Sulfur and lead isotopes of Guern Halfaya and Bou Grine deposits (Domes zone, northern Tunisia): implications for sources of metals and timing of mineralization

Jemmali, Nejib, Souissi, Fouad, Carranza, Emmanuel John M., and Vennemann, Torsten W. (2013) Sulfur and lead isotopes of Guern Halfaya and Bou Grine deposits (Domes zone, northern Tunisia): implications for sources of metals and timing of mineralization. Ore Geology Reviews, 54. pp. 17-28.

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Abstract

The Pb–Zn ore deposits in the Guern Halfaya and Bou Grine areas (northern Tunisia) are hosted mainly by dolostones in the contact zone between Triassic and Upper Cretaceous strata and by Upper Cretaceous limestones. The deposits occur as lenticular, stratiform, vein, disseminations and stockwork ore bodies consisting of sphalerite, galena, pyrite, chalcopyrite and sulfosalt (gray copper). Barite and celestite dominate the gangue, with lesser calcite. The δ34S values of barite and celestite (12.7–15.0‰) at the Oum Edeboua mine are consistent with the reduction of sulfates in Triassic evaporites within the study area (12.8 < δ34S < 14.0‰). The δ34S values in base-metal sulfides from both study areas (2.6–9.5‰) and the presence of bacterial relics suggest involvement of bacterially-mediated sulfate reduction in the mineralization. The present Pb isotope data are homogeneous with ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/204Pb and ²⁰⁸Pb/²⁰⁴Pb ratios of 18.723–18.783, 15.667–15.685 and 38.806–38.889, respectively, which suggest a single source reservoir of Pb at depth in the upper crust. The syn-diagenetic mineralization in the Bahloul Formation and the calculated age from the Pb isotopic data suggest an Upper Cretaceous age for the Pb–Zn deposits in the Guern Halfaya and Bou Grine areas. During this period, NE–SW to ENE–WSW trending regional extensional tectonic structures likely favored migration of mineralizing fluids and eventual deposition at Guern Halfaya and Bou Grine.

Item ID: 27374
Item Type: Article (Research - C1)
ISSN: 1872-7360
Keywords: Guern Halfaya, Bou Grine, diapirism, S isotopes, Pb isotopes, MVT Pb–Zn deposits, Domes zone
Date Deposited: 31 May 2013 02:19
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 100%
SEO Codes: 84 MINERAL RESOURCES (excl. Energy Resources) > 8499 Other Mineral Resources (excl. Energy Resources) > 849999 Mineral Resources (excl. Energy Resources) not elsewhere classified @ 100%
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