Lithostratigraphic analysis of the Turonian–Coniacian Bireno and Douleb carbonate Members in Jebels Berda and Chemsi, Gafsa basin, central-southern Atlas of Tunisia

摘要: Abstract The Turonian–Coniacian series of Bireno and Douleb Members (carbonate the Aleg Formation) have been examined on their sedimentology, stratigraphy faunistic contents to provide new insights into paleoenvironment evolution sea-level changes in Gafsa basin. At this scale, both are mainly made marls limestones locally include evaporites. In paper, ostracods together with benthonic planktonic foraminifers, collected from Upper Cretaceous Berda Chemsi mountains, used some chronostratigraphic precisions (age limits) these lithostratigraphic units. Accordingly, four units, belonging Formation, were recognized following an ascending order; Annaba Member (Lower Turonian), Turonian–Middle Lower Marls (Middle Turonian–Upper Turonian, Jebel Turonian–Lower Coniacian, Berda) (Coniacian). These units overlaid by Santonian age. microfacies interpreted as a shallow marine deposit lagoonal environment, shallowing upward supratidal subtidal settings scattered rudistic patch reefs. corresponding carbonate sediments affected several diagenetic stages starting at sea floor (early diagenesis), continuing near surface (meteoric diagenesis) ending subsurface (burial diagenesis).