Azilal Formation
| Azilal Formation | |
|---|---|
| Stratigraphic range: Toarcian-Middle Aalenian Polymorphum-Murchisonae | |
 Layers of the Formation in the Zahouiat Ahansal Village | |
| Type | Geological formation |
| Unit of | Tafraout Group |
| Sub-units | Dolomies du Jbel n´Ourkar |
| Underlies | |
| Overlies | |
| Area | High Atlas[1][2] |
| Thickness | 300-800 m[3] |
| Lithology | |
| Primary | Argillite, conglomerate (+quartz-dredge conglomerates) |
| Other | Brown-red marl, siltstones (micro-sandstones), sandstone-pelitic, breccias with liasic limestone elements, lagoonal shale, sandstone and volcanic minerals.[3] |
| Location | |
| Location | Azilal Province |
| Coordinates | 31°18′N 6°36′W / 31.3°N 6.6°W |
| Approximate paleocoordinates | 26°36′N 3°24′W / 26.6°N 3.4°W |
| Region | High Atlas[4][5] |
| Country | Morocco |
| Type section | |
| Named for | Azilal |
| Named by | |
| Location | Northwest side of Jbel Mesgounane, 10 kilometers east of Azilal |
| Year defined |
|
| Thickness at type section | ~250 m (820 ft) |
  Azilal Formation (Morocco) | |
The Azilal Formation, also known as "Aguerd-nˈTazoult" Formation, Toundoute Continental Series and "Wazzant" Formation (also informally called "Marnes chocolat"), is a geological unit in the Azilal, Béni-Mellal, Imilchil, Zaouiat Ahansal, Ouarzazate, Tinerhir and Errachidia areas of the High Atlas of Morocco, part of the Tafraout Group that covers the Early Toarcian to Middle Aalenian stages of the Jurassic Period.[8] While there have been atributions of it´s lowermost layers to the Latest Pliensbachian, the current oldest properly measured are part of the Earliest Toarcian regresion ("MRST10"), part of the Lower-Middle Palymorphum biozone.[8] The Azilal Formation consists mainly of claystones rich in continental plant debris and laminated microbial facies.[9] It is a continental deposit which overlies marine dolomites of equivalent age to the Rotzo Formation of Italy, mostly part of the Aganane Formation.[6] The formation is the continental to marginal marine part of a massive Siliciclastic-Carbonate platform ("Tafraout Platform"), best assigned to an alluvial environment occasionally interrupted by shallow marine incursions (tidal flat setting) and marks a dramatic decrease of the carbonate productivity under increasing terrigenous sedimentation.[10] Dinosaur remains, such the sauropod Tazoudasaurus and the basal ceratosaur Berberosaurus are known from the unit, along with several undescribed genera.[11] The toarcian High Atlas is divided in 5 units: the continental layers with paralic deposits belong to the Azilal, along the shoreface layers of the Tagoudite Formation & Tafraout Formation, connected with the offshore Ait Athmane Formation and the deeper shelf deposits of the Agoudim 1 Formation.[12]
Description
[edit]
Levêque called this unit "Marnes chocolat" in the Azilal region, made up of red-brown marls, silts (microsandstones) and conglomerates with centimetric quartz dragees. Locations at Adoumaz, Ghnim and Jbel Taguendouft (Béni-Mellal Province) 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 northern region of Ghnim and Adoumaz. The lowermost sections show a transition from sandstone limestone and/or sandstone to clay, with a thin level of green marls locally rich in ostracods. This initial layers are followed by a subtidal term, represented by an oolitic limestone, with fine lamellibranch bioclasts and variable percentages of quartz, that host also small sections of sandstone with calcareous cement and rare oolites, representing this last one is an oblique bedding, of metric dimensions, drawing on the surface mega-ripples of 3 to 5 m in wavelength.[13] The last major section represents a supratidal deposit, as shown by the presence of coarse sandstone gradually changing to red Marls with "fluer" structures and locally to paleosols. This section in Adoumaz has abundance of Paleozoic quartz grains, that are found organized in decametric channeling lenses evoking a predominantly fluvial dynamic.[13]
On the south-southwest edge of the basin towards west of Azilal (Jbel Til-Jbel Amersiaz basin and part of the M'Goun syncline), Guettioua, Demnate, Telouet, Toundoute & Marrakesh, under the Bajocian limestones (Tanant Formation) or directly under the Bajocian?-Bathonian Guettioua Formation, develops a thick a red detrital section in which pelites, sandstones and conglomerates with centimeter-sized quartz balls alternate and breccias (locally called " Wazzant Formation") with Liassic limestone elements, this last ones except near paleofaults, do not appear or have been dissolved. This sector reaches 800 m thickess in the Wazzant subasin, being very reduced to the south of it in Aït-Toutline or Aït-Iouaridène, recovering a variation of the sedimentary process formed by a complex sedimentary unit, terrigenously dominated, composed by the abundance of conglomeratic channels with quartz dragees and Paleozoic basement elements, sandstones organized in bars channeled lenticulars and red clays, the whole part of the facies is organized in metric sequences of filling and alluvial channels.[14] In addition, exceptionally, at the Wazzant area it rests in this place directly on massive dolomites, having eroded the marno-limestones of the Pliensbachian, with transitional layers. A transition between marine and continental deposits, is seen through carbonate palustrine levels and horizons of caliche, being continental layers superimposed in stratigraphic continuity on the marine carbonates of the Aganane or older Imi-n-Ifri Formation.[15] The Wazzant area river system was driven by several minor freshwater currents, likely temporal and related to the rainy seasons. It has a notorious proximal character compared to the other sections of the Azilal formation.[16]
The layers previously called "Aguerd-n'Tazoult formation" represents the most recent marginal marine layers in the Amezraï minibasin, dating from the Upper Toarcian-Aalenian periods and mark the E expansion of the Azilal Formation. It begins with layers that have many conglomerate lenses and ends with coral patch reefs. Sandstones, oolitic, and biodetritic limestones are also found throughout. Red and green marls appear in several layers.[17] In the Talmest-Tazoult area, the formation is made of yellow limestones and marls, hybrid sandstones, micritic limestones, having reef ledges in the upper part and red sandstones and marls in the lower part. Here the Dolomites of Jbel n' Ourkar member is recovered, made of yellow dolomites with intercalated multicolor marls.[7]
Strata
[edit]The layers at Azilal evolved along the central high Altas Toarcian-Aalenian Siliclastic-Carbonate Platform, and consist mostly on a succession of detritic rocks with Red Marls, deposited on an alluvial environment occasionally interrupted by shallow marine incursions, a Mudflat setting.[1][14] The unit represents a major sea regression measured in the central High Atlas, specially after the Lower Toarcian, proven by sections such as "Tarhia n’Dadès", where the Pliensbachian Choucht Formation marginal marine layers are overlain by one meter of red silt/bioclastic limestone alternations, that start a local paralic to continental environments, assigned to the Domerian Aganane Formation. Over this unit the limit with the Azilal formation is marked with a karstified subaerial exposure surface, that wears also great abundance of plant material, what overall implicates prograding terrestrial facies and a shrinking of the local carbonate platform width.[18] The base of the East Azilal Formation is not clear, there is a gradual passage between the underlying limestones of the Aganane Formation and the red pelites of the Azilal Formation. The upper limit is marked by a progressive transition to Bin-el-Ouidane limestones with the limit fixed at the base of the first massive limestones, generally “birds eyes”.[2]
In the west it rests conformably and with progressive passage either on the Aït-Bazzi Formation, or on its lateral equivalent the Aganane, as can be seen at Ait Blal and Tacht where limestone banks are gradually interspersed in the red pelites.[2] In other places is clearly discordant on the sediments of the Sinemurian-Pliensbachian which can be found barely blunted blocks in its conglomeratic levels, as can be seen in places like the N of Wazzant or Ait Bou Oulli. The western upper limit is marked by greenish clayey levels are interspersed between the red pelites, then limestone banks, gradually changuing into the Bajocian Tanant Formation, as can be seen at Tizi-n-Takiout on Aït-Blal.[2]
Evidence of volcanism contemporaneous with the deposition of the Azilal Formation is almost nonexistent, and where volcanic rocks have been assigned, they have been repositioned as either younger or CAMP. The only possible record are explosive volcanic eruption beds found associated with the outcrops at Toundoute, maybe associated to premature activity of the mobile area along the line of the South-Atlasic Fault with Trachyandesitic materials from a explosive source, like in the older Mouluya outcrops like the Tizi-nGhachou sector.[15]
| Unit | Lithology | Thickness (metres) | Fossils |
|---|---|---|---|
| 14) | Sandstone with a wine tone, composed by grains that range from 1/4 to 1 mm | 0.2 m | Non present |
| 13) | Red Pelites: these levels form the horizontal table of the Summit | 4–5 m | Non present |
| 12) | Red Sandstone composed by grains of 1/2 mm in benches of 10 to 20 cm | 1 m | Non present |
| 11) | Lithified red Pelite | 2 m | Non present |
| 10) | Coarse red sandstone (pebbles of 1 cm with other pebbles, many less than 2 to 3 cm) | 0.8–4m | Non present |
| 9) | Sandy red pelites | 2 m | Non present |
| 8) | Red pelites passing through Leafy sandstone | 2 m | Non present |
| 7) | Sandy red pelites | 8–10 m | Non present |
| 6) | Yellowish marno-conglomeratic sandstone, with bones and remains of plants, which, when not transformed into Lignite, show traces of preserved structure; this lenticular layer, which does not seem to exceed 80 cm, locally contains regions of sandstone and Calcite Geodes | 0.8 m | Sauropoda indeterminate; Vertebrate remains indet.; Macroflora Indet. |
| 5) | Bluish sandstones of fairly variable composition: fine particles of Angular Quartz, Plagioclases, abundant Chlorite, clastic Andalusite and Iron Oxide; The coarse parts consisting of Quartz and Moscovite, over Cemented Calcite; Overall surface impregnations of Malachite | 2 m | Non present |
| 4) | Yellowish marno-conglomeratic Sandstone | 0.7 m | Vertebrate remains indet.; Macroflora Indet. |
| 3) | Pelite and Bluish sandstones | 0.7 m | Non present |
| 2) | Very finely lit bistrated limestone, with green and purple grains | 0.2-0.3 m | Non present |
| 1) | Red, Bluish and Green Pelites, disposed on lenticular bands over yellow Breccia marls, parallel deposited with bodies of Calcite | 10–15 m | Non present |
Lithology
[edit]The lithology of the Azilal Formation recovers a Claystone-dominated interval, incised by metric dolomitized beds of Mudstones, Peloid-rich Packstones, Ooid-rich Grainstones, and Polymictic Conglomerates, all rich in Terrestrial plant debris, with faunal content very poor and mostly dominated by microbial facies.[1][3] This unit brings together sandstones, sometimes coarse or conglomeratics, especially red silts and some irregularly bedding carbonate horizons (lacustrine limestones?) as well as rarer coal beds.[2]
At the west this unit consists of conglomerates, sandstones and red pelites.[2] The sandstone and conglomeratic levels are lenticular with frequent oblique stratifications. While it can be complex to differenciate from the Guettioua Formation or the Oukaïmeden Sandstone, conglomerates with multicolored quartz balls of centimeter diameter are the major unique trait of the Azilal Formation.[2] This sequences record predominance of quartz grains (> 50), the rest is made up of fragments of rocks, often quartzose and schistosose with presence of vitreous rocks and spongy Glauconite; calcite cements the elements and fills vacuoles. The absence of heavy minerals and Plagioclase clearly indicate that these sandstones come from the dismantling of a non-granite base. Other proximal areas show Sieve-Conglomerate lenticular channels of ~5 m (16 ft) thickness (≤ 5 m (16 ft)), composed of several materials, such as volcanic products in Toundoute (blocks of sands composed of Feldspars, black ferruginous grains, siliceous green fragments of veins, microgeods, hummocky concretions), limestone debris with traces of roots and cracks, where in some parts traces of fine, dark brushy algal filaments are still visible, similar to blue-green algae of the genus Girvanella.[15] Finally, there are intercalations of fine, often laminated sandstone which mark the inondation facies of the channels during flood periods, being composed solely of feldspars plagioclase and to a lesser extent of orthoclase, as well as small ferruginous grains or fine silts of quartz.[15]
Microfacies
[edit]Due to the strong Dolomitization affecting the strata of this formation it is difficult to describe in detail the microfacies types, yet the following types of microfacies were distinguished:
The first include laminated algal boundstones, with broad areal are characterized by yellow dolomitized Stromatolites.[19] Characteristic of this type of microfacies are cavity channels, which are often arranged parallel to the layering. The presence of peloids is an important facies indicator for the supratidal zone, being transported into the tidal flats by periodic storms and then covered in turn by Microbial mats.[19]
The oosparites/Wackestones along dolomitic grainstones occur rarely, usually only as sparsely massive, gray to yellow layers, which are often obliquely stratified. This layers have diverse but scarce biocomponents, some of which form ooid cores and consist of Foraminifera, Echinoderms, Lamellibranch, Gastropods and Algae. Intraclasts are usually rounded. Peloids occur in a subordinate form.[19]
Biogenic pelmicrites and oomicrites/wackestones are rare facies. In addition to individual Ostracods, Mussel shells, foraminifera and Scytonemataceae Cyanobacteria (Ortonella spp.), Bioturbation is present.[19]
Dolomites, whose components are either completely recognizable or only barely identifiable, depending on the degree of dolomitization.[19]
Sandstone/Conglomerate/Marl: The sandstones of the Azilal Formation are composed of quartz clay, some Feldspar and Glauconite. Pyrite, Malachite, as well as bone and plant remains are found. In the microconglomerate gullies there are also clasts (mainly quartz, quartzite, Granite, Basalt, clay, sandstone) from the Paleozoic and to a lesser extent from the Triassic and Jurassic.[19]
Hydrogeology
[edit]The Azilal Formation constitutes a depressed zone, often intensely cultivated, rich in springs and wells. This is explained by the alternation of permeable and impermeable levels. Springs spring up at the top of this unit, under limestones (Tanant or Bin-el-Ouidane Formations), as in Bernat.[2] The numerous wells dug on the northern edge of Guettioua testify to this unit aquifer qualities, with water accumulated in the sandstone-conglomeratic levels interstratified in the pelites.[2]
Environment
[edit]
The Azilal Formation, located on the Moroccan Carbonate Platform at a palaeolatitude of 19°-20°N, developed during a major drowning episode linked to the Toarcian Anoxic event. It is bounded by the West Moroccan Arch, Anti-Atlas, and Sahara craton. Initially, local laguno-marine facies were overlain by terrigenous deposits post-Toarcian regression, filling small basins in the Atlas of Afourer and Azilal. In Demnate and nearby areas, conditions became terrestrial, while to the east at Beni-Mellal, the sea regression occurred later.[13] The Amezraï minbasin evolved as an isolated carbonate environment.[13] The formation expanded eastward during the Middle Toarcian-Aalenian, marked by tectonic calm and sedimentation of terrigenous and carbonate layers. The Azilal Formation spans post-Polymorphum levels, with notable sea regression and specific faunal assemblages confirming its Toarcian age, Meanwhile the presence of Aalenian (Bradfordernsis-Murchinsonae) Branchiopods in the frontal marine member ("Aguerd-nˈTazoult") coeval with Ammonites of the same age in the easternmost Azilal formation at the Ikerzi Area confirms the marine delimitation on a carbonate platform in the last stages of deposition.[20][19] This sequence is dominated by supratidal to intertidal layers, with abundant bird´s eyes and mudcracks that become more marine towards the E.[7]
The Azilal Formation, part of the Tafraout Group in the Western High Atlas, was deposited in a coastal environment with continental influence. It consists of terrigenous-dominated deposits, reflecting a deltaic environment with temporary emersions represented by a great variety of settings, including continental river/palustrine-dominated, paralic-tidal deposits, and tidal mudflat shorelines.[20] 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).[13] The formation's sedimentary features include raindrop impacts and ripple marks indicating channel/floodplain type fluvial system, with sand-filled channels abundant in plant roots (mostly located in fine limestone, probably from the channel margins), along with evidence of 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.[21] The high abundance of plant remains, either as fossil wood, cuticles, charcoal or Rhizoliths, reveals the presence of vegetated soils in the vicinity.[6] 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.[15] This is recorded specially in the Telouet and Demnate-Wazzant area, but also seen in more detail at Toundoute: the deposits present another channelized floodplain type fluvial system, filled with sand and plant roots/cuticles developed in E-W direction of transit, enriched by both older reworked material and unique interbedded Explosive eruption-type 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, probably as a result of early activity in the local South-Atlasic Fault.[15] The formation also shows evidence of erosion from nearby highlands,as indicates 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, locally either 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.[22][23] 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.[20] The surrounding highlands 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.[24]
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.[9]
Invertebrates
[edit]The fossil record of the Azilal Formation is very restrictive compared to the marine coeval/underliying units, like the Tafraout Formation. 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.[19] Plant remains are very abundant in places such as the north of Jbel Akenzoud and partly impregnated and/or carbonized by malachite.[19] Gastropods have been discovered in several places, but none of the specimens have been studied nor identified.[25] 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).[26][27] "Dwarf black bivalves (Lucinidae?)" in great abundance where reported from the unit at it´s type section.[2]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Ichnofossils
[edit]| Genus | Species | Location | Material | Type | Made by | Notes | Images |
|---|---|---|---|---|---|---|---|
|
|
Tubular Fodinichnia |
Domichnia and/or fodinichnia. |
|
Dwelling and feeding burrow of a suspension-feeder or deposit-feeder, associated usually with shallow waters |
 |
Brachiopoda
[edit]| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
| Curtirhynchia[13] |
|
|
Isolated shells | A brackish/marine Tetrarhynchiidae Brachiopod | |
| Globirhynchia[13] |
|
|
Isolated shells | A brackish/marine Rhynchonellidae Brachiopod | |
|
|
Isolated Shells |
A Brackish Lissajousithyrididae Brachiopod. Mostly benthonic specimens are known. The presence of this species indicates an upper Toarcian-Aalenian age for the layers where was discovered. |
Ammonites
[edit]| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
Isolated Shell |
An Ammonite of the family Hammatoceratidae. Indicator of a Middle Aalenian age for the uppermost layers, as is found also on the Middle Atlas. As well evidence of greater marine influx in the easternmost outcrops. |
Vertebrates
[edit]Several scales & teeth of fishes (Lepidotes?) are know from several locations, coming from freshwater/lagoonal layers.[7] Indeterminate dinosaurian & other vertebrates are known 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.[30]
Theropoda
[edit]| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
B. liassicus |
|
Described originally as a basal representative of the Abelisauroidea, it was recovered as a basal ceratosaur in later studies.[34] It was a medium-sized theropod, measuring 5.1 m (17 ft) long, with a weight of 200 kg (440 lb). |
 | ||
|
Indeterminate |
Two adults and one recently hatched juvenile. At least the posterior half of the skeleton is present: caudal, sacral, dorsal vertebrae, pelvis and both hind legs |
A coelophysid coelophysoid. According to Mickey Mortimer: "Assigned to Coelophysidae based on the apparent fusion between distal tarsal III and metatarsal III". It has been also proposed as a possible tetanuran.[38] That was dismissed by Benson in 2010.[39] Includes at least three different individuals that have been collected in Wazzant: two adults and a newly hatched juvenile. The former foot material resembles the Cretaceous Australian genus Kakuru, that has been proposed as a basal tyrannoraptoran. Mortimer said that "I really don't see much resemblance to Kakuru in the astragalus" and labeled it as a possible dilophosaurid or coelophysoid.[40] |
 | ||
| Theropoda[31][32][41][42] |
Indeterminate |
|
Described as a "Large theropod of uncertain affinities"[31] and as an "enigmatic theropod".[41] To quote Allain: "Two theropods have been found on Toundoute. The first theropod hasn't been described but shows a size larger than any of the know theropods of the Triassic-Early Jurassic know by now, indicating that Toarcian theropods had sizes rivaling that of late Jurassic allosaurs".[43] |
Sauropodomorpha
[edit]| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
Indeterminate |
|
Pubis and other indeterminate remains |
A gravisaurian sauropod. Quoted to resemble Tazoudasaurus |
||
|
Indeterminate |
5 dorsal & caudal vertebrae, fragmentary ribs, chevrons and several large badly determinable debris.[30][36][37] |
A eusauropodan sauropod maybe related with Spinophorosaurus. Was collected on a freshwater lagoonal depositional setting.[30] |
|||
|
Indeterminate |
A possible basal sauropod of uncertain affinities. Remains recovered represent a Juvenile |
||||
|
Indeterminate |
|
One or more vertebrae and other unidentified remains |
A possible Sauropodomorpha of uncertain affinities. P. Lévêque brought these bones back from a hill which he placed in Cretaceous strata, but more recent work has shown that the deposit is in fact in Toarcian layers. |
||
|
T. naimi |
Around 10 different specimens:Partially articulated skeleton and cranial material including complete left mandible with teeth, quadrate, jugal, postorbital, parietal, frontal and exoccipital. Associated remains of a juvenile skeleton. |
A gravisaurian sauropod related to Vulcanodon. The most complete sauropod from the Lower Jurassic Found, with adult, sub adult and juvenile specimens.[31][41][42][32] |
 |
Plantae
[edit]The Major Vegetational distribution was compared with the modern inland of the Isle of Pines.[46] In the Beni Mellal-Azilal areas paleosols show abundance of Rhizoliths of plants associated with heavily bioturbated layers.[47] 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.[45] Wood debris from the same locality showed affinity within the coniferophytes, resembling the abietoid Pinaceae or towards the Taxaceae.[15] By quantity of material the vegetation was apparently dominated by ferns, maybe concentrated in punctual wetlands (spring tuffs), followed by cycads and conifers.[15] 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).[48]
At the village of Tidrite near M'Semrir Pass, samples dominated by Pollen have been recovered.[49]
Fossil Wood
[edit]At the top of the 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. This woody pieces are considered root fragments.[50]
| Genus | Species | Stratigraphic position | Material | Habit | Notes | Images |
|---|---|---|---|---|---|---|
|
|
|
Arboreal, high canopy, linked with floodplain margins yet high aridity tolerant |
Conifer fossil wood related with Podocarpaceae inside Pinales. Probably built evergreen tropophilous forests in alluvial plains together with Agathoxylon. A genus closely related with Dacrydium and Dacrycarpus.[53] |
 |
See also
[edit]- Toarcian turnover
- Toarcian formations
- Marne di Monte Serrone, Italy
- Podpeč Limestone, Slovenia
- El Pedregal Formation, Spain
- Mizur Formation, North Caucasus
- Sachrang Formation, Austria
- Posidonia Shale, Lagerstätte in Germany
- Irlbach Sandstone, Germany
- Ciechocinek Formation, Germany and Poland
- Krempachy Marl Formation, Poland and Slovakia
- Djupadal Formation, Central Skane
- Lava Formation, Lithuania
- Whitby Mudstone, England
- Fernie Formation, Alberta and British Columbia
- Whiteaves Formation, British Columbia
- Navajo Sandstone, Utah
- Los Molles Formation, Argentina
- Mawson Formation, Antarctica
- Kandreho Formation, Madagascar
- Kota Formation, India
- Cattamarra Coal Measures, Australia
References
[edit]- ^ a b c d Jenny, J. (1985). "Carte Géologique du Maroc au 1: 100.000, feuille Azilal". Notes et Mémoires du Service Géologique du Maroc. 339 (2): 1–104. Retrieved 25 January 2022.
- ^ a b c d e f g h i j Jenny, J. (1988). "Carte géologique du Maroc au 1/100 000: feuille Azilal (Haut Atlas central). Mémoire explicatif". Notes et Mémoires du Service géologique. 378 (1): 1–122. Retrieved 25 January 2022.
- ^ a b c d Le Marrec, A.; Jenny, J. (1980). "L'accident de Demnat, comportement synsedimentaire et tectonique d'un decrochement transversal du Haut-Atlas central (Maroc)". Bulletin de la Société Géologique de France. 7 (3): 421–427. Retrieved 25 January 2022.
- ^ Peleogeographiques, C. E. R. (2002). "Les formations lithostratigraphiques jurassiques du Haut Atlas central (Maroc) : corrélations et reconstitutions paléogéographiques". Documents des laboratoires de géologie Lyon. 156 (1): 163. Retrieved 25 January 2022.
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