Cenozoic

Mesozoic

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Hudi Chert Formation

Hudi Chert Fm

Period:

Paleogene

Age Interval:

Eocene

Province:
Sudan E

Type Locality and Naming

Atbara Basin, east of Blue Nile Basin, East Sudan. The Hudi chert was first identified by Cox [1932] from Hudi Railway Station about 40 km NE of Atbara.

References:

[Fig. 1: Tectonic model of the West and Central African Rift System (WCARS) and the Central African Shear Zone (CASZ). The red arrow and rectangle represent the Shendi-Atbara Basin and study area (Modified after Fairhead, 1988b).]

[Fig. 2: Stratigraphy of the CARS (modified from Schull, 1988; McHargue et al., 1992; Guiraud and Bosworth, 1997; Gani et al., 2009; Wolela, 2009; Dou et al., 2013, 2018, 2023a; Liu and Chen, 2014; Eisawi et al., 2015; Mohammed et al., 2016; Bussert et al., 2018; Yassin et al., 2017; Mohammed Yasin et al., 2019; Gao et al., 2023)]

[Fig. 3. Stratigraphic chart of Shendi-Atbara Basin showing the rock units succession and the basin evolution (from Babkir et al., 2023).]

[Fig. 4. Map showing the location of WCARS basins in between major cratonic areas in Africa, including the subdivision into a Western, Arabian-Nubia, and Southern Austral block (modified from Genik, 1993; Meert and Lieberman, 2008).]

Lithology and Thickness

Characterized by cherts (Fig. 9 of Lenhardt et al., 2025). Composed of sub-rounded boulders, yellowish brown in color, which range in size from 5 to 20 cm. The rocks are very hard and fossiliferous with Gastropods fossils (Abujaball et al., 2021).

Lithology Pattern:

Chert

Relationships and Distribution

Lower contact

Shendi Fm, unconformably (Paleocene is absent)

Upper contact

Wadi Awatib Fm

Regional extent

Atbara Basin, Sudan

GeoJSON

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Fossils

Gastropods - Pseudoceratodes rex, P. irregularis (Blanckenhorn 1900), P. mammuth (Blanckenhorn 1900), Pila colchesteri; and plant fossil (Medeni, 1972; Abujaball et al., 2021)

Age

Eocene

Age Span:

Beginning stage:

Ypresian

Fraction up in beginning stage:

0.00

Beginning date (Ma):

56.00

Ending stage:

Priabonian

Fraction up in the ending stage:

1.0

Ending date (Ma):

33.90

Depositional setting

fluvial setting (Babkir et al., 2023). The Hudi chert rocks were regarded as lacustrine chalky posits that have been silicified into chert (Andrew et al., 1945; Cox, 1932). The source of silica was probably from silica flow from the young volcanic activity of Jebel Umm-Marafieb of NW Berber (Abujaball et al., 2021).

Depositional pattern:

Additional Information

Compiler:

Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2024) - Stratigraphic Lexicon compiled from the following books:

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

Babkir, M.D.B.H., Nton, M.E., Eisawi, A.A.M. (2023): Depositional environment and hydrocarbon exploration potential based on sedimentary facies and architectural analysis of the Upper Cretaceous Shendi Formation in Musawwarat-Naga area, Shendi-Atbara Basin, Sudan. Earth Sci. Research Jour., 27(2): 109-128