Bio- and microfacies analysis and depositional sequences of Bir Dakhl, North Eastern
Desert, Egypt
Mahmoud Hefny1, Mohamed Youssef1, 2,
1.
2.
Department of Geology, Faculty of Science, South Valley University, PO Box 83523 Qena, Egypt.
Department of Geology and Geophysics, College of Science, King Saud University, PO Box 2455, Riyadh
11451, Saudi Arabia.
Emails: mahmoud.hefny@svu.edu.eg, mymohamed@ksu.edu.sa,
Abstract:
The integration of fossil content, nature of sedimentary structures observed, petrographic examination
and microfacies analysis In Bir Dakhl section, northeastern Desert, enable to reconstruct the
environmental conditions that prevailed during the deposition of the studied Cretaceous-Paleogene Syrian
arc sequences and closely linked to the sequence stratigraphic interpretation. The study of benthic
foraminifera shows that the recognized biofacies assemblages (A and D) are influenced by sea-level
changes and could be good indicators for system tract and unconformities. Facies analysis study is
resulted in the recognition of six mixed siliciclastic-carbonate microfacies types, which characterize shelf,
slope and platform development in the studied section where sedimentation is either dominated by clastic
deposition or carbonate deposition. The Micofacies Types of carbonates are comparable with standard
microfacies Types (SMF) 3, 9, 18, 19, and 23 which evaluated to be occurring in basin, open deep shelf
margin or platform settings. The overall lithostratigraphic sequence indicates that the Bir Dakhl sequences
were most likely deposited during a major transgressive and regressive cycle of the sea during the
Cretaceous-Paleogene time and led to the formation of five 3rd –order depositional sequences, which are
bounded by unconformities and their correlative conformities.
Key words: Biofacies, microfacies, sequence stratigraphy, Bir Dakhl, North Eastern Desert, Egypt.