Palynostratigraphy of Jurrasic to Lower Cretaceous sequences from the Eastern Desert of Egypt

Abstract

Well-preserved miospore assemblages are described from three deep exploration wells in the northern part of the Eastern Desert, Egypt. The composite succession in the three boreholes investigated comprises eight formations assigned to the Jurassic-Lower Cretaceous. The Jurassic/Cretaceous boundary in the subsurface of the studied area is unconformable. A stratigraphical break of varying magnitude exists in the three wells. Miospore analysis of the studied wells yielded about 186 miospore species belonging to 80 genera. Among these, 116 pteridophytic spore species are related to 53 genera, 39 gymnosperm pollen species to 15 genera and 31 angiosperm pollen species to 12 genera. Accordingly, six miospore biozones are recognised, three in the Jurassic and three in the Lower Cretaceous. In ascending stratigraphical order, these are: Classopollis/Circulina-Deltoidospora spp. Assemblage Zone (?Toarcian-Aalenian); Verrucosisporites spp.- Converrucosisporites spp.- Trilobosporites spp. Assemblage Zone (Early Bajocian-Callovian); Cicatricosisporites spp.- Contignisporites spp. Assemblage Zone (Oxfordian-Kimmeridgian); Stellatopollis spp.-? Schrankipollis spp. Assemblage Zone (Barremian); Afropollis operculatus-Brenneripollis-Tricolpites spp. Assemblage Zone (Aptian); and Crybelosporites pannuceus-Afropollis jardinus-Tricolporopollenites Assemblage Zone (Early Albian). These biozones are compared with other contemporaneous microfloral assemblages from the Northern Gondwanan Realm.