Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism

Detailed palaeomagnetic studies of Late Palaeozoic rocks exposed in the Uspallata‐Calingasta Valley region, located at about 32d̀S 69.5d̀W in the Argentine Andean Chain, have been recently accomplished. Previous results are discussed in Valencio & Vilas (1985) and Rapalini et al. (1989). The...

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Autores principales: Rapalini, A.E., Vilas, J.F.
Formato: JOUR
Materias:
Gondwana
Late Palaeozoic
oblique subduction
palaeomagnetism
Southern Andes
tectonic rotations
Carboniferous
Permian
tectonic rotation
Argentina, San Juan
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_0956540X_v107_n2_p333_Rapalini
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_0956540X_v107_n2_p333_Rapalini2023-10-03T15:52:01Z Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism Rapalini, A.E. Vilas, J.F. Gondwana Late Palaeozoic oblique subduction palaeomagnetism Southern Andes tectonic rotations Carboniferous Gondwana oblique subduction palaeomagnetism Permian tectonic rotation Argentina, San Juan Detailed palaeomagnetic studies of Late Palaeozoic rocks exposed in the Uspallata‐Calingasta Valley region, located at about 32d̀S 69.5d̀W in the Argentine Andean Chain, have been recently accomplished. Previous results are discussed in Valencio & Vilas (1985) and Rapalini et al. (1989). The most recent studies were carried out mainly on the thick sequences of late Early Permian to Late Permian rhyolites and ignimbrites assigned to the Tambillos and Horcajo Formations. Both formations yielded palaeomagnetic pole positions (P15: 319.6d̀E, 78.9d̀S, N= 16, k= 33.5, A95= 6.5d̀ and P17: 264.8d̀E, 72.4d̀S, N= 26, k= 6.4, A95= 12d̀, respectively) concordant with the Late Palaeozoic path of South America. Preliminary palaeomagnetic results from the Middle Carboniferous Hoyada Verde Formation, exposed in the same region, suggest that these rocks carry a synfolding magnetization acquired during the Late Carboniferous, as the palaeomagnetic pole position computed from partially corrected remanence directions (C6: 356.2d̀E, 41.9d̀S, D1 = 8.3d̀, D2 = 6.0d̀) agrees with the Late Carboniferous poles from cratonic areas of South America. This concordant position of C6 definitely rules out the possibility of a Late Palaeozoic allochthony of this section of the Argentine Andean Chain. The discordant positions previously found in Late Carboniferous and early Early Permian rocks of this region are interpreted as caused by large clockwise crustal block rotations that occurred not later than the late Early Permian. A tectonic model is proposed to explain these rotations which suggests that they were associated with strike‐slip displacements parallel to the western continental margin of South America caused by an oblique subduction of the Proto‐Pacific Plate during the Early Permian. Many tectonic and geologic observations fit this model. The concordant position of C6 also suggests that a complex pattern of crustal block rotations should have developed in this continental margin. Other palaeomagnetic data suggest that similar rotations may have taken place in other areas of the Argentine Andean Chain in the Early Permian. Copyright © 1991, Wiley Blackwell. All rights reserved Fil:Rapalini, A.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Vilas, J.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0956540X_v107_n2_p333_Rapalini
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Gondwana
Late Palaeozoic
oblique subduction
palaeomagnetism
Southern Andes
tectonic rotations
Carboniferous
Gondwana
oblique subduction
palaeomagnetism
Permian
tectonic rotation
Argentina, San Juan
spellingShingle Gondwana
Late Palaeozoic
oblique subduction
palaeomagnetism
Southern Andes
tectonic rotations
Carboniferous
Gondwana
oblique subduction
palaeomagnetism
Permian
tectonic rotation
Argentina, San Juan
Rapalini, A.E.
Vilas, J.F.
Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism
topic_facet Gondwana
Late Palaeozoic
oblique subduction
palaeomagnetism
Southern Andes
tectonic rotations
Carboniferous
Gondwana
oblique subduction
palaeomagnetism
Permian
tectonic rotation
Argentina, San Juan
description Detailed palaeomagnetic studies of Late Palaeozoic rocks exposed in the Uspallata‐Calingasta Valley region, located at about 32d̀S 69.5d̀W in the Argentine Andean Chain, have been recently accomplished. Previous results are discussed in Valencio & Vilas (1985) and Rapalini et al. (1989). The most recent studies were carried out mainly on the thick sequences of late Early Permian to Late Permian rhyolites and ignimbrites assigned to the Tambillos and Horcajo Formations. Both formations yielded palaeomagnetic pole positions (P15: 319.6d̀E, 78.9d̀S, N= 16, k= 33.5, A95= 6.5d̀ and P17: 264.8d̀E, 72.4d̀S, N= 26, k= 6.4, A95= 12d̀, respectively) concordant with the Late Palaeozoic path of South America. Preliminary palaeomagnetic results from the Middle Carboniferous Hoyada Verde Formation, exposed in the same region, suggest that these rocks carry a synfolding magnetization acquired during the Late Carboniferous, as the palaeomagnetic pole position computed from partially corrected remanence directions (C6: 356.2d̀E, 41.9d̀S, D1 = 8.3d̀, D2 = 6.0d̀) agrees with the Late Carboniferous poles from cratonic areas of South America. This concordant position of C6 definitely rules out the possibility of a Late Palaeozoic allochthony of this section of the Argentine Andean Chain. The discordant positions previously found in Late Carboniferous and early Early Permian rocks of this region are interpreted as caused by large clockwise crustal block rotations that occurred not later than the late Early Permian. A tectonic model is proposed to explain these rotations which suggests that they were associated with strike‐slip displacements parallel to the western continental margin of South America caused by an oblique subduction of the Proto‐Pacific Plate during the Early Permian. Many tectonic and geologic observations fit this model. The concordant position of C6 also suggests that a complex pattern of crustal block rotations should have developed in this continental margin. Other palaeomagnetic data suggest that similar rotations may have taken place in other areas of the Argentine Andean Chain in the Early Permian. Copyright © 1991, Wiley Blackwell. All rights reserved
format JOUR
author Rapalini, A.E.
Vilas, J.F.
author_facet Rapalini, A.E.
Vilas, J.F.
author_sort Rapalini, A.E.
title Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism
title_short Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism
title_full Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism
title_fullStr Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism
title_full_unstemmed Tectonic rotations in the Late Palaeozoic continental margin of southern South America determined and dated by palaeomagnetism
title_sort tectonic rotations in the late palaeozoic continental margin of southern south america determined and dated by palaeomagnetism
url http://hdl.handle.net/20.500.12110/paper_0956540X_v107_n2_p333_Rapalini
work_keys_str_mv AT rapaliniae tectonicrotationsinthelatepalaeozoiccontinentalmarginofsouthernsouthamericadeterminedanddatedbypalaeomagnetism
AT vilasjf tectonicrotationsinthelatepalaeozoiccontinentalmarginofsouthernsouthamericadeterminedanddatedbypalaeomagnetism
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