| Tafraout Group | |
| Period: | Toarcian |
| Age: | Toarcian-Middle Aalenian Polymorphum-Murchisonae |
| Type: | Geological formation |
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| Thickness: | Aprox. 3000 m |
| Area: | High Atlas[1] [2] |
| Location: | Central High Altas |
| Coordinates: | 31.5°N -5.56°W |
| Paleocoordinates: | 26.6°N -3.4°W |
| Region: | High Atlas[3] [4] |
| Namedfor: | Douar Tafraout near Jbel/Assif Tafraout |
| Namedby: | Abdellah Milhi |
| Year Ts: | 1992 |
| Location Ts: | Right side valley of Assif Tafraout flowing in a northerly direction. The village of Tafraout lies about 1 km to the north |
| Thickness Ts: | ~550m (1,800feet) |
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. 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). 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]
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]
The Central High Atlas of Morocco is part of a double-vergent mountain belt that originated due to Cenozoic shortening and inversion of a rift that developed between the Triassic-Jurassic periods.[13] Its geometry is distinctive due to the presence of several ENE–WSW narrow rift basins, derived from four major tectonic phases: pre-rift, that was linked with the Hercynian Orogeny and the union of Pangea in the Paleozoic; syn-rift, that was developed mostly between the Late Permian-Late Triassic with several NE–SW to ENE–WSW rift-basins, al derived from the almost coeval opening of the Atlantic Ocean and Tethys Sea.[14] This rift-derived basins ended filled with continental siliciclastic sediments, and latter towards the Rhaetian stage of the Triassic affected by emissions of the Central Atlantic magmatic province.[15] It was on the so-called Post-rift phase that the local tectonics had a thermal relaxation and allowed the deposition of the Jurassic-Cretaceous carbonate platforms. The structure of the High Atlas can be defined by two main groups of faults, thrust and oblique-slip faults, that occur from W-E to NE-SW. The presence of tectonic inversion in the Atlas Mountains has shown that are an intracontinental mountain belts that appeared from the uplift of pre-existing rift systems, where here is represented by a major rift system (~2000 km) originated on the Mesozoic, that was later uplifted and inverted in the Cenozoic. The impact and convergence movements of the African-Iberian plates after the Mesozoic end with an inversion of the previous deposited strata, transporting the sediments of that and forming new low angle thrusts. Triassic, Jurassic and Cretaceous strata are confined within basins controlled by the extensional structures of the Mesozoic rift. The Jurassic basins can be grouped into two main provinces located on either side of an emerged Massif Ancien: west, where the basin was open to the Early Atlantic, being related to its passive margin, and east with several epicontinental troughs connected to the Tethys Ocean.[16] Across the Toarcian-Bajocian strata, there was a great deposition of marine shales as marls, calciturbidites and reefal limestones were accumulated in the E Central High Atlas, while on the west margin around the Massif Ancien terrestrial, specially fluvial sedimentation dominated. The present Red Beds of Azilal and the younger marls of Bin el Ouidane indicate various marine oscillations across the Toarcian-Bajocian boundary, ending its sedimentation with the major Bathonian redbeds.[17] A initial tectonic event on the Triassic-Jurassic boundary led to the formation of the Tigrinine-Taabast pull-apart basin, for example.[18] Following this event a major extensional tectonic activity (derived from the second Pangea rifting) occurred towards the end of the Pliensbachian and beginning of the Toarcian. This second major tectonic event developed towards the E-W to NE-SW, reactivating trending normal faults, what led to the drowning of the Lower Liassic carbonate platform and the predominance of marls during the Middle Liassic to Toarcian.
The Aguerd-n'Tazoult formation encompasses the most recent marginal marine strata within the Amezraï minibasin, ranging from the Upper Toarcian to Aalenian periods, marked by lower sequences with great amount of conglometatic lenses and upper limit largely characterized by the occurrence of coral patch reefs. Sandstones and oolitic and/or biodetritic limestone are often interposed. Red and green marls occur in numerous decimetre-thick layers. Occasionally there are conglomerate lenses with Liassic elements. Oblique stratification and ooid limestones are predominantly restricted to the area surrounding patch reefs. This formation denotes a transitional environment from supratidal to intertidal, exhibiting facies development similar to the underlying Trafraout Formation.[19] Local tectonic activity, primarily triggered by seismic events in the Tethyan domain, played a pivotal role in the formation process. Consequently, emergent Paleozoic strata underwent erosion owing to prevailing local conditions.[20]
This formation is predominantly exposed in the mini-basin bearing the same name, closely linked with the Tazoult Ridge, both showcasing significant evidence of diapirism during the late Lias period in the central Atlas region. Dated back to the Earliest Toarcian epochs, identified by its brachiopod fauna. The Amezraï Formation constitutes the earliest segment of this group, composed of sandstones, sandy marls, green and red marls, and biodetrital and/or oolitic limestones, with the layers ranging in thickness from centimeters to decimeters and limestone layers up to 6 meters thick sporadically within the formation. Horizons of reworking and hardgrounds are typically restricted to the limestone layers, while ripples and cross-bedding are found in the sandstone layers. Its outcrops, such as those in Jbel Azourki, consist of a mix of carbonates, sandstones, and marls, accompanied by conglomeratic facies containing Paleozoic basement elements. The vertical arrangement of these facies indicates a gradational decrease, with conglomerates, sandstones, and clays forming the lower part of the formation, transitioning to limestones, marls, and sandstones towards the top. These variations signify the erosion of sandy layers within a shallow platform environment, as evidenced by multiple criteria.[21] It´s layers are interpreted as deposits formed in an environment ranging from subtidal to supratidal, were monospecific accumulations of organisms, especially Bivalves in individual layers, may indicate restricted lagoonal depositional conditions. It is also marked compared with the older Pliensbachian units with a decreased carbonate content.
See main article: Azilal Formation.
The Tafraout Formation comprises oolitic and biodetrital limestones exhibiting cross-stratifications, arranged in channels and bars ranging from decimetric to metric scale, alongside greenish to variegated silty marls topped with lenticular layers of micro-conglomerates. These deposits were laid down on a coastal platform. This formation is primarily composed of sandstone marl, silt marl, and ooid limestone, distinctly different from the underlying layers. The most common fossils include Bivalves, which often form lumachellae, large brachiopods, gastropods, solitary corals, and echinoderm remains. Plant remains, some with malachite, are found in the sandstones and microconglomerate lenses. The rocks show various microfacies types formed under supratidal to subtidal conditions, including bio-, oosparites/grainstones, and silt marl with fine-grained terrigen detritus. The upper segment of the Tafraout Formation represents sedimentation resulting from terrigenous dispersal in the former "basin" of the upper Pliensbachian (Aganane Formation). The overall sedimentary trend indicates a progressive filling process. Initially, the presence of foraminifera assemblages, ammonite traces, and turbidite spits within the marls suggests sedimentation in an open marine environment with a circalittoral setting. Sandstone turbidites observed at the basin's northern boundary indicate material transit across the Pliensbachian platform. On the other hand, carbonate turbidites observed farther south in the Taquat N'Agrd area are likely attributed to erosion in high intra-basin regions. Moving towards the upper sections, a vertical arrangement and gradual filling process led to the formation of a supratidal carbonate coastal plain, characterized by tropical conditions akin to those observed on Andros, Bahamas. These observed sequences, displaying a "coarsening up" pattern, illustrate the advancement of a sandy beach area (sandstone) over a shallow subtidal zone (marls). The gullied limestones at the sequence's base denote phases of flooding preceding the resurgence of subtidal sedimentation.[22] The presence of micritized ooids and terrigenous quartz grains indicates episodic hypersaline conditions, while sandstones and microconglomerates are predominantly quartz with occasional feldspar, carbonate detritus, and malachite flakes. The restricted variety of organisms suggests challenging living conditions, with high subsidence rates in certain regions. Sandstone/marl alternations and limestone/marl sequences are interpreted as proximal turbidites, with shallow water organisms and plant remains likely due to rearrangements in submarine channels. The occurrence of dry cracks indicates periodic emersion phases.
The Tagoudite Formation represents a significant shift in Liassic sedimentation, replacing the carbonate turbidites of the Ouchbis Formation with predominantly siliciclastic layers. These layers comprise an irregular alternation of gray and green limestone sandstones with sandy marls and siltstones, forming megasequences with thicknesses of 10–20 m, distinguished by a decrease in siliciclastic aggregate size and an increase in marl content from bottom to top, with gradations, laminations, and ripple marks present. Microscopically, the thin-layered turbidites consist mainly of fine-grained silt, with variations in the percentage of siliciclastics and carbonate detritus over time and place. Siliciclastic portions include quartz grains, feldspar, and often glauconite, with micritic carbonate detritus ranging from 15% to 60% in a micritic matrix, with components indicating a distant source area. Pyrite can be enriched in nests or finely dispersed in individual layers. The siliciclastic turbidites suggest an open marine depositional environment, with interruptions in sedimentation and evidence of carbonate portion supply from neighboring emersion zones. Gravel stratification, lateral variations in siliciclastic grain size, and thickness fluctuations suggest different source areas, likely due to movements along paleostèration zones, reactivated during the Toarcian. The Tagoudite Formation is widespread in the Central High Atlas, wedged against paleorelief slopes or Boutonnières, with a thicknesses range up to 320 m, with variations noted in different areas of the Atlas region, including Tounfite, Rich, and Beni Mellal. In the Central Middle Atlas, sedimentation interruptions indicate emersion area formation preceding the deposition of this formation, with complete wedge-out to the east, approximately in the Midelt-Errachidia strait area.
The Tafraout Group was deposited in the Moroccan Carbonate Platform, at a palaeolatitude between 19°-20°N, around the same latitude as modern Mauritania or Cuba, and developed along a major drowning episode linked with the Toarcian Anoxic event, that led to the eustatic sea–level rise on the Early Toarcian in Europe and Africa.[23] The Azilal Formation was bracketed between several major geologically older hinterlands: the West Moroccan Arch on the W-NW, the Anti-Atlas and the Sahara craton in the S-SE.[24]
Towards the west (Afourer and Azilal province maps) the local laguno-marine facies of the Aganane Formation are directly overlain by terrigenous deposits of the Azilal Formation after the initial major Toarcian regression: red clays, conglomerates with paleozoic elements. This deposits fill many small basins in tearing in the Atlas of Afourer and Azilal, having the Demnat Accident as the major structural element in this last sector. While at Demnate, Telouet, Azilal, Skoura or Toundoute the conditions did become fully terrestrial, towards the east at Beni-Mellal the Lower Toarcian the ongoing sea regression happened latter, marked by oscillations between the Azilal Formation and the marly marine Tagoudite or the carbonate Tafraout, ending both fully overlain by the terrigenous layers towards the Middle-Late Toarcian. The Amezraï minbasin evolved as an isolated lateral equivalent, composed of intertidal to open marine carbonate environments, hosting also layers of the Tagoudite Formation, that end first overlain by the Tafraout Formation, and then in the westernmost sectors by the Azilal Formation while remaining in the central East marine-based as marks the Aguerd-nˈTazoult Formation.
The Tafraout Group co-evolved with several staggered sections from the southern edge of the Tilougguit Syncline in the north to the axis of the Aït Bouguemmez Basin in the south, showed that the depocenter zone corresponded to the disposal area located between the Talmest-Tazolt Ridge to the North and the North-Atlasic accident to the South. At Talmest-Tazoult ridge, the siliclastic-carbonate series of the Toarcian-Aalenian form a clear progressive unconformity above the carbonates of the Sinemurian-Pliensbachian, building an individualized ridge oriented NE-SW, limiting two local depressions to the South-East (Amezraï and Wahmane). The North Altas accident shows variations of thickness and facies, testifying a weak activity of the latter, in particular during the deposition of the Azilal Formation, with the reliefs created during the previous phase covered by the terrigenous layers of this last one.
Two main stages can be then distinguished in the paleogeographic evolution of the western border of the High Atlas Basin during the Toarcian-Aalenian: during the Lower Toarcian, this sector presented the same paleogeographic characteristics as those seen during the uppermost Pliensbachian, being latter followed by a reduction in the deposition areas and a filling of the Pliensbachian basins by terrigenous material from the Tagoudite & Azilal Formations. Then, with the Middle Toarcian- Aalenian, the Azilal Formation expanded towards the east as the sedimentation resumed throughout the region, where coeval layers in the Amezraï subsiding basin was filled by carbonates from the internal platform of the Tafraout and Aguerd n’Tazoult, being surrounded to the north, east and south by a coastal area with dominant terrigenous sedimentation of the own Azilal Formation. This period is marked by the individualization of the Talmest-Tazolt Ridge in the center of the basin and by a relative tectonic calm in the other coeval sectors.
Despite being claimed to have Latest Pliensbachian layers, the Azilal Formation is measured in post Polymorphum (Earliest Toarcian) levels, and impacts in the sedimentation (especially of the Béni-Mellal Province, Zaouiat Ahansal, or the Dadès Gorges) in the Middle Toarcian-Lower Aalenian, marked by a notorious sea regression, distributed in at least 6 sequences, that overlie layers with the ammonite genus Eodactylioceras and Hildoceras bifrons allow a precise localization of this initial progradation of the terrestrial settings around the Bifrons substage of the Toarcian (that can be either considered the uppermost Lower Toarcian of the lower Middle Toarcian). The layers are, at the oldest sections of this initial phase, represented by marly and silty marls and limestones as well as marginal-littoral sandstones testifying to the siltation of this sector by sandy sheets of deltaic origin. At the same time on the Amezraï basin the fauna is composed by brachiopod fauna such as Soaresirhynchia bouchardi, S. babtisrensis and Pseudogibbirhynchia jurensis that corroborate the Toarcian age and the connection between both locations. Meanwhile, the presence of Aalenian (Bradfordernsis-Murchinsonae) Branchiopods in the Aguerd n’Tazoult Formation coeval with Ammonites of the same age in the easternmost Azilal formation at the Ikerzi Area confirms the marine delimitation in the last stages of deposition. In the Azilal-Aguerd system, the "Tafraout Platform" saw a deepening towards the uppermost layers, teasing the transition to the Bin el Ouidane transgressive facies, while the lower sequences, with fine conglomerate layers and plant remains indicate a proximal delivery area and the peak of the regression, with many microlagoons that formed between the large coral patch reefs are documented by micrite and partially leached micrite.
The Tafraout Group covers most of the W High Atlas, surrounded by highlands that probably hosted dry cool (10.6 °C) to humid climate (12.30 °C), with a succession rain tundra to wet forest environments, as proven by samples from coeval layers in the External Rif Chain.[25] It was the emerged part of a Siliciclastic-Carbonate platform and represented a variety of settings, including continental river/palustrine-dominated, paralic-tidal deposits, and tidal mudflat shorelines. The terrigenous-dominated deposits of the Azilal Formation were deposited in a coastal environment with continental influence. On this facies, the fauna (composed of rare Brachiopods, poorly diversified black Bivalves or vertebrates) and the sedimentary figures (impacts of raindrops, soft pebbles, crisscrossed stratifications and "ripplemarks") reflect a confined to continental/marine deposition environment, with temporary emersions, where conditions met in a deltaic environment with saltwater/brackish influences. This terrigenous deposition can be seen from north to south as a lateral transition from a coastal facies to a fluvial facies (at Adoumaz) to a foreshore facies (Ghnim "fining up" type sequences) to a beach facies (Jbel Taguendouft "coarsening up" type sequences). The relatively small thicknesses found at the Jbel Taguendouft section would testify to the tectonic activity of the Jbel Abbadine ridge.
The flow of the fluvial-washed sediments take place in a E-NE direction, being moved to the layers of the Tafraout Formation and other coeval marine units, as well are found on fluviatile channels inside the own rocks of this unit.
The depositional environment of the Azilal formation was dominantly fluvial or alluvial, with large sandstone channels cutting through detrital conglomerate deposits. The high abundance of plant remains, either as fossil wood, cuticles, charcoal or Rhizoliths, reveals the presence of vegetated soils in the vicinity. There is also evidence ephemeral Palustrine (Sabkhas, Chotts) episodes in the form of carbonate bodies (Caliche or Calcrete levels), intercalated with conglomerate under an arid environment, as marks the development of gypsum.[26] This is recorded specially in the Telouet and Demnate-Wazzant area, but also seen in more detail at Toundoute: the deposits present a channel/floodplain type fluvial system, with sand-filled channels abundant in plant roots (mostly located in fine limestone, probably from the channel margins), developed in the near E-W direction of transit. The channel lithology shows notable enrichment of material from the Paleozoic basement and Triassic cover, with interbedded volcanic material (sand to pebbles), generally constituting more than half of the detrital components, showing clear carbonate recrystallization, suggesting that these fragments were still at high temperature during deposition and, therefore, contemporaneous with the sedimentation.[27] Lithic elements or isolated crystals found locally show no evidence of prolonged transport, probably from relatively nearby Springs, being these collected and transported by a poorly developed river system during episodic floods.The overall local climate was warm with alternating wet and dry periods have generated soils with differentiated calcareous profiles (pedogenetic nodules, Caliche), hosting active erosion on sparsely vegetated soils.The environment of the Azilal Formation becomes notorious after the Middle Toarcian, with a clear major regression that ends with a slowdown of the local sedimentary filling. The paralic deposits of this phase contain clay intervals rich in continental organic matter such as wood debris, but a rare fossil fauna consisting of abundant algae, benthic foraminifera, common oncoids, gastropods, and bivalve bioclasts. As the Lower Toarcian started, over the region, the carbonate platform was abruptly replaced by siliciclastic deposits fed by a greater surrounding hinterland weathering, measured thanks to increased plant debris and the absence of evaporite-rich intervals and semi-arid paleosols, with alternating shoreline-forest depositional contexts. This initial layers are overlied by storm-dominated deposits, with a depauperate fauna and very common occurrence of plant debris, which with the increase in ooid-rich facies suggest deposition on a warm, wet climate belt. Some of these areas, particularly the more coastal ones located in the Azilal region, have an appearance similar to that of modern Sebkhas, for example those of found in the modern Persian Gulf. These intervals have increased nutrient levels locally, as evidenced by the high amount of Phosphorus along the entire Atlas Basin.[28] These siliciclastic beds have abundant pebbles of metamorphic and igneous rocks, implying that the material must have been derived from the Paleozoic or Proterozoic, implying a hinterland that is frequently emerged and subject to erosion and the effects of diagenesis. The only ones of this nature in Morocco, that on the Atlas are located to the south in the Anti-Atlas, to the west in the Ancient Massif and the Jebilet, and to the north in the Central Meseta, all places that were subaerially exposed during the Jurassic.[29] Specifically, the Anti-Atlas shows processes of tectonic uplift, overburden erosion, which, combined with the concentration of coarse siliciclastic material in the western part of the central High Atlas (absent in the east), suggest that this area was the source of the altered Lower Toarcian sediments, allowing the tracing of the fluvial channels that developed towards the Azilal Formation.
At the same time towards the South-East the Tafraout Formation in the Amezraï basin represents a marginal marine environment, with wave ripples, cross-bedding, the Amphipoda ichnofossil Arenicolites isp. and the calcareous algae Cayeuxia sp., all deposited on diagenetic mudstone. Concretely, on Taguendouft, towards the Middle Toarcian the carbonate producers recovered locally, with the ooid grainstone replaced by wackestone to packstone beds, where heterotrophic faunal bioclasts increase, such as cephalopods, brachiopods, echinoderms, and gastropods, with occasional coral patch reefs.
Within the Trafraout Formation, facies comprising "lithiotids" (Plicatostylidae aberrant reef-forming bivalves), which are known from the Sinemurian to the Toarcian of Italy, Spain, Slovenia, Croatia, Montenegro, Albania and also in Morocco, indicate the return of carbonate activity in the Central Atlas. These Reefs showed strong zonation, starting with the bivalves Gervilleioperna and Mytiloperna, restricted to intertidal and shallow-subtidal facies.[30] Lithioperna are limited to subtidal lagoon facies and even to certain poorly oxygenated environments. Finally, Cochlearites are found in the subtidal facies, building accumulations. At Jebel Toksine in the Dades Valley, the Tafraout Formation develops a local lagoon-subtidal ecosystem in arid and humid conditions. The Jebel Toksine layers represent one of the most complete records of this type of ecosystem in Morocco, recording several generations of lithiotic growth over ~1 km of exposure (consisting of the genera Gervilleioperna, Mytiloperna, Lithioperna and Cochlearites), as well as a diverse associated fauna.
The Tagoudite & Tafraout formations recover, as seen on worldwide units an increase of weathering due to the Pl/To and T-OAE events, with increase of the siliciclastic sediment supply and increased dissolved material to the oceans. This occurred along an intensification of tropical storm events (as well Hurricane action) on the T-OAE, destroying the older carbonate platform organisms locally. This allowed to set the Azilal Formation environments, that range from a series of continental settings with river influence, increased during the T-AOE with more amounts of flora being washed, to nearshore deposits, paralic and subtidal, subject of storm and tropical storm events, all set on a warm humid climate.The aftermath of the Toarcian Oceanic Anoxic Event is also highly present on the marginal marine strata of the formation, with the so-called Toksine Section, a succession of near shore marine strata disposed along the Toarcian boundary, where its last 40 m belong to the lower part of the Azilal Formation and are composed of dolomitized Mudstones and ooidal Grainstones, that show a slowly recovering a low-depth nearshore marine environment after in the Pliensbachian-Toarcian boundary a dramatic Tethys-wide collapse of the Neritic Carbonate System happened.
There is also a local record of a Middle Toarcian Cold Snap at Jbel Akenzoud, and shows that after cold event that affect the local waters, related to the Karoo & the Atlantic Rift volcanism the present Brachiopods, based on their preserved oxygen isotope data show that warm seawater temperatures re-established during the early Late Toarcian.[31]
In the Middle Toarcian the eastern and north-eastern part of High Atlas of Todrha-Dadès, sedimentation carbonate with bioconstructions (patch-reef), develops with a thickening towards the East and a still thinning towards the West in the direction of the reef of Jbel Akenzoud, where the dew marine fossils of the formation are recovered. The Coralline faunas suffered a significant collapse visible in the locality of Ouguerd Zegzaoune, showing that sedimentation at this time took place in a distensive tectonic context. Then, towards the Late Toarcian-Aalenian boundary, the series corresponds to detrital deposits with carbonate intercalations with neritic fauna. The structural analysis shows that the sedimentation during the upper Toarcian was controlled by a tectonic game, always distensive, causing the tilting of blocks along the transverse fault of NW-SE direction, which leads to the creation of available space with openings always towards E and NE.
The central High Atlas region harbors a cluster of elongated diapirs and minibasins formed during the Lower Jurassic rifting of the Atlas basin, with the Tazoult Ridge being one such diapiric sector spanning approximately 20 km. Oriented NE-SW, it slightly deviates from the dominant ENE-WSW structural trend of the central High Atlas, flanked by the Amezraï minibasin to the south and the Tiloughite minibasin to the north. Within the Amezraï minibasin, the Tafraout group, stretching about 1500 m, is exposed.[32] These deposits, interpreted as mixed Toarcian-Aalenian sediments, led to the extrusion of the diapir on its flank and the adjacent seabed, positioning the Alenian facies of the Aguerd-nˈTazoult Formation in a sub-horizontal orientation beyond the allochthonous body. The sharp transition between the gently SE-dipping Zaouiat Ahançal Group and the steeply NW-dipping Late Aalenian-Bajocian carbonates of the Bin el Ouidane Formation is seen as a weld formed by the closure of the salt wall.[33] This period coincides with the peak of passive diapiric growth, driven by the reactivation of the central High Atlas synrift from the Pliensbachian to the Aalenian, triggering salt withdrawal and swelling of adjacent salt walls, forming the Talmest allochthonous salt sheet at its SE end. In terms of paleoenvironment, the elongated carbonate platforms of Tazoult, formed by rifts, resemble those found in the shallow waters of the Red Sea's edges, particularly in Egypt's Strait of Gubal and Saudi Arabia's Farasan Banks.
Examining local diapirism in the Upper Liassic has provided valuable insights into climate and deposition in the coexisting marine Amellago Formation. Intervals devoid of ooids indicate a wetter climate, supported by an increase in continental particles—a sign of heightened Saharan Craton weathering. Additionally, the presence of small amounts of charcoal or charred wood remnants suggests the existence of coastal forests or mangroves in the carbonate ramp of the Zaouiat Ahançal group during periods of increased local humidity.[34]
| Genus | Species | Location | Formation & Age | Material | Habitat | Notes | Images |
|---|---|---|---|---|---|---|---|
| Ammobaculites |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Ammomarginulininae. | |
| Dentalina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Nodosariinae. | |
| Everticyclammina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the Everticyclamminidae family. It represents a species related to E. virguliana, known from the Middle Jurassic of Morocco | |
| Citharina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Vaginulininae. It represents a species related to E. virguliana, known from the Middle Jurassic of Morocco | |
| Ichtyolaria |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Ichthyolariinae. | |
| Lenticulina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | Un foraminifère de la famille des Lenticulininae. | |
| Lingulina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Lenticulininae. | |
| Marginulina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Marginulininae. | |
| Nodosaria |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Nodosariinae. | |
| Ophtalmidium |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Ophthalmidiidae. | |
| Orbitopsella[35] |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Orbitopsellinae. | |
| Pseudocyclammina |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Hauraniidae. | |
| Pseudonodosaria |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Nodosariinae. | |
| Reinholdella |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A foraminifer of the family Ceratobuliminidae. | |
| Genus | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Botryococcus |
|
|
| Miospores | Member of the family Botryococcaceae inside Trebouxiales. | |
| Carinolithus |
|
|
| Calcareous Skeletons | Member of the family Calyculaceae inside Parhabdolithaceae. | |
| Luehndea |
|
|
| Cysts | A Dinoflagellate cyst, type member of Luehndeoideae. Constitutes an excellent marker ofthe Pliensbachian-Toarcian interval. | |
| Mancodinium |
|
|
| Cysts | A Dinoflagellate cyst, type member of Mancodiniaceae. Dominant genera on some layers of the Lias Delta Stage. | |
| Mendicodinium |
|
|
| Cysts | A Dinoflagellate cyst, member of Dinophyceae. | |
| Tasmanites |
|
|
| Cysts | A member of Prasinophyceae. The presence of this genus indicates fresh or brackish water inputs in the depositional environment | |
| Genre | Species | Location | Formation & Age | Material | Habitat | Notes | Images |
|---|---|---|---|---|---|---|---|
| Cayeuxia |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | An algae of the Halimedaceae family. | |
| Sestrosphera |
|
|
| Calcareous Skeleton | Shallow Marine/Lagoonal | A red algae of the Solenoporaceae family. This genus is the dominant type of fossil algae found in biozone A (Lituosepta recoarensis). | |
In the Tafraout Group, the fossil record of units like the Azilal Formation is very restrictive compared to the marine coeval/underliying units like the Amezraï or Tafraout Formations. In the Dadés area Coral patch reefs rarely occur in the middle of the unit with associated echinodems (Sea urchin spines, Crinoid fragments) lamellibranchs, gastropods, solitary corals and algae. Plant remains are very abundant in places such as the north of Jbel Akenzoud and partly impregnated and/or carbonized by malachite. Gastropods have been discovered in several places, but none of the specimens have been studied nor identified.[36] Beds with large accumulations of unidentified Ostracod valves on an endemic thin level of green marl are found at the Beni-Mellal area (Adoumaz & Col de Ghnim outcrops).[37] [38] The tubes of serpulid worms are known from Jbel Toksine, in relation to the bivalve pavements.
| Genus | Species | Location | Formation & Age | Material | Type | Made by | Images |
|---|---|---|---|---|---|---|---|
| Arenicolites[39] |
|
|
| Traces of habitation | Domichnia | ||
| Chondrites |
|
|
| Tubular Fodinichnia | Fodinichnia |
| |
| Rhizocorallium |
|
|
| Tubular Fodinichnia | Domichnia or fodinichnia |
| . |
| Scolicia |
|
|
| Locomotion or feeding trace | Fodinichnia |
| |
| Skolithos |
|
|
| Cylindrical to subcylindrical burrows | Domichnia |
| . |
| Thalassinoides |
|
|
| Tubular Fodinichnia | Fodinichnia |
| . |
| Zoophycos |
|
|
| Traces of habitation | Domichnia & Fodinichnia |
| |
The platform patch reefs in the Tafraout area are notable for their biodiversity, with some reaching heights of up to 40 m and lengths of up to 80 m, representing massive biostromes with a varied associated fossil assemblage, including bivalves, gastropods, echinoderm fragments, solitary corals, and bryozoans, found among the coral patchs.
| Genus | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Actinaraea? |
|
|
| Calcified Skeletal Pieces | A coral of the family Actinacididae. | |
| Ampakabastraea |
|
|
| Calcified Skeletal Pieces | A coral of the family Stylinidae. | |
| Archaeosmilia |
|
|
| Calcified Skeletal Pieces | A coral of the family Zardinophyllidae. These solitary corals were observed throughout the lower unit biostromes. | |
| Archaeosmiliopsis |
|
|
| Calcified Skeletal Pieces | A coral of the family Archaeosmiliidae. | |
| Enallhelia? |
|
|
| Calcified Skeletal Pieces | A coral of the family Stylinidae. | |
| Haimeicyclus |
|
|
| Calcified Skeletal Pieces | A coral of the family Oppelismiliidae. | |
| Hispaniastraea |
|
|
| Calcified Skeletal Pieces | A coral of the family Hispaniastraeidae. | |
| Lophelia? |
|
|
| Calcified Skeletal Pieces | A coral of the family Carophylliidae. | |
| Myriophyllum |
|
|
| Calcified Skeletal Pieces | A coral of the family Oppelismiliidae. | |
| Phacelostylophyllum |
|
|
| Calcified Skeletal Pieces | A coral of the family Stylophyllidae. | |
| Phacelophyllia |
|
|
| Calcified Skeletal Pieces | A coral of the family Dermosmiliidae. | |
| Periseris |
|
|
| Calcified Skeletal Pieces | A coral of the family Latomeandridae. | |
| Spongiocoenia |
|
|
| Calcified Skeletal Pieces | A coral of the family Stylophyllidae. | |
| Thecactinastraea |
|
|
| Calcified Skeletal Pieces | A coral of the family Oppelismiliidae. | |
| Genre | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Curtirhynchia |
|
|
| Isolated shells | A brackish/marine Tetrarhynchiidae (Brachiopod) | |
| Gibbirhynchia[40] |
|
|
| Isolated shells | A brackish/marine Tetrarhynchiidae (Brachiopod) | |
| Globirhynchia |
|
|
| Isolated shells | A brackish/marine Rhynchonellidae (Brachiopod) | |
| Quadratirhynchia |
|
|
| Isolated shells | A brackish/marine Tetrarhynchiidae (Brachiopod) | |
| Homoeorhynchia |
|
|
| Isolated shells | A brackish/marine Rhynchonellinae (Brachiopod). Homoeorhynchia meridionalis indicates the Toarcian Serpentinus zone and base of the Bifrons zone | |
| Liospiriferina |
|
|
| Isolated shells | A brackish/marine Spiriferinidae (Brachiopod) | |
| Pseudogibbirhynchia[41] |
|
|
| Isolated shells | A brackish/marine Pamirorhynchiinae (Brachiopod). | |
| Soaresirhynchia |
|
|
| Isolated shells | A brackish/marine Basiliolinae (Brachiopod) | |
| Sphaeroidothyris |
|
|
| Isolated shells | A brackish/marine Lobothyrididae (Brachiopod) | |
| Stroudithyris |
|
|
| Isolated shells | A Brackish/marine Lissajousithyrididae (Brachiopod). Mostly benthonic specimens are known. The presence of this species indicates an upper Toarcian-Aalenian age for the layers where was discovered. | |
| Telothyris |
|
|
| Isolated shells | A brackish/marine Lobothyrididae (Brachiopod). Relatively abundant on seashore deposits. Includes juvenile forms of Telothyris jauberti, present on benthic deposit strata. | |
"Dwarf black bivalves (Lucinidae?)" in great abundance where reported from the Azilal Formation at its type section.[42]
| Genre | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Ceratomya |
|
|
| Isolated shells | A marine Ceratomyidae (Bivalve) | |
| Cochlearites |
|
|
| Isolated shells | A brackish/marine Plicatostylidae (Bivalve). A large bivalve, with a subequivalent shell, reaching 60–70 cm high. It is one of the three main bivalves found on the Lithiotis Facies, whose accumulations generally cover megalodontid coquinas. | |
| Gervillioperna |
|
|
| Isolated shells | A brackish/marine Plicatostylidae (Bivalve). Abundant along rootlets, indicating a very shallow and restricted lagoon or marsh environment | |
| Hinnites |
|
|
| Isolated shells | A marine Pectinidae (Bivalve) | |
| Inoperna |
|
|
| Isolated shells | A marine Mytilidae (Bivalve) | |
| Lithioperna |
|
|
| Isolated shells | A brackish/marine Plicatostylidae (Bivalve). This genus was founded to be a bivalve with a byssate juvenile stage that developed different lifestyles as adults depending on the density of the individuals and the firmness of the bottom | |
| Pachygervillia[43] |
|
|
| Isolated shells | A brackish/marine Plicatostylidae (Bivalve). | |
| Opisoma |
|
|
| Isolated shells | A brackish Astartidae (Bivalve). Is considered a genus that evolved from shallow-burrowing ancestors, secondarily becoming an edge-prone semi-fauna adapted to photosymbiosis. | |
| Trichites |
|
|
| Isolated shells | A marine Pinnidae (Bivalve) | |
| Pholadomya |
|
|
| Isolated shells | A marine Pholadomyidae (Bivalve) | |
Multiple Gasteropodan faunas are know, specially associated with coral patch reefs, but lack proper studies.
| Genre | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Nerinea |
|
|
| Isolated shells | A brackish Nerineidae (Snail). Local specimens appear to have algal material on the shells, indicating restricted lagoon environments. | |
| Scurriopsis |
|
|
| Isolated shells | A brackish Acmaeidae (Patellogastropoda). | |
| Genus | Species | Location | Formation & Age | Material | Notes | Images | |
|---|---|---|---|---|---|---|---|
| Calliphylloceras |
|
|
| Isolated shells | An Ammonite of the family Calliphylloceratinae | ||
| Canavaria[44] |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. | ||
| Dactylioceras |
|
|
| Isolated shells | An Ammonite of the family Dactylioceratidae. The basis of this series is based on a regional discontinuity marked by a remarkable abundance of Eodactylites from the Lower Toarcian | ||
| Eleganticeras |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. | ||
| Harpoceras |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. | ||
| Hildaites |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. | ||
| Hildoceras |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. Characteristics of the base of the area in Bifrons | ||
| Lytoceras |
|
|
| Isolated shells | An Ammonite of the family Lytoceratidae. | ||
| Neolioceratoides |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. | ||
| Praepolyplectus |
|
|
| Isolated shells | An Ammonite of the family Hildoceratidae. |
Multiple echinoderm remains, including Crinoid articulated and fragmentary specimens and indeterminate echinoid fragments, are know from several localities, usually associated with large coral bioherms or sea trangressions.
| Genus | Species | Location | Formation & Age | Material | Notes | Images | |
|---|---|---|---|---|---|---|---|
| Arbacioida | Indeterminate |
|
| Complete specimens and isolated parts of the exoskeleton | A marine Arbacioida (Echinoidean). These sea urchins are the most abundant echinoderms on local lithiolid reefs. | ||
| Pentacrinites[45] |
|
|
| Complete specimens and isolated parts of the exoskeleton | A Crinoid of the family Pentacrinitidae |
Several scales & teeth of fishes (Lepidotes?) are know from several locations, coming from freshwater/lagoonal layers.[42] Indeterminate dinosaurian & other vertebrates are know from Mizaguène Hill, Taouja Ougourane, Aït Ouaridène, Oued Rzef & Jbel Remuai in the Azilal Province. Some of them are recovered in a "Bone bed" and others are associated with abundant plant remains.[46]
| Genus | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Leptolepis |
|
|
|
| Marine, brackish or freshwater bony fish of the family Leptolepidae. Recovered from the Tagoudite Formation, represents a genus of cosmopolitan fish, common in the Toarcian Mediterranean area. Most specimens appear to come from lagoonal facies. | |
| Leptolepididae | Indeterminate |
|
|
| Marine or brackish bony fish of the family Leptolepidae. | |
See main article: Azilal Formation.
The Major Vegetational distribution was compared with the modern inland of the Isle of Pines.[47] In the Beni Mellal-Azilal areas paleosols show abundance of Rhizoliths of plants associated with heavily bioturbated layers.[48] While there is a great amount of plant remains in the form of coal, foliar debris, cuticles, woody roots, rhizolith and ghost roots, fossil wood and unidentified macrofoliar remains the only flora with some work on it was recovered at Toundoute, as abundant infra-centimeter plant debris composed mostly by Leaflets from ferns and, less frequently, cycad pinnulae, with common cuticles and no palynomorphs.[49] Wood debris from the same locality showed affinity within the coniferophytes, resembling the abietoid Pinaceae or towards the Taxaceae. By quantity of material the vegetation was apparently dominated by ferns, maybe concentrated in punctual wetlands (spring tuffs), followed by cycads and conifers. A possible correlative flora if found in the same age layers of the Mashabba Formation (North Sinai, Egypt) and is composed by the genera Equisetites (Equisetales), Phlebopteris and Piazopteris branneri (Matoniaceae).[50] Other coeval flora includes the plants recovered on the Budoš Limestone and specially the Rotzo Formation.[51] [52]
At Jebel Toksine, lithiotid biostromes are interbedded by recessive and marly levels with woody charcoal debris (including entire trunks of wood, abundant woody plant debris preserved in the form of jet or charcoal), which suggests the presence of vegetation marginal marine that has developed a stabilizing role, which is common in relatively humid environments conducive to the development of marginal marine plants and has the propensity to develop meandering channel morphologies.
At Jebel Azourki, several marine lithofacies were recorded, from 1 to 5, but with an additional 6th of medium gray to black laminated shales with coal streaks and abundant plant fragments, the attribution of which is n is not clear, since it may be Pliensbachian or Toarcian, as may also belong to the Aganane Formation.[53] These black lithofacies shales are interpreted to represent a supratidal marsh developed at the edges of an intertidal zone and a lagoon.
Phytoclasts, spores, pollen and Tasmanites algae indicate that the palaeoenvironment of the lower Toarcian Amellago area was likely proximal continental shelf with a high terrestrial input, and notorious influence of brackish water in the depositional environment.
| Genus | Species | Location | Formation & Age | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Alisporites[54] |
|
|
| Pollen | Affinities with the families Peltaspermaceae, Corystospermaceae or Umkomasiaceae inside Peltaspermales. | |
| Callialasporites |
|
|
| Pollen | Affinities with Araucariaceae inside Coniferae. | |
| Classopollis |
|
|
| Pollen | Affinities with Cheirolepidiaceae inside Coniferae. This interval is numerically dominated by Classopollis, which usually accounts for more than 60.95% of the palynomorphs present | |
| Kraeuselisporites |
|
|
| Spores | Affinities with Selaginellaceae and probably Lycopsida. Age indicator, also present on nearby regions | |
| Ischyosporites |
|
|
| Spores | Affinities with Incertade sedis Pteridopsida or alternatively with Schizaeaceae/Anemiaceae. | |
| Quadraeculina |
|
|
| Pollen | Affinities with Podocarpaceae or Pinaceae inside Coniferophyta. | |
See main article: Azilal Formation.