1. Assistant Professor, Dept. of Earth Sciences, Faculty of Science, Sfax, Route Sokra, km 3, 5 BP 802, 3018 Sfax, Tunisia (corresponding author). E-mail: habib.abida@voila.fr
2. Chairman, J. F. Sabourin and Associates Inc., 142 rue de Varennes, Unité 11, Gatineau, Québec, Canada J8T 8G5.
3. Graduate Student, Faculty of Science of Sfax, Sfax, Sokra, km 3, 5 BP 802, 3018 Sfax, Tunisia.