Cenozoic

Cretaceous

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Mfamosing Limestone Formation

Mfamosing Limestone Fm

Period:

Cretaceous

Age Interval:

Cenomanian

Province:
Benue Trough South

Type Locality and Naming

The Asu River Gr in the Southern Benue Trough comprises the upward succession of the Ogoja Sandstone Fm, Awi Fm, Mamfe Fm, Abakaliki Fm (Abakaliki Shale Fm), and Mfamosing Limestone 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

Mfamosing Limestone Fm: this formation has an estimated thickness of 300m (Nwajide, 2013). It consists of a sanding upward shelly limestone with pelecypods, gastropods, and foraminifera as well as fragmentary crinoids and algae in the Odukpani area where its exposure is about 25m thick forming the very base of the formation. The next unit consists of an alternation of shales and limestones, with ammonites of Cenomanian age. The topmost unit consists of flaggy black shales and calcareous sandstones with Lower Turonian ammonites. 25m of the Mfamosing Limestone is exposed in the Odukpani area.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Lies on Abakaliki Fm

Upper contact

Conformably underlies the Eze-Aku Fm (Eze-Aku Shales Fm)

Regional extent

Southern Benue Trough

GeoJSON

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Fossils

Ammonites (Diploceras quadratum, Hysteroceras binum, Elobiceras lobitoense, Gyaloceras ibo, Mortoniceras ishiaguense, Acanthocerass p., Acompoceras sp.), gastropods, pelecypods (Anatinaagassizi, Panopea cf. gurgitis), foraminifera, brachiopods, crinoids, algae (Cayeuxia, Pianella – Reijers and Petters, 1997), plant remains, Thalassinoides and Planolites

Age

The entire Asu River Gr spans the Aptian through Cenomanian according to strat-chart used by Obaje (2013). Other than the Mfamosing Limestone Fm, which spans the Cenomanian, the other 4 formations are given sub-equal duration in the Aptian-Albian interval.

Age Span:

Beginning stage:

Cenomanian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

100.50

Ending stage:

Turonian

Fraction up in the ending stage:

0.1

Ending date (Ma):

93.45

Depositional setting

Transgression during Cenomanian, followed by a Regression in the upper part of this limestone formation.

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.