Cenozoic

Cretaceous

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Ameki Formation

Ameki Fm

Period:

Paleogene

Age Interval:

Eocene

Province:
Niger Delta - Outcrop

Type Locality and Naming

The Ameki Gr is an upward succession of the Ameki Fm, the Nanka Fm, and the Nsugbe Fm. The Ameki Fm is well exposed along the railway cutting in the Ameki Villlage north of Umuahia (Reyment, 1965).

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

Ameki Fm consists of grey-green sandy clays, sandy claystones and sandstones at its type locality in Eastern Nigeria. Two main lithological divisions have been recognized: a lower with fine to coarse grained sandstones with intercalations of calcareous shale and thin shelly limestone, limestone nodules; and an upper with coarse cross bedded sandstones, bands of fine grey-green sandstones and sandy clay (Whiteman, 1982). The maximum thickness estimate for the formation ranges from 1200-1500m (Nwajide, 2013).

Lithology Pattern:

Sandy claystone

Relationships and Distribution

Lower contact

The facies of the Ameki Gr (hence the Ameki Fm as its basal unit) conformably overlie the Imo Shale Fm (Imo Fm) and they pinch out eastwards and westwards (Nwajide, 2013).

Upper contact

Overlain by the Nanka Fm

Regional extent

Niger Delta outcrop to Anambra Basin

GeoJSON

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Fossils

Whale remains (Pappocetus lugardi), Nautiloid (Deltoidnautilus nwajidei), gastropods (Siphonochelus nigeriensis, Turritella sp.)

Age

Lutetian – Early Bartonian (Whiteman, 1982).

Age Span:

Beginning stage:

Lutetian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

48.07

Ending stage:

Bartonian

Fraction up in the ending stage:

0.5

Ending date (Ma):

39.37

Depositional setting

The Ameki Fm was deposited in deltaic to shallow marine environment (Whiteman, 1982).

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.