Sierra Barrosa Formation
The Sierra Barrosa Formation is a geologic formation of the Neuquén Basin in the northern Patagonian provinces of Mendoza and Neuquén. The formation dates to the Late Cretaceous, middle to late Coniacian, and belongs to the Río Neuquén Subgroup of the Neuquén Group. The formation overlies the Los Bastos Formation and is overlain by the Plottier Formation. As the underlying Los Bastos Formation, the Sierra Barrosa Formation comprises mudstones and sandstones deposited in a fluvial environment.
| Sierra Barrosa Formation Stratigraphic range: Mid-late Coniacian ~88–86 Ma | |
|---|---|
| Type | Geological formation |
| Unit of | Neuquén Group Río Neuquén Subgroup |
| Underlies | Plottier Formation |
| Overlies | Los Bastos Formation |
| Thickness | Up to 62 m (203 ft) |
| Lithology | |
| Primary | Mudstone |
| Other | Sandstone |
| Location | |
| Coordinates | 38°52′10″S 68°51′20″W |
| Approximate paleocoordinates | 42.8°S 48.4°W |
| Region | Mendoza & Neuquén Provinces |
| Country |  |
| Extent | Neuquén Basin |
| Type section | |
| Named for | Sierra Barrosa |
| Named by | 2010 |
| Year defined | Garrido |
  Sierra Barrosa Formation (Argentina) | |
Description
The formation was named by Garrido in 2010 as sandy unit conformably and transitionally overlying the Los Bastos Formation, which in turns overlies the Portezuelo Formation within which both units were formerly included. The formation in the same manner underlies the Plottier Formation, all belonging to the Río Neuquén Subgroup of the Neuquén Group in the Neuquén Basin. The unit now known as Sierra Barrosa Formation was included in the original definition by Herrero Ducloux (1938, 1939) as "Portezuelo Superior", as part of the "Portezuelo Beds" he described.[1]
The type locality of the formation is located at the southern edge of the eponymous Sierra Barrosa, to the east of Cerro Challacó. The formation at its type section reaches a thickness of 62 metres (203 ft). The formation comprises fine-to-medium grained sandstones intercalated by thin levels of mudstones. The formation has similar lithological characteristics as the Portezuelo Formation and was deposited in a fluvial environment characterized by highly sinuous channels. Based on the stratigraphic relations with the overlying and underlying units, the age has been estimated to be middle to late Coniacian.[1]
Fossil content
The formation has provided fossils of:[2]
See also
- List of dinosaur bearing rock formations
References
- Garrido, 2011, p.237
- Sierra Barrosa Formation at Fossilworks.org
- Filippi et al., 2019
- Calvo et al., 2005
- González Riga, 2003
Bibliography
- Filippi, L.S.; L. Salgado, and A.C. Garrido. 2019. A new giant basal titanosaur sauropod in the Upper Cretaceous (Coniacian) of the Neuquén Basin, Argentina. Cretaceous Research 100. 61–81.
- Garrido, Alberto C. 2011. El Grupo Neuquén (Cretácico Tardío) en la Cuenca Neuquina, 231–244. XVIII Congreso Geológico Argentino. Accessed 2020-07-07.
- Calvo, Jorge O.; Juan D. Porfiri, and Fernando E. Novas. 2007. Discovery of a new ornithopod dinosaur from the Portezuelo formation (Upper Cretaceous), Neuquen, Patagonia, Argentina. Arquivos do Museu Nacional, Rio de Janeiro 65. 471-483.
- González Riga, B.J. 2003. A new titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Mendoza Province, Argentina. Ameghiniana 40. 155–172.