Cenozoic

Cretaceous

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Araromi Formation

Araromi Fm

Period:

Cretaceous

Age Interval:

Late Cretaceous

Province:
Dahomey Basin

Type Locality and Naming

The Abeokuta Gr consists of upward succession of three formations – Ise Fm, Afowo Fm and Araromi Fm. The Araromi Fm type unit has a 307m interval between 1650 – 1957m in well Araromi-1 (Nwajide, 2013). Reynment (1965) informally named it Araromi Shale then Omatsola and Adegoke (1981) formalized it as Araromi Fm.

Synonym: Araromi Shale (Reynment,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; Zaborski et al., 1998; Jauro et al., 2007; Obaje, 2009; Nwajide, 2013

Lithology and Thickness

Araromi Fm: The formation consists of fine to medium sands at the base, overlain by seaward thickening shale (the Agbabu Shale), siltstone with thin limestones and marls. There are also thin bands of lignite and the shales are light grey to black and are highly carbonaceous (Nwajide, 2013). Synonym-

Lithology Pattern:

Sandy claystone

Relationships and Distribution

Lower contact

It rests on Afawo Fm

Upper contact

Ewekoro Fm

Regional extent

Dahomey Basin

GeoJSON

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Fossils

Sporomorphs (Cicatricosisporites sp., Pilosisporites trichopapillosus, Klukisporites pseudoreticulatus), Pollens (Multiporopollenites aff., M. muculosus), Ammonites (Pachydiscus, Sphenodiscus), Foraminifera,

Age

Maastrichtian – Early Paleocene (Nwajide, 2013); but charts seem to imply ends at K/T boundary.

Age Span:

Beginning stage:

Campanian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

83.65

Ending stage:

Maastrichtian

Fraction up in the ending stage:

1.0

Ending date (Ma):

66.04

Depositional setting

Alluvial fan setting at the basin edge of the sequence followed by a marine depositional environment within the Araromi sequence.

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.