The Tarjados Formation is an Early to Middle Triassic geologic formation in the Ischigualasto-Villa Unión Basin of La Rioja Province in northwestern Argentina. The red to whitish sandstones and conglomerates of the formation were deposited in an arid fluvial environment. The formation overlies the Talampaya Formation and is overlain by the Chañares Formation of the Agua de la Peña Group.
The formation has provided fossils of an archosaur and a kannemeyeriid dicynodont, both not yet placed in a dedicated genus. The formation crops out in the Talampaya National Park, which was designated a UNESCO World Heritage Site in 2000.Talampaya National Park at Fossilworks.org
Description The formation was first defined by Romer and Jensen in 1966,Caselli, 1998, p.22 based on a type section exposed in the Sierra de Los Tarjados.Balabusic et al., 2001, p.14 The Tarjados Formation, as the underlying Talampaya Formation, belongs to the Paganzo Group.Tarjados Formation at Fossilworks.org
The formation is exposed in the Talampaya National Park of La Rioja Province. The Tarjados Formation is overlain by the Chañares Formation, separated by a regional unconformity.Balabusic et al., 2001, p.26
The formation, reaching a maximum thickness of ,Aceituno Cieri et al., 2015, p.60Monetta et al., 2000, p.648 comprises red to greenish grey sandstones,Monetta et al., 2000, p.644 deposited in an eolian and playa-lacustrine to fluvial environment.Ezcurra et al., 2015, p.476 The sediments were deposited under arid,Balabusic et al., 2001, p.28 or semi-arid conditions.
The formation has provided fossils of an archosaur and a kannemeyeriid dicynodont, both not yet placed in a dedicated genus.Ezcurra et al., 2015, p.478Ezcurra et al., 2015, p.479
See also Santa Maria Formation, contemporaneous fossiliferous formation of the Paraná Basin in southeastern Brazil Katberg Formation, contemporaneous fossiliferous formation of the Karoo Basin in South Africa Fremouw Formation, contemporaneous fossiliferous formation of Antarctica
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