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Paper Number: 125
Determination
of Cu mineralized zones utilizing number-size (N-S) fractal modeling in
Takht-e-Gonbad porphyry deposit (SE Iran)
Eskandarnejad
Tehrani, M.1, Afzal, P.2 and Ghaderi,
M.3
1Young
Researchers and Elite club, South Tehran Branch, Islamic Azad
University, Tehran, Iran, mohammad.eskandarnejad@gmail.com
2Department
of Mining Engineering, South Tehran Branch, Islamic Azad University,
Tehran, Iran
3Department
of Economic Geology, Tarbiat Modares University, Tehran, Iran
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The purpose of this study is to determine different Cu mineralized
zones using number-size (N-S) fractal modeling in Takht-e-Gonbad
porphyry deposit (SE Iran). This deposit is situated about 70 km NE of
Sirjan City, SE Iran. In addition, this porphyry deposit is located on
the south of Kerman Cenozoic magmatic arc (KCMA), which most of Cu
porphyry deposits of Iran occurred in this arc [1]. Based on geological
map of Takht-e-Gonbad, Eocene volcanic-pyroclastic rocks and Neogene
sediments are the main rock types. Moreover, phyllic alteration is the
main alteration type in this deposit and also, hypogene ore zone
consists of pyrite, chalcopyrite and minor magnetite and
molybdenite.
The number-size fractal model
proposed by Mandelbrot [4], can be used to describe the distribution of
geochemical population without any pre-processing of data. The model can
been expressed by the following equation:
N(≥r)=cr-D
Where r denotes the element concentration; N(≥r) is the cumulative
number of concentration greater than or equal to r; c is a constant and
D is the fractal dimension of the concentration distribution [2].
Figure 1: Cu N-S log-log plot in Takht-e-Gonbad deposit
In this research, 2830 samples were collected from 39 drill cores in
this deposit and analyzed by ICP-AES for elements that relate to Cu
mineralization. Based on the subsurface data obtained from drill core,
the deposit were modelled by RockWorks.15 software. 3D model of Cu
distribution in this deposit was generated with kriging estimation. The
N-S model was utilized to the lithogeochemical dataset of this deposit
for separating Cu mineralization zones resulting from N-S log-log plot
for Cu (Fig. 1). The severity of elemental enrichment is illustrated by
slope changes of line segments (breakpoints) in log-log plots. Four
breakpoints exist in N-S plot, the range of leached, oxidation, hypogene
and supergene zones are 0.1589 % - 0.5011 %, 0.5011 % - 1.2589 %, 1.2589
% - 2.5118 % and >2.5118 %, respectively.
The result derived via the fractal model were controlled by
mineralogical study and XRD analysis. Carranza [3] proposed a method for
calculation of overlap correlation between two binary models by a
logratio matrix. The supergene enrichment zone contains Cu≥2.51%. In
addition, different mineralized zones can be detected via the N-S
fractal modeling. The supergene enrichment, hypogene and oxidation zones
delineated via N-S fractal model were correlated with geological
zonation models along of the application of logratio matrix. The
overlapping results which reveals that the hybrid method is proper for
outlining of mineralized zones in the porphyry deposit.
References:
[1] Asadi S et al. (2014) Earth-Sci. Rev. 138:25-46
[2] Mohammadi A et al. (2013) Arab J Geosci. 6:4387-4398
[3] Carranza E J M (2011) J. Geochem. Explor. 110:167-185
[4] Mandelbrot B B (1983) The fractal geometry of nature.
W.H.Freeman, San Fransisco, 468 p.
