Delineation of gold mineralized zones using concentration–volume fractal model in Qolqoleh gold deposit, NW Iran

The aim of this study is to delineate and recognize the different gold mineralized zones based on surface and subsurface lithogeochemical Au data utilizing concentration–volume (C–V) model in the Qoloqoleh gold vein deposit, NW Iran. C–V modeling outlined six geochemical populations and four mineralized zones for Au element based on log–log plot which was correlated with the mineralized veins from geological data. Extremely mineralized veins are higher than 14.12 ppm in Au grade, which are correlated with surface weathered zone by oxidized pyrites. The main phase of gold mineralization where Au grade typically ranges between 3.98 and 14.12 ppm is associated with thick quartz veins. Moderately and weakly mineralized zones ranging from 0.354 to 3.98 ppm Au derived by C–V model were correlated with narrow quartz veins that contain minor sulfides in the deposit. Barren host rocks obtained by C–V modeling were correlated with barren quartz veins in the deposit. The results were compared with a geological model, showing a strong positive correlation between mineralized zones and quartz-sulfide veins hosted by meta-volcanic rocks and sericite schist. Results examined via the C–V fractal model illustrate that the interpreted zones based on the fractal model, mineralogical, SEM and EPMA analyses have strong correlation with highly and moderately silicic mineralized veins consisting of sulfides and Au. To certify this, a logratio matrix was employed to validate the C–V fractal model for Au and two lithological units namely meta-volcanic rocks and sericite schists indicating the overall accuracy of 0.56 and 0.58 respectively.