Ajali Fm
Period:
Cretaceous
Age Interval:
Maastrichtian
Province:
Anambra Basin
Type Locality and Naming
Located close to the the Ajali River, northwest of the Ninth River Corner, near Enugu (Reyment, 1965)
Synonym: Ajali Sandstone Fm
References: Reyment, 1965; Adeleye, 1975; Dessauvagie, 1975; Kogbe, 1976; Petters, 1978; Offodile, 1980; Whiteman, 1982; Benkhelil,1989; Okosun, 1992; Guiraud, 1993; Akande et al., 1998; Zaborski et al., 1998; Jauro et al., 2007; Obaje, 2009; Nwajide, 2013
Lithology and Thickness
Consists of friable, white, cross-bedded sandstones with thin beds of white mudstone near the base. Large scale cross bedding is common and irregular bands of intra-formational breccia occur. It is said to be 1500ft thick along the Enugu escarpment north of the Oji River (Simpson, 1954).
Lithology Pattern:
Sandstone
Relationships and Distribution
Lower contact
Directly rests on the basement complex at River Oluwa in Ondo State, and rests on the Mamu Fm along the tributary of River Orle near Ugbeke village and south of the Ankpa Plateau (Nwajide, 2013)
Upper contact
Conformably underlies the Nsukka Fm.
Regional extent
Anambra basin
GeoJSON
{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[8.5,4.7],[8.7,5],[7.9,5.7],[8.3,8.5],[7.5,8.3],[6.7,7.5],[7.3,6.6],[7.4,6],[7.8,5.9],[8.1,5],[8.5,4.7]]]]}}
Fossils
Ostracods (Cytherella, Ovocytheridea, Bairdia sp.) Foraminifera (Haplophragmoides, Ammobaculites), Angiosperm leaves impressions
Age
middle Maastrichtian
Age Span:
Beginning stage:
Maastrichtian
Fraction up in beginning stage:
0.3
Beginning date (Ma):
70.33
Ending stage:
Maastrichtian
Fraction up in the ending stage:
0.7
Ending date (Ma):
67.88
Depositional setting
Regressive delta complex – Deltaic depositional setting (Whiteman, 1982), Fluvio-deltaic (Nwajide, 2013)
Depositional pattern:
Regressive
Additional Information
Compiler:
Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2024)- Stratigraphic Lexicon compiled from the following books:Nigeria: Its Petroleum Geology, Resources and Potential, by Arthur Whiteman, 1982; (Volume 1) Published by Graham and Trotman Ltd.A review of the Cretaceous System in Nigeria by P. M. Zaborski (1998) In Africa Geoscience Review, Vol.5, No.4, pp385-483.
Geology and Mineral Resources of Nigeria by Nuhu George Obaje, Published by Springer-Verlag Berlin Heidelberg 2009; http://www.springer.com/series/772.
Geology of Nigeria Sedimentary Basins, Nwajide C. S., 2013; Published by CSS Bookshops Limited, Lagos Nigeria.