| This paper analyzes the characteristics of geological structure of Niuxinshan diggings in Jinwuhuajian gold mine on the basis of the field facts, identification indoors and analysis of testing reports. The features of geological structure in the region include: stratums, combination of rocks, ore-controlling structure, characteristics of metamorphic rock and magmatic rock, characteristics of spatial arrangement and shape of ore body, mechanism of gold transfer and deposition, and regularity of gold occurrence.In the region of eastern Hebei province, the stratums mainly consist of metamorphic rocks in Archean and sedimentary rocks in Middle-Late Proterozoic; the structure includes the dome of Qianxi rocks in Archean, the fold belt of Zunhua rocks in Archean and the Malanyu anticlinorium in Yanshanian; the magmatic rocks are mainly granitic intrusive rocks in Indosinian and Yanshanian.The Zunhua rocks in Archean which exposes in the mining area mainly consist of plagioclase amphibolite and amphibolite plagioclase gneiss and belong to hypometamorphic rocks. Its gold content is higher than average value of crust (4 ppb). Its protolith is meso-basic submarine volcanic-sedimentary rocks, which is carrier of mantle gold. The magmatic rock body of Niuxinshan mountain in Yanshanian is the center of gold mineralization. Its intrusion is separated into 2 periods, porphyritic granite of medium-sized grain is formatted in early period and its gold content is similar to that of average value of crust. Medium-sized grain granite is formatted in later period, which invaded the early granite, and its gold content is generally over 40 ppb. They are probably the ore-forming parent rock. Structure in the age of Archean in the mining area is the compression-shear fracture system, the anticlinorium of Goukouzi and the synclinoria in Shuiyugou. The main structure in age of Yanshanian is anticlinorium of Niuxinshan mountain, which is crossing anticlinorium of Goukouzi. The superposition of the core of 2 anticlinoriums leads to the intrusion of magma in Yanshanian. The bending of anticlinorium of Niuxinshan mountain causes open of the northeast section of the compression-shear fracture system in mining area.90% of gold-bearing quartz veins in the mining area is orientation of north-northeast. Their northwest inclinations are between 20°and 45°and are inclined to slightly steepen in deeper area. Most of these quartz veins are quasi laminate and straight in shape and parallel in space. These quartz veins is distributed in offset about 50m or its multiples according to its orientation. The mineralization of thick one in quartz veins is low and the mineralization of fine quartz veins and broken surrounding rocks is high. |
PDF Full Text Request