浆作用的产物 ,早期成矿作用发生于西秦岭碰撞造山期 ,晚期喜马拉雅期区域整体构造隆升使矿体金品位进一步提高 ,显示了该矿床多期次幕式成矿作用特征。更多还原

【Abstract】 The Dashui gold deposit is located in the south of West Qinling Mountains between Qinling orogenic zone and Songpan-Ganzi orogenic zone. The mineralization can be divided into the primary ore-forming stage and the supergene oxidation-secondary enrichment stage. Lying in the west Qinling orogenic belt,the deposit is controlled by the NWW-trending fault zone. The host rocks of the gold mineralization are mainly Triassic altered limestone and adamellite dikes. The δ 34 S values of pyrite range from -1.8 to +4.5 per mil with a mean of 2.40‰,reflecting a deep source of sulfur. Oxygen isotope data of calcite from ores indicate that calcite has δ 18 O values ranging from -22.4 to -11.1 per mil. The calculated δ 18 O water values of calcite range from -4.32 to +8.33 per mil and the δD values range from -61.1 to -101 per mil,suggesting that the ore fluids were mainly derived from the magma at the early stage of mineralization. Nevertheless,the values at the late ore-forming stage decrease,indicating the mixture of meteoric waters at the time of mineralization. Homogenization temperatures of fluid inclusions are relatively low,varying from 100 to 400 ℃ and mostly in the range of 150～200 ℃,with a peak value of 175 ℃. Salinities exhibit a wide range from 2.70 to 9.10 wt.% NaClequiv.,with a mean of 4.88 wt.% NaClequiv. In addition,the early gold mineralization occurred between 196 Ma and 182.8 Ma,and the late gold mineralization took place between 72.15 Ma and 41.21 Ma,as shown by the Rb-Sr isochron dating of inclusions from calcite in ores. This means that the Dashui gold deposit has at least two gold ore-forming stages.更多还原