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.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.
Location and geological context The Jadet calcarenite formation is located in the Plagne and Saint-Martory anticlines in the central part of the Haute-Garonne department (Petites Pyrénées) in Occitania region. 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..
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.. 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.
Lithostratigraphy and depositional environment The formation was studied in the 1980s in the Jadet quarry where the outcrops are virtually no longer visible today. 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.
These sediments were deposited in a coastal environment under tidal influence (sandy foreshore, tidal channels, tidal marsh).
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.
Vertebrates Fish + Fishes of the Calcarenites du Jadet Formation Genus Species Material Notes Images Chondrichthyes indet. Indeterminate Teeth Enchodus indet. E. cf. faujasi A dentary fragment bearing four teeth
Crocodilians + Crocodylia of the Calcarenites du Jadet Formation Genus Species Material Notes Images Crocodilia indet. Indeterminate A caudal vertebra
Dinosaurs + Dinosauria of the Calcarenites du Jadet Formation Genus Species Material Notes Images Hadrosauridae indet. Indeterminate A partial left dentary
See also List of dinosaur-bearing rock formations List of stratigraphic units with dinosaur trace fossils Dinosaur eggs
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