| 其他摘要 | The quartz-vein gold deposit is the typical representative of gold deposits in Jinping, southeast of Guizhou province. Based on the previouse work, HuaQiao, BaKe and PingQiu, these three deposits were selected for this study, all of which are typical gold deposits in this area. The summarization of their metallogenic background, geological characteristics of deposit, mineral assemblage, gold content and occurrence are given in the thesis. According to these research foundation and gold ore-controlling simulation experiments, we explore the metallogenic condition in lithology and tectonics, and get several major conclusions listed as follows:
1. The study area is located in the southwest of Xuefeng old continent. Two transmeridional faults developed in the region are tens of kilometers apart, which build a regional graben structure. During the Caledonian movement, regional deformation towards the NE led to the formation of folded belts and several NE-trending paralleled shear zones. These shear zones controlled the location and occurrence of gold deposits.
2. The rocks of the strata, where gold deposit occurred in, contain much volcanic debris, belonging to the Xia Jiangqun Group of upper Proterozoic. Large numbers of samples collected from upper Proterozoic were analyzed. The results show that the average gold contents are 2～15ppb, which is richer than the upper Clarke value(1.8ppb). Particularly, the samples collected from the sandstone, slate and the axis of anticline, with a more content of volcanic debris, reveal much higher gold content. This kind of correlation implicate that the the source of ore-forming material is probably involved in the surrounding rocks.
3. Ore-forming simulating experiments were carried out in this study. The results show that, ductile deformation (fold) and brittle deformation (fault) took place under high-temperature and high-pressure conditions. Ore-forming materials were activated, transported and enriched during the deformation. Finally concordant and discordant gold-bearing quartz veins formed. Multiple deformation during the simulation experiments helped the ore-forming materials to be concentrated, and the formation of enriched orebodies in the axis of complex anticlines was finally resulted. The experimental results confirmed the gold ore-controlling structures model for the shear zones-anticline-quartz vein.
4. It is believed that the Gold deposits in Jingping are turbidite-hosted quarzt-vein type gold deposit. The period of mineralization was Caledonian period. Ore bodys are controlled by Xiajiang Group stratum, anticline and faults. Mineraliztion foreground and exploration potential of ore deposit are very hopeful. Gold in ore body exists as native Au and as isomorphism dispersed in sulfide. The place with strong wall-rock alteration or sharp change of occurrence, the boundary or fault mud between vein and wall-rock and convergent place of various type ore body are favorable place for gold enrichment. These symbols for ore body exploration should be noticed during the process of prospecting, mining, beneficiation and metallurgy. |
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