甘肃大桥金矿地质特征及其发现的意义

GEOLOGICAL CHARACTERISTICS OF DAQIAO GOLD DEPOSIT IN GANSU PROVINCE AND ITS SIGNIFICANCE IN PROSPECTING FOR GOLD DEPOSIT

大桥金矿地处南秦岭印支褶皱带北缘,位于合作—两当金锑汞成矿带东段。金矿化赋存于三叠纪下部建造层下岩组(Ta-1)硅质角砾岩中,硅质角砾岩均呈层状产出,层位稳定,沉积特征明显。金矿化严格受硅质角砾岩控制,金矿体呈层状和似层状。矿石结构主要有粒状结构、交代残余结构、填隙结构,矿石构造有浸染状构造、斑点状构造、脉状—网脉状构造、角砾状构造、纹层状构造和块状构造等。综合上述认为,该金矿具有明显的层控和岩控特征,属沉积改造型金矿。该矿床的发现对西秦岭地区金矿找矿工作具有十分重要的意义。

Daqiao gold deposit is located in the north margin of Indo-Sinian fold belt of south Qinling, and in the east section of Hezuo-Linagdang gold-antimony-mercury metallogenic belt. The gold mineralization exists in the lower member of Triassic Formation in which the siliceous breccia presents itself in bedded style, unalterable level, and marked sedimentary characteristics. The gold mineralization is strictly controlled by siliceous breccia rock, gold ore bodies present themselves in bedded or like bedded style. The textures of ore are mostly granular, metasomatic relict, and filling up interspace, and its structures are mostly disseminated, spotted, veinstockwork, brecciated, stratified, and massive. The gold deposit has remarkably strata-and lithology-controlled characteristics, and belong to sedmentary and reformation type deposit. Discovering of the gold deposit has an important signigficance in prospecting for gold in west Qinling.