Cenozoic

Mesozoic

Information provided by geoscience team at Ahmadu Bello University, Zaria, Nigeria --see About

K2 Formation

K2 Fm

Period:

Cretaceous

Age Interval:

Campanian-Maastrichtian

Province:
Chad S

Type Locality and Naming

Doba Basin and Doseo Basin. The Southern Chad Basin (consists of the Bongor, Doseo, Doba, and Salamat basins)

References: Lenhardt et al., 2025; Dou et al., 2022

[Fig. 1: Simplified map of the West and Central African Rift System showing the major basins (from Lenhardt et al., 2025).]

[Fig. 2: Stratigraphy of the basins of the Central African Rift System (from Lenhardt et al., 2025)]

[Fig. 3: Composite stratigraphic column of the Doseo Basin. R_t– resistivity; GR – natural gamma (Fig 4. of Dou et al., 2022)]

[Fig. 4: Comprehensive column of sedimentary strata in the Doseo Basin of the Southern Chad Basin (from Hong et al., 2024)]

Lithology and Thickness

The formation is made up of shaly sandstone and was deposited during the second Rift Episode II (Fig. 9 of Lenhardt et al., 2025). According to fig. 4 of Dou et al. (2022), the K2 Formation in Doseo Basin is about 150 – 400 m thick and made up of an almost equal amount of sandstones and mudstones.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

unconformably onto the Miandoun Fm in the Doba Basin; and unconformably on the Koma Fm in the Doseo Basin

Upper contact

Unconformably overlain by Alluvium (Paleocene is a hiatus) in the Doba Basin, and is overlain unconformably by the T1 Fm in the Doseo Basin

Regional extent

Doba Basin and Doseo Basin, Southern Chad

GeoJSON

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Fossils

Age

Campanian-Maastrichtian

Age Span:

Beginning stage:

Campanian

Fraction up in beginning stage:

0.00

Beginning date (Ma):

83.65

Ending stage:

Maastrichtian

Fraction up in the ending stage:

1.0

Ending date (Ma):

66.04

Depositional setting

Fluvial-lacustrine (Dou et al., 2022)

Depositional pattern:

Additional Information

Compiler:

Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2025) - Stratigraphic Lexicon compiled from the following articles:

Lenhardt, N., Omietimi, E. J., Edegbai, A. J., Schwark, L., Catuneanu, O., Fairhead, J. D., Gotz, A. E. (2025): Traversing the rift: A review of the evolution of the West and Central African Rift System and its economic potential. Earth-Science Reviews, 261: pp. 1-39

Dou L., Xiao K., Du Y., Wang L., Zhang X., Cheng D., Hu Y. (2022): Exploration discovery and hydrocarbon accumulation characteristics of the Doseo strike-slip and inverted basin, Chad. Petroleum Exploration and Development, 49 (2): pp.247-256.