The western edge of the Mediterranean Pelagian Platform: A Messinian mixed siliciclastic–carbonate ramp in northern Tunisia |
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| Authors: | Pierre Moissette Jean-Jacques Cornée Beya Mannaï-Tayech Mohsen Rabhi Jean-Pierre André Efterpi Koskeridou Henriette Méon |
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| Institution: | 1. Faculty of Earth Sciences, University of Silesia, 60 B?dzińska St., 41-200 Sosnowiec, Poland;2. Institute of Geological Sciences, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, Poland;3. Department of Chemistry, University of California, Irvine, CA, USA;4. Division of Science and Mathematics, East Georgia State College, Swainsboro, GA, USA;1. Paleontological institute, University of Zürich, Karl Schmid-Strasse 4, 8006 Zürich, Switzerland;2. BCG Parc de la Rouvraie 28, 1018 Lausanne, Switzerland;3. Institute of Earth Surface Dynamics, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland;4. Department of Earth Sciences, University of Geneva, 13 rue des Maraîchers, 1205 Geneva, Switzerland;5. Guangxi Bureau of Geology and Mineral Resources, Jiangzheng Road 1, 530023 Nanning, China;1. Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università degli Studi di Parma, Parco Area delle Scienze 157/A, 43124 Parma, Italy;2. Dipartimento di Scienze Biologiche, Geologiche e Ambientali, University of Bologna, Via Zamboni 67, I-40126 Bologna, Italy;3. Istituto di Scienze Marine (ISMAR-CNR), Consiglio Nazionale delle Ricerche, Via Gobetti 101, 40129 Bologna, Italy;4. Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, MA 02543, USA;5. Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy |
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| Abstract: | The marine Messinian deposits of Tunisia cover a narrow littoral strip some 300 km long between the northern Bizerte and Cap Bon areas and the central–eastern Sahel region. Litho- and biofacies analysis of six stratigraphic sections reveals the distinctive features of these deposits.The lower Messinian deposits are characterized by ubiquitous siliciclastics and abundant oolitic/bioclastic limestones organized in an eastward facing ramp. Westward (landward), this ramp changes into coastal lagoons, sometimes containing evaporites. Eastward, the ramp passes to the reefal Pelagian Platform extending as far as Lampedusa.Two main sedimentary cycles are distinguished: 1) an early Messinian siliciclastic retrogradational then oolitic/bioclastic progradational cycle (Beni Khiar Formation and lower Oued bel Khedim Formation); 2) a late Messinian brackish to continental cycle that probably accumulated in rapidly subsiding lagoons (Oued el Bir Formation and upper Oued bel Khedim Formation). The Tunisian early Messinian cycle is partly eustatically controlled, but the late Messinian cycle cannot be confidently correlated to other well-known Messinian series because of tectonic movements.The lower Messinian deposits of Tunisia are also characterized by abundant suspension-feeding organisms (molluscs and bryozoans) and rare corals, calcareous algae, echinoids, and larger benthic foraminifers. The proposed palaeoenvironmental model shows that the lower Messinian ramp of Tunisia was located on a current-protected margin and subjected to continent-derived sediment and nutrient supply. Eastward, nutrient influx diminished and a shallow-water isolated carbonate platform with coralgal facies developed between the western and the eastern Mediterranean basins. The main hydrological connection between these two basins occurred through a narrow seaway situated to the northeast of the Pelagian Platform, south of Sicily and Malta. |
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