GPSW-7 WELL, Sample 50: Early/Lower Cenomanian, Egypt

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Angiospermae
Afropollis jardunus
>20 rank
Dinophyceae - Gonyaulacales - Goniodomaceae
Dinopterygium cladoides Deflandre 1935
0,5 rank
Dinophyceae - Gonyaulacales - Areoligeraceae
Cyclonephelium vannophorum Davey 1969
1-4 rank
Dinophyceae - Gonyaulacales
Xiphophoridium alatum Sarjeant 1966
1-4 rank
Dinophyceae - Gonyaulacales - Gonyaulacaceae
Florentinia berran Below 1982
0,5 rank
see common names

Geography
Country:Egypt State/province:north Western Desert
Coordinates: 30.0° North, 28.0° East (view map)
Paleocoordinates:9.8° North, 23.1° East
Basis of coordinate:estimated from map
Time
Period:Cretaceous Epoch:Late/Upper Cretaceous
Stage:Cenomanian 10 m.y. bin:Cretaceous 5
Key time interval:Early/Lower Cenomanian Pollen zone: Afropollis jardinus/Elaterosporites klaszii
Age range of interval:100.50000 - 93.90000 m.y. ago
Stratigraphy
Formation:Bahariya
Local section:Bahariya Local bed:2037-2040 m
Local order:top to bottom
Stratigraphy comments: This formation was defined by Said (1962), and El Akkad and Issawi (1963) measured its type section which is located at Gebel El Dist, north of the Bahariya Oasis to be 170 m thick. It is overlain by the Abu Roash Formation and underlain by the Kharita Formation. The age of the Bahariya Formation is Cenomanian (Schlumberger, 1984); Cenomanian (Abdel Kireem and Ibrahim, 1987), based on foraminifera; and late Albian–early Cenomanian (El Beialy, 1994c), and early Cenomanian (Mahmoud and Moawad, 1999), based on palynology. The Bahariya Formation is subdivided into six units, of which unit I (upper pay) and unit IV (lower pay) are potential hydrocarbon-bearing zones based on lithologic and electric log markers (Schlumberger, 1984).
Lithology and environment
Primary lithology:gray lithified calcareous mudstone
Secondary lithology:black,gray lithified calcareous "shale"
Lithology description: The studied sequence ranges from 1918 to 2170 m (252 m thickness), and is composed of alternating grey calcareous mudstone to grey and black shale with minor sandstone interbeds.
Environment:shallow subtidal indet.
Geology comments: The sedimentary succession in the GPTSW-7 well starts at the base with the deposition of the Bahariya Formation, in a shallow marine and fluvio-deltaic environment (Schlumberger, 1984). The palynofloras from the early Cenomanian Bahariya Formation are dominated by pteridophytic spores, gymnosperm and angiosperm pollen (Fig. 6) and phytoclasts. Miospores are represented mainly by some smooth forms assigned to Deltoidospora and Triplano- sporites and by sculptured forms such as Cicatricosisporites, among
others. The high abundance of Crybelosporites suggests a fresh- water environment. The gymnosperm pollen are dominated by Araucariacites, produced by conifer vegetation developed on the relatively dry hinterland associated with ephedroids and Class- opollis/Circulina, both of which are commonly interpreted as derived from xerophytes (Schrank and Mahmoud, 1998). The percentage of marine dinocyst elements (dominant in some samples) is indicated (Fig. 6), and they are dominated by the marginate genus Cyclonephelium, thus indicating coastal to near- shore environment (Eshet et al., 1992; Li and Habib, 1996). The smooth- and thin-walled acritarch Leiosphaeridia is attributable to fresh to brackish water algae (Schrank and Mahmoud, 1998).
The AOM–Phytoclast–Palynomorph ternary plot of Tyson (1993) (Fig. 5A) as well as the ternary plot of Roncaglia and Kuijpers (2006) (Fig. 5B) suggest that the Bahariya Formation was deposited in a shallow marine to fluvio-deltaic setting with high terrestrial/ fresh-water influx.
Taphonomy
Modes of preservation:soft parts,original sporopollenin
Size of fossils:microfossils
Collection methods and comments
Collection excludes:all microfossils
Collection methods:core,chemical
Reason for describing collection:biostratigraphic analysis
Metadata
Database number:140428
Authorizer:C. Jaramillo Enterer:G. Doria
Research group:paleobotany
Created:2013-03-09 06:56:12 Last modified:2013-03-08 13:56:12
Access level:the public Released:2013-03-09 06:56:12
Creative Commons license:CC BY
Reference information

Primary reference:
43920. S. El Beialy, H. S. El Atfy, M. S. Zavada, E. M. El Khoriby, and R. H. Abu-Zied. 2010. Palynological, palynofacies, paleoenvironmental and organic geochemical studies on the Upper Cretaceous succession of the GPTSW-7 well, North Western Desert, Egypt. Marine and Petroleum Geology 27:370-385 [C. Jaramillo/G. Doria/G. Doria]