Cenozoic

Cretaceous

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Eze-Aku Formation

Eze-Aku Fm

Period:

Cretaceous

Age Interval:

Upper Cretaceous

Province:
Benue Trough South

Type Locality and Naming

Eze-Aku Gr consists of the consists of the upward succession of Igumale Fm,), Nkalagu Limestone Fm and. Eze-Aku Shales Fm (Eze-Aku Fm). Eze-Aku Fm: type locality is at Eze-Aku town, Awgu Division (Geological Survey of Nigeria and Shell D’Arcy, in International Stratigraphic Lexicon 1956)

Synonym: Eze-Aku Shale 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

Eze-Aku Fm: Upper unit of Eze-Aku Gr in Benue Trough South consists of hard, flaggy, calcareous shales and siltstones which are grey or black in color and have yielded many impressions of Inoceramus. In the Southern Benue Trough, the Eze-Aku Shale is said to be about 2000 ft thick by Cratchley and Jones (965).

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

Lies conformable beneath the Awgu Fm

Upper contact

Lies over the Nkalagu Fm

Regional extent

Southern to Central Benue Trough

GeoJSON

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Fossils

Foraminifera, Ammonites, Gastropods

Age

Eze-Aku Gr in this region spans the Turonian; therefore the 3 formations are given semi-equal durations.

Age Span:

Beginning stage:

Turonian

Fraction up in beginning stage:

0.7

Beginning date (Ma):

90.74

Ending stage:

Turonian

Fraction up in the ending stage:

1.0

Ending date (Ma):

89.39

Depositional setting

Marine depositional environment due to marine transgression in the Lower Benue Trough during the Turonian. It records the deep marine conditions that prevailed in the region, with sedimentation influenced by both pelagic and hemipelagic processes.

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.