Cenozoic

Cretaceous

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Igumale Formation

Igumale Fm

Period:

Cretaceous

Age Interval:

Upper Cretaceous

Province:
Benue Trough South

Type Locality and Naming

Eze-Aku Gr consists of the upward succession of Igumale Fm,), Nkalagu Limestone Fm and. Eze-Aku Shales Fm (Eze-Aku 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

Igumale Fm: The Lower unit of Eze-Aku Gr in Benue Trough South is primarily of sandstones (fine to coarse-grained), shales (dark grey to black, suggesting deposition in low-energy environments), and limestones.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Lies unconformably over the Asu River Gr (Mfamosing Fm)

Upper contact

Lies conformable beneath the Ngumale 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 Turonian; therefore the 3 formations are given semi-equal durations. But top black shales of underlying Mfamosing Limestone Fm has lowermost Turonian ammonites)

Age Span:

Beginning stage:

Turonian

Fraction up in beginning stage:

0.1

Beginning date (Ma):

93.45

Ending stage:

Turonian

Fraction up in the ending stage:

0.4

Ending date (Ma):

92.10

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.