甘肃寨上大型金矿床南、北矿带地质地球化学特征对比研究

Comparative study on the geological and geochemical characteristics of south and north ore-belt in Zhaishang gold deposit,Gansu Province

寨上金矿床以F5断裂为界,可分为南、北2个矿带,在地质、地球化学特征方面存在差异。北矿带位于背斜北翼下二叠统十里墩组地层中,南矿带产于背斜核部中泥盆统安家岔组、上泥盆统大草滩组地层中。流体包裹体研究显示,矿床总体具有中低温、低盐度、低密度、低压力和较浅的成矿深度,南矿带相对于北矿带成矿温度、流体盐度、密度要高,成矿压力以及成矿深度要大。南北矿带可能为一个统一的热液成矿系统,浅部表现为类似于北矿带的微细浸染型金矿化,深部表现为类似于南矿带的脉状富金多金属矿化。

Zhaishang gold deposit can be divided into south and north ore-belt with the F5 fault as boundary, and geological and geochemical difference exists between them. The north ore-beh occurs in lower Permian Shilidun group at north limb of the anticline and the south ore belt is located in the mid-Devonian Anjiacha group and upper-Devonian Dacaotan group in the core of the anticline. The inclusions study shows that the ore-forming hydrothermal fluid is char- acterized with min-low temperature,low salinity, density and pressure which suggest ores formed in the shallow. How- ever, compared with the north ore-belt, the ore forms from fluids with higher temperature, salinity, density, pressure and in deeper position in the south ore-belt. The south and north ore-beh belong to a unified hydrothermal system, which presents micro-fine disseminated gold mineralization in the shallow as the case in north ore belt and rich-gold polymetallic vein type mineralization in the deeper part as in south ore belt.