Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)

ABSTRACT. Crustal thickening by horizontal shortening and associated deformation have been broadly considered as prime mechanisms for mountain building in the Central Andes of western South America. However, timing and structural style ofAndean orogeny in northernmost Chile remains to be fully under...

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Autores principales:	Herrera,Sebastián, Pinto,Luisa, Deckart,Katja, Cortés,Javier, Valenzuela,Javier Ignacio
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2017
Materias:	Central Andes Structure Western Cordillera Western Altiplano Syntectonic deposits U-Pb ages
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062017000200001
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spelling	oai:scielo:S0718-710620170002000012017-07-07Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)Herrera,SebastiánPinto,LuisaDeckart,KatjaCortés,JavierValenzuela,Javier Ignacio Central Andes Structure Western Cordillera Western Altiplano Syntectonic deposits U-Pb ages ABSTRACT. Crustal thickening by horizontal shortening and associated deformation have been broadly considered as prime mechanisms for mountain building in the Central Andes of western South America. However, timing and structural style ofAndean orogeny in northernmost Chile remains to be fully understood. By means of this contribution we attempt to unravel the Cenozoic tectonostratigraphy and structural architecture of a narrow segment within the Western Cordillera (western flank of the Altiplano plateau), based on detailed structural mapping, available and new geochronological data gathered from the Aquine region (~19°15’ S). The geology of this area indicates that compressive tectonics dominated for ~21 Myr, between 27 Ma and 6 Ma, and that onset of deformation probably occurred in the middle Eocene (after ca. 49 Ma). According to angular unconformities registered throughout the region, three principal compressive episodes have been determined: (1) middle Eocene-late Oligocene (ca. 49-27 Ma); (2) late Oligocene-middle Miocene (ca. 27-14 Ma); and (3) middle-latest Miocene, 14-6 Ma. Paleogene and Neogene structural development within the Aquine region was concomitant to activity on the bordering West and East Vergent Thrust Systems (WTS and ETS), which controlled uplift of the western Altiplano since the late Oligocene-early Miocene, located at the foot of the Precordillera and within the eastern part of the Western Cordillera, respectively. Major structures in the western segment of the region are high-angle, east-vergent, substratum-involving thrusts that affect late Mesozoic and Cenozoic volcanic and sedimentary intra-arc deposits. Unalike, a west-vergent fold-and-thrust belt is developed in the southeastern segment of the region, involving only Miocene deposits. These contrasting structural styles and opposite vergences indicate a combination of thin- and thick-skinned tectonics in a "pop-up" like structural array. Growth strata and sedimentological features in alluvial and fluvial sandstones and conglomerates of the upper Miocene Mauque Formation suggest the occurrence of syntectonic deposition. In addition, gentle angular unconformities within upper Oligocene-upper Miocene arc deposits suggest that sedimentation and volcanism developed synchronic to compressive tectonics throughout the Miocene and coeval to deposition in the active bordering thrust systems (WTS and ETS). The interpreted tectonostratigraphic development of the study area is similar to but slightly diachronic with the Cenozoic evolution in the Belén region (18°-19° S) of northernmost Chile. We interpret that east- and west-vergent thrusts within the Western Cordillera, are deeply rooted in a crustal-scale "pop-up" structure that accommodated Cenozoic deformation on the western flank of the Altiplano. Uplift as a consequence of contraction along the Western Cordillera was coeval to late Paleogene block exhumation and subsequent Neogene development of fold-and-thrust belts on the eastern border of the Altiplano. The main structural characteristics within the Aquine region suggest that inversion of an Upper Cretaceous intra-arc basin was of major relevance for the Cenozoic structural development of the Western Cordillera.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.44 n.2 20172017-05-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062017000200001en10.5027/andgeoV44n2-a01
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Central Andes Structure Western Cordillera Western Altiplano Syntectonic deposits U-Pb ages
spellingShingle	Central Andes Structure Western Cordillera Western Altiplano Syntectonic deposits U-Pb ages Herrera,Sebastián Pinto,Luisa Deckart,Katja Cortés,Javier Valenzuela,Javier Ignacio Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)
description	ABSTRACT. Crustal thickening by horizontal shortening and associated deformation have been broadly considered as prime mechanisms for mountain building in the Central Andes of western South America. However, timing and structural style ofAndean orogeny in northernmost Chile remains to be fully understood. By means of this contribution we attempt to unravel the Cenozoic tectonostratigraphy and structural architecture of a narrow segment within the Western Cordillera (western flank of the Altiplano plateau), based on detailed structural mapping, available and new geochronological data gathered from the Aquine region (~19°15’ S). The geology of this area indicates that compressive tectonics dominated for ~21 Myr, between 27 Ma and 6 Ma, and that onset of deformation probably occurred in the middle Eocene (after ca. 49 Ma). According to angular unconformities registered throughout the region, three principal compressive episodes have been determined: (1) middle Eocene-late Oligocene (ca. 49-27 Ma); (2) late Oligocene-middle Miocene (ca. 27-14 Ma); and (3) middle-latest Miocene, 14-6 Ma. Paleogene and Neogene structural development within the Aquine region was concomitant to activity on the bordering West and East Vergent Thrust Systems (WTS and ETS), which controlled uplift of the western Altiplano since the late Oligocene-early Miocene, located at the foot of the Precordillera and within the eastern part of the Western Cordillera, respectively. Major structures in the western segment of the region are high-angle, east-vergent, substratum-involving thrusts that affect late Mesozoic and Cenozoic volcanic and sedimentary intra-arc deposits. Unalike, a west-vergent fold-and-thrust belt is developed in the southeastern segment of the region, involving only Miocene deposits. These contrasting structural styles and opposite vergences indicate a combination of thin- and thick-skinned tectonics in a "pop-up" like structural array. Growth strata and sedimentological features in alluvial and fluvial sandstones and conglomerates of the upper Miocene Mauque Formation suggest the occurrence of syntectonic deposition. In addition, gentle angular unconformities within upper Oligocene-upper Miocene arc deposits suggest that sedimentation and volcanism developed synchronic to compressive tectonics throughout the Miocene and coeval to deposition in the active bordering thrust systems (WTS and ETS). The interpreted tectonostratigraphic development of the study area is similar to but slightly diachronic with the Cenozoic evolution in the Belén region (18°-19° S) of northernmost Chile. We interpret that east- and west-vergent thrusts within the Western Cordillera, are deeply rooted in a crustal-scale "pop-up" structure that accommodated Cenozoic deformation on the western flank of the Altiplano. Uplift as a consequence of contraction along the Western Cordillera was coeval to late Paleogene block exhumation and subsequent Neogene development of fold-and-thrust belts on the eastern border of the Altiplano. The main structural characteristics within the Aquine region suggest that inversion of an Upper Cretaceous intra-arc basin was of major relevance for the Cenozoic structural development of the Western Cordillera.
author	Herrera,Sebastián Pinto,Luisa Deckart,Katja Cortés,Javier Valenzuela,Javier Ignacio
author_facet	Herrera,Sebastián Pinto,Luisa Deckart,Katja Cortés,Javier Valenzuela,Javier Ignacio
author_sort	Herrera,Sebastián
title	Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)
title_short	Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)
title_full	Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)
title_fullStr	Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)
title_full_unstemmed	Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30’ S)
title_sort	cenozoic tectonostratigraphic evolution and architecture of the central andes in northern chile based on the aquine region, western cordillera (19°-19°30’ s)
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2017
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062017000200001
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Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19°30&#8217; S)

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