Mineralogy, fluid inclusions and stable isotope study of epithermal Au-Ag-Bi-Te mineralization from the SE Afar Rift (Djibouti)

Type Article
Date 2019-08
Language English
Author(s) Moussa N.1, 2, 3, Boiron M.C-4, Grassineau N.V.5, Asael Dan6, Fouquet Yves2, Le Gall Bernard3, Rolet Joël3, Etoubleau Joel2, Delacourt Christophe3
Affiliation(s) 1 : IST, Centre d’Etudes et de Recherches de Djibouti, B.P. 486, Djibouti
2 : IFREMER, Centre de Brest, BP 70, 29280 Plouzané, France
3 : UMR/CNRS 6538 Géosciences Océan, UBO-IUEM, Place Nicolas Copernic, 29280, Plouzané, France
4 : GéoRessources, Université de Lorraine, CNRS, CREGU, Boulevard des Aiguillettes, B.P. 70239, F-54506, Vandœuvre-lès-Nancy, France
5 : Department of Earth Sciences, Royal Holloway University of London, EGHAM Surrey TW20 0EX, UK
6 : Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA
Source Ore Geology Reviews (0169-1368) (Elsevier BV), 2019-08 , Vol. 111 , P. 102916 (14p.)
DOI 10.1016/j.oregeorev.2019.05.002
WOS© Times Cited 1
Keyword(s) Fluid inclusions, Stable isotopes, Hydrothermal, Epithermal system, SE Afar Rift, Djibouti
Abstract

In this paper, the mineralogy, fluid inclusions and stable isotopes of hydrothermal veins from the SE part of the Afar Rift (Djibouti) were studied. Mineralization occurs as gold-silver in quartz/carbonate veins and is mainly associated with felsic volcanism. The morphologies and textures of quartz show crustiform colloform banding, massive and breccias. Microthermometric measurements were made on quartz-hosted two phases (liquid + vapor) inclusions. Mean homogenization temperature ranges from 150°C to 340°C and ice-melting temperatures range from -0.2°C to - 1.6°C indicating that inclusion solutions contain 0.35 to 2.7 eq. wt. % NaCl. Furthermore, δ18O and δ13C values from calcite range from 3.7 to 26.6 ‰ and -7.5 to 0.3 ‰, respectively. The presence of platy calcite and adularia are consistent with boiling conditions. Our study shows that the deposit of precious-metal deposition occurred at around 250°C and is linked to a fluid generated by the mixture of magmatic fluid, hydrothermal fluid and seawater.

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Moussa N., Boiron M.C-, Grassineau N.V., Asael Dan, Fouquet Yves, Le Gall Bernard, Rolet Joël, Etoubleau Joel, Delacourt Christophe (2019). Mineralogy, fluid inclusions and stable isotope study of epithermal Au-Ag-Bi-Te mineralization from the SE Afar Rift (Djibouti). Ore Geology Reviews, 111, 102916 (14p.). Publisher's official version : https://doi.org/10.1016/j.oregeorev.2019.05.002 , Open Access version : https://archimer.ifremer.fr/doc/00494/60528/