Akata Fm
Period:
Paleogene
Age Interval:
Cretaceous, Paleocene, Neogene
Province:
Niger Delta - Offshore
Type Locality and Naming
The Cenozoic section of the Niger Delta is divided into three formations, representing prograding depositional facies that are distinguished mostly on the basis of sand-shale ratios. The type unit for the claystone-dominated Akata Formation is the Akata-1 well, a wildcat drilled 80 km east of Port Harcourt. The interval of interest is 7,180 11,121 ft. (3,941 ft. or 1,182.3 m). The bottom of well did not reach the base of the formation.
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; Jauro et al., 2007; Zaborski et al., 1998; Obaje,2009; Nwajide, 2013
[Fig 1. Stratigraphic successions in the Benue Trough and the Nigerian sector of the Chad Basin]
Lithology and Thickness
The Akata Fm at the base of the delta is of marine origin and is composed of thick shale sequences (potential source rock), turbidite sand (potential reservoirs in deep water), and minor amounts of clay and silt. The sediments were deposited in prodelta environments. The sand percentage here is generally less than 30% dark gray uniform shales, especially in its upper part. It tends to be sandy in the upper parts from where it grades into the Agbada Formation. The top of the formation is not clearly defined.
Lithology Pattern:
Claystone
Relationships and Distribution
Lower contact
Overlie oceanic crust or older continental margin sediments
Upper contact
Overlain conformable by the Agbada Fm
Regional extent
Niger Delta offshore. The formation underlies the whole of the Niger Delta complex south of the Imo Shale Fm outcrop area and is taken as the down-dip equivalent of the Agbada Fm sandy-claystone lithofacies (Whiteman,1982, p. 131). At present the Akata facies is being deposited on the slope to lower part of the prodelta slope.
GeoJSON
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Fossils
fossil spores, foraminifera and calcareous nannoplankton.
Age
Late Cretaceous-Recent. The average span is put here for display purposes as base-Cenomanian (underlying oceanic crust begins in Albian?) to base-Miocene using the mid-point of the delta-facies transect of Fig.7 in the USGS report.
Age Span:
Beginning stage:
Cenomanian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
100.50
Ending stage:
Chattian
Fraction up in the ending stage:
1.0
Ending date (Ma):
23.04
Depositional setting
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.