Guichón Formation
Late Cretaceous geological formation in Uruguay
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The Guichón Formation is a Late Cretaceous geologic formation of the Paysandú Group in Uruguay. Dinosaur remains are among the fossils that have been recovered from the formation.[1]
| Guichón Formation | |
|---|---|
| Stratigraphic range: Aptian-Santonian ~ | |
| Type | Geological formation |
| Unit of | Paysandú Group |
| Underlies | Mercedes Formation |
| Overlies | Arapey Formation |
| Thickness | Up to >100 m (330 ft) (in wells) |
| Lithology | |
| Primary | Sandstone |
| Other | Conglomerate |
| Location | |
| Coordinates | 32.0°S 57.7°W |
| Approximate paleocoordinates | 38.4°S 30.0°W |
| Region | Paysandú Department |
| Country | Uruguay |
| Extent | Norte Basin |
| Type section | |
| Named for | Guichón |
  Guichón Formation (Uruguay) | |
Description
The Guichón Formation comprises mainly pink-greyish to reddish sandstones, which contain moderate to well-sorted, subrounded, fine to medium-sized grains in a pelitic matrix. These sandstones (which compositionally are feldspathic wackes) are either massive or may instead exhibit parallel lamination, cross-lamination and graded bedding. These lithologies were deposited in southwest-trending alluvial–fluvial systems comprising low-sinuosity channels traversing through sandy plains. Subordinate to the already mentioned sandstones are conglomeratic and pelitic lithologies, interpreted as channel-fill and overbank deposits, respectively. It is inferred that the Guichón Formation was deposited in warm, semi-arid climatic conditions.[2] The formation has been correlated to the Puerto Yeruá Formation of northwestern Argentina.[3]
The formation reaches a thickness of more than 100 metres (330 ft) in wells perforating the formation.[4] It is overlain by the Mercedes Formation and overlies the Arapey Formation.[5]