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Muteh, Chah Khaton, Senjedeh |
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Iran |
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Au
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Muteh gold deposit is located within the Sanandaj-Sirjin tectonic zone, approximately 240 km south-west of Tehran, Esfahan Province in western Iran. The known deposit is a small, but histroically significant resource.
The Sanandaj-Sirjin tectonic zone lies within the Zagros Orogen which resulted from Cretaceous and Tertiary convergence between the Eurasian and Afro-Arabian plates and is part of the Alpine to Tethyan belt. The Zagros Orogen is composed of three parallel, NW-SE trending belts, namely the Tertiary Urumieh-Dokhtar Magmatic Belt to the north-east (hosting porphyry and skarn type ores), the Sanandaj-Sirjin Tectonic Zone, and the Zagros Fold Belt to the south-west.
The Sanandaj-Sirjin Tectonic Zone is composed of parallel, north-west oriented belts of Mesozoic and Tertiary marine and continental sedimentary and lower to mid-Palaeozoic metamorphic rocks (gneiss, marble, amphibolite, mica schist, phyllite, quartzite) which are deformed by north-west trending folds partly overturned to the south and southwest, southwest-verging thrusts, and northwest-trending high-angle reverse faults, all of which resulted in thickening of the crust and Tertiary uplift of the zone. Late Jurassic to Eocene calc-alkaline magmatism characteristic of the zone has a peak activity during Late Cretaceous, interpretted to be linked to north-eastward subduction beneath Central Iran. Subsequent Tertiary calc-alkaline magmatism defines the adjacent Urumieh-Dokhtar magmatic belt to the north-east.
Host rocks to the gold deposit are predominantly schists and gneisses with lesser amphibolite and quartzite, local marble and magnetite horizons. These metamorphics and sediments are intruded by leucogranites. In the vicinity of the Muteh gold deposit, the metamorphic and granitic rocks have a sub-horizontal mylonitic foliation, with a northeast-trending stretching lineation. Gold mineralisation appears to be controlled by a northwest-trending conjugate fault system of north-east and south-west dipping normal faults and joints which crosscut the ductile fabric of the host rocks and contain gold-bearing quartz-pyrite-carbonate veins.
Both the ductile fabric in the host rocks and the auriferous brittle structures are interpreted to have formed within a single, continuous extensional event, which commenced with ductile deformation and gradually progressed into brittle deformation.
Hydrothermal alteration associated with ore formation comprises quartz, muscovite, pyrite, dolomite-ankerite and albite, crosscutting the ductile fabric and overprinting the metamorphic minerals of the host rocks. Pyrite, which is the dominant opaque mineral, is the major phase associated with gold. Chalcopyrite, marcasite, bismuth, galena, sphalerite and pyrrhotite are minor to rare.
Muscovite samples from the alteration zone and from one quartz vein from the orebodies yield 40Ar/39Ar ages of between 55.7 and 38.5 Ma (Eocene).
The current Muteh gold mine comprises two main ore zones, in the Chah Khaton and Senjedeh open pits, with seven smaller occurrences. Tonnages estimated comprise a total, including both remaining resources and past production of (Moritz, et al., 2006):
1.79 Mt @ 2.85 g/t Au - Chah Khaton,
including 0.38 Mt @ 3.31 g/t Au as of nonrefractory oxide ore, and 1.41 Mt @ 2.73 g/t Au as refractory sulphide ore.
1.76 Mt @ 2.57 g/t Au - Senjedeh,
including 0.84 Mt @ 2.61 g/t Au as of nonrefractory oxide ore, and 0.92 Mt @ 2.54 g/t Au as refractory sulphide ore.
The most recent source geological information used to prepare this decription was dated: 2006.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Moritz R, Ghazban F and Singer B S, 2006 - Eocene Gold Ore Formation at Muteh, Sanandaj-Sirjan Tectonic Zone, Western Iran: A Result of Late-Stage Extension and Exhumation of Metamorphic Basement Rocks within the Zagros Orogen: in Econ. Geol. v101 pp 1497-1524
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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