Cenozoic

Cretaceous

Neoproterozoic

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Wurno Formation

Wurno Fm

Period:

Cretaceous

Age Interval:

Late Maastrichtian

Province:
Sokoto Basin (S. Iullemmeden Basin)

Type Locality and Naming

The Rima Gr is divided into three packages–Taloka, Dukamaje, and Wurno formations (Nwajide, 2013).The base of the sequence is Taloka Fm, the Middle sequence is Dukamaje Fm and the Top of the sequence is Wurno Fm. The type section of the Taloka Fm is at Taloka, near Goronyo, Sokoto Province (Whiteman, 1982). The formation is exposed on the hill southwest of Dukamaje (Whiteman, 1982). The type section is behind Wurno village in a 50m exposure (Nwajide, 2013).

Synonym: Taloka Fm Lower Sandstones and Mudstones (Jones, 1948), Dukamaje Fm (Clay-Shale Group (Raeburn and Tattam, 1930).

Reference section: Reyment,1965; Adeleye,1975; Kogbe,1976; Dessauvagie, 1975; Petters, 1978; Offodile, 1980; Whiteman, 1982; Benkhelil,1989; Okosun, 1992; Guiraud, 1993; Akandeet al., 1998; Zaborskiet al., 1998; Jauroet al., 2007 ; Obaje,2009; Nwajide, 2013

[Fig. 1. Stratigraphic successions in the Nigerian sector of the lullummeden Basin (Sokoto Basin)]

Lithology and Thickness

Wurno Fm consists of thin friable fine-grained sandstones intercalated with soft mudstone and shale (Ogilbee and Anderson, 1965). The formation locally contains carbonaceous matter and iron sulfide and characterized by load casts, bioturbation and flaser bedding (Nwajide, 2013).

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Overlies the Dukamaje Fm

Upper contact

Overlain by the Dange Fm (base of Sokoto Gr)

Regional extent

Iullemmeden Basin

GeoJSON

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Fossils

Rima Gr contains Mussels, Mososaurian bones, fish teeth (Raeburn and Tattam, 1930), Foraminifera (Miliamina, Trochammina), Ophiomorpha, Skolithos, thalassinoides, worm fecal castings, Ammonites (Lybicoceras), Arenaceous foraminifera (Miliammina, Trochammina, Haplophragmoides, Textularia, Ammobaculites, Ammodiscus), Mososaurus fossil (Mososaurusnigeriensis), fossil fish (Lamnaappendiculata, Lamnalibyca, Schizorhizastroemeri, Sphanoduslybicus), Ammonite (Lybicocerasafikpoensis), bivalves, echinoids, corals, Pelecypods, gastropods, Ammonites (Lybicoceras), Foraminifera (Ammodiscus, Nonion, Nonionella, Gavelinella, Orbignyainflata)

Age

Maastrichtian (assumed here to be the upper third)

Age Span:

Beginning stage:

Maastrichtian

Fraction up in beginning stage:

0.67

Beginning date (Ma):

68.06

Ending stage:

Maastrichtian

Fraction up in the ending stage:

1.0

Ending date (Ma):

66.04

Depositional setting

Taloka Fm showed the initial stages of deposition in fluvial and deltaic environments, followed by transition into shallow marine settings of the Dukamaje Fm and followed by the Wurno Fm which indicates a further deepening and stabilization of marine conditions, with the development of a carbonate platform.

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.