Bajo de la Carpa Formation

Bajo de la Carpa Formation
Stratigraphic range: Santonian
Type Geological formation
Unit of Neuquén Group
Underlies Anacleto Formation
Overlies Plottier Formation
Thickness Up to 150 m
Lithology
Primary Sandstone
Other Mudstone, Siltstone
Location
Country  Argentina

The Bajo de la Carpa Formation is a geologic formation that outcrops in Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the first of two formations belonging to the Río Colorado Subgroup within the Neuquén Group. Formerly that subgroup was treated as a formation, and the Bajo de la Carpa Formation was known as the Bajo de la Carpa Member.[1]

At its base, this formation conformably overlies the Plottier Formation of the older Rio Neuquén Subgroup, and it is in turn overlain by the Anacleto Formation, the youngest and uppermost formation of the Neuquén Group.[2]

The Bajo de la Carpa Formation can reach 150 meters thick in some locations, and consists mainly of sandstones of various colors, all of fluvial origin, with thin layers of mudstone and siltstone in between. Geological features such as geodes, chemical nodules, impressions of raindrops, and paleosols (fossil soils) are commonly found in this formation as well.[3]

Age

Era: Mesozoic
Period: Late Cretaceous
Faunal stage: Santonian
Absolute Age: ~86 to ~83 mya

Paleontology

Comahuesuchus brachybuccalis
Notosuchus terrestris

Animal fossils are abundant within the Bajo de la Carpa Formation:

Small nests with eggs inside, found in this formation, probably belonged to Neuquenornis or a related taxon. Fossil wasp nests have also been found in these rocks.[3]

See also

Footnotes

  1. ↑ Sánchez et al. (2006)
  2. ↑ Fossa Mancini et al. (1938), Leanza et al. (2004)
  3. 1 2 Leanza et al. (2004), Sánchez et al. (2006)

References

  • Fossa Mancini, E.; Feruglio, E.; Yussen de Campana, J.C. (1938): Una reunión de geólogos de YPF y el problema de la terminología estratigráfica ["A YPF geologists' reunion and the problem of stratigraphy terminology"]. Boletín de Informaciones Petroleras 15: 1-67.
  • Leanza, H.A.; Apesteguia, S.; Novas, F.E. & de la Fuente, M.S. (2004): Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. Cretaceous Research 25(1): 61-87. doi:10.1016/j.cretres.2003.10.005 (HTML abstract)
  • Sánchez, Maria Lidia; Heredia, Susana & Calvo, Jorge O. (2006): Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén [Sedimentary paleoenvironments in the Upper Cretaceous Plottier Formation (Neuquen Group), Confluencia, Neuquén]. Revista de la Asociación Geológica Argentina 61(1): 3-18. PDF fulltext
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