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 d ...

whose history affected many of the older rocks of Cuyo in

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. 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 ultramaf ...

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

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

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

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

s to be a single block with Cuyania. The San Rafael Block 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 Geology of North America, 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 ...

, 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: ''wikt:pan-, pan-'', "all", ''wikt:νότος, -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neo ...

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

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