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Saint-Chinian Formation

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Saint-Chinian Formation
Stratigraphic range: Tremadocian
Geragnostus mediterraneus
TypeGeologic formation
UnderliesLa Maurerie Formation
OverliesLa Dentelle Formation
Thicknessaround 500 m
Lithology
PrimaryShale
OtherSandstone
Location
Coordinates43°25′07″N 2°56′43″E / 43.418624°N 2.945366°E / 43.418624; 2.945366
Region Occitanie
Country France
Type section
Named forSaint-Chinian
Saint-Chinian Formation is located in France
Saint-Chinian Formation
Saint-Chinian Formation (France)

The Saint-Chinian Formation is a geological formation composed of shales with limestone inclusions, dating from the Lower Ordovician (Tremadocian).

It is one of the six geological formations from the Saint-Chinian Cambro-Ordovician basin, comprising, from the most ancient to the most recent : La Dentelle Formation, Saint-Chinian Formation, La Maurerie Formation, Cluse de l'Orb Formation and Setso member, Foulon Formation and Landeyran Formation. This formation outcrops on the southern flanks of the Montagne Noire in Southern France.[1]

The formation received its name from the small city of Saint-Chinian, a commune located in the Hérault department in Occitania.

It is dated from the biostratigraphic sub-zone characterized by Taihungshania miqueli and Asaphelina barroisi berardi.[1]

Paleoenvironment

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The thin nature of the silico-clastics deposits, the presence of slump, combined with a trilobite fauna dominated by members of the Asaphidae family indicates a marine environment of external distal platform.[2]

Paleofauna

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Shales of the Saint-Chinian Formation bears in certain areas accumulations of phosphated nodules, each potentially bearing a trilobite. Those are the so-called "schistes à gateaux"[3]..

Nautiloids

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Genus Species Locality Age Notes Images
Cyclostomiceras C. thorali Euloma filacovi Zone Late Tremadocian A cyclostomiceratid ellesmerocerid[4]
Saloceras S. chinianense Euloma filacovi Zone Late Tremadocian An eothinoceratid ellesmerocerid[4]
S. murvielense Euloma filacovi Zone Late Tremadocian An eothinoceratid ellesmerocerid[4]
S. pradense Taihungshania miqueli acme Subzone Late Tremadocian An eothinoceratid ellesmerocerid[4]
Rioceras R. escandei Euloma filacovi Zone ; Asaphelina barroisi berardi and Taihungshania miqueli Subzone Late Tremadocian A rioceratid ellesmerocerid[4]
Felinoceras F. constrictum Euloma filacovi Zone Late Tremadocian A rioceratid ellesmerocerid[4]
Annbactroceras A. martyi Euloma filacovi Zone Late Tremadocian A baltoceratid orthocerid[4]
A. felinense Euloma filacovi Zone Late Tremadocian A baltoceratid orthocerid[4]
Bactroceras B. mourguesi Euloma filacovi Zone Late Tremadocian A baltoceratid orthocerid[4]
Cochlioceras C.? aff. roemeri Euloma filacovi Zone ; Asaphelina barroisi berardi and Taihungshania miqueli Subzone Late Tremadocian A baltoceratid orthocerid[4]
Thoraloceras T. bactroceroides Euloma filacovi Zone ; Asaphelina barroisi berardi and Taihungshania miqueli Subzone Late Tremadocian A troedsonellid dissidocerid[4]
Lobendoceras L. undulatum Euloma filacovi Zone ; Asaphelina barroisi berardi and Taihungshania miqueli Subzone Late Tremadocian A protocameroceratid endocerid[4]

Trilobites

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Genus Species Locality Age Notes Images
Paramegalaspis P. immarginata Prades-sur-Vernazobre Late Tremadocian-Early Arenig An asaphid[5]
Asaphellus A. frequens Prades-sur-Vernazobre Late Tremadocian-Early Arenig An asaphid[5]
A.? sp. Félines-Minervois Late Tremadocian-Early Arenig An asaphid[5]
Aocaspis A. macrophtalma La Rouvelane, près de Prades-sur-Vernazobre Late Tremadocian-Early Arenig An nileid[6]
Geragnostus G. occitanus Saint-Chinian Early Arenig A geragnostid[7]
G. callavei Saint-Chinian Early Arenig A geragnostid[7]
G. pusio Saint-Chinian Early Arenig A geragnostid[7]
Micragnostus M. languedocensis Saint-Chinian Early Arenig A micragnostid[7]
Trinodus T. chinianensis Saint-Chinian Early Arenig A trinodid[7]
T. corpulentus Saint-Chinian Early Arenig A trinodid[7]
T. abruptus Saint-Chinian Early Arenig A trinodid[7]
T. oviformis Saint-Chinian Early Arenig A trinodid[7]

Echinoderms

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Genus Species Locality Age Notes Images
Arauricystis A. primaeva A cornute stylophoran[12]
A. occitana A cornute stylophoran[12]
Cothurnocystis C. fellinensis A cornute stylophoran[12]
C. courtessolei A cornute stylophoran[12]
Phyllocystis P. blayaci A cornute stylophoran[12]
P. crassimarginata A cornute stylophoran[12]
Thoralicystis T. griffei A cornute stylophoran[12]
Trigonocarpus T. singularis A cornute stylophoran[12]
Chauvelicystis C. spinosa A cornute stylophoran[12]
C. vizcainoi A cornute stylophoran[12]
Galliaecystis G. lignieresi A cornute stylophoran[12]
G. ubaghsi A cornute stylophoran[12]
Amygdalotheca A. griffei A cornute stylophoran[12]
Anatifopsis A. trapeziiformis A mitrate stylophoran[12]
Balanocystites B. escandei A mitrate stylophoran[12]
Peltocystis P. cornuta A mitrate stylophoran[12]
Vizcainocarpus V. dentiger A mitrate stylophoran[12]
Chinianocarpos C. thorali A mitrate stylophoran[12]
Minervaecystis M. vidali A solute homoistelean[12]
Balantiocystis B. thorali An eocrinoïd[12]
Aethocrinus A. moorei A cladide crinoïd[12]
Macrocystella M. azaizi A dichoporite rhombifere. Two subspecies are present : M. a. paucicristatus and M. a. multicristata [12]
Hemicystites H. boehmi A edrioasteroïd[12]
?Pyrgocystis ?P. sp. A edrioasteroïd[12]
Chinianaster C. levyi A goniactinid stelleroïd[12]
Villebrunaster V. thorali A goniactinid stelleroïd[12]
Ampullaster A. ubaghsi A goniactinid stelleroïd[12]
Pradesura P. jacobi A stenurid stelleroïd[12]

Other fossil remains of marine animals are known from the formation:[13]

References

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  1. ^ a b "L'Ordovicien du bassin de Saint-Chinian" (PDF). Excursion ASNAT. 21 September 2019.
  2. ^ Vidal, Muriel (1996). "Some Asaphidae from the Saint-Chinian Formation, Lower Ordovician, Montagne Noire (France): Systematics and palaeoenvironments". Geobios. 29 (6): 725–744. doi:10.1016/S0016-6995(96)80018-0.
  3. ^ Thoral, Marcel (1946). "Cycles géologiques et formations nodulifères de la Montagne Noire". Publications du musée des Confluences, Année 1946. 1: 1–63.
  4. ^ a b c d e f g h i j k l Kröger, B.; Evans, D. H. (2011). "Review and palaeoecological analysis of the late Tremadocian – early Floian (Early Ordovician) cephalopod fauna of the Montagne Noire, France". Museum für Naturkunde. 14(1): 5–34. doi:10.1002/mmng.201000013.
  5. ^ a b c Vidal, M. (1996). "Quelques Asaphidae (Trilobita) de la Formation de Saint-Chinian, Ordovicien inférieur, Montagne Noire (France): Systématique et paléoenvironnements". Geobios. 29(6): 725–744. doi:10.1016/S0016-6995(96)80018-0.
  6. ^ Dolambi, T.; Gond, P. (1992). "Aocaspis nov. gen., nouveau Trilobite Nileidae de l'Ordovicien inférieur de Montagne Noire (France)". Geobios. 25(2): 213–224. doi:10.1016/S0016-6995(06)80400-6.
  7. ^ a b c d e f g h Howell, B. F. (1935). "Cambrian and Ordovician trilobites from Herault, southern France". Journal of Paleontology. 9 (3): 222–238.
  8. ^ Capera, J. C.; Courtessole, R.; Pillet, J. (1978). "Contribution à l'étude de l'Ordovicien inférieur de la Montagne Noire : biostratigraphie et révision des Agnostida". Annales de la Société Géologique du Nord. 98 (1): 67–87.
  9. ^ Thoral, M. (1935). Imprimerie de la Charité (ed.). Contribution à l'étude paléontologique de l'Ordovicien inférieur de la Montagne Noire et révision sommaire de la faune cambrienne de la Montagne Noire. Montpellier. pp. 362 pp.{{cite book}}: CS1 maint: location missing publisher (link)
  10. ^ a b Vizcaino, D.; Alvaro, J.; Lefebvre, B. (2001). "The lower Ordovician of the southern Montagne Noire". Annales de la Société Géologique du Nord. 8 (2): 213–220.
  11. ^ Alvaro, J.; Lefebvre, B.; Vizcaino, D. (2001). "Catalogue of the fossil species defined in the Lower Paleozoic of the southern Montagne Noire". Annales de la Société Géologique du Nord. 8 (2): 227–232.
  12. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab Vizcaïno, D.; Lefebvre, B. (1999). "Les échinodermes du Paléozoïqueinférieur de Montagne Noire: Biostratigraphie et paléodiversité". Geobios. 32(2): 353–356. doi:10.1016/S0016-6995(99)80049-7.
  13. ^ Babin, C.; Courtessole, R.; Melou, M.; Pillet, J.; Vizcaino, D.; Yochelson, E. L. (1982). Brachiopodes (Articulés) et mollusques (bivalves, rostroconches, monoplacophores, gastéropodes) de l'Ordovicien inférieur (Trémadocien-Arenigien) de la Montagne Noire (France méridionale). pp. 1–63.
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