Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly

The western retroarc of the Southern Andes between 38° and 40° S is formed by a NNW-elongated ridge not associated with stacked thrust sheets. On the contrary, during the last 4-3 Ma this ridge was affected by extensional deformation, regional uplift and related folding on a very broad scale. Receiv...

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Autores principales:	Folguera, Andrés, Tunstall, Cynthia, Garcia Morabito, Ezequiel, Ramos, Victor Alberto
Publicado:	2007
Materias:	Andean gravity Asthenospheric anomalies Retroarc extension Retroarc volcanism Thermal uplift asthenosphere Cenozoic crustal structure crustal thickness deformation extensional tectonics folding gravimetry Mesozoic Nazca plate slab tectonic plate thrust uplift South America Indicator minor
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00401951_v439_n1-4_p129_Folguera http://hdl.handle.net/20.500.12110/paper_00401951_v439_n1-4_p129_Folguera
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

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spelling	paper:paper_00401951_v439_n1-4_p129_Folguera2023-06-08T15:03:52Z Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly Folguera, Andrés Tunstall, Cynthia Garcia Morabito, Ezequiel Ramos, Victor Alberto Andean gravity Asthenospheric anomalies Retroarc extension Retroarc volcanism Thermal uplift asthenosphere Cenozoic crustal structure crustal thickness deformation extensional tectonics folding gravimetry Mesozoic Nazca plate slab tectonic plate thrust uplift South America Indicator minor The western retroarc of the Southern Andes between 38° and 40° S is formed by a NNW-elongated ridge not associated with stacked thrust sheets. On the contrary, during the last 4-3 Ma this ridge was affected by extensional deformation, regional uplift and related folding on a very broad scale. Receiver function analysis shows that the drainage divide area and adjacent retroarc lie over an attenuated crust. Expected crustal thickness at these latitudes is around 38 km, whereas in this part of the retroarc the thickness is less than 32 km. The causes for such attenuation have been linked to a moderate steepening of the subducted Nazca plate beneath the South American plate, which is suggested by a westward shift and narrowing of the magmatic arc during the last 4 to 5 Ma. Gravimetric studies show that the upper plate did not react homogeneously to slab steepening, but ancient sutures and lithospheric discontinuities deeply buried under Mesozoic to Cenozoic sequences in the retroarc were locally reactivated. These processes resulted in an asthenospheric anomaly that correlates at the surface with the area of Pliocene to Quaternary doming, widespread extension and three radial troughs. Two of the troughs have accommodated substantial amounts of extension, but the third was probably aborted at an early stage. Moreover, the presence of an anomalous concentration of calderas and large volcanic centers over the proposed asthenospheric anomaly, and their age distribution, may indicate minor migration of the asthenospheric anomaly between 4 and 2 Ma through the western South American plate. © 2007 Elsevier B.V. All rights reserved. Fil:Folguera, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Tunstall, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:García Morabito, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ramos, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2007 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00401951_v439_n1-4_p129_Folguera http://hdl.handle.net/20.500.12110/paper_00401951_v439_n1-4_p129_Folguera
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Andean gravity Asthenospheric anomalies Retroarc extension Retroarc volcanism Thermal uplift asthenosphere Cenozoic crustal structure crustal thickness deformation extensional tectonics folding gravimetry Mesozoic Nazca plate slab tectonic plate thrust uplift South America Indicator minor
spellingShingle	Andean gravity Asthenospheric anomalies Retroarc extension Retroarc volcanism Thermal uplift asthenosphere Cenozoic crustal structure crustal thickness deformation extensional tectonics folding gravimetry Mesozoic Nazca plate slab tectonic plate thrust uplift South America Indicator minor Folguera, Andrés Tunstall, Cynthia Garcia Morabito, Ezequiel Ramos, Victor Alberto Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly
topic_facet	Andean gravity Asthenospheric anomalies Retroarc extension Retroarc volcanism Thermal uplift asthenosphere Cenozoic crustal structure crustal thickness deformation extensional tectonics folding gravimetry Mesozoic Nazca plate slab tectonic plate thrust uplift South America Indicator minor
description	The western retroarc of the Southern Andes between 38° and 40° S is formed by a NNW-elongated ridge not associated with stacked thrust sheets. On the contrary, during the last 4-3 Ma this ridge was affected by extensional deformation, regional uplift and related folding on a very broad scale. Receiver function analysis shows that the drainage divide area and adjacent retroarc lie over an attenuated crust. Expected crustal thickness at these latitudes is around 38 km, whereas in this part of the retroarc the thickness is less than 32 km. The causes for such attenuation have been linked to a moderate steepening of the subducted Nazca plate beneath the South American plate, which is suggested by a westward shift and narrowing of the magmatic arc during the last 4 to 5 Ma. Gravimetric studies show that the upper plate did not react homogeneously to slab steepening, but ancient sutures and lithospheric discontinuities deeply buried under Mesozoic to Cenozoic sequences in the retroarc were locally reactivated. These processes resulted in an asthenospheric anomaly that correlates at the surface with the area of Pliocene to Quaternary doming, widespread extension and three radial troughs. Two of the troughs have accommodated substantial amounts of extension, but the third was probably aborted at an early stage. Moreover, the presence of an anomalous concentration of calderas and large volcanic centers over the proposed asthenospheric anomaly, and their age distribution, may indicate minor migration of the asthenospheric anomaly between 4 and 2 Ma through the western South American plate. © 2007 Elsevier B.V. All rights reserved.
author	Folguera, Andrés Tunstall, Cynthia Garcia Morabito, Ezequiel Ramos, Victor Alberto
author_facet	Folguera, Andrés Tunstall, Cynthia Garcia Morabito, Ezequiel Ramos, Victor Alberto
author_sort	Folguera, Andrés
title	Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly
title_short	Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly
title_full	Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly
title_fullStr	Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly
title_full_unstemmed	Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly
title_sort	crustal attenuation in the southern andean retroarc (38°-39°30′ s) determined from tectonic and gravimetric studies: the lonco-luán asthenospheric anomaly
publishDate	2007
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00401951_v439_n1-4_p129_Folguera http://hdl.handle.net/20.500.12110/paper_00401951_v439_n1-4_p129_Folguera
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_version_	1768546059931353088

Crustal attenuation in the Southern Andean retroarc (38°-39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly

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