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Tafraout Group

Tafraout Group
Stratigraphic range: Toarcian-Middle Aalenian 182–172 Ma Polymorphum-Murchisonae
The village of Zaouiat Ahançal (in the foreground) and the strata of the formations (in the background).
TypeGeological Group
Sub-units
  • "Aguerd-nˈTazoult Formation"
  • "Amezraï Formation"
  • Azilal Formation
  • Tafraout Formation
  • Tagoudite Formation
Underlies
Overlies
ThicknessApprox. 3000 m
Lithology
Primary
  • Limestone (Aguerd-nˈTazoult)
  • Clays (Amezraï)
  • claystone, conglomerate (Azilal)
  • Oolitic grainstones (Tafraout)
  • Siliclastic sandstones/mudstones, marls (Tagoudite)
Location
LocationAssif Tafraout
Coordinates31°30′N 5°34′W / 31.50°N 5.56°W / 31.50; -5.56
Approximate paleocoordinates26°36′N 3°24′W / 26.6°N 3.4°W / 26.6; -3.4
RegionHigh Atlas & Middle Atlas[1][2]
Country Morocco
Type section
Named forDouar Tafraout near Jbel/Assif Tafraout
Named byAbdellah Milhi
LocationRight side valley of Assif Tafraout flowing in a northerly direction. The village of Tafraout lies about 1 km to the north
Year defined1992
Thickness at type section~550 m (1,800 ft)
Tafraout Group is located in Morocco
Tafraout Group
Tafraout Group (Morocco)

The Tafraout Group (Also Tafraoute Group or Zaouiat Ahançal Group) is a geological group of formations of Toarcian-Aalenian (Lower Jurassic-Middle Jurassic) age in the Azilal, Béni-Mellal, Imilchil, Zaouiat Ahansal, Ouarzazate, Tinerhir, Tinejdad and Errachidia areas of the High Atlas (with the Tagoudite Fm reaching areas like Rich in the Middle Atlas) of Morocco.[3][4] The Group represents the remnants of a local massive Siliciclastic-Carbonate platform ("Tafraout Platform"), best assigned to succession W-E of alluvial environment occasionally interrupted by shallow marine incursions (tidal flat setting) and inner platform to open marine settings, and marks a dramatic decrease of the carbonate productivity under increasing terrigenous sedimentation.[5][6][7] Fossils include large reef biotas with richness in "lithiotid" bivalves and coral mounts ("Patch reef", Tafraout Formation[8]), but also by remains of vertebrates such as the sauropod Tazoudasaurus and the basal ceratosaur Berberosaurus, along with several undescribed genera.[9] While there have been attributions of its lowermost layers to the Latest Pliensbachian, the current oldest properly measured are part of the Earliest Toarcian regression ("MRST10"), part of the Lower-Middle Palymorphum biozone.[3]

This group is composed of the following units, which extend from west to east: the Azilal Formation (continental to subtidal, including its synonyms the "Aït Hani Formation", "Wazzant Formation" and the "Continental Series of Toundoute", as well includes part of the "Amezraï" & "Aguerd-nˈTazoult Formation"); the Tafraout Formation (deposited in a subtidal to inner platform environment, includes part of the "Aguerd-nˈTazoult Formation") & the Tagoudite Formation (including the "Tamadout Formation" & part of the "Amezraï Formation", shallow subtidal to open pelagic).[8] They are connected with the offshore Ait Athmane Formation and the deeper shelf deposits of the Agoudim 1 Formation.[10] Overall, this group represents a mixed carbonate-siliciclastic system of several hundred meters thick, dominated by deposits of shallow marine platforms linked to a nearby hinterland dominated by conglomerates.[11] The strata of the group extend towards the central High Atlas, covering different anticlines and topographic features along the mountain range.[12]

The after-effects of the Toarcian Oceanic Anoxic Event are also very present in the marginal marine strata of the Tafraout Group, with the Toksine Section recording a dramatic collapse on the scale of the Tethys of the neritic carbonate system.[13]

  1. ^ Peleogeographiques, C. E. R. (2002). "Les formations lithostratigraphiques jurassiques du Haut Atlas central (Maroc) : corrélations et reconstitutions paléogéographiques". Documents des laboratoires de géologie Lyon. 156 (1): 163. Retrieved 25 January 2022.
  2. ^ El Bchari, F.; Ibouh, H.; Souhel, A.; Taj-Eddine, K.; Canérot, J.; Bouabdelli, M. (2001). "Cadre stratigraphique et étapes de structuration de la plate-forme liasique d'Aït Bou Guemmez (Haut-Atlas central, Maroc)". Revista de Geociências. 16 (3): 163–172. Retrieved 25 January 2022.
  3. ^ a b Krencker, F.-N.; Fantasia, A.; El Ouali, M.; Kabiri, L.; Bodin, S. (2022). "The effects of strong sediment-supply variability on the sequence stratigraphic architecture: Insights from early Toarcian carbonate factory collapses". Marine and Petroleum Geology. 136: 105469. Bibcode:2022MarPG.13605469K. doi:10.1016/j.marpetgeo.2021.105469. ISSN 0264-8172.
  4. ^ Hauptmann, Manfred (1990). "Untersuchungen zur Mikrofazies, Stratigraphie und Paläogeographie jurassischer Karbonat-Gesteine im Atlas-System Zentral-Marokkos". Selbstverlag Fachbereich Geowissenschaften, FU Berlin. doi:10.23689/fidgeo-6546.
  5. ^ Ettaki, M; Ouahhabi, B.; Dommergues, J. L.; Meister, C.; Chellaï, E. H. (2011). "Analyses biostratigraphiques dans le Lias de la bordure sud de la Téthys méditerranéenne: l'exemple de la frange méridionale du Haut-Atlas central (Maroc)". Bulletin de la Société Géologique de France. 182 (6): 521–532. doi:10.2113/gssgfbull.182.6.521. Retrieved 25 January 2022.
  6. ^ Jenny, J. (1985). "Carte Géologique du Maroc au 1: 100.000, feuille Azilal". Notes et Mémoires du Service Géologique du Maroc. 339 (2): 1–104. Retrieved 25 January 2022.
  7. ^ Jenny, J. (1988). "Carte géologique du Maroc au 1/100 000: feuille Azilal (Haut Atlas central). Mémoire explicatif". Notes et Mémoires du Service géologique. 378 (1): 1–122. Retrieved 25 January 2022.
  8. ^ a b Milhi, Abdellah (1992). Stratigraphie, Fazies und Paläogeographie des Jura am Südrand des zentralen Hohen Atlas (Marokko). Selbstverlag Fachbereich Geowissenschaften, FU Berlin. OCLC 763029903.
  9. ^ Ibrahim, N.; Sereno, P. C.; Zouhri, S.; Zouhri, S. (2017). "Les dinosaures du Maroc–aperçu historique et travaux récents" (PDF). Mémoires de la Société Géologique de France. 180 (4): 249–284. Retrieved 21 April 2023.
  10. ^ Stüder, M.; du Dresnay, R. (1980). "Deformations synsedimentaires en compression pendant le Lias superieur et le Dogger, au Tizi n'Irhil (Haut Atlas central de Midelt, Maroc)". Bull. Soc. Géol. Fr. 34 (3): 391–397. doi:10.2113/gssgfbull.S7-XXII.3.391. Retrieved 28 March 2022.
  11. ^ Ettaki, Mohammed; Chellaï, El Hassane (2005-07-01). "Le Toarcien inférieur du Haut Atlas de Todrha–Dadès (Maroc) : sédimentologie et lithostratigraphie". Comptes Rendus Geoscience. 337 (9): 814–823. Bibcode:2005CRGeo.337..814E. doi:10.1016/j.crte.2005.04.007. ISSN 1631-0713.
  12. ^ Dresnay, Renaud du (1971-01-01). "Extension et developpement des phenomenes recifaux jurassiques dans le domaine atlasique marocain, particulierement au Lias moyen". Bulletin de la Société Géologique de France. S7-XIII (1–2): 46–56. doi:10.2113/gssgfbull.s7-xiii.1-2.46. ISSN 1777-5817.
  13. ^ Bodin, S.; Krencker, F. N.; Kothe, T.; Hoffmann, R.; Mattioli, E.; Heimhofer, U.; Kabiri, L. (2016). "Perturbation of the carbon cycle during the late Pliensbachian–early Toarcian: New insight from high-resolution carbon isotope records in Morocco". Journal of African Earth Sciences. 116 (2): 89–104. Bibcode:2016JAfES.116...89B. doi:10.1016/j.jafrearsci.2015.12.018.
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