Application of multifractal modeling technique in systematic lithogeochemical survey to identify Au-Cu anomalies in the Siah-Jangal area, Southeastern of Iran

Identifying the geochemical anomalies from background is a fundamental task in exploration geochemistry. This research is based on the application of concentration-area (C-A) method at the Siah-Jangal Au porphyry system in southeastern Iran. Lithogeochemical datasets (n = 399) were used in this geochemical survey which was conducted for the exploration for Au mineralization. Moreover, similar surveys were also carried out for As, Cu, and Mo exploration in this region. Anomalous threshold values for the mineralized zone were computed and compared with the statistical methods based on the data obtained from chemical analysis of samples for the lithological units. Several anomalies at a local scale were identified for Au (281 ppb), As (649 ppm), and Cu (20 ppm). The obtained results suggest existence of local Au anomalies that its magnitude generally is above 400 ppb. The C-A log-log plots show existence of three stages of Au and Cu enrichment. The second and most important enrichment event is responsible for the presence of Au at grades above 400 ppb. The obtained results have been interpreted using rather extensive set of information available for the study area, consisting of structural interpretation and alteration data. Various structural features and corresponding alteration show that the geologic structures play an important role in the discrimination of geochemical anomalies and element distribution in the Siah-Jangal area.