中文摘要：

石英脉型黑钨矿床“五层楼”垂直形态分带模式是中国地质工作者提出的经验成矿模式,在钨矿找矿中发挥了重要作用,然而该模式的形成机制尚未阐明.文章通过定量分析漂塘钨矿床脉体形态和成矿元素统计分布特征在垂向上的变化趋势,发现随着深度增加,脉幅分形维数逐渐减小,表明宽脉比例逐渐增加和脉体系统连通性增强.钨锡品位的分形维数都向深部逐渐降低,说明高品位矿石比例增加.钨锡含量都服从混合对数正态分布,二者在深部都由三个子分布组成,均值较高的子分布反映了漂塘最主要钨矿的成矿阶段;在浅部钨含量由两个子分布构成,锡含量服从单-对数正态分布.钨锡含量子分布数量随深度增加而增加,反映深部成矿期次叠加多于浅部.成矿元素分形维数在深部较低是由深部均值较高的子分布造成的,深部多期次裂隙张开和成矿充填过程可能是深部宽脉较多的重要原因.

英文摘要：

Field geologists proposed an empirical model named “five-floor” vertical morphological zonation in the vein-type tungsten deposits in China in the 1980s. This model has been playing an important role in exploration in this type of tungsten deposits. However, the mechanisms forming such a zonation are still enigmatic. We study the vertical variation trend of vein thickness and the statistical distribution of ore element concentration in the Piaotang tungsten deposits in South China using fractals and mixed distributions of ore grade. We find that the fractal dimension of vein thickness decreases downwards. This indicates an increase in the proportion of thick veins and the connectivity of fracture systems that bear the veins. The grades of tungsten and tin show a similar trend with the vein thickness, suggesting that the proportion of high-grade ores also increases downwards. The grades of tungsten and tin follow a mixed log-normal distribution. Both tungsten and tin concentrations contain three components at deeper levels, while they have single or two components at shallower levels. This suggests that the ore veins at deeper levels may be produced by more ore fluid pulses than those at shallower levels. The component with higher average grades may lower the fractal dimension of ore grades at deeper levels. Multiple fracture opening and infilling processes may be an important reason to explain why veins at deeper levels are wider than those at shallower levels on average.