The Candeleros Formation (formerly known as the Candeleros Member of the "Río Limay Formation") is a geologic formation that crops out in the Río Negro, Neuquén, and Mendoza provinces of northern Patagonia, Argentina. It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup. Formerly that subgroup was treated as a formation, and the Candeleros Formation was known as the Candeleros Member.
Stratigraphic range: Early Cenomanian-Early Turonian
|Unit of||Neuquén Group|
Río Limay Subgroup
|Overlies||Lohan Cura Formation|
|Thickness||300 m (980 ft)|
|Other||Conglomerate, siltstone, paleosol|
|Region||Mendoza, Neuquén & Río Negro Provinces|
|Named for||Candeleros Hill|
The type locality of the Candeleros Formation is Candeleros Hill in Neuquén Province, after which the formation was named by Wichmann in 1929. This formation unconformably overlies the Lohan Cura Formation, and it is in turn overlain by the Huincul Formation, also a unit of the Neuquén Group. The sediments of the latter are of lighter greenish and yellow colors and the boundary between the Candeleros and Huincul formations is easily recognizable.
The Candeleros Formation is almost 300 metres (980 ft) thick in some sections. Overall, the formation represents an ancient braided river system, made up mostly of sandstones and conglomerates. There are also isolated sections that represent eolian (wind-blown) deposition, as well as siltstones deposited under swamp conditions. Paleosols (soil deposits) are common in some sections as well.
The Candeleros Formation has a very diverse fossil fauna, including:
- dipnoan fish (including Ceratodus argentinus)
- eilenodontine rhynchocephalians (including Priosphenodon avelasi)
- primitive snakes (including Najash rionegrina)
- several turtles (including 2 species of Prochelidella)
- rebbachisaurid sauropods (Limaysaurus, Nopcsaspondylus and Rayososaurus)
- titanosaurian sauropods (including Andesaurus)
- abelisaurid theropods (Ekrixinatosaurus and unnamed form)
- a carcharodontosaurid theropod (Giganotosaurus)
- a dromaeosaurid theropod (Buitreraptor gonzalezorum)
- an alvarezsaurid theropod (Alnashetri)
- a basal coelurosaurian (Bicentenaria)
- cladotherian mammals (including Cronopio dentiacutus)
- ichnofossils of Sousaichnum monettae, Limayichnus major, Bonaparteichnum tali, Bressaniichnus patagonicus, Deferraiichnum mapuchense, Abelichnus astigarragae and Picunichnus benedettoi
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- Sánchez et al., 2006
- Wichmann, 1929
- Leanza et al., 2004
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- Leonardi, 1994, p.79
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