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Tunis, Tunisia

Boussen S.,Tunis el Manar University | Sghaier D.,Tunis el Manar University | Chaabani F.,Tunis el Manar University | Jamoussi B.,Laboratoire Central dAnalyses et dEssais | And 2 more authors.
Applied Clay Science | Year: 2015

Clay deposits of the Aleg formation (Jebel Romana of the northern Chotts range, southern-east Tunisia) were sampled and investigated for their, mineralogical, chemical, rheological, and physical characteristics to develop their potential use as drilling mud. X-ray diffraction revealed a predominance of smectite (≥90%) with minor amounts of kaolinite and illite. Calcite, quartz and gypsum were also detected. Results show that the main oxides in the samples were SiO2, Al2O3, and Fe2O3, whereas the other oxides were present only in small quantities. However, the relatively high Na2O and MgO content is also one of the favorable points considered in terms of swelling and viscosity features. Standard tests show that the rheological behavior of the clay suspensions is unsuitable for preparing drilling muds. Therefore, the activation of these clays was performed using the most popular Na2CO3 in a wet condition. The drilling muds qualities of the Upper Cretaceous smectite-rich clay from Jebel Romana, significantly improved with additive sodium carbonate. The Ca-montmorillonite was completely converted into Na-montmorillonite after addition of 3% Na2CO3. The activation of the Aleg clay with soda influenced the viscosities, swelling indices and specific surface area. The optimum conditions for the preparation of high quality materials for drilling mud were investigated by studying the effects of clay minerals percentage, Na2CO3 concentration, activation time and temperature. Commercial bentonite samples imported from Algeria (A.G) were also included as reference materials. The optimum parameters for activation can be achieved under the operating conditions of 3% Na2CO3 concentration, 60min activation time, 75°C heating temperature and clay concentration of 75g/l. Under these conditions, the rheological and physical properties including apparent viscosity, surface area and swelling index showed a maximum values. Therefore, by alkali activation, it is possible to upgrade smectite from Jebel Romana to meet the minimum API viscosity (15cp); mud yield value (90barrels/sh.ton) and swelling index (22ml) standards. In addition, the apparent viscosity and mud yield efficiency was obtained around pH10, as 18cp, 101.93 (barrels/sh.ton), respectively. So, to achieve higher quality, optimization needs to be carried out in the formulation of batches or in the processing conditions. The utilization of these clays, after their upgrading and activation, can represent a value-added to the Tunisian economy by preventing the importation of bentonite. © 2015 Elsevier B.V.

The detailed study of the Sidi Kralif Formation in Jebel Meloussi allowed to identify the principal zones and subzones of calpionellids and ammonites in the Lower to Middle Berriasien. Thus, the B2, B3, C1 and C2 subzones of calpionellids, the Grandis Subzone and Occitanica Zone of ammonites have been well characterized. Calpionellids associations of biozones of the studied section were compared with the associations reported in other regions of the globe, particularly the South-East of France and the external Rif (Morocco).

Fanti F.,University of Bologna | Cau A.,Museo Geologico Giovanni Capellini | Hassine M.,Office National des Mines
Journal of African Earth Sciences | Year: 2014

Isolated sauropod remains including vertebrae and a humerus from the Aïn El Guettar Formation (Albian, Early Cretaceous) of Tunisia are described. Vertebrae include a slightly procoelous anterior caudal vertebra, amphicoelous middle caudal vertebrae, and strongly procoelous distal caudal vertebrae. The humerus has an anteroposteriorly compressed shaft, robust deltopectoral crest restricted laterally and prominent condyles bounding a distinct distal fossa. The morphological characters present in the specimens suggests that isolated remains can be referred to at least two distinct sauropod taxa.The anterior caudal vertebra is referred to Rebbachisauridae, whereas remaining caudal vertebrae show titanosauriform and titanosaurian derived features (anteriorly placed neural arches and, in the posterior vertebrae, distincly procoelous centra); finally, the humerus may pertain to a somphospondylian titanosauriform, perhaps the same taxon represented by the middle and posterior caudal vertebrae. This study introduces some of the oldest titanosauriform remains from Northern Africa and provides additional data on the stratigraphic and geographic distribution of this clade during the Early Cretaceous. © 2013 Elsevier Ltd.

Othmani M.A.,Laboratory of Materiaux Utiles | Othmani M.A.,Tunis el Manar University | Souissi F.,Laboratory of Materiaux Utiles | Benzaazoua M.,University of Quebec | And 3 more authors.
Mine Water and the Environment | Year: 2013

Flotation tailings associated with the extraction of Pb and Zn in the Touiref mining district, Tunisia, contain galena, sphalerite, pyrite, and marcasite in a carbonate gangue. The geochemical behaviour of oxidized and unoxidised tailings were consistent with their mineralogical and chemical characteristics. The leaching proceeded under neutral to slightly alkaline condition (pH 7. 3-8. 5), and positive Eh (250-470 mV). The concentrations of sulfate and Ca released during the leaching tests were associated with the neutralization of acidity by carbonates and the dissolution of gypsum initially present in the tailings. The iron precipitated, but significant amounts of Zn (5-3,300 μg/L), Cd (3-18 μg/L), and Pb (28-83 μg/L) were released during leaching, with the latter two exceeding international environmental norms (5 μg/L for Cd and 10 μg/L for Pb). © 2012 Springer-Verlag Berlin Heidelberg.

Fanti F.,University of Bologna | Cau A.,Museo Geologico Giovanni Capellini | Hassine M.,Office National des Mines | Contessi M.,University of Bologna
Nature Communications | Year: 2013

Recent interpretations of the postcranial anatomy of sauropod dinosaurs differ about pneumatic features supporting an avian-like ventilatory system; the most conservative workers reject most postcranial pneumatizations as being unambiguous evidence of abdominal air sacs. Here we describe the first articulated dinosaur skeleton from Tunisia and refer it to a new rebbachisaurid sauropod, Tataouinea hannibalis gen. et sp. nov. The Tunisian specimen shows a complex pattern of caudosacral and pelvic pneumatization-including the first report of an ischial pneumatic foramen among Dinosauria-strongly supporting the presence of abdominal air sacs. Character optimization among Rebbachisauridae indicates that in the caudal vertebrae, pneumatization of the neural arches preceded that of the centra; in the pelvis, pneumatization of the bones adjacent to the sacrum preceded that of more distal elements. Tataouinea was more closely related to European nigersaurines than to otherwise Gondwanan rebbachisaurids; this supports an Afro-European route for rebbachisaurid dispersal. © 2013 Macmillan Publishers Limited. All rights reserved.

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