Abanico Formation ( es, Formación Abanico) is a thick sedimentary formation exposed in the
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
of
Central Chile.
[ The formation has been deposited in a timespan from the ]Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...
to the Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
. Abanico Formation's contact with the overlying Miocene Farellones Formation has been the subject of differing interpretations since the 1960s.[Godoy, 2012] A small part of the formation crops out in the Mendoza Province
Mendoza, officially Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the republic o ...
of western Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
.[Muñoz et al., 2006]
Description
The sediments accumulated in the Abanico Extensional Basin within a context of the Andean orogeny
The Andean orogeny ( es, Orogenia andina) is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system alon ...
. The basin had a north-south elongated shape that spanned the latitudes of 29–38° S. Tectonic inversion from 21 to 16 million years ago made the basin collapse and the sediments to be incorporated to the Andean ranges.[Charrier et al., 2006, pp.93-94] The northern part of the basin inverted before the southern part.[ Parts of the formation are known to have experienced ]Prehnite-pumpellyite facies
The prehnite-pumpellyite facies is a metamorphic facies typical of subseafloor alteration of the oceanic crust around mid-ocean ridge spreading centres.
It is a metamorphic grade transitional between zeolite facies and greenschist facies repr ...
metamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of ch ...
.[Muñoz et al., 2010]
Paleontological significance
The Tinguiririca fauna is known from the fossils found in the Abanico Formation near the Tinguiririca River
Tinguiririca River is a river of Chile located in the Libertador General Bernardo O'Higgins Region. It rises in the Andes, at the confluence
In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join ...
. The rich faunal assemblage of the paleontological site, located in the La Gloria Member and dated at 33 to 31 Ma, gave name to the Tinguirirican South American land mammal age
The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...
(SALMA), together with the Friasian The Friasian age is a period of geologic time (16.3–15.5 Ma) within the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It follows the Santacrucian and precedes the Colloncuran age.
...
named after the Río Frías Formation of the Aysén Region
The Aysén del General Carlos Ibáñez del Campo Region ( es, Región de Aysén, , '), often shortened to Aysén Region or Aisén,Examples of name usage1, official regional government site refers to the region as "Región de Aysén"., Chile's of ...
, the only ages defined in Chile.[
]
Fossil content
The following fossils have been recovered from the formation:
References
Bibliography
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Further reading
* Charrier, R., Bustamante, M., Comte, D., Elgueta, S., Flynn, J.J., Iturra, N., Muñoz, N., Pardo, M., Thiele, R. y Wyss, A.R. 2005. The Abanico Extensional Basin: regional extension, chronology of tectonic inversion, and relation to shallow seismic activity and Andean uplift. Neues Jahrbuch für Geologie und Paläontologie Abh. 236: 43-77
* J. J. Flynn and A. R. Wyss. 2004. A polydolopine marsupial skull from the Cachapoal Valley, Andean Main Range, Chile. ''Bulletin of the American Museum of Natural History'' 285:80-92
* J. J. Flynn, A. R. Wyss, R. Charrier and C. C. Swisher. 1995. An Early Miocene anthropoid skull from the Chilean Andes. ''Nature'' 373(6515):603-607
* Fock, A., Charrier, R., Farias, M. y Muñoz, M. 2006. Fallas de vergencia oeste en la Cordillera principal de Chile: inversión de la cuenca Abanico (33°-34°S). Asociación Geológica Argentina, Serie Publicación Especial 6: 48-55
* Godoy, E., Navarro, M. y Rivera, O. 1996. Zonas triangulares en el borde occidental de la Cordillera Principal (32°30'- 34°30' l.s.), Chile: Una solución a la paradoja Abanico - Farellones 13° Congreso Geológico Argentino y 3° Congreso de Exploración de Hidrocarburos, Actas 2: 373-381, Buenos Aires
* R. B. Hitz, J. J. Flynn, and A. R. Wyss. 2006. New Basal Interatheriidae (Typotheria, Notoungulata, Mammalia) from the Paleogene of Central Chile. ''American Museum Novitates'' 3520:1-32
* M. J. Novacek, A. R. Wyss, D. Frassinetti and P. Salinas. 1989. A new ?Eocene mammal fauna from the Andean Main Range. ''Journal of Vertebrate Paleontology'' 9(3 Supp.):34A
* Vergara, M.; Morata, D.; Villarroel, R.; Nyström, J.O.; Aguirre, L. 1999. 40Ar/39Ar ages, very low grade metamorphism and geochemistry of the volcanic rocks from “Cerro El Abanico”, Santiago Andean Cordillera (33º30’S-70º25’W). In International Symposium on Andean Geodynamics, No. 4, Extended Abstracts: 785-788. Göttingen
* A. R. Wyss, J. J. Flynn, C. C. Swisher, III, R. Charrier, and M. A. Norell. 1992. Fossil mammals from the central Chilean Andes: a new interval in the South American land mammal succession, and implications for Eocene-Oligocene events and Andean tectonics. Abstracts and Program, Fifth North American Paleontological Convention 318
{{Geology of Chile, state=expanded
Geologic formations of Chile
Eocene Series of South America
Oligocene Series of South America
Miocene Series of South America
Paleogene Chile
Neogene Chile
Geologic formations of Argentina
Paleogene Argentina
Neogene Argentina
Rupelian Stage
Priabonian Stage
Fossiliferous stratigraphic units of South America
Paleontology in Chile
Geology of O'Higgins Region
Geology of Santiago Metropolitan Region
Geology of Valparaíso Region
Geology of Mendoza Province