Estimation of the Kahang Porphyry Cu-Mo Deposit (Northeast of Isfahan) by Using Conventional and Fractal Kriging

Abstract

Kahang porphyry Cu-Mo deposit in Isfahan province was discovered using Landsat TM data
and diagnosis of its alteration system. The aim of this study was to estimate the eastern anomaly
mass of Cu-Mo Kahang deposit. Before estimating the reserve, deep geochemistry of the area was
performed to determine the zoning series and to determine the erosion level indicators. In-depth
geochemistry of the region was performed to determine the series of zoning and the erosion level
indices before estimating the reserve. To determine the zonality of the elements, the average
standard of the samples in 50, 68, 80 and 100 m composites has been calculated and then elements
zonality series has been determined. In comparison with porphyrycopper standard zonality
sequences, the zonality of 80m composites including Co – Be – Ba – As – Mn – Pb – Zn – Sb – Cu
– Ag – Mo – Bi were found to be present at Kahang. The geochemical ratio indices of As/Mo and
(As.Mn)/(Cu.Mo) were found to be indicative of present erosion surface. Geophysical and
magnetometric profiles were used in the geophysical surveys of the area. Then, the threedimensional estimation of the copper grade in the estimation space was performed using
conventional Kriging. In order to simulate the highly variable nature of surface part of deposit, a
fractal simulation algorithm based on exponential variogram parameters and the values of 2H and
1/2VH parameters for simulation were determined. Through applying E-type estimation method
on 30 realizations the ore reserve was estimated at 3407500 tons (13630 tons Cu content) using a
fractal kriging of 2500 ppm Cu. Due to the discontinuity in the region's speculations, the fractal
simulation method showed more realistic results and well separated the low-grade and high-grade
areas.