Miandoun Fm
Period:
Cretaceous
Age Interval:
Coniacian-Santonian
Province:
Chad S
Type Locality and Naming
Doba Basin. The Southern Chad Basin (consists of the Bongor, Doseo, Doba, and Salamat basins)
References: Lenhardt et al., 2025
[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)]
Lithology and Thickness
The formation is made up entirely of shales (Fig. 9 of Lenhardt et al., 2025)
Lithology Pattern:
Claystone
Relationships and Distribution
Lower contact
In Doba Basin, it conformably overlies the lower part of the Kome Fm.
Upper contact
K2 Fm, unconformably
Regional extent
Doba Basin, Southern Chad. It is a claystone equivalent in the sandstone of the upper part of the Kome Fm in the Doseo Basin. The GeoJSON used here spans both basins to emphasize the clay-rich interval.
GeoJSON
{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[16.55,9.52],[18.6,9.55],[19.77,10.03],[23.53,11.35],[22.84,9.98],[20.72,8.81],[18.28,8.06],[15.5,8.3],[14.04,8.94],[14.65,9.69],[16.55,9.52]]]]}}
Fossils
Age
Coniacian-Santonian (Doba Basin))
Age Span:
Beginning stage:
Coniacian
Fraction up in beginning stage:
0.00
Beginning date (Ma):
89.39
Ending stage:
Santonian
Fraction up in the ending stage:
1.0
Ending date (Ma):
83.65
Depositional setting
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