Application of an improved zonality index model integrated with multivariate fractal analysis: epithermal gold deposits

The main goal of this present study is to apply an improved zonality index to epithermal gold ores based on staged factor and number-size (N-S) fractal analysis. This technique was utilized in Bardaskan district, NE Iran, which is epithermal gold mineralization. An improved zonality index is a proportion of factors including ore and pathfinder elements based on rock samples. Consequently, two factors were selected after four stages of the staged factor analysis which consist on F-4 (As-Fe-Mo-S) and F 3-4 (Au-Ag). Based on these factors, (F1-4)/(F3-4) is determined as an improved zonality index. In addition, the improved zonality index was categorized by fractal modeling. The N-S model demonstrates that the major anomalies of this improved zonality index are associated with silicification as main alteration zone and the intersections of faults, particularly in the NE and northern parts of the Bardaskan region. Additionally, additional rock samples with Au higher than 100 ppb are located in anomalous parts of the improved zonality index and marginal parts of this area with high values of this index contain pathfinders of gold mineralization, especially As based on this methodology. This methodology could be strongly considered in the exploration of different types of mineral deposits and the classification of the target anomalies.