Identifying geochemical anomalies associated with Cu mineralization in stream sediment samples in Gharachaman area, northwest of Iran

• The SCB technique was used for mapping anomalies based on stream sediment samples.
• PCA was used to determine multi-element geochemical signatures.
• The hybrid method combining SCB technique and PCA is a useful way to identify stronger anomalies.

The aim of this paper was to delineate Cu anomalies in the eastern part of Gharachaman 1:100,000 sheet, which was located in Sahand–Bazman magmatic belt, northwest of Iran. The sample catchment basin (SCB) technique was applied on stream sediment data to prospect Cu and its related pathfinder at Gharachaman area; then the concentration–area (C–A) multifractal model was performed on positive Cu and Mo residuals to separate different population and mapping anomalies. The spatial distributions of residuals Cu and Mo, based on threshold values via C–A multifractal analysis, showed high anomaly in the northeast and southeast of the studied area, where intrusive rocks were underlain by the basaltic breccias. Furthermore, principle component analysis (PCA) was conducted on the results of SCB technique in order to determine multi-element geochemical signatures that reflected the presence of mineralization. As a result, four components were defined which could explain nearly 83% of the variability. Meanwhile, PC3 represented a Cu–Mo association and reflected a multi-element mineralization related to the hydrothermal Cu deposit occurrence. Finally, the C–A analysis was performed on positive scores of PC3. The PC3 scores map displayed less anomalous areas than uni-element of residual Cu map, probably due to the characteristic of PCA method that eliminated false anomalies. Studies proved that using this hybrid method (SCB and PCA) could be a useful technique to recognize the stream sediment anomalies in the preliminary stages of prospecting concealed mineral deposits.