Tagoudite Formation
Geological formations in Morocco
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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[1]) of Morocco.[2][3]
- Aït Abdi Formation
- Aït Hani formation
- Agoudim Formation
- Amellago Formation
- Bin el Ouidane Formation
- Tafraout Formation
- Aberdouz Formation
- Aganane Formation
- Choucht Formation
- Ouchbis Formation
| Tagoudite Formation | |
|---|---|
| Stratigraphic range: Early-Middle Toarcian | |
Profile at Jebel Akenzoud (Dadès Gorges) where the Tagoudite, Tafraout and Azilal Fms can be seen. (B) Close-up view of the left side ooidal shoal with lateral accretions (white arrows). (C) Stratigraphic correlation. (D) Close up of the right side shoulder. (E) Close up on the erosion surface. | |
| Type | Geological Formation |
| Underlies |
|
| Overlies |
|
| Thickness | 230 m (750 ft) |
| Lithology | |
| Primary | Siliclastic Sandstone/Mudstone, Marlstone |
| Location | |
| Location | Er-Rich |
| Coordinates | 31.49°N 5.58°W |
| Approximate paleocoordinates | 26.6°N 3.4°W |
| Region | High Atlas and Middle Atlas |
| Country | Morocco |
| Type section | |
| Named for | Tagoudite Pass near Er-Rich |
| Named by | Riccardo Bernasconi |
| Year defined | 1983 |
| Region | Er-Rich, Midelt Province |
| Thickness at type section | ~70 m (230 ft) |
  Tagoudite Formation (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.[4] 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.[4] 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.[5] 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.[6]
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.[7] 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.[7]
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.[8][9][10] Dinoflagellates are rare and limited to taxa such as Luehndea, Mancodinium and Mendicodinium.[11]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Foraminifera
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Dentalina[12] |
|
|
Tests/shells | A foraminifer of the family Nodosariinae. | |
| Citharina[13] |
|
|
Tests/shells | A foraminifer of the family Vaginulininae. | |
| Everticyclammina[12][14] |
|
|
Tests/shells | A foraminifer of the Everticyclamminidae family. | |
| Ichtyolaria[12][15] |
|
|
Tests/shells | A foraminifer of the family Ichthyolariinae. | |
| Lenticulina[16][15][17] |
|
|
Tests/shells | A foraminifer of the family Lenticulininae. | |
| Lingulina[16] |
|
|
Tests/shells | A foraminifer of the family Lenticulininae. | |
| Marginulina[16] |
|
|
Tests/shells | A foraminifer of the family Marginulininae. | |
| Ophtalmidium[14][16][18][17] |
|
|
Tests/shells | A foraminifer of the family Ophthalmidiidae. | |
| Orbitopsella[19] |
|
|
Tests/shells | A foraminifer of the family Orbitopsellinae. | |
| Pseudocyclammina[12][14] |
|
|
Tests/shells | A foraminifer of the family Hauraniidae. | |
| Pseudonodosaria[16][15] |
|
|
Tests/shells | A foraminifer of the family Nodosariinae. | |
| Reinholdella[12][14][17] |
|
|
Tests/shells | A foraminifer of the family Ceratobuliminidae. | |
| Verneuilinoides[15] |
|
|
Tests/shells | A foraminifer of the family Verneuilinoidinae |
Ichnofossils
| Ichnogenus | Ichnospecies | Location | Made by | Images |
|---|---|---|---|---|
| Arenicolites[20][21] |
|
|
 | |
| Asteriacites[7] |
|
|
 | |
| Chondrites[21] |
|
|
 | |
| Diplocraterion[7] |
|
|
 | |
| Paleodictyon[7] |
|
|
||
| Phymatoderma[7] |
|
|
||
| Rhizocorallium[22][21] |
|
|
 | |
| Scolicia[20] |
|
|
||
| Skolithos[21] |
|
|
 | |
| Thalassinoides[20][21] |
|
|
 | |
| Zoophycos[20][21] |
|
|
 |
Brachiopoda
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Quadratirhynchia[23] |
|
|
Shells | A brachiopod of the family Tetrarhynchiidae | |
| Homoeorhynchia[24][23] |
|
|
Shells | A brachiopod of the family Rhynchonellinae. | |
| Pseudogibbirhynchia[23] |
|
|
Shells | A brachiopod of the family Pamirorhynchiinae | |
| Soaresirhynchia[23] |
|
|
Shells | A brachiopod of the family Basiliolinae | |
| Telothyris[24][23] |
|
|
Shells | A brachiopod of the family Lobothyrididae. |
Mollusks
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Alectryonia[25] |
|
|
Shells | A marine member of the family Ostreidae. |  |
| Calliphylloceras[26] |
|
|
Shells | An ammonite of the family Calliphylloceratinae | |
| Canavaria[26] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Chlamys[25][27] |
|
|
Shells | A marine member of the family Pectinidae. |  |
| Dactylioceras[28][29][26] |
|
Shells | An ammonite of the family Dactylioceratidae. |  | |
| Eleganticeras[31][26] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Gryphaea[25][32] |
|
|
Shells | A saltwater/brackish bivalve of the family Gryphaeidae. |  |
| Harpax[25] |
|
|
Shells | A marine member of the family Plicatulidae. | |
| Harpoceras[31][26] |
|
|
Shells | An ammonite of the family Hildoceratidae. |  |
| Hildaites[26][30] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Hildoceras[28][29][33] |
|
|
Shells | An ammonite of the family Hildoceratidae. |  |
| Juraphyllites[34][26] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Lytoceras[26] |
|
|
Shells | An ammonite of the family Lytoceratidae. | |
| Murleyiceras[25] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Neithea[25] |
|
|
Shells | A marine member of Neitheidae. | |
| Neolioceratoides[34][26] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Paltarpites[34][25][30] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Platyacra[35] |
|
|
Shells | A trochoidean, member of the family Angariidae | |
| Praepolyplectus[26] |
|
|
Shells | An ammonite of the family Hildoceratidae. | |
| Purpurina[35] |
|
|
Shells | A caenogastropodan, member of the family Purpurinidae |  |
| Pholadomya[36] |
|
|
Shells | A marine member of the family Pholadomyidae. | |
| Spondylus[27] |
|
|
Shells | A marine member of the family Spondylidae. |  |
| Trichites[36] |
|
|
Shells | A marine member of the family Pinnidae. |
Arthropoda
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Bairdia[37] |
|
|
Shells | A marine ostracod of the family Bairdiinae. | |
| Bairdiacypris[37] |
|
|
Shells | A marine ostracod of the family Bairdiinae. | |
| Kinkelinella[37] |
|
|
Shells | A marine ostracod of the family Protocytheridae. Local dominant Lower Toarcian taxon | |
| Ogmoconcha[37] |
|
|
Shells | A marine ostracod of the family Healdiidae. | |
| Polycope[38] |
|
|
Shells | A marine ostracod of the family Polycopidae. |
Echinodermata
Rare Ophiuroid impressions can be observed.[39]
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Apiocrinites[40] |
|
|
Columnar ossicles | A crinoid of the family Apiocrinitidae | |
| Cotylederma[40] |
|
|
Columnar ossicles | A crinoid of the family Cotyledermatidae | |
| Diplechinus[40] |
|
|
Ambulacrum, spines | An echinoid of the family Stomechinidae | |
| Diplocidaris[40] |
|
|
Ambulacrum, spines | An echinoid of the family Diplocidaridae | |
| Dubarechinus[40] |
|
|
Ambulacrum, spines | An echinoid of the family Orthopsidae | |
| Firmacidaris[40] |
|
|
Ambulacrum, spines | An echinoid of the family Cidaridae | |
| Hemicidaris[40] |
|
|
Ambulacrum, spines | An echinoid of the family Hemicidaridae | |
| Pentacrinites[40] |
|
|
Columnar ossicles | A crinoid of the family Pentacrinitidae |  |
| Polypedina[40] |
|
|
Ambulacrum, spines | An echinoid of the family Pedinidae |
Actinopteri
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Leptolepis[41][42] |
|
|
|
Marine 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.[43] This interval is numerically dominated by Classopollis, which usually accounts for more than 60.95% of the palynomorphs present.[43]
| Genus | Species | Location | Material | Notes | Images |
|---|---|---|---|---|---|
| Alisporites[44] |
|
|
Pollen | Affinities with Peltaspermaceae or Corystospermaceae | |
| Callialasporites[44] |
|
|
Pollen | Affinities with Araucariaceae. |  |
| Classopollis[44] |
|
|
Pollen | Affinities with Cheirolepidiaceae. | |
| Cyathidites[44] |
|
|
Spores | Affinities with Cyatheaceae. |  |
| Kraeuselisporites[44] |
|
|
Spores | Affinities with Selaginellaceae. |  |
| Ischyosporites[44] |
|
|
Spores | Affinities with Schizaeaceae/Anemiaceae. |  |
| Quadraeculina[44] |
|
|
Pollen | Affinities with Podocarpaceae or Pinaceae. |  |
See also
- Toarcian turnover
- Toarcian formations
- Tafraout Formation, SISTER UNIT, Morocco
- Azilal Formation, SISTER UNIT, Morocco
- Aganane Formation, Morocco
- Calcaires du Bou Dahar, Morocco
- 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