Tagoudite Formation

The Tagoudite Formation is a geological formation of Toarcian age in the Béni-Mellal, Imilchil, Tinerhir, Tinejdad and Errachidia areas of the High 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 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 that thrive in dark, organic-rich sediments where chemical gradients provide energy. Frequent turbidity currents, high organic content, 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

marks oscillations of negative carbon isotope excursions at T-OAE and Pliensbachian-Toarcian transition, dominated by open marine haptophytan or incertade sedis coccoliths like Biscutum, Carinolithus, 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

Ichnofossils

Brachiopoda

Mollusks

Arthropoda

Echinodermata

Rare Ophiuroid impressions can be observed.

Genus	Species	Location	Material	Notes	Images
Apiocrinites	A. amalthei	Agoudim Amellago	Columnar ossicles	A crinoid of the family Apiocrinitidae
Cotylederma	C. spp.	Agoudim Amellago	Columnar ossicles	A crinoid of the family Cotyledermatidae
Diplechinus	D. despujolsi D. spp.	Agoudim Amellago	Ambulacrum, spines	An echinoid of the family Stomechinidae
Diplocidaris	D. menchikofli	Agoudim Amellago	Ambulacrum, spines	An echinoid of the family Diplocidaridae
Dubarechinus	D. despujolsi	Agoudim Amellago	Ambulacrum, spines	An echinoid of the family Orthopsidae
Firmacidaris	F. precincta	Agoudim Amellago	Ambulacrum, spines	An echinoid of the family Cidaridae
Hemicidaris	H. termieri	Agoudim Amellago	Ambulacrum, spines	An echinoid of the family Hemicidaridae
Pentacrinites	P. spp.	Agoudim Amellago	Columnar ossicles	A crinoid of the family Pentacrinitidae
Polypedina	P. tounatensis	Agoudim Amellago	Ambulacrum, spines	An echinoid of the family Pedinidae

Actinopteri

Viridiplantae

, 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.

Genus	Species	Location	Material	Notes	Images
Alisporites	A. spp.	Amellago	Pollen	Affinities with Peltaspermaceae or Corystospermaceae
Callialasporites	C. trilobatus C. spp.	Amellago	Pollen	Affinities with Araucariaceae.	File:Araucaria_cunninghamii_cones.jpg\|thumb\|174x174px\|Callialasporites was probably related to modern plants such as Araucaria.\|center
Classopollis	C. spp.	Amellago	Pollen	Affinities with Cheirolepidiaceae.
Cyathidites	C. minor	Amellago	Spores	Affinities with Cyatheaceae.	File:Cyathea_arborea.JPG\|thumb\|144x144px\|Cyathidites was probably related to modern plants such as Cyathea.\|center
Kraeuselisporites	K. reissingeri	Amellago	Spores	Affinities with Selaginellaceae.	File:Selaginella_sp_at_Paithalmala.jpg\|thumb\|144x144px\|Kraeuselisporites was probably related to modern plants such as Selaginella.\|center
Ischyosporites	I. ''variegatus	Amellago	Spores	Affinities with Schizaeaceae/Anemiaceae.	File:Anemia_phyllitidis_kz05.jpg\|thumb\|215x215px\|Ischyosporites was probably related to modern plants such as Anemia.\|center
Quadraeculina	Q. anaellaeformis	Amellago	Pollen	Affinities with Podocarpaceae or Pinaceae.	File:Dacrycarpus_dacrydioides_cones2.jpg\|thumb\|155x155px\|Quadraeculina was probably related to modern plants such as Dacrycarpus''.\|center