Ogwashi-Asaba Fm
Period:
Paleogene, Neogene
Age Interval:
Oligocene - Miocene
Province:
Niger Delta - Outcrop
Type Locality and Naming
it is mainly found in Benin, Onitsha, and Owerri Provinces but extends into the eastern and western Nigeria (Whiteman, 1982).
Synonym: Lignite Shales (Parkinson, 1907)
References: Reyment,1965; Adeleye,1975; Kogbe,1976; Dessauvagie, 1975; Petters, 1978; Offodile, 1980; Whiteman, 1982; Benkhelil,1989; Okosun, 1992; Guiraud, 1993; Akandeet al., 1998; Zaborski et al., 1998; Jauro et al., 2007; Obaje, 2009; Nwajide, 2013
[Fig 1. Stratigraphic successions in the Benue Trough and the Nigerian sector of the Chad Basin]
Lithology and Thickness
It consists of white, blue, pink clays, cross-bedded sands, carbonaceous mudstones, shales and seams of lignite (Nwajide, 2013). Some of the lignite are estimated to be about 20ft thick (Whiteman, 1982).
Lithology Pattern:
Sandy claystone
Relationships and Distribution
Upper contact
Generally conformable or slightly unconformable with the overlying Benin Fm
Regional extent
Niger Delta outcrop
GeoJSON
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Fossils
Pollen
Age
Oligocene through Miocene? (NOTE: Top put here as base-Tortonian to allow overlying Benin Fm on graphics)
Age Span:
Beginning stage:
Rupelian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
33.90
Ending stage:
Tortonian
Fraction up in the ending stage:
0.0
Ending date (Ma):
11.63
Depositional setting
Upper floodplain environment (Okezie and Onuogu, 1985)
Depositional pattern:
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.