Within the eastern portion of the Carletonville gold field, the gold- and uranium-rich Carbon Leader reef of the Central Rand Group (Witwatersrand Supergroup) is truncated by an erosion channel. This channel is asymmetrical and lenticular in shape, measuring 150 to 180 m in width and up to 100 m in depth. High-resolution seismic data show that the erosion channel cuts from the Carbon Leader reef into all older units of the Central Rand Group down to the Roodepoort Formation of the underlying West Rand Group. A total of seven boreholes were drilled into the channel, revealing that it is composed of quartzite at its base (9 m thick), overlain by deformed (lower) and laminated (upper) chloritoid-bearing shale (21 m thick) and quartzite (18 m thick). The Carbon Leader reef is highly enriched in gold (5–40 g/t Au), whereas the gold tenor of the erosion channel fill is in general much lower (<1 g/t Au), although locally grades of as much as 3.8 g/t Au are reached. Detailed seismic, sedimentological, and petrographic analyses revealed that the channel was filled with locally sourced sediments from the Main Formation. A closed-system mass balance further demonstrates that gold in the erosion channel could have been entirely sourced from the Carbon Leader reef. Sediment load played a crucial role in the distribution of gold in the channel, thus supporting a stratigraphically controlled modified placer model for the origin of gold in the Carbon Leader reef.

中文翻译：

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威特沃特斯兰德盆地（南非）金矿床冲蚀通道的重要性：来自卡尔顿维尔金矿场的碳前锋礁的证据

在Carletonville金矿场的东部，中央兰德集团（Witwatersrand Supergroup）的富含金和铀的Carbon Leader礁被一条侵蚀通道截断。该通道是不对称的，呈透镜状，宽度为150至180 m，深度最大为100 m。高分辨率地震数据显示，侵蚀通道从碳前锋礁切入中兰特集团的所有较旧单元，再下至下西兰德集团的鲁德普特组。总共在该通道中钻了七个钻孔，表明它是由底部的石英岩（9 m厚），变形的（下部的）和层状的（上部）含类藻酸盐的页岩（21 m的厚度）和石英岩的（上部）覆盖的。 18 m厚）。碳领导者礁富含金（5-40克/吨金），侵蚀通道填充的金年限通常要低得多（<1 g / t Au），尽管局部品位高达3.8 g / t Au。详细的地震，沉积学和岩石学分析表明，该河道充满了来自主岩层的本地沉积物。封闭系统的质量平衡进一步表明，侵蚀通道中的金本来可以完全来自Carbon Leader礁。沉积物负荷在通道中金的分布中起着至关重要的作用，从而支持了地层控制的修饰铅矿模型，用于碳前导礁中金的来源。岩石学分析表明，该河道充满了来自主岩层的局部沉积物。封闭系统的质量平衡进一步表明，侵蚀通道中的金本来可以完全来自Carbon Leader礁。沉积物负荷在通道中金的分布中起着至关重要的作用，从而支持了地层控制的修饰铅矿模型，用于碳前导礁中金的来源。岩石学分析表明，该河道充满了来自主岩层的局部沉积物。封闭系统的质量平衡进一步表明，侵蚀通道中的金本来可以完全来自Carbon Leader礁。沉积物负荷在通道中金的分布中起着至关重要的作用，从而支持了地层控制的修饰铅矿模型，用于碳前导礁中金的来源。