Early Cretaceous biostratigraphy and palaeoenvironment of the northern Western Desert, Egypt: an integrated palynological and micropalaeontological approach

Palynological analyses of the Lower Cretaceous Alam El Bueib and Alamein members of the Burg El Arab Formation from the OBA. S-C and OBA. 3-1/1A wells, northern Western Desert, Egypt yielded 44 species of pteridophytic spores, 13 gymnosperm pollen, 9 angiosperm pollen, 24 dinoflagellate cysts, a diverse assemblage of foraminiferal test linings, freshwater algae, tasmanitids, and fungal hyphae. Such palynological data allow for the identification of two sporomorph biozones arranged from youngest to oldest as: Afropollis jardinus-Murospora florida-Duplexisporites generalis Assemblage Zone (SM I; late Barremian-Aptian) and Dicheiropollis etruscus Total Range Zone (SM II; late Hauterivian-early Barremian). In addition, one dinocyst biostratigraphic phase (D I) which occurs in the Alam El Bueib and Alamein members has been recognized and is referred to the Berriasian-Barremian. The Alam El Bueib and Alamein members were deposited in a near-shore marine environment (inner shelf). This is indicated by the predominance of terrestrial microfloral elements and the relative poverty of dinocysts. The climate during the deposition of the Alam El Bueib and Alamein members was warm and humid to semi-arid. The presence of Orbitolina, which is considered an excellent biostratigraphic marker for Early and mid-Cretaceous rime as well as good palaeoecological and palaeoenvironmental indicator, added confidence to the obtained results.