Dorotea Formation
The Dorotea Formation is a geological formation in the Río de Las Chinas Valley of the Magallanes Basin in Patagonian Chile whose strata date back to the Campanian to Maastrichtian of the Late Cretaceous.[1]
| Dorotea Formation Stratigraphic range: Late Campanian-Maastrichtian ~72–66 Ma | |
|---|---|
| Type | Geological formation |
| Underlies | Man Aike Formation |
| Overlies | Tres Pasos Formation |
| Thickness | 100–350 m (330–1,150 ft) |
| Lithology | |
| Primary | Sandstone, claystone |
| Other | Conglomerate |
| Location | |
| Coordinates | 50.7°S 72.5°W |
| Approximate paleocoordinates | 52.9°S 60.5°W |
| Region | Magallanes Region |
| Country |  Chile |
| Extent | Río de Las Chinas Valley, Magallanes Basin |
| Type section | |
| Named for | Sierra Dorotea |
| Named by | Katz |
| Year defined | 1963 |
  Dorotea Formation (Chile) | |
Description
The Dorotea Formation was first described by Katz in 1963. The formation comprises sandstones with frequent conglomerate lenses, concretionary levels and claystones. The Dorotea Formation includes calcareous sandstones with abundant marine invertebrate and fragmentary vertebrate fossils. Hervé et al. (2004) obtained a maximum radiometric age of 67.4 ± 1.5 Ma from detrital zircons contained in sandstones of the Dorotea Formation.[2]
The mudstones and sandstones of the formation were deposited in a fluvial environment. The formation conformably overlies the Tres Pasos Formation and is unconformably overlain by the Lutetian to Bartonian Man Aike Formation.[3] The thickness of the formation ranges from 100 metres (330 ft) in the Sierra Baguales in the north to 350 metres (1,150 ft) in the eponymous Sierra Dorotea in the south.[4]
Fossil content
The following fossils were reported from the formation:[5]
- Amphibians
- Anura indet.[6]
- Panchelidae indet.[6]
- Reptiles
- Mammals
- Magallanodon baikashkenke[8]
- Mammalia indet.[6]
- Fish
- Ischyrhiza chilensis[4]
- Carcharias sp.[4]
- Serratolamna indet.[4]
- Insects
- Dorotheus guidensis[9]
- Bivalves
- Pterotrigonia cazadoriana[2]
- Ammonites
- Gunnarites sp.[2]
- Pachydiscus aff. gollevilensis[2]
See also
- List of dinosaur-bearing rock formations
- Quiriquina Formation
- Allen Formation, Campanian to Maastrichtian fossiliferous formation of the Neuquén Basin
- Angostura Colorada Formation, Campanian to Maastrichtian fossiliferous formation of the North Patagonian Massif
- La Colonia Formation, Campanian to Maastrichtian formation of the Cañadón Asfalto Basin
- Colorado Formation, Campanian to Maastrichtian fossiliferous formation of the Colorado Basin
- Lago Colhué Huapí Formation, Campanian to Maastrichtian fossiliferous formation of the Golfo San Jorge Basin
References
- Dorotea Formation at Fossilworks.org
- Otero et al., 2009
- Goin et al., 2020, p.9
- Otero et al., 2015, p.240
- Río de las Chinas Valley at Fossilworks.org
- Alarcón Muñoz et al., 2020
- Otero et al., 2015
- Goin et al., 2020
- Kuschel, 1959
Bibliography
- Alarcón Muñoz, J., S. Soto-Acuña, L. M. E. Manríquez, R. A. Fernández, D. Bajor, J. P. Guevara, F. Suazo Lara, M. A. and A. O. Vargas. 2020. Freshwater turtles (Testudines: Pleurodira) in the Upper Cretaceous of Chilean Patagonia. Journal of South American Earth Sciences . . Accessed 2020-06-12.
- Goin, Francisco J., and al et. 2020. First Mesozoic Mammal from Chile: the southernmost record of a Late Cretaceous Gondwanatherian. Boletín del Museo Nacional de Historia Natural, Chile 69. 5-31. Accessed 2020-06-12.
- Otero, R.A.; S. Soto Acuña; C. Salazar, and J.L. Oyarzún. 2015. New elasmosaurids (Sauropterygia, Plesiosauria) from the Late Cretaceous of the Magallanes Basin, Chilean Patagonia: Evidence of a faunal turnover during the Maastrichtian along the Weddellian Biogeographic Province. Andean Geology 42. 237-267. Accessed 2020-06-12.
- Otero, R.A.; M.E. Suarez, and J.P. Roux. 2009. First record of elasmosaurid plesiosaurs (Sauropterygia: Plesiosauria) in upper levels of the Dorotea Formation, Late Cretaceous (Maastrichtian), Puerto Natales, Chilean Patagonia. Andean Geology 36. 342-350. Accessed 2020-06-12.
- Kuschel, G. 1959. Un curculionido del Cretácico Superior - primer insecto fósil de Chile. Investigaciones Zoológicas Chilenas 5. 49-54.