川西丹巴地区磨子沟金矿床金、银赋存状态及成因

磨子沟金矿床位于四川省丹巴县,大地构造位置位于扬子准地台西缘,松潘-甘孜造山带东缘,泥盆系危关组炭质千枚岩、板岩是主要的赋矿围岩。成矿过程分为沉积成矿期、热液成矿期和表生风化期,其中热液期是金的主要成矿期。通过显微镜观察,扫描电镜、电子探针成分分析,矿物晶体化学式计算等手段和方法,研究了矿床中Au、Ag的赋存状态和主要载金矿物的特征。金以裂隙金、包裹体金、粒间金为主,银主要以类质同像赋存于方铅矿和硫盐矿物中。载金矿物黄铁矿生物结构发育,表明生物成矿作用是金矿床形成过程中的重要作用。矿体受特定层位和断裂的控制,围岩蚀变强烈。根据矿床产出的大地构造环境、赋矿围岩特征、构造控矿、层位控矿、矿物共生特点等分析结果,丹巴磨子沟金矿床为沉积-热液改造型金矿床。

Gold and silver occurrence and its genesis in the Mozigou gold deposit, Danba area, western Sichuan, China

Mozigou gold deposit is located in the margin of the Yangtze and east of Songpan-Ganzi orogenic belt, Danba County, Sichuan Province, with Devonian Weiguan Formation Carbonaceous slate as its ore-bearing country rocks. Mineralization can be divided into sedimentary mineralization, hydrothermal ore-forming period and hypergene weathering period.And the hydrothermal ore-forming is the main period of gold mineralization. The authors studied the deposition of gold, silver occurrence status, and the main characteristics of gold-bearing minerals by means of microscopic observation, scanning electron microscopy, electron probe composition analysis, and mineral crystal chemical formula calculation. Thus we found out gold was mainly inclusion, fracture and intergranular gold. Silver is main form of isomorphic occur in Galena and Sulphosalts. Gold-bearing minerals pyrite had biological structures, which indicated that bio-mineralization played an important role during the formation stage of gold deposits. Ores are controlled by specific strata and fractures, and have endured strong wall-rock alteration. According to the deposit characteristics of tectonic environment, ore-rock, structural control, layer position control and mineral paragenesis etc., authors can ascertain the Mozigou gold deposit can be regarded as micro-disseminated gold deposits, and the type is sedimentary-hydrothermal reworked deposits.