Delineation of alteration zones based on Sequential Gaussian Simulation and concentration–volume fractal modeling in the hypogene zone of Sungun copper deposit, NW Iran

Abstract

The main aim of this study is the identification of potassic, phyllic and propylitic alteration zones in the hypogene zone of the Sungun Cu porphyry deposit (NW Iran) based on drillcore data, utilizing sequential geostatistical simulation (SGS) and concentration–volume (C–V) fractal model. C–V log–log plots were generated for the results obtained by 10 realizations and the average of those realizations (E-type) which was used for the determination of Cu threshold values for the alteration zones. Based on correlation between geological models and the results derived via SGS and C–V fractal modeling by log ratio matrix, the propylitic zone has Cu values <0.005% as a result of simulation numbers (sims) 1, 5 and 9 with overall accuracy (OA) of 0.94. Additionally, the phyllic alteration contents of Cu values between 0.25% and 0.63% with OA of 0.70 are delineated by E-type. Moreover, a correlation between C–V fractal modeling of realizations and the potassic alteration zone derived via the geological model reveals that this alteration zone has Cu values higher than 2.23% (sims 1, 5 and 9) with OA of 0.816. The results of this research reveal that phyllic alteration due to having many existing geological samples with the grades close to the average ore grade (0.44%) of the Sungun deposit has a proper overlap with E-type; however, potassic and propylitic alterations containing the highest and lowest ore grades have a strong overlap with sims 1, 5 and 9.