Principal Cordillera (
Spanish: Cordillera Principal) is the
Andean mountain range that makes up the boundary between Central Chile and neighbouring areas of Argentina. It is also a
continental divide between the Atlantic and the Pacific watersheds.[1] It extends in a north–south direction in the Argentine provinces of
La Rioja,
San Juan and
Mendoza and the Chilean regions of
Valparaíso,
Santiago,
O'Higgins and
Maule. To the east of the Principal Cordillera lies the
Frontal Cordillera which is fully in Argentina.[1]Aconcagua, the tallest mountain outside Asia, lies in the Principal Cordillera.[1]
Geological history
What is today the Principal Cordillera was once a
depression that accumulated sediments.[2] Lava flows from ancient volcanoes also found their way to the depression. Today these sequences of
sedimentary and volcanic rock can be observed high in the Andes, implying their basin was closed and uplifted by
tectonic inversion. The said rocks are grouped in the
Abanico and
Farellones Formation.[2] Tectonic inversion took place 21 to 16 million years (Ma) ago,[2] yet the associated pulse of uplift continued until about 8 Ma ago.[3] The Miocene
continental divide was about 20 km to the west of the modern water divide that makes up the
Argentina–Chile border.[4] Subsequent
river incision shifted the divide to the east leaving old
flattish surfaces hanging.[4] Compression and uplift in this part of the Andes has continued into the present.[4] The Principal Cordillera had risen to heights that allowed for the development of
valley glaciers about 1 Ma ago.[4]
References
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abc"Orografía de Mendoza". El Portal de Mendoza (in Spanish). Cámara de Turismo de Mendoza and Cooperativa El Portal de Mendoza. Retrieved June 29, 2019.
Charrier, Reynaldo; Pinto, Luisa; Rodríguez, María Pía (2006). "3. Tectonostratigraphic evolution of the Andean Orogen in Chile". In Moreno, Teresa; Gibbons, Wes (eds.). Geology of Chile. Geological Society of London. pp. 21–114.
ISBN9781862392199.