The Precordillera Terrane or Cuyania was an ancient

microcontinent Continental crustal fragments, partly synonymous with microcontinents, are pieces of continents that have broken off from main continental masses to form distinct islands that are often several hundred kilometers from their place of origin. Caus ...

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its ow ...

whose history affected many of the older rocks of Cuyo in

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 List of South American countries by area, second-largest ...

. It was separated by

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...

from the

Chilenia Chilenia was an ancient microcontinent or terrane whose history affected many of the older rocks of central Chile and western Argentina. It was once separated by oceanic crust from the Cuyania terrane to which it accreted at ~420-390 Ma when Cuya ...

terrane which accreted into it at ~420-390 Ma when Cuyania was already amalgamated with

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final sta ...

. The hypothesized Mejillonia Terrane in the coast of northern Chile is considered by some

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...

s to be a single block with Cuyania. The

San Rafael Block The San Rafael Block or San Rafael Massif (Spanish: ''Bloque de San Rafael'' or ''Macizo de San Rafael'') is an uplifted area in central Mendoza Province, Argentina. The San Rafael Block is both a geographic and a tectonic unit. From a tectonostr ...

crops out 200 km to the south of the other exposures of Cuyania and is the southern extension of the terrane. The Precordillera has been hypothesised to have been derived from

Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...

, the core of North America, which was attached to the western margin of South America during the Precambrian when virtually all continents formed a "proto-

" supercontinent known as

Pannotia Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontine ...

. The Precordillera was then part of a proposed "Texas Plateau", a promontory attached to Laurentia similar to the way the

Falkland Plateau Falkland may refer to: * Falkland, British Columbia, a community in Canada * Falkland, Nova Scotia, a community in Canada * Falkland Islands, an archipelago in the south Atlantic Ocean * Falkland, Fife, a former burgh in Fife, Scotland ** Falklan ...

is attached to South America today. The Texas Plateau was detached from the Gondwana in a rift around 455 Ma after which it collided with the proto-Andean margin of South America, an event known as the Taconic- Famatinian orogeny, and the Precordillera got left behind at its present location within South America.

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* * * * Geology of Chile Geology of Argentina Historical continents Terranes Geology of the Andes {{palaeo-geo-stub

See also

References

Bibliography