Corda Formation
Geologic formation in Tocantins, Brazil
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The Corda Formation is a red sandstone geologic formation in the Parnaíba Basin in Tocantins, Brazil. It was formed during the Neoaptian to Eoalbian series of the Early Cretaceous.
| Corda Formation | |
|---|---|
| Stratigraphic range: Late Aptian-Early Albian ~ | |
| Type | Geological formation |
| Underlies | Sardinha Formation |
| Overlies | Itapecuru Formation |
| Lithology | |
| Primary | Red sandstone |
| Location | |
| Coordinates | 5.7°S 47.5°W |
| Approximate paleocoordinates | 5.1°S 14.8°W |
| Region | Tocantins |
| Country | Brazil |
| Extent | Parnaíba Basin |
| Type section | |
| Named for | Corda River |
  Corda Formation (Brazil) | |
Large-scale fossil sauropod tracks have been reported from the formation.[1][2][3][4]
Origin
The Corda Formation is characterized by reddish sandstones, that were probably deposited in windy deserts and fast flowing freshwater streams. Therefore, fossils are very rare.[1]
Occurrence
This formation outcrops in the central part of the Parnaíba Basin, between the mouth of the Araguaia River in the west the Parnaíba River in the east.[1]
Lithology
The Corda Formation consists largely of red sandstone, with very fine to medium grain size, rich in zeolites and iron oxide. Where whinstones[clarification needed] are overlaying fragments of this rock are also present. Typical structures of wind dunes (cross bedding, ripples, and grain flow) are common. This is consistent with deposition in a desert system.[1]
See also
- List of dinosaur-bearing rock formations
- Sauropod tracks
- Romualdo Formation, contemporaneous fossiliferous formation of the Araripe Basin
- Itapecuru Formation, contemporaneous fossiliferous formation of the São Luis and Parnaíba Basins