Lisandro formation

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The Lisandro Formation , also known as the Cerro Lisandro Formation , is a series of continental sedimentary rocks of the Upper Cretaceous Argentina , known for its fossil fauna. It is the youngest member of the Río Limay subgroup, the lowest section of the Neuquén group . In the past, this subgroup was considered a formation itself, with the Lisandro formation known as the (Cerro) Lisandro member . These rocks were deposited in the late Cenomanian and early Turonian about 94 to 91 million years ago. Outcrops of this geological formation can be found in the Argentine province of Neuquén ; Type locality is a hill called Cerro Lisandro.

The Lisandro Formation lies concordantly on the Huincul Formation and is covered by the Portezuelo Formation , which belongs to the Río Neuquén subgroup. With a thickness of 35 to 75 meters, it is the smallest of the three formations of the Río Limay subgroup. The rocks are reddish clay and siltstones that were probably deposited under marshy conditions. Usually the reddish rocks of the Lisandro Formation are easy to distinguish from the greenish to yellowish deposits of the Huincul Formation.

Fossils of the formation include seashells, fish, turtles, crocodiles, and at least one species of birds. Dinosaurs are not as common as in some of the other Neuquén group formations. Among the finds are an abelisauroid theropod and ornithopods such as Anabisetia .

Individual evidence

  1. ↑ Maria Lidia Sánchez, Susana Heredia, Jorge O. Calvo: Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén [Sedimentary palaeoenvironments in the Upper Cretaceous Plottier Formation, Neuquén group), Confluencia . In: Revista de la Asociación Geológica Argentina . tape 61 , no. 1 , 2006, p. 3–18 ( PDF ( memento of July 25, 2011 in the Internet Archive )).
  2. ^ E. Fossa Mancini, E. Feruglio, JC Yussen de Campana: Una reunión de geólogos de YPF y the problema de la terminología estratigráfica . In: Boletín de Informaciones Petroleras . tape 15 , 1938, pp. 1-67 .
  3. ^ HA Leanza, S. Apesteguia, FE Novas, MS de la Fuente: Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages . In: Cretaceous Research . tape 25 , no. 1 , 2004, p. 61-87 , doi : 10.1016 / j.cretres.2003.10.005 .