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Bir Amrane Gr
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Bir Amrane Gr base reconstruction

Bir Amrane Gr

Period: 
Tonian

Age Interval: 
late Tonian


Province: 
Taoudeni Basin

Type Locality and Naming

This formation is mainly in the eastern portion (e.g., Hank sub-basin) of the Taoudeni Basin, which a vast intracratonic sedimentary basin spanning parts of Mauritania, Mali, Algeria, Burkina Faso and Guinea.

Synonym:

References: Martin-Monge et al., 2016

[Fig. 1: Location of the Taoudeni Basin Province and the four assessment units defined in the study by Brownfield et al. (2015).]

[Fig. 2: The Taoudeni Basin (Taupin et al., 2017)]

[Fig. 3: Abolag-1 well, R well and Atar Group type section stratigraphy, facies description and correlation in the Taoudeni Basin, and organic richness profile in the Abolag-1 well (Claue,1981; Rooney et al.2009; Trompette,1973; Albert-Villanueva et al. 2016).]

[Fig. 4: Generalized stratigraphy of the Taoudeni Basin in Mauritania. Lithostratigraphic name equivalences are provided for the Adrar, Hank and Hodh depocentres. The major discontinuities are numbered and reference to global glacial and tectonic events is provided. (From Martin-Monge et al. (2016) as modified after Lahondere et al. (2003, 2005).]


Lithology and Thickness

The Bir Amrane Gr is characterized at the base by sandstones, in the midsection by carbonates, and sandy pelites in the upper part (Martin-Monge et al., 2016). It is equivalent to the Assabet el Hassiane Gr in the Adrar Subbasin, and the Aioun Gr in the Hodh-Afolle Subbasin.


Lithology Pattern: 
Sandy claystone


Relationships and Distribution

Lower contact

Unconformably overlies the Eib Nous Fm of the El Mreiti Gr

Upper contact

Unconformably overlain by the Jbeliat Gr of latest Cryogenian glacial deposits.

Regional extent

Eastern part of the Taoudeni Basin.


GeoJSON

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Fossils


Age 

See Hohd Super Gr entry for discussion of age assignments to Neoproterozoic units. Assigned as upper Tonian (same as Assabet El Hassiane Gr in the Adrar Subbasin), because it is terminated by the scour and lowstand associated with the onset of the Cryogenian glacial episode

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.4

    Beginning date (Ma): 
888.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
0.9

    Ending date (Ma):  
748.00

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

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

Taylor, C. D. and Giles, S. A. (2013): Mineral Potential for Sediment-Hosted Copper Deposits in the Islamic Republic of Mauritania: Phase V, Deliverable 75. U.S. Geological Survey, Reston, Virginia

Martin-Monge, A., Baudino, R., Gairifo-Ferreira, L. M., Tocco, R., Badali, M., Ochoa, M., Haryono, S., Soriano, S., El Hafiz, N., Mez, J. H., Chacon, B., Brisson, I., Grammatico, G., Varade, R., and Abdallah, H. (2016): An unusual Proterozoic petroleum play in Western Africa: the Atar Group carbonates (Taoudeni Basin, Mauritania). In: Sabato Ceraldi, T., Hodgkinson, R. A. & Backe, G. (eds) Petroleum Geoscience of the West Africa Margin. Geological Society, London, Special Publications, 438, http://doi.org/10.1144/SP438.5

Kah, L. C., Bartley, J. K., and Stagner, A. F. (2009): Reinterpreting a Proterozoic enigma: Conophyton-Jacutophyton stromatolites of the Mesoproterozoic Atar Group, Mauritania. International Association of Sedimentologists, Special Publication, 41: pp. 277-295

Bradley, D. C., Motts, H. A., Horton, J. D., Giles, Stuart, and Taylor, C. D. (2015): Geologic Map of Mauritania (Phase V, Deliverables 51a, 51b, and 51c), Chap. A1 of Taylor, C. D., ed., Second Projet de Renforcement Institutionnel du Sector Minier de la Republique Islamique de Mauritanie (PRISM-II): U.S. Geological Survey Open-File Report 2013-1280-A1, 3 pl., http://dx.doi.org/10.3133/ofr20131280