Scholarlink

The mineral deposits of the north-western part of Tunisia occurred within the Mesozoic and Cenozoic geodynamic evolution framework of the eastern margin of North Africa. Despite several suggestions, the origin of metals and fluids associated with these types of mineralizations has remained uncertain. In this study, lead isotopic ratios are used to provide new evidence concerning the source of metals and the mineralization timing at Chouichia, El Hairech, Kef El Agueb, Ain El Bey and J. Hallouf- Sidi Bouaouane mines. Analyzes were carried out by MC-ICP-MS in the laboratories of Bureau Veritas Mineral (Vancouver, Canada) on sulfide-sulfosalt mineral extractions and fresh whole rock. Data indicate relatively variable lead isotopic ratios: from 18.2204 to 18.9473 for 206Pb/204Pb, 15.4700 to 15.8602 for 207Pb/ 204Pb and 38.0187 to 39.5610 for 208Pb/204Pb.The uranogenic and thorogenic diagrams, the genetic classification and tectonic discrimination Δβ–Δγ diagrams indicate a source of Pb, and therefore the metals involved in the mineralizations, from the contribution of several reservoir types and/or their mixing in variable proportions. The contribution of the mantle reservoir, with a slight orogeno-crustal and magmatic mixing, is well expressed at Chouichia, El Hairech, and Kef El Agueb. The relatively radiogenic character of the sulfides-sulfosalts of the Ain El Bey deposits and the karstic galena of the J.Hallouf-Bouaouane deposits, reflect contamination of the mineralizing fluids by an orogenic material which would come from the Alpine and Atlas orogens as well as their immediate sub-surface substratum. This latter would be the extension, in Tunisia, of the Hercynian orogenic belt of North Africa outcropping in Morocco and Algeria in which crustal material is particularly, enriched in Th and U. Age calculations of the mineralization establishment according to the two stages of the lead isotopic model, give an average age of 25 Ma. This assumes polyphase mineralizations spread over time and continue until the Pliocene through Tertiary and Neogene magmatism. The main drains of mineralizing fluids would be the rooted accidents of Cap Serrat-Ghardimaou, Ras-El-Korane but also that of Fej-Et-Tamer controlling, in particular, the mineral deposits of Chouichia, Kef El Agueb and the surrounding regions.

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Lead Isotopes Ratios as Tracers of Pb–Zn and Fe-Cu Ore Deposits at the Front of the Northwest Tunisian Thrust Domain: Source of Metals and Mineralization Timing

  • 会议论文

  • 发表日期：

    2025年

查看全文
  • Rania Ben Aissa,
  • Wiem Ben Aissa,
  • Said Tlig,
  • Rabah Alouani

摘要

The mineral deposits of the north-western part of Tunisia occurred within the Mesozoic and Cenozoic geodynamic evolution framework of the eastern margin of North Africa. Despite several suggestions, the origin of metals and fluids associated with these types of mineralizations has remained uncertain. In this study, lead isotopic ratios are used to provide new evidence concerning the source of metals and the mineralization timing at Chouichia, El Hairech, Kef El Agueb, Ain El Bey and J. Hallouf- Sidi Bouaouane mines. Analyzes were carried out by MC-ICP-MS in the laboratories of Bureau Veritas Mineral (Vancouver, Canada) on sulfide-sulfosalt mineral extractions and fresh whole rock. Data indicate relatively variable lead isotopic ratios: from 18.2204 to 18.9473 for 206Pb/204Pb, 15.4700 to 15.8602 for 207Pb/ 204Pb and 38.0187 to 39.5610 for 208Pb/204Pb.The uranogenic and thorogenic diagrams, the genetic classification and tectonic discrimination Δβ–Δγ diagrams indicate a source of Pb, and therefore the metals involved in the mineralizations, from the contribution of several reservoir types and/or their mixing in variable proportions. The contribution of the mantle reservoir, with a slight orogeno-crustal and magmatic mixing, is well expressed at Chouichia, El Hairech, and Kef El Agueb. The relatively radiogenic character of the sulfides-sulfosalts of the Ain El Bey deposits and the karstic galena of the J.Hallouf-Bouaouane deposits, reflect contamination of the mineralizing fluids by an orogenic material which would come from the Alpine and Atlas orogens as well as their immediate sub-surface substratum. This latter would be the extension, in Tunisia, of the Hercynian orogenic belt of North Africa outcropping in Morocco and Algeria in which crustal material is particularly, enriched in Th and U. Age calculations of the mineralization establishment according to the two stages of the lead isotopic model, give an average age of 25 Ma. This assumes polyphase mineralizations spread over time and continue until the Pliocene through Tertiary and Neogene magmatism. The main drains of mineralizing fluids would be the rooted accidents of Cap Serrat-Ghardimaou, Ras-El-Korane but also that of Fej-Et-Tamer controlling, in particular, the mineral deposits of Chouichia, Kef El Agueb and the surrounding regions.