Plottier Formation

__NOTOC__The Plottier Formation is a geologic formation that outcrops in the Argentine Patagonian provinces of Río Negro and Neuquén. It is the younger of two formations belonging to the Río Neuquén Subgroup within the Neuquén Group, with the oldest rocks dating from the late Coniacian and its youngest maybe from the very start of the Santonian. Formerly that subgroup was treated as a formation, and the Plottier Formation was known as the Plottier Member.Sánchez "et al." (2006)]

A section near the Neuquén City airport, north of the town of Plottier, is the type locality of the Plottier Formation [Fossa Mancini "et al." (1938)] . At its base, this formation grades into the Portezuelo Formation, and it is in turn overlain conformably by the Bajo de la Carpa Formation, a unit of the Río Colorado Subgroup.

The Plottier Formation is the smallest formation within the Neuquén Group, with a maximum thickness of only 25 meters. It is differentiated from the underlying Portezuelo Formation primarily by its higher content of argillites (mud deposits) and was deposited under fluvial conditions. In 2006, a detailed lithostratigraphic and paleoecological study of a section of the Plottier Formation was published. This section contained alluvial deposits laid down by what was essentially a low-gradient wandering river throughout the millions of years, but often was of a single-channel type with little meandering. [Leanza "et al." (2004), Sánchez "et al." (2006)]

Age

Era: Mesozoic
Period: Late Cretaceous
Faunal stage: late Coniacian – ?early Santonian
Absolute Age: ~88 to ~86 mya

Paleontology

Few animal fossils are known from this formation, including:
* titanosaurid sauropods (including ""Antarctosaurus" giganteus")
* a basal coelurosaurian theropod
* at least one mammal

There are also ichnofossils left on the river's mudflats, as well as fossil freshwater bivalves.

ee also

* List of fossil sites

Footnotes

References

* (1993): Enantiornithine (Aves) Tarsometatarsi from the Cretaceous Lecho Formation of Northwestern Argentina. "American Museum Novitates" 3083: 1-27. [English with Spanish abstract] [http://digitallibrary.amnh.org/dspace/bitstream/2246/4981/1/N3083.pdf PDF fulltext]
* (2002): Bird footprints from the Anacleto Formation (Late Cretaceous), Neuquén, Argentina. "Ameghiniana" 39(4): 453-463. [English with Spanish abstract] [http://www.biology.ualberta.ca/faculty/philip_currie/uploads/pdfs/2002/2002Bird_Footprints.PDF PDF fulltext]

* (1938): Una reunión de geólogos de YPF y el problema de la terminología estratigráfica ["A YPF geologists' reunion and the problem of stratigraphy terminology"] . "Boletín de Informaciones Petroleras" 15: 1-67.
* (2004): Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. "Cretaceous Research" 25(1): 61-87. doi|10.1016/j.cretres.2003.10.005 (HTML abstract)

* (2006): Bird tracks from Liaoning Province, China: New insights into avian evolution during the Jurassic-Cretaceous transition. "Cretaceous Research" 27(1): 33-43. doi|10.1016/j.cretres.2005.10.007 (HTML abstract). Erratum: doi|10.1016/j.cretres.2008.06.002
* (2005): Osteology of the sauropod embryos from the Upper Cretaceous of Patagonia. "Acta Palaeontologica Polonica" 50(1): 79–92. [http://www.app.pan.pl/archive/published/app50/app50-079.pdf PDF fulltext]

* (2006): Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén [Sedimentary paleoenvironments in the Upper Cretaceous Plottier Formation (Neuquen Group), Confluencia, Neuquén] . "Revista de la Asociación Geológica Argentina" 61(1): 3-18. [Spanish with English abstract] [http://www.scielo.org.ar/pdf/raga/v61n1/v61n1a01.pdf PDF fulltext]