Bajada Colorada Formation

The Bajada Colorada Formation is a geologic formation of the southern Neuquén Province in the Neuquén Basin of northern Patagonia, Argentina. The formation belongs to the Mendoza Group and is Late Berriasian to Early Valanginian in age. The formation is renowned for preserving fossil remains of Bajadasaurus pronuspinax, a genus of dicraeosaurid dinosaurs named after the formation.

Bajada Colorada Formation
Stratigraphic range: Late Berriasian-Early Valanginian
~140–134 Ma
TypeGeological formation
Unit ofMendoza Group
UnderliesAgrio Formation
OverliesQuintuco & Picún Leufú Formations
Lithology
PrimarySandstone, conglomerate
OtherSiltstone, claystone
Location
Coordinates39.8°S 69.7°W / -39.8; -69.7
Approximate paleocoordinates38.8°S 32.2°W / -38.8; -32.2
RegionNeuquén Province
Country Argentina
ExtentNeuquén Basin
Type section
Named byRoll
Year defined1939
Bajada Colorada Formation (Argentina)

Description

The Bajada Colorada Formation, first defined by Roll in 1939, pertains to the Mendoza Group.[1] It overlies the Quintuco and Picún Leufú Formations and is overlain by the Agrio Formation. The contact with the Agrio Formation is discordant and the unconformity has been dated to 134 Ma.[2] The formation is laterally equivalent with the Mulichinco Formation.[3] The formation comprises red and greenish-brown, fine to coarse grained conglomerates and thick-bedded sandstones with well developed bands of light brown siltstones and reddish, pinkish grey and purple-reddish claystones.[4] The formation was deposited in a fluvial environment, and the paleoenviroment resembled a braided river system with well-preserved channels and paleosols.[5]

X-ray diffraction studies of sediments belonging to the Bajada Colorada Formation have revealed the presence of smectite, chlorite, illite and kaolinite.[1]

Fossil content

The formation has provided fossils of:[6][7]

See also

References
  1. Moyano Bohórquez, 2004
  2. Leanza, 2005, p.151
  3. Howell et al., 2005, p.4
  4. Leanza et al., 2011, p.120
  5. Gallina et al., 2014, p.2
  6. Bajada Colorada locality at Fossilworks.org
  7. Canale, Juan I.; Apesteguía, S.; Gallina, P.A.; Gianechini, F.A.; Haluza, A. (2017). "The oldest theropods from the Neuquen Basin: Predatory dinosaur diversity from the Bajada Colorada Formation (Lower Cretaceous: Berriasian-Valanginian), Neuquen, Argentina". Cretaceous Research. 71: 63–70. doi:10.1016/j.cretres.2016.11.010.

Bibliography
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