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Klerksdorp会矿田(南非)的上维特瓦特斯兰德(Witwatersrand)与Venters-dorp系的元古代含金铀沉积层中金的形态是用电子显微扫描方法研究的。金的形态可分为三类型:(1)碎屑金;(2)重结晶金;(3)与碳质物伴生的金。不同地层部位金中的银含量(以成色表示)是通过附加的扫描电子显微镜上的能量色散x射线显微分析器测定的。 碎屑金最初是在离源区搬运了不到30公里沉积下来的,这是通过将维特瓦特斯兰德系中的金与近代冲积砂矿床进行比较而查明的。第二种类型的金由碎屑金小规模地重结晶生成。原始的Lichenlike植物簇部分地圈闭碎屑金于它们的纤维中,因此,金就加入其植物构造中,而形成第三种类型的金。 三种类型金的成色是相等的。银的无选择性重分配发生于碎屑金形成第二和第三种类型金的期间。金中的银含量随地层而变化。根据金的成色,在克菜克斯道普金矿田的主要矿化层,即Vaal矿脉中发现了两种不同相。 在维特瓦特斯兰德时期由于缺氧和还原环境,在河流搬运金的过程中没有银的溶滤。维持瓦特斯兰德金成色的变化可以归结为原生金矿床中银含量变化所造成的,这些原生金矿床很可能是位于维特瓦特斯兰德盆地周围的太古代绿岩——花岗岩区。 在Klerksdorp金矿田具重要经济价值的地层单元中发现,金中的银含量相对较少。
The morphology of gold in the Proterozoic uranium-bearing deposits of the Witwatersrand and Venters-dorp facies in the Klerksdorp minefield (South Africa) was studied electron microscopy. The morphology of gold can be divided into three types: (1) scrap gold; (2) recrystallization gold; and (3) gold associated with carbonaceous matter. The silver content (represented by color) in the gold of the different formations was determined by an additional energy dispersive x-ray microanalyser on a scanning electron microscope. Detrital gold was originally deposited within less than 30 km of the source area as evidenced by the comparison of gold in the Vittwat Silan with modern alluvial deposits. The second type of gold is produced by the small scale recrystallization of scrap gold. The original Lichenlike plant clusters partially trap the detritus in their fibers, so gold joins its plant architecture and forms a third type of gold. The quality of the three types of gold is equal. Non-selective redistribution of silver occurs during the formation of the second and third types of gold from detrital gold. The silver content in gold varies with the formation. According to the fineness of the gold, two different phases were found in the main mineralized layer of the Kakeksdaupu gold field, the Vaal vein. Due to the lack of oxygen and reducing environment during the Vitevæslands, there was no silver solu- tion during river handling of gold. Maintaining the Wattslander gold color can be attributed to changes in the silver content of the native gold deposits, most probably the Archean greenstone-granite area around the Viterw Slander Basin. In stratigraphic units of significant economic value in the Klerksdorp gold field, it is found that the silver content in gold is relatively small.