Variable structural controls through time in the Southern Central Andes (~36°S)

The Southern Central Andes at 36°S have been recognized as an orogenic belt where contraction, accommodated mainly by basement structures, is associated with the inversion of a Late Triassic-Early Jurassic extensional detachment. Based on a structural cross-section, constrained by field data, 2D sei...

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Autores principales:	Orts,Darío L, Folguera,Andrés, Giménez,Mario, Ramos,Víctor A
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2012
Materias:	Central Andes Malargüe fold and thrust belt Tectonic inversion Brittle-ductile transitions Orogenic front Foreland basin Argentina
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062012000200002
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spelling	oai:scielo:S0718-710620120002000022012-07-11Variable structural controls through time in the Southern Central Andes (~36°S)Orts,Darío LFolguera,AndrésGiménez,MarioRamos,Víctor A Central Andes Malargüe fold and thrust belt Tectonic inversion Brittle-ductile transitions Orogenic front Foreland basin Argentina The Southern Central Andes at 36°S have been recognized as an orogenic belt where contraction, accommodated mainly by basement structures, is associated with the inversion of a Late Triassic-Early Jurassic extensional detachment. Based on a structural cross-section, constrained by field data, 2D seismic and bore-hole information, and the processing of Bouger anomalies, we propose a polyphasic tectonic evolution. In the westernmost sector, along the axis of the Cordillera, NW to NNW basement structures were inverted, being a first order control in the generation of frontal narrow N-trending thin-skinned belts. This slip transfer is controlled by the Late Jurassic main detachment. These structures have low gravity anomalies that cross obliquely the main Andean trend. East of this inversion domain, beneath the frontal thin-skinned belts, seismic information reveals that Late Triassic wedge-like depocenters did not experience substantial inversion. To the east double-vergent basement blocks define the Andean emergent orogenic front at these latitudes. These contractional structures truncate gravity anomalies defined by basement discontinuities, indicating that they are not related to tectonic inversion, in contraposition to the westernmost domain. Two contractional phases were distinguished. The oldest is Late Cretaceous in age, as inferred from onlap relations in Upper Cretaceous strata identified in seismic lines. These successions have a maximum age of 97 Ma as inferred by U-Pb in detrital zircons published in previous studies in the area. Contrastingly, the easternmost sector was mainly deformed in Late Miocene times as inferred from less than 18 Ma old synorogenic deposits. Moreover, contractional mechanisms varied through time for each specific sector. While Late Cretaceous contractional tectonics was generated by tectonic inversion and subordinate thin-skinned deformation, it is proposed that Late Miocene deformation was controlled mainly by brittle-ductile transitions at the upper crust with no major influence of previous structures. This fact can be explained by a higher thermal flux achieved in the retroarc area in the last 17 Ma due to the eastward arc expansion during a shallow subduction regime.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.39 n.2 20122012-05-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062012000200002en
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Central Andes Malargüe fold and thrust belt Tectonic inversion Brittle-ductile transitions Orogenic front Foreland basin Argentina
spellingShingle	Central Andes Malargüe fold and thrust belt Tectonic inversion Brittle-ductile transitions Orogenic front Foreland basin Argentina Orts,Darío L Folguera,Andrés Giménez,Mario Ramos,Víctor A Variable structural controls through time in the Southern Central Andes (~36°S)
description	The Southern Central Andes at 36°S have been recognized as an orogenic belt where contraction, accommodated mainly by basement structures, is associated with the inversion of a Late Triassic-Early Jurassic extensional detachment. Based on a structural cross-section, constrained by field data, 2D seismic and bore-hole information, and the processing of Bouger anomalies, we propose a polyphasic tectonic evolution. In the westernmost sector, along the axis of the Cordillera, NW to NNW basement structures were inverted, being a first order control in the generation of frontal narrow N-trending thin-skinned belts. This slip transfer is controlled by the Late Jurassic main detachment. These structures have low gravity anomalies that cross obliquely the main Andean trend. East of this inversion domain, beneath the frontal thin-skinned belts, seismic information reveals that Late Triassic wedge-like depocenters did not experience substantial inversion. To the east double-vergent basement blocks define the Andean emergent orogenic front at these latitudes. These contractional structures truncate gravity anomalies defined by basement discontinuities, indicating that they are not related to tectonic inversion, in contraposition to the westernmost domain. Two contractional phases were distinguished. The oldest is Late Cretaceous in age, as inferred from onlap relations in Upper Cretaceous strata identified in seismic lines. These successions have a maximum age of 97 Ma as inferred by U-Pb in detrital zircons published in previous studies in the area. Contrastingly, the easternmost sector was mainly deformed in Late Miocene times as inferred from less than 18 Ma old synorogenic deposits. Moreover, contractional mechanisms varied through time for each specific sector. While Late Cretaceous contractional tectonics was generated by tectonic inversion and subordinate thin-skinned deformation, it is proposed that Late Miocene deformation was controlled mainly by brittle-ductile transitions at the upper crust with no major influence of previous structures. This fact can be explained by a higher thermal flux achieved in the retroarc area in the last 17 Ma due to the eastward arc expansion during a shallow subduction regime.
author	Orts,Darío L Folguera,Andrés Giménez,Mario Ramos,Víctor A
author_facet	Orts,Darío L Folguera,Andrés Giménez,Mario Ramos,Víctor A
author_sort	Orts,Darío L
title	Variable structural controls through time in the Southern Central Andes (~36°S)
title_short	Variable structural controls through time in the Southern Central Andes (~36°S)
title_full	Variable structural controls through time in the Southern Central Andes (~36°S)
title_fullStr	Variable structural controls through time in the Southern Central Andes (~36°S)
title_full_unstemmed	Variable structural controls through time in the Southern Central Andes (~36°S)
title_sort	variable structural controls through time in the southern central andes (~36°s)
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2012
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062012000200002
work_keys_str_mv	AT ortsdariol variablestructuralcontrolsthroughtimeinthesoutherncentralandes36s AT folgueraandres variablestructuralcontrolsthroughtimeinthesoutherncentralandes36s AT gimenezmario variablestructuralcontrolsthroughtimeinthesoutherncentralandes36s AT ramosvictora variablestructuralcontrolsthroughtimeinthesoutherncentralandes36s
_version_	1714205835084693504

Variable structural controls through time in the Southern Central Andes (~36°S)

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