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Argiles de Mehden Yahya Formation
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Argiles de Mehden Yahya Fm base reconstruction

Argiles de Mehden Yahya Fm

Period: 
Devonian

Age Interval: 
Frasnian


Province: 
Reggane Basin, Ahnet Basin, Mouydir Basin

Type Locality and Naming

SW Algeria. Its Type Locality is at Mehden Yahya, while the Type Section is at Adrar Morat (Wendt et al., 2006).

Synonym: Argiles de Mehden Yahia Fm

References: Wendt et al., 2006.


Lithology and Thickness

The Argiles de Mehden Yahya Fm is about 170–700 m thick, and it is characterised at the base by some tens of metres of bituminous styliolinid grainstones and packstones with interlayers of black shales and limestone nodules, and at the top by a several hundred metres thick pile of polychrome clays (Wendt et al., 2006). The formation is a monotonous sequence of varicoloured (black, brown, grey, green, red, pink) clays with rare calcareous mudstone levels, ironstone nodules and layers and some millimetre-thin, fine-grained sandstone interlayers. The latter are characterized by low-angle cross-bedding capped by erosional (storm) events (Wendt et al., 2006).


Lithology Pattern: 
Claystone


Relationships and Distribution

Lower contact

It conformably overlies the Calcaires de Azzel Matti Fm (Reggane Basin) or Calcaires de Takoula Fm (Ahnet Basin)

Upper contact

It is conformably overlain by the Gres de Mehden Yahya Fm.

Regional extent

SW Algeria. 75,000 Km2


GeoJSON

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Fossils

Brachiopods, conodonts, nautiloids, ostracods, and rare fish remains.


Age 


Age Span: 

    Beginning stage: 
Frasnian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
378.90

    Ending stage: 
Frasnian

    Fraction up in the ending stage: 
0.65

    Ending date (Ma):  
373.83

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

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

Wendt J., Kaufmann B., Belka Z., Korn D (2008): Carboniferous Stratigraphy and Depositional Environments in the Ahnet Mouydir Area (Algerian Sahara). In: Facies. DOI 10.1007/s10347-008-0176-y

Wendt J., Kaufmann B., Belka Z., Klug C. & Lubeseder S. (2006): Sedimentary evolution of a Palaeozoic basin and ridge system: the Middle and Upper Devonian of the Ahnet and Mouydir (Algerian Sahara). Geol. Mag. 143 (3) pp. 269–299. doi:10.1017/S0016756806001737

Derder M, E.M., Henry B., Amenna M., Bayou B., Djellit H., Guemache M. A., Hemmi A. (2009): New structural implications for the central Sahara (Algeria), from the revisited Upper Carboniferous “Hassi Bachir” Formation: Paleomagnetic constraints. Tectonophysics, 463: pp.69–76.

Perron P., Guiraud M., Vennin E., Moretti I., Portier E., L. Le Pourhiet, M. Konaté (2018): Influence of basement heterogeneity on the architecture of low subsidence rate Paleozoic intracratonic basins (Reggane, Ahnet, Mouydir and Illizi basins, Hoggar Massif). Solid Earth, 9: pp.1239-1275.