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Mineralogical and Geochemical Constraints on the Genesis of the Carbonate‐Hosted J ebel G hozlane Pb–Zn Deposit ( N appe Zone, N orthern T unisia)
Author(s) -
Jemmali Nejib,
Souissi Fouad,
Carranza Emmanuel John M.,
Vennemann Torsten W.
Publication year - 2013
Publication title -
resource geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 43
eISSN - 1751-3928
pISSN - 1344-1698
DOI - 10.1111/j.1751-3928.2012.00208.x
Subject(s) - galena , sphalerite , geology , calcite , mineralogy , geochemistry , pyrite
The Pb–Zn deposit at J ebel G hozlane, in the N appe zone (northern T unisia), is hosted by T riassic dolostones and E ocene limestones and is located along faults and a thrust‐sheet boundary. The sulfide mineralization of the deposit consists mainly of galena and sphalerite and occurs as vein, stockwork, breccia, dissemination and replacement ores. Three hydrothermal stages are involved in the formation of the ores: stage I is dominated by celestite‐barite, hydrothermal dolomite DII , colloform sphalerite, and galena I ; stage II consist of galena II ; and stage III contains calcite. Galena in the deposit yielded average 206 Pb / 204 Pb , 207 Pb / 204 Pb and 208 Pb / 204 Pb ratios of 18.705, 15.667 and 38.734, respectively, suggesting a single upper crustal source reservoir for metals. Trace element data indicate the presence of Zn ‐ and As ‐free galena and As ‐rich galena (with 0.2–0.5% As ). Sphalerite contains 0.4% As , 0.7–0.9% Cd and 0.1–1.5% Fe . Microthermometric analysis of fluid inclusions in celestite shows that the deposit formed from fluids composed of heterogeneous mixtures of saline (19.5 ± 1 wt% NaCl eq.) aqueous solutions sourced from basinal brines, and gaseous CO 2 ‐rich phases bearing low amounts of CH 4 , N 2 and/or H 2 S , at temperatures of 172 ± 5°C.