Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Geochemical characteristics, nature, and genesis of hypogene gold and silver in the Sar Cheshmeh porphyry copper deposit, Kerman

Document Type : Original Research Paper

Authors
Behnam Shafiei 1
Jamshid Shahbpour 1
Mahmoud Sadloo 2
1 Department of Geology, Faculty of Science, Shahid Bahonar University of Kerman, Kerman, Iran
2 Geology office, Mine Affairs, Sar Cheshmeh Copper Complex, Kerman, Iran
Abstract
The Sar Cheshmeh porphyry copper deposit it located in the southeastern part of the central Iranian tectono - magmatic belt, in Kerman province. This deposit has a sulfide ore reserve of 1200 million tones, and contains an average grade of 0.7% copper and 0.03% molybdenum.
 
Based on this study, the actual average gold and silver grades are respectively 0.04 g/t and 0.97 g/t. The highest gold and silver grades occur in the intense philic ± argillic Sar Cheshmeh stock and also in the intense biotitic andesite, and have the same distribution as the high hypogene copper grade.
The strong positive correlation between Au and Cu (r= 0.7), Au and Ag (r=0.6) and Ag and Cu (r= 0.5), indicates similar condition of formation, and co-precipitation of gold and silver with copper in the form of invisible grains, solid solution in the chalcopyrite and probable presence of a visible gold and silver in the form of electrum or Ag poor native gold.
According to the genetic model proposed here, unlike copper, the hypogene gold and silver mineralization is not limited to a particular hydrothermal alteration process. Perhaps during evolution of the porphyry system, deposition of Au and Ag gradually increased, and in the final stages, Au and Ag appeared in the form of epithermal veins. This study indicates that the Sar Cheshmeh deposit is a gold-poor porphyry copper deposit, and some clear particulars like: huge tonnage, classic morphology, the scarcity of magnetite in the potassic alteration zone (0.4%), and the high grade of molybdenum, introduce this deposit as a perfect type - example of a PCD-Mo, which is related to the calc- alkaline magmatism in continental margin setting.
Keywords
Porphyry copper
Geochemical characteristics
Sar Cheshmeh
Kerman

Subjects

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Scientific Quarterly Journal of Geosciences
Volume 9, 33-34
Autumn & Winter 2000, vol. 9, No. 33-34
Autumn 2000
Pages 34-49