Generation of integrated geochemical-geological predictive model of porphyry-Cu potential, Chahargonbad District, Iran

Geochemical surveys are essential in most modern mineral
explorations. Since Au and Cu are, respectively, pathfinder
and indicator for porphyry copper deposits [1], in this paper, a
geochemical potential map of Chahargonbad area is prepared
by analysing stream sediment geochemical data of those
elements, including elementary statistics of the raw
geochemical data, mean, maximum, minimum, standard
deviation and skewness of loge-transformed data and finally
providing histograms of loge-transformed data. Moreover,
using the advantages of the fuzzy logic theory, a geologicallyconstrained
predictive porphyry-Cu potential map is prepared.
For this purpose, specific relations of known porphyry-Cu
deposits and structural features in the Chahargonbad area, that
is provided by weights of evidence modelling, maps of fuzzy
membership values for hydrothermal alteration units,
lithologic formations, batholithic pluton margins, pluton
centroids and faults-fractures are prepared. Porphyry-Cu
potential zones are delineated by using the fuzzy gamma
operator to combine the mentioned evidential layers. The
results of the study show that the area could be divided into
four areas: good potential (0.43%), moderate potential
(0.82%), weak potential (19.76%) and non-potential for
porphyry-Cu deposits (78.99%). A good spatial coincidence is
obtained by comparing the geochemical anomaly maps with
the porphyry-Cu potential map obtained via the fuzzy logic
method.