南秦岭东河地区金矿床特征及成因分析

南秦岭东河金矿位于南秦岭西段,属南秦岭成矿带西成金铅锌多金属成矿带的东延部分,为陕甘川金成矿三角地带.区内出露地层为中上志留统舟曲岩组、志留系—泥盆系大河店组,其中,中上志留统舟曲岩组上岩段(S2+3z3)是金矿化产出的主要层位;区内断裂构造十分发育,主要表现为平行分布的近东西的层间挤压破碎带,为区内主要的控矿构造;区内构造破碎带内及旁侧发育的石英脉与金矿化关系密切.工作区内共圈定金矿体8条,矿体均近东西走向,其中主要矿体Au-8长度390m,平均厚度2.54m,Au平均品位为2.41×10-6.东河地区金矿床主要受断裂构造的控制;其次岩性、岩浆岩对金矿的形成也起一定的作用.通过对本区成矿地质背景、矿床地质特征、控矿因素等方面的研究,认为研究区金矿床为沉积-叠加改造型中-低温热液金矿床.

Characteristic and Genesis of the Au Deposits in Donghe Region,Southern Qinling

The Donghe gold deposit, served as a part of the eastern extension of southern Qinling Au-Pb-Zn deposit belt, is located in the west segment of southern Qinling. The mainly exposed strata in this area are Middle-Upper Silurian Zhouquyan Formation (S2+3) and Silurian-Devonian Dahedian Formation (S-D), meanwhile, the upper section of Zhouqu Formation (S2+3z3) serves as the main layer for gold mineralization in this region. The fault structures are fully developed, which are regional major ore-controlling structures, showing as an EW-trending interformational fracture zone with nearly parallel distribution. Within the regional tectonic fracture zones and its two sides, the quartz veins have close relationship with gold mineralization. Totally, 8 gold ore-bodies have been delineated there, all of them are distributed as nearly E-W trending. In which, the Au-8 is the major ore body with the length and thickness are 390 and 2.54 meters, respectively, meanwhile, its average gold grade is 2.41×10-6. The Donghe gold deposits are mainly controlled by faults. Besides, lithology and magmatic rocks are also playing a certain role in the enrichment and formations of gold deposit. After analyzing regional geological background, geological characteristics of mineral deposit and ore-controlling factors, the Donghe gold deposit is classified as sedimentary reformed and superimposed exothermal-epithermal deposit.