| Guichón Formation | |
| Type: | Geological formation |
| Period: | Turonian |
| Age: | Aptian-Santonian ~ |
| Prilithology: | Sandstone |
| Otherlithology: | Conglomerate |
| Namedfor: | Guichón |
| Region: | Paysandú Department |
| Coordinates: | -32°N -57.7°W |
| Paleocoordinates: | -38.4°N -30°W |
| Unitof: | Paysandú Group |
| Underlies: | Mercedes Formation |
| Overlies: | Arapey Formation |
| Thickness: | Up to >100m (300feet) (in wells) |
| Extent: | Norte Basin |
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]
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. The formation has been correlated to the Puerto Yeruá Formation of northwestern Argentina.[2]
The formation reaches a thickness of more than 100m (300feet) in wells perforating the formation.[3] It is overlain by the Mercedes Formation and overlies the Arapey Formation.[4]
The following fossils have been reported from the formation:[5] [6]