The Tagoudite Formation (also known as the "Upper Tamadout Formation") is a geological formation of Toarcian (Lower Jurassic) age in the Béni-Mellal, Imilchil, Tinerhir, Tinejdad and Errachidia areas of the High Atlas (reaching areas near Rich in the Middle Atlas) of Morocco.
Description
The Tagoudite Formation marks a major shift in Liassic sedimentation, replacing the carbonate turbidites of the Ouchbis Formation with mostly siliciclastic layers. These layers alternate between gray and green sandstone, sandy marls, and siltstones, forming sequences up to 20 meters thick. They show a decrease in grain size and an increase in marl content from bottom to top, with features like ripple marks and laminations. Microscopically, the turbidites are mainly fine silt, with varying amounts of quartz, feldspar, and carbonate detritus, and occasional pyrite. This formation suggests an open marine environment with sediment interruptions and materials coming from distant areas. It is widespread in the Central High Atlas, with thicknesses reaching up to 320 meters, and varies across different regions like Tounfite and Beni Mellal. In the Central Middle Atlas, sedimentation was interrupted by emersion before the formation's deposition. The deposits of the Tagoudite Formation are mostly restricted to the central High Atlas, with a thickness of approx. 200 m in the northwest vs at 30–70 m in the southeast, but retaining around 200 m at center areas like Foum Tillicht. More at the E it starts to disappear like at the Cirque de Jaafar, SW of Midelt or more at the E at Bou Redine Gorges, were the Agoudim Formation directly overlies the Pliensbachian.
Small (-1 cm) rounded ridges and troughs wrinkle structures occur on the tops of fine-grained turbidite beds deposited rapidly in deep, low-light conditions, too deep for photosynthetic mats. The wrinkles were likely formed by chemosynthetic microbial mats, sulfur-oxidizing bacteria (Beggiatoaceae, Thioploca spp., and similar Gammaproteobacteria) that thrive in dark, organic-rich sediments where chemical gradients provide energy. Frequent turbidity currents, high organic content (including woody debris), and sulfide-rich pore waters created ideal conditions for these mats to grow and for their textures to be preserved. Low animal activity due to toxic sulfide levels further enhanced preservation.
Biota Phytoplankton marks oscillations of negative carbon isotope excursions at T-OAE and Pliensbachian-Toarcian (Pl-To) transition, dominated by open marine haptophytan or incertade sedis coccoliths like Biscutum, Carinolithus (including the index C. superbus, marker of the Polymorphum biozone), Calcivascularis, Calyculus, Lotharingius, Mitrolithus, Parhabdolithus or Schizosphaerella, measured in the Tagoudite Fm in areas like Amellago or Talghemt. Dinoflagellates are rare and limited to taxa such as Luehndea, Mancodinium and Mendicodinium.
Foraminifera GenusSpeciesLocationMaterialNotesImagesDentalina D. terquemi D. sp. Bou-OumardoulTests/shellsA foraminifer of the family Nodosariinae.Citharina C. sp. Taquat N'AgrdTests/shellsA foraminifer of the family Vaginulininae.Everticyclammina E. sp. Aguerd N´Igli Aguerd N´Wahmane Col de Ghnim Ouguerd Zegzaoune Tizi n-M´BarekTests/shellsA foraminifer of the Everticyclamminidae family.Ichtyolaria I. carinata I. gr.major Bou-Oumardoul TalghemtTests/shellsA foraminifer of the family Ichthyolariinae.Lenticulina L. matutina L. gottingensis L. acutiangulata L. münsteri L. toarcense L. chichery L. sp. Anergui Bou-Oumardoul Taquat N'Agrd TalghemtTests/shellsA foraminifer of the family Lenticulininae.Lingulina L. brizaeformis L. pupa L. dentaliformis L. tenera Bou-Oumardoul Taquat N'AgrdTests/shellsA foraminifer of the family Lenticulininae.Marginulina M. prima M. spinata Taquat N'AgrdTests/shellsA foraminifer of the family Marginulininae.Ophtalmidium O. concentricum O. sp. Aguerd N´Igli Anergui Bou-Oumardoul Ilourhmane Jebel Toksine Ouguerd Zegzaoune Taquat N'Agrd TimghissineTests/shellsA foraminifer of the family Ophthalmidiidae.Orbitopsella O. praecursor Col de GhnimTests/shellsA foraminifer of the family Orbitopsellinae.Pseudocyclammina P. sp. Aguerd N´Igli Bou-OumardoulTests/shellsA foraminifer of the family Hauraniidae.Pseudonodosaria P. tennis P. multicostata P. gr.pygmea P. sp. Bou-Oumardoul Ilourhmane Ouguerd Zegzaoune Talghemt Taquat N'AgrdTests/shellsA foraminifer of the family Nodosariinae.Reinholdella R. sp. Anergui Bou-OumardoulTests/shellsA foraminifer of the family Ceratobuliminidae.Verneuilinoides V. cf.subvitreus TalghemtTests/shellsA foraminifer of the family Verneuilinoidinae
Ichnofossils IchnogenusIchnospeciesLocationMade byImagesArenicolites A. ispp. Bou-Oumardoul Ilourhmane Jbel Taguendouft Jebel Toksine Ouguerd Zegzaoune Tamadoute Taquat N'Agrd Tougza Amphipoda Arenicolidae Capitellidae Sipuncula SpionidaAsteriacites A. ispp. Bou-Oumardoul Starfish OphiuridaChondrites C. ispp. Agrd N´Igli Bou-Oumardoul Ilourhmane Jebel Toksine Ouguerd Zegzaoune Polychaeta SipunculaDiplocraterion D. ispp. Bou-Oumardoul Echiurans Enteropneustans Polychaeta Sipunculans Paleodictyon P. ispp. Bou-Oumardoul Bacteria HexactinellidPhymatoderma P. granulata Bou-Oumardoul Holothurians Spatangoids SpionidsRhizocorallium R. parallelum R. ispp. Agrd N´Igli Aït Allal Jbel Akenzoud Jbel Taguendouft Jebel Toksine NW Dades Valley Todrha-Dades Wahmane Actinopterygii Decapoda PolychaetaScolicia S. ispp. Bou-Oumardoul Ilourhmane Ouguerd Zegzaoune Echinoids GastropodaSkolithos S. ispp. Jbel Taguendouft Jebel Toksine Decapoda Phoronidans PolychaetaThalassinoides T. ispp. Bou-Oumardoul Ilourhmane Jebel Toksine Ouguerd Zegzaoune Actinopteri Anomura Decapoda Dipnoi Polychaeta SipunculaZoophycos Z. ispp. Agrd N´Igli Aït Allal Bou-Oumardoul Ilourhmane Jebel Toksine Ouguerd Zegzaoune Wahmane Arenicolidae Capitellidae Sipuncula Spionida
Brachiopoda GenusSpeciesLocationMaterialNotesImagesQuadratirhynchia Q. vasconcellosi Akka n'Igoulzane Jebel Bou Ifliyou Jebel Ich TaskouineShellsA brachiopod of the family TetrarhynchiidaeHomoeorhynchia H. meridionalis H. batalleri Akka n'Igoulzane Jebel Bou Ifliyou Jebel Ich Taskouine Oued MijdiderShellsA brachiopod of the family Rhynchonellinae.Pseudogibbirhynchia P. jurensis Jebel Ich TaskouineShellsA brachiopod of the family PamirorhynchiinaeSoaresirhynchia S. tamazirta S. bouchardi Jebel Ich TaskouineShellsA brachiopod of the family BasiliolinaeTelothyris T. jauberti T. arnaudi Akka n'Igoulzane Jebel Bou Ifliyou Jebel Ich TaskouineShellsA brachiopod of the family Lobothyrididae.
Mollusks GenusSpeciesLocationMaterialNotesImagesAlectryonia A. (Lopha) amellagensis Agoudim AmellagoShellsA marine member of the family Ostreidae.Calliphylloceras C. nilssoni AmellagoShellsAn ammonite of the family CalliphylloceratinaeCanavaria C. aff. zancleana C. cf. rosenbergi AmellagoShellsAn ammonite of the family Hildoceratidae.Chlamys C. semiarticulatus C. aff.uhligi Agoudim Amellago Bou DaharShellsA marine member of the family Pectinidae.Dactylioceras D. (Orthodactylites) aff. crosbeyi D. cf.helianihoides D. (Eodactylites) mirabile D. (Eodactylites) simplex D. (Eodactylites) cf.polymorphum D. (Eodactylites) pseudocommune D. pseudocrassulosum D. cf. tauromenense D. (Orthodactylites) andaluciensis Agoudim Agounou Almou-n' Tarzekt Amellago Jbel Aouloum Jbel Bou Hamid Jbel Taguendouft SE Cherket Tagounit Talghemt Tamadoute Taquat N'Agrd TougzaShellsAn ammonite of the family Dactylioceratidae.Eleganticeras E. exaratum E. sp. Amellago Foum TillichtShellsAn ammonite of the family Hildoceratidae.Gryphaea G. sportella G. cristata G. (Bilobissa) sp. Agoudim Ait Athmane AmellagoShellsA saltwater/brackish bivalve of the family Gryphaeidae.Harpax H. spp. Agoudim Aït-Haceïne AmellagoShellsA marine member of the family Plicatulidae.Harpoceras H. serpentinum H. pseudoserpentinum H. falciferum H. subplanatum AmellagoShellsAn ammonite of the family Hildoceratidae.Hildaites H. striatus H. wrighti H. cf. striatus Agounou AmellagoShellsAn ammonite of the family Hildoceratidae.Hildoceras H. sublevisoni H. lusitanicum H. bifrons H. spp. Agrd N´Igli Aït Allal Akka n'Igoulzane Foum Tillicht Ouguerd Zegzaoune Taquat N'Agrd WahmaneShellsAn ammonite of the family Hildoceratidae.Juraphyllites J. libertus TalghemtShellsAn ammonite of the family Hildoceratidae.Lytoceras L. monpianense L. paulosiomaiicum L. ex gr. villae Agoudim AmellagoShellsAn ammonite of the family Lytoceratidae.Murleyiceras M. sp. Almou-n' TarzektShellsAn ammonite of the family Hildoceratidae.Neithea N. ayarii Agoudim AmellagoShellsA marine member of Neitheidae.Neolioceratoides N. hoffmanni Amellago TalghemtShellsAn ammonite of the family Hildoceratidae.Paltarpites P. paltum P. (Paltarpites) madagascariense P. cf.palius P. sp. Ait el Abbas Jbel Aouloum TalghemtShellsAn ammonite of the family Hildoceratidae.Platyacra P. (Asperilla) russoi AmellagoShellsA trochoidean, member of the family AngariidaePraepolyplectus P. sp. AmellagoShellsAn ammonite of the family Hildoceratidae.Purpurina P. rudis AmellagoShellsA caenogastropodan, member of the family PurpurinidaePholadomya P. bucardium P. fidicula P. spp. Agrd N´Igli AmellagoShellsA marine member of the family Pholadomyidae.Spondylus S. numidus Aghbalou N'KerdousShellsA marine member of the family Spondylidae.Trichites T. spp. Agrd N´Igli AmellagoShellsA marine member of the family Pinnidae.
Arthropoda GenusSpeciesLocationMaterialNotesImagesBairdia B. aff.carinata B. spp. TalghemtShellsA marine ostracod of the family Bairdiinae.Bairdiacypris B. spp. TalghemtShellsA marine ostracod of the family Bairdiinae.Kinkelinella K. sermoisensis K. sp. TalghemtShellsA marine ostracod of the family Protocytheridae. Local dominant Lower Toarcian taxonOgmoconcha O. sp. TalghemtShellsA marine ostracod of the family Healdiidae.Polycope P. spp. Bou-OumardoulShellsA marine ostracod of the family Polycopidae.
Echinodermata Rare Ophiuroid impressions can be observed. GenusSpeciesLocationMaterialNotesImagesApiocrinites A. amalthei Agoudim AmellagoColumnar ossiclesA crinoid of the family ApiocrinitidaeCotylederma C. spp. Agoudim AmellagoColumnar ossiclesA crinoid of the family CotyledermatidaeDiplechinus D. despujolsi D. spp. Agoudim AmellagoAmbulacrum, spinesAn echinoid of the family StomechinidaeDiplocidaris D. menchikofli Agoudim AmellagoAmbulacrum, spinesAn echinoid of the family DiplocidaridaeDubarechinus D. despujolsi Agoudim AmellagoAmbulacrum, spinesAn echinoid of the family OrthopsidaeFirmacidaris F. precincta Agoudim AmellagoAmbulacrum, spinesAn echinoid of the family CidaridaeHemicidaris H. (Dorycidaris) termieri Agoudim AmellagoAmbulacrum, spinesAn echinoid of the family HemicidaridaePentacrinites P. spp. Agoudim AmellagoColumnar ossiclesA crinoid of the family PentacrinitidaePolypedina P. tounatensis Agoudim AmellagoAmbulacrum, spinesAn echinoid of the family Pedinidae
Actinopteri GenusSpeciesLocationMaterialNotesImagesLeptolepis L. spp. Jbel Bou Hamid Semiarticulated specimensMarine bony fish of the family Leptolepidae.
Viridiplantae Phytoclasts, spores, pollen and Tasmanites & Botryococcus 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. This interval is numerically dominated by Classopollis, which usually accounts for more than 60.95% of the palynomorphs present. GenusSpeciesLocationMaterialNotesImagesAlisporites A. spp. AmellagoPollenAffinities with Peltaspermaceae or CorystospermaceaeCallialasporites C. trilobatus