| Guettioua Formation | |
|---|---|
| Stratigraphic range: Bathonian-Callovian ~ | |
| Type | Geological formation |
| Underlies | Iouaridène Formation |
| Overlies | Tilougguit Formation / Tanant 3 limestones (variable) |
| Thickness | Highly variable: 80–600+ m (typically 150–600 m in type area) |
| Lithology | |
| Primary | Sandstone |
| Other | Siltstone, marl, conglomerate |
| Location | |
| Coordinates | 32°30′N 5°48′W / 32.5°N 5.8°W / 32.5; -5.8 |
| Approximate paleocoordinates | 27°54′N 1°24′W / 27.9°N 1.4°W / 27.9; -1.4 |
| Region | Azilal Province, Béni Mellal Province, Ouarzazate Province |
| Country | Morocco |
| Extent | Béni Mellal-Khénifra, Central High Atlas (Guettioua, Aït-Attab, Aït-Toutline, Aït-Ourir, Toundoute nappe) |
| Type section | |
| Named for | Guettioua (cuvette des Guettioua) |
| Named by | E. Roch |
Guettioua Formation (Morocco) Location of the Guettioua Formation in Morocco | |
The Guettioua Formation or Formation des Grès des Guettioua is a geological formation in Morocco. It dates to the Bathonian stage of the Middle Jurassic.1 It largely consists of continental red sandstone and is the lateral equivalent of the marine El Mers Formation. It´s synonyms include Grès de Wansero, Grès des Guettioua or Infracénomanien/Jurassique continental.23
History
The formation was introduced by E. Roch in 1933 for the red beds in the Guettioua basin overlying Bajocian limestones. Its age was long debated, initially considered "Dogger", later assigned to the Cretaceous by some authors due to apparent basal unconformities.3 Jenny, Le Marrec & Monbaron (1981) restricted the name to the red sandstones above Bajocian limestones and below the Iouaridène Formation, confirming a Bathonian age through dinosaur correlations, palynology of the overlying unit, revised radiometric dating of associated volcanics, and lateral facies comparisons with the El Mers and Anemzi formations.3
Description
The Guettioua Formation is composed almost exclusively of reddish detrital sediments ranging from conglomerates to silts, varied quartz content, all brick-red, although gray-yellow conglomeratic channels occur, often containing plant debris, bone fragments, and occasionally azurite and malachite.34 The sandstones are feldspathic, with rounded quartz grains, feldspars (labradorite, bytownite), micas, volcanic rock fragments (rhyolites), and hematite.56 The formation records the Atlas first basaltic event (locally B1), formed by numerous lava flows that flowed towards the north and northwest of the basins.7 Due to the lenticular and channelized nature of the unit, no single type section is representative.3 The base may show a progressive transition with the underlying Tanant 3 Formation or a progressive syntectonic unconformity, resting on various older units down to the Imi-n-Ifri Formation in places. Upper boundary passes gradually upward into the red pelites of the Iouaridène Formation, known for abundant dinosaur trackways.4
Sedimentology
The formation represents predominantly continental, deltaic to palustrine (marsh/lacustrine margin) environments.34 Diagnostic features include conglomeratic channels, raindrop impressions, ferric oxide staining, cross-stratification, lenticular bedding, abundant plant trunks, and terrestrial vertebrates.6 Synsedimentary tectonics caused significant thickness variations, basin tilting, and intraformational unconformities. Associated magmatic activity includes basaltic flows, dykes, and gabbroic intrusions in some areas (especially Aït-Attab and Aït-Toutline).347
Thickness varies significantly (from 10–20 m in the Ait Ourir area to 500–600 m in the Msemrir syncline) due to syn-depositional tectonics and differential subsidence. The formation is widely exposed in the axial zone and northern front of the Central High Atlas, with occurrences also along the southern margin.8 Fluvial paleocurrent data indicate a dominant sediment transport toward the north-east and east. The western part of the Central High Atlas (Marrakesh High Atlas sector) acted as a topographic high supplying clastic material, while major depocenters and distributive fluvial fans developed eastward. This pattern reflects an early relief differentiation within the Atlas domain during the Bathonian.8
The formation extends with relatively consistent facies to the Ait Ourir region. West of Demnate, distinction from underlying red units is difficult. Thickness varies strongly due to tectonic activity. Eastward, marls and pelites intercalate, producing variegated ("Neapolitan slice") facies. It is also recognised on the southern flank of the High Atlas.8
Biota
Invertebrates
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Genus/Family | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Conichnus9 | C. isp. | Tizi N'Talghemt | Plug-shaped vertical burrows | Made by clams or snails | |
| Rhizocorallium9 | R. commune | Tizi N'Talghemt | Spreite burrows | Polychaetes? | |
| Thalassinoides9 | T. suevicus | Tizi N'Talghemt | Three-dimensional large burrow system | Decapod crustacean? | |
| Unionida indet.10 | Indeterminate | Wawmda | Shells | Freshwater Bivalve |
Amniotes
| Genus/Family | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Anchisauripus?11 | A. isp. | Msemrir | Footprints | Neotheropod tracks | |
| Atlasaurus12 | A. imelakei | Wawmda | "Numerous fragments from several individuals"1314 | Either Brachiosaur or Eusauropod |  |
| Carmelopodus11 | cf.C. untermannorum | Msemrir | Footprints | Ceratosauria tracks | |
| Carnosauria indet.15 | Indeterminate | Msemrir | Footprints | Incertade Sedis | |
| Changpeipus11 | C. carbonicus | Msemrir | Footprints | Neotheropod tracks | |
| Crocodylopodus16 | C. isp. | Msemrir | Footprints | Crocodylomorpha tracks | |
| Eubrontes9 | E. isp. | Tizi N'Talghemt | Footprints | Neotheropod tracks | |
| Grallator17 | cf. G. isp. | Msemrir | Footprints | Neotheropod tracks | |
| Iguanodontipus9 | I. burreyi; I. isp. | Tizi N'Talghemt | Footprints | Iguanodont tracks | |
| Kayentapus11 | cf.K. isp. | Msemrir | Footprints | Neotheropod tracks | |
| Lacertipus?18 | L.? isp. | Msemrir | Footprints | Lacertiform (Squamata? or Rhynchocephalia?) | |
| Sauropoda indet.15 | Indeterminate | Aît Issa | Indeterminate bones | Incertade Sedis | |
| Indeterminate | Tizi-n-Isly | Footprints | Incertade Sedis | ||
| Theropoda indet.121517 | Indeterminate | Wawmda | Teeth | Incertade Sedis | |
| Indeterminate | Aît Issa; Msemrir | Footprints | Incertade Sedis | ||
| Toyamasauripus9 | T. isp. | Tizi N'Talghemt | Footprints | Ornithopod? tracks | |
| Trisauropodiscus19 | T. isp. | Msemrir | Footprints | "Avian-like" theropod or ornithopod trackmakers |
Plants
| Genus/Family | Species | Location/Level | Material | Notes | Images |
|---|---|---|---|---|---|
| Baculatiporites20 | B. piloleus | LM494, Demnate | Spores | Ferns spores of the family Osmundaceae | |
| Classopollis20 | C. senegalensis | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | |
| Concavissimisporites20 | C. verrucosus | LM494, Demnate | Pollen | Ferns spores of the family Lygodiaceae |  |
| Corollina20 | C. bussonii | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | |
| C. caratinii | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | ||
| C. quezelii | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | ||
| C. yvesi | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | ||
| Cupressacites20 | C. oxycedroides | LM494, Demnate | Pollen | Conifer pollen, family Cupressaceae |  |
| Deltoidospora20 | D. minor | LM494, Demnate | Spores | Ferns spores Incertade Sedis | |
| Diadocupressacites20 | D. moghrebiensis | LM494, Demnate | Pollen | Conifer pollen, family Cupressaceae(?) | |
| Ephedripites20 | E. sp. 1 | LM494, Demnate | Pollen | Gnetalean pollen of the family Ephedraceae |  |
| E. sp. 2 | LM494, Demnate | Pollen | Gnetalean pollen of the family Ephedraceae | ||
| E. sp. 3 | LM494, Demnate | Pollen | Gnetalean pollen of the family Ephedraceae | ||
| Exesipollenites20 | E. sp. | LM494, Demnate | Pollen | Conifer pollen, family Cupressaceae | |
| Ginkgocycadophytus20 | G. nitidus | LM494, Demnate | Pollen | Ginkgoales or Cycad pollen | |
| Ichyosporites20 | I. sp. | LM494, Demnate | Spores | Lycopodiaceae or Anemiaceae | |
| Leptolepidites20 | L. verrucatus | LM494, Demnate | Spores | Ferns spores of the family Dennstaedtiaceae |  |
| Matonisporites20 | M. sp. | LM494, Demnate | Spores | Ferns spores of the family Matoniaceae |  |
| Perinopollenites20 | P. sp. | LM494, Demnate | Pollen | Conifer pollen, family Cupressaceae | |
| Perotrilites20 | P. granulatus | LM494, Demnate | Spores | Ferns spores of the family Marsileaceae |  |
| Rotverrusporites20 | R. tenuis | LM494, Demnate | Pollen | Ferns spores of the family Ophioglossaceae |  |
| Spheripollenites20 | S. psilatus | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | |
| S. cf. subgranulatus | LM494, Demnate | Pollen | Conifer pollen of the family Hirmeriellaceae | ||
| Todisporites20 | T. major | LM494, Demnate | Spores | Ferns spores of the family Osmundaceae |  |
| Tuberositriletes20 | T. sp. | LM494, Demnate | Spores | Ferns spores of the family Lygodiaceae |
See also
See also
References
References
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- 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.
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