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Quartzites de Hamra Formation
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Quartzites de Hamra Fm base reconstruction

Quartzites de Hamra Fm

Period: 
Ordovician

Age Interval: 
Floian-Dapingian


Province: 
Ahnet Basin, Mouydir Basin

Type Locality and Naming

Synonym: Hamra Quartzite Fm; Hamra Fm

References: Peron et al., 2018, 2019


Lithology and Thickness

“The Quartzites de Hamra is one of the most important petroleum reservoirs in Algeria’s Paleozoic basins. For example, hosts a productive gas field in central Ahnet Basin. This formation has homogeneous facies and a broad regional extent; it was deposited on the margin of the late-Early Ordovician sea in a shallow-marine environment, but its sedimentological and stratigraphic context remains poorly understood at the regional scale. The sandstone is intensely bioturbated “Skolithos pipe-rock”. The formation underwent significant subsidence during its history, resulting in major siliceous diagenesis that altered its mechanical properties and caused a complete loss of porosity. Nevertheless, it was naturally fractured by several fracture systems whose infilling with late-stage siliceous minerals filled those fractures; however, our knowledge remains very incomplete. The ‘Quartzites de Hamra’ were deposited on a sandy tidal ramp influenced by waves. Their stratigraphic architecture results from the combined effects of relative sea-level variations and deformation episodes associated with the repeated reactivation of Pan-African structures.” (extracts from Nihed Kracha, 2012, Thesis Univ. Lille; translated from the French).


Lithology Pattern: 
Coarse-grained sandstone


Relationships and Distribution

Lower contact

It conformably overlies the Leg Gres d'El Atchane Fm.

Upper contact

It is conformably overlain by Les Gres de Ouargla Fm.

Regional extent

Widespread in SW Algeria, 75,000 Km2. Corresponds to the middle of Les Gres Fm of Reggane Basin.


GeoJSON

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Fossils

Skolithos trace fossils.


Age 

lower-middle Floian

Age Span: 

    Beginning stage: 
Floian

    Fraction up in beginning stage: 
0.2

    Beginning date (Ma): 
475.92

    Ending stage: 
Floian

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
474.17

Depositional setting

Sandy tidal ramp influenced by waves


Depositional pattern:  


Additional Information


Compiler:  

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

Kracha, N. (2012): Relations entre sedimentologie, fracturation naturelle et diagenese d’un reservoir a faible permeabilite. Application aux reservoirs de l’Ordovicien, Basin de l’Ahnet, Sahara Central, Algerie. Doctorate thesis, Univ. Lille 1, France. (accessed via http://doc.univ-lille1.fr)

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.