Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America

The Paleozoic evolution of southwestern Gondwana apparently involved the accretion of several large suspect terranes at different times and under different tectonic circumstances. The recent acquisition of paleomagnetic data from Paleozoic rocks of this region, albeit still scarce, permit establishm...

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Autores principales: Rapalini, Augusto Ernesto, Conti, Carlos Manuel
Publicado: 1999
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00721077_v336_n_p171_Rapalini
http://hdl.handle.net/20.500.12110/paper_00721077_v336_n_p171_Rapalini
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_00721077_v336_n_p171_Rapalini2025-07-30T17:46:52Z Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America Rapalini, Augusto Ernesto Conti, Carlos Manuel The Paleozoic evolution of southwestern Gondwana apparently involved the accretion of several large suspect terranes at different times and under different tectonic circumstances. The recent acquisition of paleomagnetic data from Paleozoic rocks of this region, albeit still scarce, permit establishment of some constrains on the tectonic and paleogeographic evolution of some of these terranes. A reliable paleomagnetic pole from the Early Cambrian Cerro Totora Formation in northern Precordillera confirms that the Argentine Precordillera is an exotic terrane that was part of or adjacent to Laurentia, very likely at the Ouachita Embayment, in the Early Cambrian. Paleomagnetic poles from an Early Ordovician magmatic belt in northwest Argentina permit the identification of a peri-Gondwanic-rotated terrane, called the Eastern Puna-Famatina terrane, with volcanic arc affinities. Early Paleozoic paleomagnetic poles from the Western Puna (Sierra de Almeida, Chile) were previously interpreted as evidence of a para-autochthonous nature of the Arequipa-Antofalla Massif that rotated successively clockwise and counterclockwise. New preliminary paleomagnetic data in the same region (Salar del Rincón, Argentina) are not easily reconciled with the previous data, unless a Late Ordovician pre-tectonic remagnetization is assumed for the latter. The paleomagnetic and geologic data permit an alternate interpretation based on the fact that the Arequipa and Antofalla blocks can be considered as different terranes. In this case the paleomagnetic data obtained so far is representative of the Antofalla block alone and suggests at least 1,000-km latitudinal displacement of this block with respect to its present position in the South American margin since the Late Cambrian-Early Ordovician. Accretion of this terrane to the Gondwana margin must have occurred in latest Ordovician. Paleozoic paleomagnetic poles from Patagonia indicate that this terrane shares a common apparent polar wander path (APWP) with Gondwana since the Early Devonian. This suggests that no significant movement occurred between these two crustal blocks since that time. Many questions regarding the complex tectonic evolution of southwestern South America that can potentially be addressed by paleomagnetism remain unanswered. Fil:Rapalini, A.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Conti, C.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1999 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00721077_v336_n_p171_Rapalini http://hdl.handle.net/20.500.12110/paper_00721077_v336_n_p171_Rapalini
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description The Paleozoic evolution of southwestern Gondwana apparently involved the accretion of several large suspect terranes at different times and under different tectonic circumstances. The recent acquisition of paleomagnetic data from Paleozoic rocks of this region, albeit still scarce, permit establishment of some constrains on the tectonic and paleogeographic evolution of some of these terranes. A reliable paleomagnetic pole from the Early Cambrian Cerro Totora Formation in northern Precordillera confirms that the Argentine Precordillera is an exotic terrane that was part of or adjacent to Laurentia, very likely at the Ouachita Embayment, in the Early Cambrian. Paleomagnetic poles from an Early Ordovician magmatic belt in northwest Argentina permit the identification of a peri-Gondwanic-rotated terrane, called the Eastern Puna-Famatina terrane, with volcanic arc affinities. Early Paleozoic paleomagnetic poles from the Western Puna (Sierra de Almeida, Chile) were previously interpreted as evidence of a para-autochthonous nature of the Arequipa-Antofalla Massif that rotated successively clockwise and counterclockwise. New preliminary paleomagnetic data in the same region (Salar del Rincón, Argentina) are not easily reconciled with the previous data, unless a Late Ordovician pre-tectonic remagnetization is assumed for the latter. The paleomagnetic and geologic data permit an alternate interpretation based on the fact that the Arequipa and Antofalla blocks can be considered as different terranes. In this case the paleomagnetic data obtained so far is representative of the Antofalla block alone and suggests at least 1,000-km latitudinal displacement of this block with respect to its present position in the South American margin since the Late Cambrian-Early Ordovician. Accretion of this terrane to the Gondwana margin must have occurred in latest Ordovician. Paleozoic paleomagnetic poles from Patagonia indicate that this terrane shares a common apparent polar wander path (APWP) with Gondwana since the Early Devonian. This suggests that no significant movement occurred between these two crustal blocks since that time. Many questions regarding the complex tectonic evolution of southwestern South America that can potentially be addressed by paleomagnetism remain unanswered.
author Rapalini, Augusto Ernesto
Conti, Carlos Manuel
spellingShingle Rapalini, Augusto Ernesto
Conti, Carlos Manuel
Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America
author_facet Rapalini, Augusto Ernesto
Conti, Carlos Manuel
author_sort Rapalini, Augusto Ernesto
title Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America
title_short Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America
title_full Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America
title_fullStr Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America
title_full_unstemmed Paleomagnetic constraints on the evolution of Paleozoic suspect terranes from southern South America
title_sort paleomagnetic constraints on the evolution of paleozoic suspect terranes from southern south america
publishDate 1999
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00721077_v336_n_p171_Rapalini
http://hdl.handle.net/20.500.12110/paper_00721077_v336_n_p171_Rapalini
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AT conticarlosmanuel paleomagneticconstraintsontheevolutionofpaleozoicsuspectterranesfromsouthernsouthamerica
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