Candeleros Formation
Geologic formation in Argentina
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The Candeleros 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.[2]
| Candeleros Formation | |
|---|---|
| Stratigraphic range: early Cenomanian ~ [1] | |
Candeleros Formation near Cerro El Vagon, Neuquen, Argentina | |
| Type | Geological formation |
| Unit of | Neuquén Group Río Limay Subgroup |
| Underlies | Huincul Formation |
| Overlies | Lohan Cura Formation |
| Thickness | 300 m (980 ft) |
| Lithology | |
| Primary | Eolian sandstone |
| Other | Conglomerate, siltstone, paleosol |
| Location | |
| Coordinates | 39.4°S 69.2°W |
| Approximate paleocoordinates | 46.5°S 45.5°W |
| Region | Mendoza, Neuquén & Río Negro Provinces |
| Country | Argentina |
| Extent | Neuquén Basin |
| Type section | |
| Named for | Candeleros Hill |
| Named by | Wichmann |
| Year defined | 1929 |
  Candeleros Formation (Argentina) | |
Description
The type locality of the Candeleros Formation is Candeleros Hill in Neuquén Province, after which the formation was named by Wichmann in 1929.[3] This formation unconformably overlies the Lohan Cura Formation, and it is fused with the Huincul Formation, also a unit of the Neuquén Group. The sediments of the latter are of lighter greenish and yellow colors and the fused boundary between the Candeleros and Huincul formations is easily recognizable.[4]
The Candeleros Formation is almost 300 metres (980 ft) thick in some sections. Overall, the formation represents a part of the ancient Kokorkom desert with 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.[2][4]The base of the formations age is correlated to the "Violaceous Sandstones" whose age is estimated at 98.6 ± 2.5 Ma.[5] Based on available evidence, the Candeleros formation is placed between the lower and upper Cenomanian.[5]
Fossil content
The Candeleros Formation has a very diverse fossil fauna, including fish, frogs, mammals, rhynchocephalians, snakes, turtles, notosuchians, pterosaurs, and abundant dinosaurs including rebbachisaurid and titanosaurian sauropods and diverse theropods, and the enigmatic armored Jakapil.
Ichnofossils found in the formation include those assigned to Sousaichnum monettae, Limayichnus major, Bressaniichnus patagonicus, Deferraiichnum mapuchense, and Picunichnus benedettoi.[6]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Fish
Amphibians
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Avitabatrachus[7] | A. uliana | El Gigante | Lower | Fragmentary skull and postcranial skeleton | A pipimorph frog |
Dinosaurs
Ornithischians
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Jakapil[8] | J. kaniukura | Cerro Policía | Upper[8] | A partial skeleton including several osteoderms and a complete lower jaw | Possibly a basal thyreophoran[9] |  |
Sauropods
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Andesaurus | A. delgadoi | Near Villa El Chocon | Lower | A partial skeleton | A basal titanosaurian sauropod |  |
| Campananeyen[10] | C. fragilissimus | Barda Atravesada de Las Campanas | Lower | A fragmentary skeleton | A rebbachisaurid sauropod |  |
| Limaysaurus | L. tessonei | Upper | A rebbachisaurid sauropod | |||
| Nopcsaspondylus | N. alarconensis | left bank of Limay River | A single lost vertebra | A rebbachisaurid sauropod | ||
| Rayososaurus | R. agrioensis | Agrio del Medio | Upper | A left scapula, an almost complete right scapular blade, and the distal three-quarters of a left femur. | A rebbachisaurid sauropod | |
| Titanosauria | Indeterminate | Upper[11] | A giant titanosaurian sauropod, probably exceeding Patagotitan in size[12] |
Theropods
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Abelichnus | A. astigerrae | A footprint | ||||
| Alnashetri | A. cerropoliciensis | La Buitrera | Upper[13] | A fragmentary skeleton including leg and foot bones | An alvarezsauroid |  |
| Bicentenaria | B. argentina | Ezequiel Ramos Mexia Reservoir | Upper[14] | Much of a skeleton | A coelurosaur |  |
| Buitreraptor | B. gonzalezorum | La Buitrera | Upper [13] | Several partial skeletons | A dromaeosaurid |  |
| Ekrixinatosaurus | E. novasi | Bajo del Añelo | Upper[15] | A partial skeleton | An abelisaurid |  |
| Giganotosaurus | G. carolinii | Los Candeleros and Villa El Chocón | Upper/Lower | A partial skull and a disarticulated postcranial skeleton,a dentary, and teeth.[16] Found in the upper part of the formation.[16] | A carcharodontosaurid |  |
Pterosaurs
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Azhdarchidae[17] | Indeterminate | Ezequiel Ramos Mexía Reservoir | Upper | A partial cervical vertebra | An azhdarchid |
Other reptiles
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Araripesuchus | A. buitreraensis | La Buitrera, Cerro Policía and El Pueblito. | Upper | Multiple skull specimens. | A small notosuchian crocodyliform |  |
| A manzanensis | Upper | A partial skull and lower jaw | ||||
| A. patagonicus | El Chocón. | Lower | An anterior half of the skull with an articulated mandible, lacking the most anterior portion of the rostrum and also preserves part of the postcranium | |||
| Najash | N. rionegrina | Upper | A basal snake |  | ||
| Priosphenodon | P. avelasi | Upper | An eilenodontine rhynchocephalian |  | ||
| Tika | T. giacchinoi | Upper | A sphenodontine rhynchocephalian |
Mammals
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Cronopio | C. dentiacutus | La Buitrera | Upper | Skull bones and teeth | A small meridiolestidan mammal |  |
Turtles
| Taxa | Species | Locality | Member | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Prochelidella[18] | P. buitreraensis | Upper | A small chelid turtle | |||
| Elkanemys[19] | E. pritchardi | Upper | A bothremydid turtle |
See also
- List of fossil sites
- Bajo Barreal Formation, contemporaneous fossiliferous formation of the San Jorge Basin
- Cerro Fortaleza Formation, contemporaneous fossiliferous formation of the Austral Basin
- Alcântara Formation, contemporaneous fossiliferous formation of the São Luís-Grajaú Basin, Brazil
- List of dinosaur bearing rock formations
