Aganane Formation

The Aganane Formation (also known as Aït Chitachen, Aït Bazzi or Assemsouk Formation in the High Atlas and Calcaires de Tizi Nehassa in the Middle Atlas) is a Pliensbachian (Early Jurassic), with some levels being potentially Latest Sinemurian, geologic formation in the Khenifra, Midelt, Azilal, Béni-Mellal, Ouarzazate, Tinerhir and Errachidia areas, in the Middle and High Atlas of Morocco, being the remnant of a local massive Carbonate platform, and known mostly for its rich tracksites (up to 1350 tracks in 1988) including footprints of dinosaurs. It may also include the fossiliferous levels of the Calcaires du Bou Dahar, if true, it would be one of the richest Early Jurassic formations in the entire tethys area.

This formation has been dated to the Pliensbachian stage of the Lower Jurassic, thanks to the find of the ammonite '' Arieticeras cf. algovianum'', indicator of Middle Domerian (=Uppermost Pliensbachian) in the upper zone, and lower delimitation by the foraminifers '' Mayncina termieri'' and '' Orbitopsella praecursor'' (indicators of Carixian=Lower Pliensbachian age). The dinosaur tracksites are all located a few metres below the Pliensbachian-Toarcian limit, being coeval and connected with the lowermost layers of the continental Azilal Formation. The Aganane Formation was also coeval with the Jbel Taguendouft Formation, all developed along a local "platform-furrow" in the Middle Atlas Mountains, that act as a barrier controlling the western border of the Jurassic Atlas Gulf. The nearshore sections, including both carbonate platforms and close to sea terrestrial facies where located on an isolated internal domain thanks to the control of the barrier, allowing the Aganane Formation to develop on a hot and humid climate, where a local algal marsh had intermittent progradations, intercalated with a layer of terrigenous continental origin. The ichnosites were developed in tidal flats and coastal deposits suitable to sea flooding.

The Aganane Formation is a member of the Pliensbachian facies section of the Central Atlas, which are distributed from west to east: The sequences referred to either the synonyms "Aït Chitachen" & "Aït Bazzi" Formations at W sectors such as Demnate or Telouet (continental-fluvial, coastal lagoon) and the Aganane itself at the Azilal area, where the village of the same name is found. At Tazoult, part of the Azilal profile contacts the bottom with the karst Talmest-Tazoult Formation, then a section where the Aganane itself indicates an eastward expansion of the carbonate facies, finally, a westward advance of the Imilchil pelagic facies, mostly part of the Jbel Choucht Formation or Ouchbis Formation.

__TOC__

Lithology

The Aganane Formation, is a thick carbonate-dominated sequence, reaching up to 600 meters in thickness. It lies between the dolomites and limestones of the Imi-n-Ifri Formation below and the red sandstones and pelites of the Tafraout Group above. The transition to the overlying and underlying formations is generally gradual, though local erosion can create discordances.

The proximal series towards SW of the Demnate accident are dominated by very confined brecciated and dolomitic facies containing gypsum lenses, mapped as the "Aït-Bazzi Formation". Its characteristic facies include yellowish cavernous dolomites as well red marls, are common, while gypsum facies were discovered on drillings. Red sandstone-pelitic facies with rhizoliths often forms the base and can be widely found (Jbel Rat, Foum Jem'a, Rbat, Ait Athmane...). Within this sequence the formation also exhibits yellowish dolomite laminations with small cavities due to clay leaching, gypsum deposits present in smaller amounts and evidence of periodic desiccation, inferred from microbreccias and vertical microcracks.

Towards Azilal the unit primarily consists of well-bedded cyclic carbonate rocks, dominated by dolomitic and calcareous beds, often exhibiting dry joints. The dolomites are typically yellowish to reddish and fine-grained, while the limestones are gray to beige and biodetritic. Interbedded sequences of impure limestone and red marl, often in decameter-thick layers, are present, particularly at the base and middle sections. The limestones are generally rich in fossils, including large bivalves (Astartidae, Plicatostylidae), large foraminifera ('' Orbitopsella''), and algae. At Talmest-Tazoult it was divided in 3 sub-units: A.g. 1 (50 m) starts with red marls and features fossil-rich limestones with bivalves, brachiopods, and foraminifera like '' Mesoendothyra'', evolving from mudstones to oolitic grainstones, capped by an oxidized discontinuity. A.g. 2 (40 m) mirrors this lithology but stands out for its biostratigraphic microfauna (e.g., '' Pseudocyclammina liasica''), spanning packstones to biomicrites with algae and oncoliths. A.g. 3 (40 m) begins above an emersion surface and ends the formation with thick, fossiliferous limestones transitioning to detrital deposits, marked by tectonic cracks at its top. Together, these units depict a shallow marine setting with periodic exposure, varying regionally in thickness and facies.

Characteristic features include:

* Dolomitized stromatolitic boundstones: alternating yellow and light laminations, with peloids and intraclasts in a dismicritic to microsparitic matrix.
* Bio-pelmicrites/mudstones to wackestones: biogenic components include echinoderms, gastropods, foraminifera, ostracods, and terrigenous quartz grains.
* Bio-intra-oosparites/packstones to grainstones: contain foraminifera, gastropods, echinoderms, lamellibranchiates, and algae (''Cayeuxia'').
* Biostromes with large bivalves, found particularly in patch reefs and limestone bars.
* Intraformational megabreccias, composed of angular clasts in thick lenticular beds, often linked to submarine slumps.
* Microfacies diversity, including biomicrites, packstones, grainstones, and stromatolithic bindstones, with common ooids, peloids, echinoderms, gastropods, bryozoans, and corals.
* Eventstones and siliceous nodules, particularly in the southwestern sections, where alternating asymmetrical cycles (0.5–100 m thick) suggest periodic environmental fluctuations.

The presence of stromatolites, tepee structures, and desiccation cracks suggests periodic exposure and drying, reinforcing the interpretation of a dynamic coastal to intertidal system.

Description

The Aganane Formation is characterized as representing the coastal-shallow sector of a massive carbonate platform were carbonates of this unit were subjected to an examination of the diagenetic characteristics, where changes in the surface environment were consistently reflected in a sequence of rocks by diagenetic characteristics, maybe a tentative correlation of major events, such as Hurricanes. This succession exhibits significant lateral (west-to-east) variations, reflecting an evolving depositional system. From west to east it transitions from red marly lagoonal-brackish facies, to lagoonal facies (occasionally evaporitic), to marly-dolomitic or marly-calcareous lagoonal-marine facies. At the eastern edge of the Afourar map, it becomes coralligenous, integrating with the underlying calcareous-dolomitic series to form a reefal complex. This reefal barrier isolates from cephalopod-rich facies of the inner Atlas, complicating stratigraphic correlations.

The supratidal sector was diverse, including continental deposits with abundant quartz-rich cricundant deposits and fluvial channels, as well as others composed of considerable thicknesses of stratified gypsum and chicken-wire cargneules, lime and dolomite shales and marls, with drying cracks, caliche crusts and vadose pisoliths. These sediments suggest a continental zone bordering river courses, connected to coastal sectors where shales and siltstones derived from Sabkhas in which interstitial evaporites were formed. To the north of the Demnate fault, there existed an extensive subsiding tidal flat where carbonate deposits containing gypsum remnants and stromatolitic laminites formed, interspersed with desiccation polygons, gypsum precipitated in sebkhas along the edge of a low continent, indicative of a possibly arid climate. Along the Demnate fault's edge, active during this period, lignite layers were intercalated, likely resulting from the degradation of forests located to the south, indicated by root traces in sandstones at the base of the formation (locally referred as "Aït-Bazzi Formation") in Aït Tioutline, as well seen W-E as red marls with paleosols to a chaotic dolomitic sequence in W Zaouiat Ahansal. The area was inhabited by both herbivorous and carnivorous dinosaurs that roamed an expansive coastal marshland.

In the intertidal zone, pelletoid lime packstones and wackestones, often bioturbated, reflect shallow, low-energy conditions, with variable amounts of terrigenous material. Fenestral fabrics and occasional bivalve species further support intertidal or shallow subtidal environments. Mudstones and wackestones, occasionally with bivalve remains, suggest low-energy conditions, with evidence of shallow, brackish-water environments. Oolitic lime grainstones, well-sorted and cross-bedded, indicate high-energy conditions likely associated with tidal distributary bars, while crinoid and mollusc packstones suggest quieter waters around shoals. Algal laminated boundstones developed in both supratidal and intertidal zones, following present-day patterns such as Shark Bay in Australia or the Persian Gulf. Whereas the pelletoid lime packstone/wackestone facies most likely represented tidal flat areas, or analogs to modern coastal mangrove growth. Additionally, more massive facies with large Plicatostylidae separated the tidal flat from the open sea with Ammonites, whose western extension bordered the eastern edge of Azilal.

Subtidal deposits include both those of an intertidal nature, indicating shallow water or coastal lagoons, with extensive accumulations of skeletal lime packstones, oolitic tidal deltas and offshore bars, oncoliths and coral reefs, and occasional bivalves '' Opisoma'' spp., while further east the more open subtidal conditions are represented by flint-bearing calcareous shales and sparse faunas where ammonites begin to appear.

Locations such as Ait Athmane, Aghbalou N'Kerdous or Assemsouk recover the typical Sinemurian-Pliensbachian Plicatostylidae reefs, composed by aggrupations of aberrant bivalves. Locally, these reefs were developed as shallow subtidal, cross-bedded floatstones, later evolving to layers with evidence of subaerial exposure, including lagoonal marls, and bioturbated red mudstones with root traces and calcrete. These layers are abundant on the aberrant Plicatostylidae bivalves '' Lithioperna'' and '' Cochlearites'', as well common corals, gastropods, the astartidae bivalve '' Opisoma'' and oncoids, all living in a sheltered lagoon in the interior of the local carbonate platform, similar to the Rotzo Formation of the Trento Platform. On Jebel Azourki several biofacies can be seen: tabular, erosive structures formed by tidal channels, mound-like forms with bivalves growing in place, cross-bedded deposits from lateral channel migration and bioherms with clustered bivalves, forming on flats or channel bends. The "Assemsouk Structure" is a massive bivalve-dominated reef (125 m high, 1250 m long), features bioherm growth stages with corals and stromatolites, bordered by a reef wall on the east. It was first interpreted as a "Mud Mound", but later was seen to be a carbonate body that became a narrow turbiditic trough (<3 km wide) due to faulting and was later buried under marine marls, with the "mound" as a preserved block from the original platform. The environment spans from supratidal flats to subtidal zones, with eastern laminated shales transitioning to marine grainstones, indicating a regressive phase with barrier island formation separating intertidal deposits from deeper biodetritic slope deposits, all later covered with laminated shales with coal streaks and abundant plant fragments, recording an anoxic coastal lagoon.

Diapirism

At Talmest-Tazoult, the presence of diapirs (like the "Tazoult salt wall") is remarkable. In the Pliensbachian, this area begins with the deposition of the Jbel Choucht carbonate platform, followed by uplift and salt wall growth causing erosion of the karst and deposition of syn-diapiric breccias, conglomerates, and sandstones (Talmest-Tazoult Formation), and then is invaded from the west by the shallow marine carbonate platform of the Aganane Formation. At this time, a decrease in the growth rate of the diapir is detected compared to the Sinemurian. In fact, with the eastward extension of the Aganane Formation, the Tazoult salt wall registers a major change towards shallower facies, confirming a higher diapir relief and a decrease in water depth towards this area during the Pliensbachian, not excluding a complete stop of diapir activity in this interval. Pliensbachian carbonate platforms likely formed above salt walls, similar to the La Popa Basin (Monterrey). Small-scale karstic cavities filled with meteoric sediments at the platform top further highlight this transition. The Aganane limestones were later overprinted by modified marine fluids during burial, leading to localized dolomitization under reducing conditions. This transformation suggests a late diagenetic phase linked to burial processes, potentially continuing into early shallow burial stages. The diapirs remained as bathymetric highs and emerged islands that allowed the proliferation of Plicatostylidae and other organism colonies during the deposition of the Aganane Fm, as well they created hemipelagic deeper facies between them.

Climate

The Pliensbachian High Atlas trough, situated within a photozoan-dominated carbonate system that formed in a warm, semi-arid to arid climate. The presence of organisms that thrive in clear, nutrient-poor tropical waters along with features like ooids, evaporites (gypsum), and calcretes, all point to such conditions. Sediments and fossil assemblages across different platform zones further suggest that this area experienced high evaporation rates and limited freshwater input, typical of a semi-arid to arid climatic belt, as evidenced by widespread evaporite minerals, desiccation features, and subaerial diagenetic fabrics. The scarcity of terrigenous material and the prevalence of wind-transported red mud and fine sand further indicate low precipitation, with strong winds (common in modern regions like the Persian Gulf and Shark Bay in Australia) serving as a key sediment transport mechanism. Periodic storms, similar to Shark Bay's winter gales, significantly shaped sedimentation, leaving behind erosional and depositional structures consistent with arid environments. The surrounding low-lying hinterland experienced little runoff and was primarily eroded by wind.

Salinity in the trough varied, with high levels in marginal intertidal and supratidal zones, inferred from the lack of marine faunas, abundant evaporites, and comparisons to modern analogs like Shark Bay and the Persian Gulf, where restricted circulation elevates salinity. Maps based on biota, evaporite distribution, and algal mat tolerances (modeled after Shark Bay) show normal oceanic salinities in the southern inlet and eastern areas, while the northern trough had persistently high salinities. However, ''Ophiomorpha'' burrows near Ait Ourir suggest occasional normal marine salinities in the trough's center during maximum transgression (seen in the older Imi-n-Ifri Formation). Intertidal zones periodically supported salt-tolerant plants, forming thin organic seams in low-salinity areas.

Sedimentary structures like cross-bedding in oolite and clastic shoals, as well as channel directions, were recorded but showed high variability and no consistent trends, likely due to the complex interplay of tidal currents, islands, promontories, mud mounds, shoals, and storm influences in this tidally dominated environment.

Depositional settings

The lower and middle parts of the Aganane Formation mainly consist of light gray dolomitic limestone, often with a rhythmic layering. This environment represents a shallow, coastal area similar to modern tidal flats where seawater periodically covered the land during high tides. Areas like Ait Athmane or Tizi n'Terghist record rhizoliths (including massively rooted levels), tree trunks, red clay with paleosols and pisoids, which are indicative of pedogenic or freshwater vadose conditions with periodic exposure to air and fresh water. In other localities are mainly biodetritic limestones, showing emersion structures at their top (dolomitization, mud cracks, roots and plant remains, footprints of Dinosaurs). A significant portion of this environment was influenced by coastal lagoon and supratidal plains, areas only occasionally submerged by the sea, like at Assemsouk, were clastic carbonate deposits record cross-bedding structures and with abundant remains of plants or at Aghbalou N'Kerdous with red lagoonal calcareous siltstones and limestone beds with microbial crenulations.. Red and white marls mixed with thin dolomite layers suggest periods of exposure to the air, with sediments deposited by rivers and occasional flooding from the sea. This setting is comparable to the modern Persian Gulf's sabkha environments, where salt flats and shallow waters mix. Evidence of land exposure includes features like mudcracks and evaporite crystals. Occasional storm events likely washed in marine sediments, indicated by brecciated layers (broken rock fragments). Dinosaur footprints found in these layers suggest a nearby vegetated land area with sufficient rainfall to support life, and thus high annual precipitation, suggesting overall tropical conditions reminiscent of the modern Andros Island model in the Bahamas.

Further offshore, the platform transitioned into a more open lagoon setting, where shallow marine conditions dominated. The rocks here include mud-rich limestones and dark biodetrital limestones (formed from broken fossil fragments). This part of the formation often shows signs of marine life, including llamellibranchs, gastropods, brachiopods, with calcareous algae ('' Palaeodasycladus'', '' Solenopora'', etc.) oncoliths and Foraminifers. Some layers contain large bivalves like Plicatostylidae, occasionally forming shell beds. These shell accumulations and their arrangement suggest the influence of tidal currents, creating small channels within the lagoons. The presence of gray, organic-rich sediments indicates a low-oxygen, calm-water environment where fine carbonate mud accumulated.. Subtidal influences are observed in oncolitic lime wackestones, indicating a relatively low-energy environment with occasional mixing from higher-energy conditions.

In the more open, wave-exposed parts of the platform, the sediment becomes coarser and contains reef-related deposits. These deposits include bioclastic limestones (composed of broken shells and coral fragments) with large coral colonies and sea urchins. The corals likely formed small patch reefs, protecting the inner platform from strong wave action. The transition between these reef zones and the inner platform was gradual, with occasional storm events depositing coarse sediments into the quieter lagoon areas. This reef barrier acted as a natural protection for the lagoon, allowing finer sediments to accumulate behind it.

Small cycles within the bank with frequent reworking and/or rearrangement phenomena demonstrate the importance of episodic storms, which repeatedly led to the displacement of individual facies zones. The only slightly consolidated bottom of the extensive, shallow lagoon areas was repeatedly reworked, with thicknesses of 2–4 meters are characteristic of restrictive lagoonal berelches in the lee of offshore bars or reef belts. The asymmetric large cycles are interpreted, with some reservations, as regressive cycles in connection with global sea level fluctuations and regional tectonic development.

Paleogeography

During the Pliensbachian, the region was situated at a nearly tropical paleolatitude and marked the western boundary of the ancient "Atlas Gulf," which faced the Tethys Sea to the East. The Aganane Formation is located largely within the "Grand e Accident du Nor d'Altasien" or North Atlas Fault, the largest and most important of the Central High Atlas faults. During the late Pliensbachian, 200 m of carbonate sediments accumulated south of the fault on an overturned block, while to the north more than 700 m of similar material accumulated. This fault line probably marked the northern boundary of a Paleozoic basement peninsula that advanced eastward from the Tichka Massif into the Atlas Trench.

In the Haute Moulouya area (Middle Atlas), deposition was controlled by pre-existing subsidence, with the formation occurring only in areas that had already subsided before the Jurassic transgression. In one sector within this area (Itzer Facies), the formation's deposits were previously misidentified as Cretaceous. In the Causse d’Ajdir area, fossil finds indicate a Carixian to basal Domerian age. The formation exhibits southwest-directed sediment transport and is characterized by siliceous nodule-rich deposits in certain areas, particularly those associated with intraplatform basins.

The facies generally have a low bathymetry, evolving from east to west from a lagoon-marine facies to brackish facies. At the level of the Azilal Province-Beni-Mellal Atlas, the Pliensbachian occurs on both sides of the Demnat Fault: to the southwest of the fault, the "Aït Bazzi Formation" with dolomitic and red marly facies (lagoonal and lagoon-evaporitic facies), while to the northeast the Aganane Formation dominates.. Towards the south, the "basin" facies ends at the bottom of the gulf near the Jbel Oukarde accident, at the western end of the Tilougguite syncline, with the limit corresponding to the present-day course of the Azilal-Anergui submeridian fault. On the Amezraï and Aït Bouguemmez basins, a platform was established, were the Aganane Formation presents more or less the same characteristics as those described in the Beni-Mellal area. At Ait Bou Guemmez, the upper Aganane Formation records the development of a lagoonal environment south of the Jbel Tizal- Jbel Azourki accident, which evolves to a more or less open subtidal platform environment north of this accident.

The paleogeographic evolution of our region can be described in three main stages:

*The Lower Pliensbachian ("Carixian"), which follows the typical Sinemurian paleogeographic pattern with foreshores and prolonged emersion facies (paleosols, karsts and teepee-shaped structures), the latter being mainly observed on the southern slopes of the central High Atlas, evolving on the subtidal platform of the Upper Sinemurian, with Plicatostylidae colonizing for the first time the main areas located in line with the active accidents, notably the fault located NE-SW, separating the Tilougguite trough to the SE from its limiting platform to the NW.
*The "middle" Pliensbachian ("Carixian" - lower "Domerian") marine environment gradually resettles along the western edge of the High Atlas Basin, with maximum opening of depositional environments in the Carixian-Domerian transition (rhythmic mamocalcic sedimentation in the Tilougguit Trench, turbidite facies on the SE edge of the Beni-Mellal platform and subsident lagoons in the other sectors). At the same time, the NW-SE-trending Demnate Fault and the N70-trending North Atlas Fault become evident, whereas the southern edge of the Telouet Graben does not appear to have changed significantly during the Middle Lias like its counterpart in the northern part of the range, being here the main site of the shallow sedimentation of the Aganane Formation. Towards the Tinghir meridian, open sea facies are encountered.
*The last facies belong to the Upper Pliensbachian (Upper Domerian) where the paleogeography of the Central High Atlas becomes very contrasted, with emersion of a vast sector of the platform (At Demnate), leading to the development of paleosols and karst and the accumulation of lignite deposits along tectonically active faults. At the same time, there is a filling of the Tilougguite ditch by carbonate and terrigenous sedimentation, showing small basins like Tamadout and Taquat N'Agrd with a sedimentation with a gravity component, and shoals (Jbel Taguendouft) with condensed deposits. Finally an intensification of the activity of the North leading to the deepening of the central platform (creation of the new basin of Amezraï), to the individualization of strongly subsident zones in the aplomb of this accident (gutter of Jbel Azourki-Jbel Aroudane) and to the birth of the first wrinkles in the center of the high-Atlasic basin.

Foraminifera

Local Foraminifers have been the major reference to establish the local different environmental settings, as its distribution is clearly based on cyclic sedimentary evolution: the base banks "Term A" represents a shallow subtidal setting with rich thanatocoenosis of '' Siphovalvulina'', '' Mayncina'' or '' Orbitopsella'', associated with an intensely bioturbated environment, analogous to present Bahamas, Florida or Persian Gulf. In the Aganane type section limestone beds (biopelmicrite) rich in ''Orbilopsella'', '' Haurania'' or '' Pseudopfenderina'' could be interpreted as brought by tidal currents covering the supratidal zone. In "Term B" a thanatocoenosis of monospecific Foraminifera with ''Mayncina'' ''termieri,'' ''Pseudopfenderina'' or '' Lituosepta compressa'' are common, interpreted as allochthonous, resulting from sorting in an intertidal environment higher than supratidal, under or alternated with the supratidal laminations and the storm breccias, as well in rarer cases covering ( aeolian origin?) surface of the supratidal coastal plain. The Aganane Foraminifera in Terms "D" and "E" underwent significant evolutionary and environmental changes. During D, the foraminiferal population was dominated by '' Planisepta'', a smaller morphovariant of ''Lituosepta'', which persisted after the decline of larger orbitopsellids like ''Orbitopsella'' due to internal biological factors and mechanical instability related to their large size. The population remained stable until the Middle Domerian anoxic crisis, which triggered a microfaunal turnover. E saw the emergence of smaller, simpler foraminifera such as '' Haurania'' ''gracilis'' and '' Paleocyclammina'' ''liasica'', adapted to eutrophic lagoon conditions.

Invertebrates

Ichnofossils

Anthozoa

The Reef facies of the Aganane Formation featured a nearshore, tropical setting. Late Pliensbachian corals of the Aganane Formation are mainly limited to ''Retiophyllia'', ''Thamnasteria'' and ''Archaeosmilia''. Dominant Plicatostylidae bivalves, in a way akin to modern ''Crassostrea'', thrived in both clear and turbid waters, forming biostromes and bioherms in protected lagoons. Their growth outpaced sediment accumulation thanks to soft carbonate mud and their own fecal matter providing support. Fluctuating water depths influenced habitat suitability, with lithiotids adapting to shallow subtidal environments. Co-existing scleractinian corals, possibly photosymbiotic, suggest warm, clear, oligotrophic conditions, yet their symbiotic nature is hard to confirm in fossils. These corals were sensitive to changes in environmental parameters like temperature and salinity.

Porifera

Brachiopoda

Bivalves

Gastropoda

Ammonites

Annelida

Crustacea

Dinosauria

Theropoda

Sauropodomorpha

Several tracks, classified under a "Morphotype 3", were originally attributed to Thyreophoran (Stegosaur?) dinosaurs, even recently suggested to come from the ichnogenera '' Deltapodus?, Luluichnus?'' and ''Tetrapodosaurus?.'' It must be noted that this tracks are badly preserved and unusually large for an armoured dinosaur of early jurassic age (some up to 60 cm), and so likely are misidentified Sauropodomorph tracks.''''

Rhodophyta

Viridiplantae

Photo Gallery

File:Desiccation Rnim.jpg, Desiccation cracks in a dolomitized limestone bench, emersive cycle top of the Lagoon
File:Calcretes et ammonites.jpg, Ammonites and belemnites displaced on the supratidal plain ("teepee") by a storm wave or a tidal current
File:Brèche de tempête.jpg, Storm breach at the top of a metric regressive sequence
File:Pisolithes vadoses.jpg, Vadose pisoliths and "birdseyes" in coastal carbonate sand, emergent; outer shelf
File:Keystone vugs meniscus.jpg, Aerial, supratidal (vadose) diagenesis in a carbonate sand with foraminifera displaced by tidal currents and storm waves on the shelf
File:Calcretes remaniés dolomie.jpg, Thin layer: calcretes (calcareous crusts) reworked in a gravelly coastal sediment, partly dolomitized
File:Ciment stalactite vadose.jpg, Stalactite cement at the top of a "keystone vug" typical of diagenesis in a vadose environment, at the top of an emersive cycle (L=0.3 mm)
File:Calcretes et birdseyes.jpg, Calcretes (calcareous crust) and "birdseyes" in a gravelly coastal sediment
File:Teepee supratidal flat.jpg, Diagenetic structure in "teepee" on the supratidal plain, formed by the increase in volume of the sediment following the crystallization of carbonates (dolomite)
File:Brèche de tempête (2).jpg, Hurricane Breccia, with dolomitic matrix. Top of emersive cycle.

See also

* List of dinosaur-bearing rock formations
** List of stratigraphic units with theropod tracks
** List of stratigraphic units with sauropodomorph tracks
** List of stratigraphic units with ornithischian tracks

References

{{Reflist

Jurassic System of Africa
Early Jurassic Africa
Jurassic Morocco
Pliensbachian Stage
Limestone formations
Dolomite formations
Ichnofossiliferous formations
Paleontology in Morocco
Sandstone formations
Claystone formations
Shale formations
Conglomerate formations