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Cretaceous

Jurassic

Triassic

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Compiled by: Jacques LeBlanc (2022), Stratigraphic Lexicon: The Sedimentary Formations of The Republic of Niger, Africa. Colnes Publishing (Tallin, Estonia), 365 pp. For more information see "About"

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Oleki Formation

Oleki Fm

Period:

Cretaceous, Paleogene

Age Interval:

Lower Cretaceous to Paleocene (8c)

Province:
East Niger Rift Basin - Bilma Sub-basin

Type Locality and Naming

Mount Oleki at about 60 km NW of Séguédine (Type section stratigraphy in Fig. 2); named by Faure, 1966, p. 257, 258, 274, 285.

References: Faure, 1966; Fabre et al., 1983;

Synonym: Formation de l’Oleki

Equivalent(s): The combined Tiffa Fm, Cheffadène Fm, Arentigué Fm, Séguédine Fm and Emi-Bao Fm at the center of the Bilma Sub-Basin, as well as the combined Achegour Fm, Exerza Fm, Zoo Baba Fm, Kafra Fm and Bilma Fm in the south of the Bilma Sub-Basin (Fig. 1).

[Figure 1. Representative diagram of the facies variations towards the North of the Bilma basin (Faure, 1966, p. 281). The Oleki Fm would be to the right, where all the facies come together.]

Lithology and Thickness

Continental formation comprising coarse sandstones with conglomerate levels and kaolinitic siltstones with coarse quartz. The stratification is lenticular or cross-bedded. Thickness is 164 m at the type locality (Fig. 2)

[Figure 2. Lithological succession of the Oleki Fm at the type locality (Faure, 1966, p. 259).]

Lithology Pattern:

Coarse-grained sandstone

Relationships and Distribution

Lower contact

Precambrian is below

Upper contact

Overlain by Chad Fm

Regional extent

See Fig. 1

GeoJSON

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Fossils

Age

Lower Cretaceous to Paleocene

Age Span:

Beginning stage:

Aptian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

117.30

Ending stage:

Thanetian

Fraction up in the ending stage:

1.0

Ending date (Ma):

56.00

Depositional setting

Continental

Depositional pattern:

Additional Information

Compiler:

Jacques LeBlanc (2022), Stratigraphic Lexicon: The Sedimentary Formations of The Republic of Niger, Africa. Colnes Publishing (Tallin, Estonia), 365 pp. https://doi.org/10.47909/978-9916-9760-6-7 (or via https://sites.google.com/site/leblancjacques)