1Department of Geology, Faculty of Sciences of Tunis, Campus Universitaire El-Manar, 2092 El Manar, Tunis, Tunisia
2Organic Petrology Group, Birbal Sahni Institute of Palaeosciences, 53-University Road, Lucknow 226007, India
3Department of Applied Geosciences and Geophysics, Montanuniversität Leoben, Peter-Tunner-Str. 5, A-8700 Leoben, Austria