The Cordillera Darwin Metamorphic Complex is a geologic complex 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, caus ...

s located in southern

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

. It has been suggested that the Cordillera Darwin Metamorphic Complex is analogous to the Eastern Andes Metamorphic Complex. 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 (fl ...

rocks containing

kyanite Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure Polymorphism (materials science), polymorph of andalusite and sillimanite, and the presence of kyani ...

and

sillimanite Sillimanite or fibrolite 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 ...

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

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

purportedly in association with the closure of the

Rocas Verdes Basin The Rocas Verdes ophiolites () are a series of greenschists and other rocks constituting ophiolites in Magallanes Region, southernmost Chile. The Rocas Verdes ophiolites represent the continental-oceanic crust that existed in a back-arc basin in th ...

. 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 ...

s of Cordillera Darwin Metamorphic Complex are unrelated to Tierra del Fuego Igneous and Metamorphic Complex 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