Application of fractal modeling and delineation of hydrothermal alterations in the separation of Zn, Pb, Cu, and Ba anomalies in Varcheh 1: 100000 sheet (south of Arak)

Fractal modeling is a useful tool for classifying various natural phenomena. Fractal methods evaluate relationships between all parameters, such as geochemical data and spatial distribution, without any data normalization. For this reason, fractal models are more exact and closer to reality. In this study, 1292 samples of Stream sediments on the 1:100000 geological sheet of Varcheh in the south of Arak were surveyed for geochemical exploration and analyzed by the ICP-MS method to detect 15 elements. The statistical parameters of Zn, Pb, Cu, and Ba, and histograms for these 15 elements showed a right-skewed distribution. In this case, the fractal method is among the best techniques for separating anomalies from the background. The element data were analyzed by the concentration-number (C-N) fractal method and then matched to alteration zones and faults plotted by ASTER multispectral imagery to detect minerals. The C-N fractal diagram was plotted for Zn, Pb, Cu, and Ba, and the most intensive anomalies for these elements have a grade greater than 524.8, 794.3, 223.9, and 944.1, respectively. Integrating the anomaly maps for Zn, Pb, Cu, and Ba with iron oxide, proplytic, argillic, and silicic alterations, fault maps, and the maps of mines and Varcheh mineral indices showed that the metal mines have mainly occurred in regions with a high fault density. The separated Pb and Zn anomalies are consistent and related to high fault and fracture density regions. They are also highly correlated with the silicic alteration plotted in the region.