DBPapers
DOI: 10.5593/sgem2011/s03.152

U–PB GEOCHRONOLOGY AND PB ISOTOPE CHARACTERISTICS OF CHAH ZARD AG–AU EPITHERMAL DEPOSIT, WEST–CENTRAL IRAN

AUTHOR/S: M. GHADERI, H. KOUHESTANI, K. ZAW, S. MEFFRE
Monday 1 August 2011 by Libadmin2011

11th International Multidisciplinary Scientific GeoConference SGEM2011, www.sgem.org, SGEM2011 Conference Proceedings/ ISSN 1314-2704, June 20-25, 2011, Vol. 1, 1039-1046 pp

ABSTRACT

The Chah Zard Ag–Au epithermal deposit is located within an andesitic to rhyolitic
volcanic complex in central part of Urumieh–Dokhtar Magmatic Arc (UDMA), west–central Iran. The deposit is formed in breccia bodies dominantly hosted by rhyolite porphyries. Geological field relationships show that epithermal mineralization occurred
in close association with a phreatomagmatic fracturing event, being localized in breccia cements, and formed as disseminated sulfides in the matrix of the more permeable breccias, and in veins cutting breccia bodies. No volcanic and/or subvolcanic flow and domes have been observed to cross-cut zones of alteration, phreatomagmatic breccias or
veining. The volcanic rocks are high K, calc–alkaline, and show rare earth and trace elements features characteristic of arc magmatism. Zircons extracted from intermediate and felsic volcanic rocks of the Chah Zard deposit yield concordant U–Pb ages of 6.29±0.29, 6.25±0.29 and 6.19±0.24 Ma, and a mean age of 6.24±0.16 Ma. This age is interpreted to represent the maximum age of mineralization of the Chah Zard deposit, and may indicate that there was a previously unrecognized mineralization event in UDMA. Galena mineral separates from the breccia cements and veins have uniform lead isotope ratios of 206Pb/204Pb=18.71–18.77, 207Pb/204Pb=15.61–15.73, and
208Pb/204Pb=38.95–39.01, implying derivation of Pb from a homogeneous upper crustal source.

Keywords: Epithermal, breccia, U–Pb, Chah Zard, Iran

PAPER 2011/s03.152: U–PB GEOCHRONOLOGY AND PB ISOTOPE CHARACTERISTICS OF CHAH ZARD AG–AU EPITHERMAL DEPOSIT, WEST–CENTRAL IRAN

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