甘肃冯家场金矿床地质特征及找矿方向

Geological features and prospecting direction of the Fengjiachang gold deposit, Gansu

冯家场金矿床位于祁连—北秦岭加里东造山带接合部位,金矿化严格受震旦—奥陶系李子园群木其滩组和近EW向断裂及小山坡闪长岩枝联合控制。在2 0km2矿区范围发现4条等间距平行展布的金矿化带,金矿化主体为石英脉型,次为构造蚀变岩型。金矿物以银金矿为主,次为金银矿。金的赋存状态以粒间金为主,裂隙金和包裹体金次之,最大粒度0 58mm×0 96mm×0 22mm,Au品位8×10-6～10×10-6。成矿阶段包括石英脉、黄铁矿 石英、黄铁矿细脉、多金属硫化物、方解石 石英阶段,多金属硫化物阶段为主要成矿阶段。已发现的金矿化断裂与岩体内外接触带为本区找矿方向。

The Fengjiachang gold deposit is located in the adjoining part of Qilian to North Qinling orogenic belt. The gold mineralization is controlled by the nearly EW striking fault in Liziyuan Group Muqitan Formation of Sinian to Ordovician system and andesite branch of Xiaoshanpo strictly. It has been found there were 4 gold ore-forming belts that spread in parallel and equal distance. The major gold mineralization types are the quartz-vein types, others are the tectonic alternation rock types. The gold minerals are dominated by the electrum, and others are the gold-silver mineral. Gold occurs mainly in shape of interparticle gold, fissure gold or inclusion gold are taken the second place. The largest gold grain size is 0.58 mm×0.96 mm×0.22 mm, gold grade are 8×10^(-6)～10×10^(-6).The mineralization stages include: quartz, pyrite-quartz, pyrite veinlet, multi-metal sulfide and calcite-quartz. The multi-metal sulfide stage is the main mineralization stage among them. The founded gold mineralization fault and the internal or external contact zone of rock bodies provide the direction of gold prospecting in this area.