First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?

Time and tectonic processes involved in docking of the Argentine Precordillera. (Cuyania terrane) against SW Gondwana has been a matter of much debate. A paleomagnetic study on the Early Caradoc Pavón Formation, exposed in the San Rafael block, province of Mendoza, Argentina, is presented. After det...

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Autores principales: Rapalini, A.E., Cingolani, C.A.
Formato: JOUR
Materias:
Gondwana
Laurentia
Ordovician
Paleomagnetism
Precordillera
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_1342937X_v7_n4_p1089_Rapalini
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_1342937X_v7_n4_p1089_Rapalini
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spelling todo:paper_1342937X_v7_n4_p1089_Rapalini2023-10-03T16:09:42Z First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau? Rapalini, A.E. Cingolani, C.A. Gondwana Laurentia Ordovician Paleomagnetism Precordillera Time and tectonic processes involved in docking of the Argentine Precordillera. (Cuyania terrane) against SW Gondwana has been a matter of much debate. A paleomagnetic study on the Early Caradoc Pavón Formation, exposed in the San Rafael block, province of Mendoza, Argentina, is presented. After detailed thermal and alternating field demagnetizations two geologically significant magnetic components were defined. A widespread post-tectonic component (A) is present in most sites of the Pavón Formation, with dual polarities, and is coincident with the characteristic remanence isolated from a Permo-Triassic rhyolitic dome intruding the sediments. Its pole position (83.7°S, 271.0°E, dp = 6.8°, dm = 9.0° N = 11 sites) falls on the Late Permian-Early Triassic South American reference poles suggesting that this component was acquired during the Choiyoi magmatic phase. A second component (B) also shows dual polarities and a positive fold test suggesting a primary origin. Unblocking temperatures and rock magnetic experiments indicate that B is carried either by hematite or magnetite at different sites. Anisotropy of magnetic susceptibility results suggest a depositional fabric and no remanence distortion due to deformation or compaction. A paleomagnetic pole computed from this remanence (PV) falls on 3.6°N, 346.4°E (dp = 2.9°, dm = 4.6° n = 22 samples). It indicates a paleolatitude around 26°S for deposition of Pavón sediments and constrains the paleogeographic evolution of Cuyania during the Ordovician, which was still at subtropical latitudes by the Early Caradoc. PV is consistent with the Laurentian Late Ordovician reference pole if Cuyania remains attached to SE Laurentia for the Early Caradoc, while it shows a significant cw rotation with no paleolatitude anomaly respect to the Gondwana reference pole when kept in its present position in SW South America. These comparisons are interpreted in three possible alternatives for the paleogeographic and tectonic setting of Cuyania in the Late Ordovician. © 2004 Inernational Association for Gondwana Research, Japan. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_1342937X_v7_n4_p1089_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
Laurentia
Ordovician
Paleomagnetism
Precordillera
spellingShingle Gondwana
Laurentia
Ordovician
Paleomagnetism
Precordillera
Rapalini, A.E.
Cingolani, C.A.
First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?
topic_facet Gondwana
Laurentia
Ordovician
Paleomagnetism
Precordillera
description Time and tectonic processes involved in docking of the Argentine Precordillera. (Cuyania terrane) against SW Gondwana has been a matter of much debate. A paleomagnetic study on the Early Caradoc Pavón Formation, exposed in the San Rafael block, province of Mendoza, Argentina, is presented. After detailed thermal and alternating field demagnetizations two geologically significant magnetic components were defined. A widespread post-tectonic component (A) is present in most sites of the Pavón Formation, with dual polarities, and is coincident with the characteristic remanence isolated from a Permo-Triassic rhyolitic dome intruding the sediments. Its pole position (83.7°S, 271.0°E, dp = 6.8°, dm = 9.0° N = 11 sites) falls on the Late Permian-Early Triassic South American reference poles suggesting that this component was acquired during the Choiyoi magmatic phase. A second component (B) also shows dual polarities and a positive fold test suggesting a primary origin. Unblocking temperatures and rock magnetic experiments indicate that B is carried either by hematite or magnetite at different sites. Anisotropy of magnetic susceptibility results suggest a depositional fabric and no remanence distortion due to deformation or compaction. A paleomagnetic pole computed from this remanence (PV) falls on 3.6°N, 346.4°E (dp = 2.9°, dm = 4.6° n = 22 samples). It indicates a paleolatitude around 26°S for deposition of Pavón sediments and constrains the paleogeographic evolution of Cuyania during the Ordovician, which was still at subtropical latitudes by the Early Caradoc. PV is consistent with the Laurentian Late Ordovician reference pole if Cuyania remains attached to SE Laurentia for the Early Caradoc, while it shows a significant cw rotation with no paleolatitude anomaly respect to the Gondwana reference pole when kept in its present position in SW South America. These comparisons are interpreted in three possible alternatives for the paleogeographic and tectonic setting of Cuyania in the Late Ordovician. © 2004 Inernational Association for Gondwana Research, Japan.
format JOUR
author Rapalini, A.E.
Cingolani, C.A.
author_facet Rapalini, A.E.
Cingolani, C.A.
author_sort Rapalini, A.E.
title First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?
title_short First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?
title_full First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?
title_fullStr First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?
title_full_unstemmed First late Ordovician paleomagnetic pole for the Cuyania (Precordillera) terrane of western Argentina: A microcontinent or a Laurentian plateau?
title_sort first late ordovician paleomagnetic pole for the cuyania (precordillera) terrane of western argentina: a microcontinent or a laurentian plateau?
url http://hdl.handle.net/20.500.12110/paper_1342937X_v7_n4_p1089_Rapalini
work_keys_str_mv AT rapaliniae firstlateordovicianpaleomagneticpoleforthecuyaniaprecordilleraterraneofwesternargentinaamicrocontinentoralaurentianplateau
AT cingolanica firstlateordovicianpaleomagneticpoleforthecuyaniaprecordilleraterraneofwesternargentinaamicrocontinentoralaurentianplateau
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