The Eastern Andes Metamorphic Complex is a large coherent but varied group of

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, cau ...

and

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particle ...

s –in other words a

geologic complex In geology, a complex is a lithodemic unit consisting of two or more lithodemes of more than one genetic class ( metamorphic, igneous or sedimentary). The law of superposition is inapplicable to intrusive, highly deformed, or metamorphic bodies of ...

– that crops out in the eastern

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and ...

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 ...

in Chile and Argentina. The metamorphic grade of rocks varies but does not exceed

greenschist facies Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically and 2–10 kilobars (). Greenschists commonly have an abundance of green minerals such as chlorite, ...

, the only exception to this are rocks near

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s affected by

contact 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 chem ...

. The sedimentary

protolith A protolith () is the original, unmetamorphosed rock from which a given metamorphic rock is formed. For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other kind of non-metamorphic rock and t ...

s sedimented in the Late Paleozoic. The pressures and temperatures of metamorphism of the Eastern Andes Metamorphic Complex are different those usually expected from

accretionary complex An accretionary wedge or accretionary prism forms from sediments accreted onto the non- subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the ...

es. The

sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s of the Eastern Andes Metamorphic Complex were likely deposited in a passive continental margin. Cordillera Darwin Metamorphic Complex shows affinity with the Eastern Andes Metamorphic Complex albeit both complexes lie hundreds of kilometers from each other.

References

Geology of Aysén Region Geology of Magallanes Region Geology of Santa Cruz Province, Argentina Metamorphic complexes Lithodemic units of Argentina Lithodemic units of Chile {{MagellanAntarctic-geo-stub