Application of fractal models to delineate mineralized zones in the Pulang porphyry copper deposit, Yunnan, southwestern China
<p>The aim of this study is to delineate and identify various mineralized zones and barren host rocks based on surface and subsurface lithogeochemical data from the Pulang porphyry copper deposit, southwestern China, utilizing the number–size (N-S), concentration–volume (C-V) and power-spectru...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-08-01
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| Series: | Nonlinear Processes in Geophysics |
| Online Access: | https://www.nonlin-processes-geophys.net/26/267/2019/npg-26-267-2019.pdf |
| Summary: | <p>The aim of this study is to delineate and identify various mineralized zones
and barren host rocks based on surface and subsurface lithogeochemical data
from the Pulang porphyry copper deposit, southwestern China, utilizing the
number–size (N-S), concentration–volume (C-V) and power-spectrum–volume
(S-V) fractal models. The N-S model reveals three mineralized zones
characterized by Cu thresholds of 0.28 % and 1.45 %: <span class="inline-formula"><0.28</span> %
Cu represents weakly mineralized zones and barren host rocks,
0.28 %–1.45 % Cu represents moderately mineralized zones, and
<span class="inline-formula">></span> 1.45 % Cu represents highly mineralized zones. The results
obtained by the C-V model depict four geochemical zones defined by Cu
thresholds of 0.25 %, 1.48 % and 1.88 %, representing nonmineralized
wall rocks (<span class="inline-formula">Cu<0.25</span> %), weakly mineralized zones
(0.25 %–1.48 %), moderately mineralized zones (1.48 %–1.88 %) and
highly mineralized zones (<span class="inline-formula">Cu>1.88</span> %). The S-V model is used by
performing a 3-D fast Fourier transformation of assay data in the frequency
domain. The S-V model reveals three mineralized zones characterized by Cu
thresholds of 0.23 % and 1.33 %: <span class="inline-formula"><0.23</span> % Cu represents
leached zones and barren host rocks, 0.23 %–1.33 % Cu represents
hypogene zones, and <span class="inline-formula">>1.33</span> % Cu represents supergene enrichment
zones. All the multifractal models indicate that high-grade mineralization
occurs in the central and southern parts of the ore deposit. Their results
are compared with the alteration and mineralogical models resulting from the
3-D geological model using a log-ratio matrix. The results show that the S-V
model is best at identifying highly mineralized zones in the deposit.
However, the results of the C-V model for moderately and weakly mineralized
zones are also more accurate than those obtained from the N-S and S-V models.</p> |
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| ISSN: | 1023-5809 1607-7946 |