Ilaro Fm
Period:
Paleogene
Age Interval:
Lutetian – Priabonian
Province:
Dahomey Basin
Type Locality and Naming
This unit was showed by the GSN Borehole No. 2611, drilled north of Ilaro, shows a transition from the arenaceous lower parts of the formation into the underlying shales of the Oshosun Fm. From the GSN BH No.1582 drilled in Akinsinde, Jones and Hockey (1964) recorded over 80m of sands and shales comprising the formation. Ilaro Town (Nwajide, 2013).
References: Reyment, 1965; Adeleye, 1975; Kogbe,1976; Dessauvagie, 1975; 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
The sands are characteristically medium to coarse grained, clayey, and poorly sorted, with subangular grains. Pebble beds are common. Clays and shales intercalate sands.
Lithology Pattern:
Coarse-grained sandstone
Relationships and Distribution
Lower contact
Overlies the Oshosun Fm
Upper contact
Unconformably underlies the Benin Fm.
Regional extent
Dahomey Basin
GeoJSON
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Fossils
gastropods, lamellibranchs, foraminifera, ostracods, fish remains
Age
Eocene
Age Span:
Beginning stage:
Lutetian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
48.07
Ending stage:
Priabonian
Fraction up in the ending stage:
1.0
Ending date (Ma):
33.90
Depositional setting
Marine – regressive cycles (Nwajide, 1982). It represents a significant phase of sedimentation during the Eocene, capturing the transition from predominantly marine to more fluvial and deltaic conditions.
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.