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Tafraout Group
Geological formations in Morocco / From Wikipedia, the free encyclopedia
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 and Errachidia areas of the High Atlas of Morocco.[5] 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.[6] Fossils include large reef biotas with richness in "lithiotid" bivalves and coral mounts ("Patch reef", Tafraout Formation[7]), but also by remains of vertebrates such as the sauropod Tazoudasaurus and the basal ceratosaur Berberosaurus, along with several undescribed genera.[8] 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.[5] This group is composed of the following units, which extend from west to east: the Azilal Formation (continental to subtidal, including its synonyms the "Wazzant Formation" and the "Continental Series of Toundoute"); the Amezraï Formation (intertidal environment); the Aguerd-nˈTazoult Formation (intertidal environment); the Tafraout Formation (deposited in a subtidal to inner platform environment) & the Tagoudite Formation (including the "Tamadout Formation", shallow subtidal to open pelagic).[7] They are connected with the offshore Ait Athmane Formation and the deeper shelf deposits of the Agoudim 1 Formation.[9] 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.[10] The strata of the group extend towards the central High Atlas, covering different anticlines and topographic features along the mountain range.[11]
Tafraout Group | |
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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). | |
Type | Geological formation |
Sub-units |
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Underlies |
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Overlies |
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Area | High Atlas[1][2] |
Thickness | Aprox. 3000 m |
Lithology | |
Primary |
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Location | |
Location | Central High Altas |
Coordinates | 31.50°N 5.56°W / 31.50; -5.56 |
Approximate paleocoordinates | 26.6°N 3.4°W / 26.6; -3.4 |
Region | High Atlas[3][4] |
Country | ![]() |
Type section | |
Named for | Douar Tafraout near Jbel/Assif Tafraout |
Named by | Abdellah Milhi |
Location | Right side valley of Assif Tafraout flowing in a northerly direction. The village of Tafraout lies about 1 km to the north |
Year defined | 1992 |
Thickness at type section | ~550 m (1,800 ft) |
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.[12]