Calcarenites du Jadet Formation

Jadet Calcarenites Formation
Stratigraphic range: Late Cretaceous (Late Maastrichtian)
~
TypeGeological formation
UnderliesMarnes d'Auzas Formation
OverliesLestaillats Marls Formation
ThicknessAbout 15 m (49 ft)
Lithology
PrimaryCalcarenites
OtherClay
Location
Coordinates43°08′N 0°55′E
RegionOccitania
CountryFrance
Calcarenites du Jadet Formation is located in France
Calcarenites du Jadet Formation
Calcarenites du Jadet Formation (France)
Calcarenites du Jadet Formation is located in Occitanie
Calcarenites du Jadet Formation
Calcarenites du Jadet Formation (Occitanie)
Calcarenites du Jadet Formation is located in Haute-Garonne
Calcarenites du Jadet Formation
Calcarenites du Jadet Formation (Haute-Garonne)

The Calcarenites du Jadet Formation is a Mesozoic geologic formation in France. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.[1]

Location and geological context

The Jadet calcarenite formation is located in the Plagne and Saint-Martory anticlines[nb 1] in the central part of the Haute-Garonne department (Petites Pyrénées) in Occitania region.[3] As this region is covered with very dense vegetation, the outcrops of this formation have mainly been studied in abandoned or active quarries located particularly near the villages of Auzas, Laffite-Toupière, and Saint-Martory.[4].

The Jadet calcarenite formation constitutes the top of the Ausseing Group. The latter also includes, in its middle part, the Lestaillats Marls Formation and, in its lower part, the Nankin 2 limestone Formation. The Jadet calcarenite formation is overlain by the Marnes d'Auzas Formation.[5][6]. In the Aurignac anticline, located north of the Plagne and Saint-Martory anticlines, the layers equivalent to the Ausseing group do not show marly intercalation and are grouped under the name of Nankin facies limestones.[5] · [3]

Lithostratigraphy and depositional environment

The formation was studied in the 1980s in the Jadet quarry where the outcrops are virtually no longer visible today.[7] In this quarry, the exposed part of the formation reached a thickness of approximately 15 m and consisted primarily of calcarenites. The quarry floor consisted of reddish-brown bioclastic calcarenites rich in bivalves and orbitoids. Next came 8 m of massive, reddish-brown to ochre sandy calcarenites, divided into two 4 m-thick sequences separated by a 30 to 50 cm-thick layer of green to red clays. These calcarenites contained thin lenses of red clay that graded laterally into alignments of soft pebbles outlining various internal structures, such as cross-stratification, low-angle oblique lamination, and—more rarely—planar parallel lamination. After a gap in visibility of approximately 1 m, the section ended with non-sandy, ochre-yellow calcarenites (3 m exposed) of tuffoid appearance, with parallel and then cross-bedding plane stratifications, and rare alignments of soft pebbles.[8][9]

These sediments were deposited in a coastal environment under tidal influence (sandy foreshore, tidal channels, tidal marsh).[10][2][11]

Fossil content

The formation yielded marine invertebrates (bivalves, gastropods, echinoderms including the starfish Dipsacaster jadeti) as well as rare remains of marine and terrestrial vertebrates.[12][13][14][15]

Vertebrates

Fish

Fishes of the Calcarenites du Jadet Formation
Genus Species Material Notes Images
Chondrichthyes indet.[16] Indeterminate Teeth
Enchodus indet.[17][18] E. cf. faujasi A dentary fragment bearing four teeth

Crocodilians

Crocodylia of the Calcarenites du Jadet Formation
Genus Species Material Notes Images
Crocodilia indet.[19][20] Indeterminate A caudal vertebra

Dinosaurs

Dinosauria of the Calcarenites du Jadet Formation
Genus Species Material Notes Images
Hadrosauridae indet.[12] Indeterminate A partial left dentary[21]

See also

Notes

  1. ↑ The Saint-Martory anticline is also referred to as the Saint-Marcet anticline by Buffetaut and Cavin.[2].

References

  1. ↑ Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.
  2. 1 2 Buffetaut & Cavin 1995, p. 31.
  3. 1 2 Laurent 2003, p. 30-32 ; 31 (fig.7) ; 32 (fig.8).
  4. ↑ Lepicard 1985, p. 49, 55, 56 (fig.28) ; 57 (planche 1).
  5. 1 2 Laurent, Bilotte & Le Loeuff 2002, p. 123 (fig.2).
  6. ↑ Laurent 2003, p. 30-32, 31 (fig.7).
  7. ↑ Bilotte 2019, p. 9-13.
  8. ↑ Lepicard 1985, p. 55, 56 (fig.28) ; 57 (plate 1).
  9. ↑ Breton, Bilotte & Sigro 1995, p. 36 (fig.1) ; 37.
  10. ↑ Breton, Bilotte & Sigro 1995, p. 37.
  11. ↑ Bilotte 2019, p. 10.
  12. 1 2 Paris & Taquet 1973, p. 17-27.
  13. ↑ Breton, Bilotte & Sigro 1995, p. 35-42.
  14. ↑ Buffetaut, Cavin & Sigro 1995, p. 31-34.
  15. ↑ Bilotte 2019, p. 10 ; 13 (fig.3).
  16. ↑ Bilotte 2019, p. 13 (fig.3).
  17. ↑ Buffetaut & Cavin 1995, p. 32 (fig.1A-C) ; 32-33.
  18. ↑ Laurent 2003, p. 36-37 ; plate 4 (fig.14).
  19. ↑ Buffetaut & Cavin 1995, p. 32 (fig.1D-G) ; 33.
  20. ↑ Laurent 2003, p. 15-16 ; 42.
  21. ↑ Paris & Taquet 1973, p. 23 (fig.4); 24, plate 1.

Bibliography

  • Bilotte, Michel (2019). "La carrière du Jadet, site d'un faciès particulier du Calcaire nankin (Maastrichtien des Petites Pyrénées de la Haute-Garonne), dégradée par une exploitation mécanisé" (PDF). Bulletin de la Société d’Hisoire Naturelle de Toulouse. 155: 9–13.
  • Laurent, Yves (2003). "Les faunes de vertébrés continentaux du Maastrichtien supérieur d'Europe : systématique et biodiversité". Strata, Série 2. 41: 1–81.
  • Lepicard, Béatrice (1985). "Le Crétacé terminal et le Paléocène basal dans les Petites-Pyrénées et les Dômes annexes. Biostratigraphie-Sédimentologie". Strata, Série 2. 4: 1–276.
This page is issued from Wikipedia. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.