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Accueil du site → Doctorat → Allemagne → 2007 → A metallogenetic model for carbonate-hosted non-sulphide zinc deposits based on observations of Mehdi Abad and Irankuh, Central and Southwestern Iran

Martin-Luther-Universität Halle-Wittenberg, (2007)

A metallogenetic model for carbonate-hosted non-sulphide zinc deposits based on observations of Mehdi Abad and Irankuh, Central and Southwestern Iran

Reichert, Jörg

Titre : A metallogenetic model for carbonate-hosted non-sulphide zinc deposits based on observations of Mehdi Abad and Irankuh, Central and Southwestern Iran

Auteur : Reichert, Jörg

Université de soutenance : Martin-Luther-Universität Halle-Wittenberg,

Grade : Doctor rerum naturalium (Dr. rer. nat.) 2007

Résumé
The proposed metallogenetic model is based on observations from the Iranian non-sulphide zinc deposits Mehdi-Abad and Iran-Kuh. The emplacement of non-sulphide ore can be generally subdivided into an "oxidation stage", which is followed by a "post-oxidation stage". The non-sulphide zinc ore spectrum has two end members : red zinc ore, rich in Zn (>20%), Fe (>7%), Pb - (As) and white zinc ore with typically high zinc grades (up to 40%) but low concentrations of iron (42- ions during the oxidation stage leads to the precipitation of (under these conditions) highly insoluble anglesite. Most of the zinc (up to 80% at pH 6 or 97% at pH 5) leaves the oxidation zone and precipitates as smithsonite in adjacent parts of the carbonate host rock due to a high PCO2 environment. During the "post-oxidation stage" the PCO2 decreases and reaches the level of atmospheric PCO2. Under these conditions, hydrozincite becomes stable and starts to replace smithsonite. The "post-oxidation stage" is also associated with the successive formation of local zinc (hydro-) silicates, depending on the availability of SiO2 within the solution. Generally, arid climates provide the best conditions for the preservation of non-sulphide deposits. The limited availability of meteoric water and deep to very deep water tables protect the non-sulphide ore from subsequent dissolution.

Mots clés  : Zinc lead supergene oxidation armouring hemimorphite smithsonite hydrozincite cerussite Mehdi-Abad Iran-Kuh

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