Tafraout Group

The group is alocated within of the mountain belt that is the Central High Atlas, formed by the inversion of a rift from the Triassic-Jurassic periods, due to Cenozoic tectonic activity. Overall region's structure comes from four main tectonic phases: the pre-rift phase tied to the formation of Pangaea, the syn-rift phase during the Late Permian to Late Triassic, influenced by the opening of the Atlantic Ocean and Tethys Ocean, and the post-rift phase, where Jurassic-Cretaceous carbonate platforms formed. Several tectonic events during the Triassic-Jurassic boundary reactivated normal faults, leading to the dominance of marls during the Middle Liassic to Toarcian. Azilal Formation Informally known as "Marnes chocolat" in the Azilal region, and represents a continental to marginal marine unit made up of red brown marls, silts (microsandstones) and conglomerates with centimetric quartz dragees. More marine-influenced sections near Beni Mellal are composed by a succession of reddish-brown tints with terrigenous dominance: sandstone, clays with paleosols and sandstone limestones sometimes dolomitized, with marmorized levels in paleosols towards the N. Here, it evolves from lower sections with transition from sandstone to limestone and/or sandstone to clay, with a thin level of green marls locally rich in ostracods. Then is followed by subtidal term, represented by an oolitic limestone with fine lamellibranch bioclasts and variable percentages of quartz and sandstone with calcareous cement and rare oolites drawing on the surface mega-ripples of 3 to 5 m in wavelength. It ends with supratidal deposits made of coarse sandstone gradually changing to red Marls with "fluer" structures and locally to paleosols with fluvial decametric channeling lenses. Oolitic grainstones and packstones, cross-stratified with alpha-type ooids, dominate basal and upper parts, indicating high-energy shoals. Oncolitic and stromatolitic marly limestones, well-stratified with lenticular bioherms, occur medially. Massive bioclastic limestones with crinoid-polyp reefs and condensation zones are common. Green, indurated azoic marls and gritty sandstones form cm-mthick intercalations. Abrupt facies transitions reflect halokinetic subsidence in a rift basin. It was deposited in a shallow marine peritidal-supratidal platform. In the Ait Hani area at Tinejdad the "Aït Hani formation" has been suggested to be the upper part of the Azilal formation, but is part of the Bajocian units instead. Tafraout Formation The Tafraout Formation can be divided in 4 members and is a 30–1000 m thick carbonate-siliciclastic unit, deposited in a Tethyan rift basin (The Central High Atlas Diapiric Province) with halokinetic influences. Consists of oolitic and bioclastic limestones, wackestones, silt marls, and quartz-rich sandstones with minor feldspar and carbonate debris with cross-stratifications, found in channels and bars, alongside greenish marls and micro-conglomerates. It overlies basal discontinuities and is capped by an emersion surface with desiccation cracks and ferruginized crusts. The oldest segment, previously know as "Amezraï Formation" is predominantly terrigenous and marked by quartz-rich sandstones, azoic green to yellow marls, and oolitic limestones ranging from oo-intramicrites to oosparites, and cross-bedded sandstones with herringbone structures, asymmetrical ripples, lignite debris, forming high-energy deltaic channels and tidal bars. Nodular limestone bars, locally up to six meters thick, display compaction breccias and hardgrounds, while green marly sandstones highlight lagoonal retention. Synsedimentary faulting, combined with halokinetic subsidence, induced rapid facies changes and erosional breaks, with clastic input derived from uplifted Paleozoic substrates. Condensation horizons contain brachiopods, bivalves, and gastropods, but bioherms are absent. , with exposed facies of the Tafraout Group as "Upper Lias"|229x229px The succeeding interval, marked by lack of large-scale slumping, shows stratigraphic shift into green marl-dominated sequences, intercalated with nodular, stylolitic limestones ranging from biomicrocrites to recrystallized packstones, red sandstones, slumped channel fills, and bioclastic grainstones with oncolites from lagoonal to tidal flat settings with turbidite deposits, sometimes large coral colonies form early patch reefs. Marls contain fine lamination, terrigenous detritus, and distal turbidite layers, sometimes punctuated by thin lensing sandstones and microconglomerates. Above, the succession returns to more proximal facies, with quartz-rich sandstones, silt-marls, green marly and cross-bedded sandstones, oolitic/bioclastic limestones, including brachiopod-rich packstone bars and condensation zones with bivalves and gastropods, signifying ooid shoals and carbonate units ranging from biodetrital packstones to oolitic grainstones. Microfacies include tangential ooids, intraclasts, peloids, and micritized carbonate fragments. Cross-bedded sandstones and ripple-marked surfaces with drying cracks and plant debris record emersion and supratidal influence. Microconglomerates incorporating metamorphic and magmatic clasts document tectonic supply from the basin margins, while high subsidence rates controlled turbidite influx and rapid lateral facies shifts. Thick carbonate bars and lumachelle horizons represent reworked shoal and bar-top settings within a tectonically active shallow platform. The youngest member, by far the thickest, is fully carbonate-dominated, with marly micrites, oosparites, bioclastic limestones, and well-developed coral patch reefs attaining 10-40 meters in height. These reefal bodies, composed of framestones and boundstones, occur in stacked horizons and are often flanked by lamellibranch accumulations and coral–bivalve eventstones. Ooid limestones exhibit cross-bedding near reef margins, while emersion horizons with desiccation cracks mark episodic exposure, reflecting subtidal carbonate platforms and lagoons. Stromatactis-like cavities and extensive bioturbation are widespread, reflecting synsedimentary cementation and rapid subsidence associated with halokinetic tectonics. Microconglomerates with older clasts add further evidence of syndepositional tectonism. Overall, this unit evolves from deltaic sand-dominated deposits to deeper marls, followed by shoal-associated grainstones and culminating in carbonate platforms with coral patch reefs. == Paleogeography ==

The Tafraout Group was deposited on the Central High Atlas Diapiric Rift basin, a Carbonate Platform at a palaeolatitude of 19–20°N, developed between the Anti-Atlas, the West Moroccan Arch, and the Sahara craton. At the base of the succession, carbonate production was interrupted and replaced by terrigenous input that accumulated in subsiding basins exposed in Telouet, Toundoute, Afourar and Azilal, consisting mainly of continental to fluvial/palustrine facies, with the "Demnate Accident" fault acting as a key structural control. In parallel, more central and eastern regions such as Beni Mellal, the Dadès Gorges, and Zaouiat Ahansal retained mixed carbonate–siliciclastic deposits under marine influence, dated thanks to ammonites and Brachiopods in the basal Tafraout Formation. Northern Atlasic Front transitions from a foreland basin (Tadla Plain) to the Jbel Ighnayene culmination, filled by a homogeneous continental Azilal Fm affected by thrust tectonics and faulting. Next is the Abbadine diapiric complex, with multiple minibasins (Ouaouizaght, Taguelft, and Tilougguite) separated by salt walls (Abbadine and Addendoum) that influenced local sedimentation, with progressive thinning and truncation of Toarcian-Aalenian facies near diapirs. Increased Toarcian sedimentation led to burial of older carbonates and calcite precipitation. In the proper Tafraout area nearby proximal facies are frequently stacked in thick >2 km successions passing to >3 km in the surrounding minibasins. == Paleoenvironment ==

. The Tafraout Group covers most of the W High Atlas, surrounded by highlands that probably hosted rain tundra to wet forest environments, as proven by samples from coeval layers in the External Rif Chain. The Continental section was deposited in environments influenced by floodplain rivers, with reworked material and in Toundoute unique interbedded volcanic rocks, with carbonate recrystallization suggesting were contemporaneous with the sedimentation, probably derived from early activity in the South-Atlasic Fault. The direction of the fluvial sediments take place in a E-NE direction, as shown on channels inside the own rocks of this unit. Other features include Raindrop impressions and ripple marks indicating floodplains, with lateral sand channels abundant in plant roots, along with evidence of ephemeral palustrine (Sabkhas, Chotts) episodes in the form of carbonate bodies (Caliche/Calcrete levels), intercalated with conglomerates and gypsum, particularly in areas like Azilal, Toundoute and Telouet. However, alternating grey-green marls and ammonite-bearing sequences on the hanging wall suggest open marine conditions and distal turbidites, similar to the lowermost Agoudim Formation. Finally, the fourth member records the return of the carbonate factory, dominated by corals, reflecting deposition on a continuously deepening platform where subsidence outpaced sedimentation. A major fall of the sea level happened in the Middle Toarcian-Aalenian, with the recovery of coral reefs (though now with barely few Plicatostylidae). Later, as conditions deepened and became more oligotrophic, sponge–coral–microbialite patch reefs reappeared, mainly in shoreface to deeper settings. == Biota ==

Beds with large accumulations of unidentified Ostracod valves on an endemic thin level of green marl are found at the Beni-Mellal area (Adoumaz and Col de Ghnim outcrops). Foraminifera Ichnofossils Porifera Anthozoa Currently non-sampled important assamblages include: • In the Dadés-Assif Tafraout areas large coral patch reefs rarely occur in the middle of the unit with associated echinodems (sea urchin spines, crinoid fragments) bivalves, gastropods, Bryozoa, serpulid annelids, branchiopods, solitary corals and algae. • The Ait Allal reef complex appears in the form of lenticular constructed masses (10 to 30 m long, 10 to 15 m wide and 3 to 4 m high) which pass laterally, towards the south-east and the north-east, to sandstone horizons. Echinodermata Multiple echinoderm remains, including crinoid articulated and fragmentary specimens and echinoid fragments (mostly spines and plates), are known from several localities, usually associated with large coral bioherms or sea trangressions. Annelida Dinosauria Indeterminate dinosaurian and other vertebrates are known from Mizaguène Hill, Taouja Ougourane, Aït Ouaridène, Oued Rzef and Jbel Remuai in the Azilal Province. Some of them are recovered in a "Bone bed" and others are associated with abundant plant remains. Unidentifed small tridactyl footprints are know from W of Azilal town.'' Other plant remains include coal beds, leaflets, cuticles, rhizoliths, fossil wood and other indeterminate plant debris. • Top of the Azilal Formation at the Idemrane geosite, unidentified pieces of wood fossils of variable sizes were recovered (largest over 20 cm in length) showing traces of iron oxides, considered root fragments. • At Mizaguène Hill (Azilal) lenticular marno-conglomeratic sandstone levels filled with plant remains are found, maybe derived from a lagoon. • At Taquat N'Agrd the uppermost Tafraout Fm is capped by a +10 m succession of coal beds intercalated with limestones. • North of Jbel Akenzoud and partly impregnated and/or carbonized by malachite. • At Aguerd n'Igli the Tafraout Fm starts with sandstone marls with plants, and in upper sections includes bioclastic limestones-sandstones and green-yellow marls in color also rich in plant debris. • At Tizi n-M'Barek a carbonate bar on top of marls with associated plant debris and bivalves. • At Jebel Azourki and Jebel Toksine, woody plant debris, including shales with coal streaks, bioclastic limestones-sandstones rich in debris, charcoal and cuticle fragments suggests vegetation in a humid, marginal marine environment, maybe a salt marsh. • At M'Semrir Pass, samples dominated by Pollen have been recovered in the Tafraout and Azilal Fms. == See also ==