The Cordillera Darwin Metamorphic Complex is 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 ...

composed chiefly of

metamorphic rock 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 ...

s located in southern

Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla ...

. It has been suggested that the Cordillera Darwin Metamorphic Complex is analogous to the

Eastern Andes Metamorphic Complex The Eastern Andes Metamorphic Complex is a large coherent but varied group of metamorphic and sedimentary rocks –in other words a geologic complex– that crops out in the eastern Patagonian Andes in Chile and Argentina. The metamorphic grade o ...

. The Cordillera Darwin Metamorphic Complex is the only metamorphic complex in the southern Andes known to have

amphibolite facies Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose ...

rocks containing

kyanite Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks generally ...

and

sillimanite Sillimanite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut. Occurrence ...

which evidences high-grade metamorphism. High-grade metamorphism took place during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

purportedly in association with the closure of the Rocas Verdes Basin. The

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 of Cordillera Darwin Metamorphic Complex are unrelated to

Tierra del Fuego Igneous and Metamorphic Complex Tierra del Fuego Igneous and Metamorphic Complex is a geological basement complex known from boreholes in northern Tierra del Fuego. The complex is made up of foliated igneous rocks of Cambrian age including orthogneiss. It underlies unconformab ...

despite present-day proximity.

References

Geology of Magallanes Region Geology of Tierra del Fuego Metamorphic complexes Lithodemic units of Argentina Lithodemic units of Chile {{MagellanAntarctic-geo-stub