Application of sequential Gaussian simulation and concentration-volume fractal model to delineate alterations in hypogene zone of miduk porphyry copper deposit, SE Iran

Abstract

The paper presents a quantitative modeling for delineating alteration zones in hypogene zone of Miduk porphyry copper deposit (SE Iran) based on drill core data. The main goal of this study is applying Sequential Gaussian Simulation (SGS) and Concentration-Volume (C-V) fractal model based on Cu grades to separate different alteration zones. In this study, 10 realizations were generated using the SGS modeling and C-V log-log plots were created for them to determine Cu threshold values which delineate alteration zones. Correlation derived from log ratio matrix, which was used to compare between geological and C-V fractal results, shows that Cu values less than 0.575% from simulation number 9 (sim 9) has more overlapped voxels with phyllic alteration zone by overall accuracy (OA) of 0.75. Furthermore, the comparison revealed that sim 9 with Cu values between 0.575% and 0.933% and OA of 0.88 can determine propylitic alteration. Spatial correlation between the potassic alteration zone resulted from 3D geological modeling and high concentration zones for the C-V fractal model shows that the alteration zone has Cu values between 0.955% and 1.380% (sims 2, 3 and 4) with OA of 0.71. Finally, based on correlation between classes in the geological and the fractal models of hypogene zone, this research resulted that potassic alteration, which is the richest zone, has a strong overlap with sims 2, 3 and 4 while phyllic and propylitic alterations, with lower grades, have an appropriate overlap with sim 9.