Application of fractal models to delineate mineralized zones in the Pulang porphyry copper deposit, Yunnan, Southwest China

Abstract. The purpose of the paper is to depict various mineralized zones and the barren host rock in accordance with the subsurface and surface lithogeochemical data using the concentration-volume (C-V) and power spectrum-volume (S-V) fractal models within the Pulang copper deposit, southwest China. Results obtained by concentration-volume model depict four geochemical zones defined by Cu thresholds of 0.25 %, 1.38 % and 1.88 %, which represent non-mineralized wall rocks (Cu   1.88 %). S-V model is utilized by performing 3D fast Fourier transformation for assay data in the frequency domain. The S-V method indicates three mineralized zones characterized by Cu threshold values of 0.23 % and 1.33 %. The zones of  1.33 % Cu represent supergene enrichment zones. Both the multifractal models show that high grade mineralization is located at the center and south of Pulang deposit. The results are in contrast with alteration and mineralogical models resulted from the 3D geologic model utilizing the logratio matrix method. Better results were obtained from S-V model to delineate high grade mineralization of Pulang deposit. However, results of C-V method of moderate and weak grade mineralization are more precise than the results gained from S-V method.