Belén Metamorphic Complex

Belén Metamorphic Complex
Belén Metamorphic Complex
Stratigraphic range: Paleozoic
Type	Complex
Underlies	Lupica Formation
Lithology
Primary	Amphibolite, orthogneiss, serpentinite
Other	Mica schist
Location
Region	Arica y Parinacota Region
Country	Chile

The Belén Metamorphic Complex (Spanish: Complejo metamórfico Belén) is a group of metamorphic and igneous rocks that crops out in the western edge of the Altiplano plateau in the interior of northernmost Chile. ^[1] The rocks of the complex metamorphosed during the Early Paleozoic era but the original protoliths formed in the Proterozoic eon.^[1]^[2] This make rocks of the Belén Metamorphic Complex the oldest rocks known in Chile.^[1] To the west the rocks of the Belén Metamorphic Complex thrust along Chapiquiña-Belén fault over sediments of Cenozoic age including ignimbrites of the Oxaya Formation and rocks of Lupica Formation.^[1]^[3] At their peak conditions of metamorphism rocks reached temperatures and pressures of 700 C and 7 kbar.^[3] The timing of the metamorphism matches the age of the Famatinian orogeny in the Argentine Northwest.^[3] Rocks of the Belén Metamorphic Complex were involved in one or more orogenies in the Early Paleozoic.^[3]

Rocks of the complex include foliatied amphibolite, orthogneiss, serpentinite and lesser amounts of quartz-rich mica schist.^[1]^[3]

The rocks of complex have experienced continuous exhuming during the last 15 million years as part of the ongoing Andean orogeny, with an apparent exhumation spurt 11 to 7 million years ago.^[2]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "Esquistos de Belén". Geositios (in Spanish). Retrieved 2023-01-12.
^ ^a ^b García, Marcelo; Aguilar, Germán; Rodríguez, María Pía; Metcalf, James (2022). "(U-Th)/He ages of Proterozoic-Paleozoic basement rocks from northern Chile (18-19° S) and implications on the Neogene uplift history of the Western Cordillera". Andean Geology. 49 (3): 313–326. doi:10.5027/andgeoV49n3-3402. S2CID 253148429.
^ ^a ^b ^c ^d ^e Hervé, Francisco; Faundez, Victor; Calderón, Mauricio; Massonee, Hans-joachim; Willner, Arne P. (2007). "2. Metamorphic and plutonic basement complexes". In Moreno, Teresa; Gibbons, Wes (eds.). Geology of Chile. Geological Society of London. pp. 5–25. ISBN 978-1-86239-219-9.

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[geositios-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "Esquistos de Belén". Geositios (in Spanish). Retrieved 2023-01-12.

[exhumation-2] García, Marcelo; Aguilar, Germán; Rodríguez, María Pía; Metcalf, James (2022). "(U-Th)/He ages of Proterozoic-Paleozoic basement rocks from northern Chile (18-19° S) and implications on the Neogene uplift history of the Western Cordillera". Andean Geology. 49 (3): 313–326. doi:10.5027/andgeoV49n3-3402. S2CID 253148429.

[Hervetal2007-3] Hervé, Francisco; Faundez, Victor; Calderón, Mauricio; Massonee, Hans-joachim; Willner, Arne P. (2007). "2. Metamorphic and plutonic basement complexes". In Moreno, Teresa; Gibbons, Wes (eds.). Geology of Chile. Geological Society of London. pp. 5–25. ISBN 978-1-86239-219-9.

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