Palynostratigraphy and paleoenvironmental significance of the Cretaceous succession in the Gebel Rissu-1 well, north Western Desert, Egypt Salah El Beialy a,⇑ , Maher El-Soughier b , Sayed Abdel Mohsen b , Haytham El Atfy a a Geology Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt b Geology Department, Faculty of Science, South Valley University, Aswan, Egypt article info Article history: Received 6 May 2010 Received in revised form 13 October 2010 Accepted 27 October 2010 Available online 5 November 2010 Keywords: Palynostratigraphy Cretaceous Pollen Spores Egypt abstract Palynological investigation of the Cretaceous Abu Roash, Bahariya, Kharita, Alamein, Alam El Bueib and Betty formations, encountered in the Gebel Rissu-1 well, north Western Desert, Egypt yielded 27 species of pteridophytic spores, 24 of gymnosperm pollen, 25 of angiosperm pollen and 11 of dinoflagellate cysts in addition to some acritarchs, foraminiferal test linings and freshwater algae. This enabled us to recog- nize five miospore biozones arranged from youngest to oldest as: Classopollis brasiliensis–Afropollis cf. kahramanensis–Dichastopollenites ghazalataensis Assemblage Zone (Late Cenomanian); Elaterosporites klaszii–Sofrepites legouxae–Afropollis jardinus Assemblage Zone (Middle/Late Albian–Early Cenomanian); Pennipollis peroreticulatus–Duplexisporites generalis-Tricolpates Assemblage Zone (Early Aptian–Early Albian); Tucanopollis crisopolensis–Afropollis sp. Assemblage Zone (Barremian) and Appendicisporites cf. tricornitatus–Ephedripites spp. Assemblage Zone (Late Neocomian). The Early Cretaceous Kharita, Alam El Bueib and the Betty formations encountered in the Gebel Rissu-1 well are interpreted to indicate oxic proximal and distal shelf deposits, characterized by type III/IV, V ker- ogen, which is gas prone but having little potential to produce hydrocarbons. The Upper Cretaceous Abu Roash and Bahariya formations are characterized by a distal suboxic–anoxic and marginal dysoxic–anoxic environment, and their kerogen type III/II indicates gas/oil prone nature. The Bahariya and Kharita Albian–Cenomanian sediments in the present study witnessed the onset of a semi-arid to arid climate, with local or seasonal humid conditions, based on the continuous high abundance of the elaterates pollen and Afropollis-producing plants that inhabited the paleotropical humid coastal plains. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The subsurface Cretaceous deposits of the north Western Desert, Egypt have been the subject of several palynological studies that have primarily concentrated on taxonomy, palynostratigraphy and paleoenvironmental interpretations. These studies were initi- ated by the work of Urban et al. (1976) followed by a series of pa- pers listed in El Beialy et al. (2008, 2010a) and Zobaa et al. (2008). El Beialy et al. (2008) investigated the Bahariya Formation from the GPTSW-7 well to throw light on the palynostratigraphy, palynofa- cies and source rock evaluation. Zobaa et al. (2008) studied the ker- ogen and palynomorphs contents in the Bahariya Formation and Abu Roash ‘‘G’’ Member sediments in the Razzak 7 well, north Western Desert, Egypt, to examine the changes in their organic components and use them to interpret paleoenvironmental condi- tions and biostratigraphy. El Beialy et al. (2010a) studied the sub- surface Cretaceous of the Abu Roash and Bahariya formations in well GPTSW-7, based on the palynological analyses of 71 cuttings samples, of which 24 have also been analyzed for geochemistry, in addition to three sidewall cores analyzed for vitrinite reflectance (R o ). They also recognized four palynological zones and three subz- ones in addition to a poorly fossiliferous interval ranging in age from Coniacian–Santonian to Early Cenomanian. The palynology and palynostratigraphy of the Alam El Bueib Formation in the Gebel Rissu-1 borehole (Lat. 29°57 0 39.5 00 N and Long. 30°24 0 15 00 E) drilled by AMOCO (1969) in the north Western Desert (Fig. 1) has been previously studied by Obeid (2003) and is assigned to the Early Aptian age. In this work we present a pal- ynological, palynostratigraphical and palynofacies investigation of 20 cuttings samples collected from different formations in the same well (Fig. 2), except the Alamein Formation, for which no samples are available. The objectives of this study are to: (1) identify and document the palynofloral ranges for pollen, spores and dinoflagellate cysts, (2) construct a palynostratigraphic framework for the studied suc- cession, (3) analyze palynofloral and palynofacies data to assist in subsequent environmental interpretations and hydrocarbon evaluation. 1464-343X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jafrearsci.2010.10.007 ⇑ Corresponding author. Fax: +20 50 2246781. E-mail address: syelbeialy@mans.edu.eg (S. El Beialy). Journal of African Earth Sciences 59 (2011) 215–226 Contents lists available at ScienceDirect Journal of African Earth Sciences journal homepage: www.elsevier.com/locate/jafrearsci