Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina

A palaeomagnetic study has been carried out on late Palaeozoic rocks exposed in the Sierras Australes thrust and fold belt of Buenos Aires province (Argentina), in the early Permian red sandstones and clay siltstones of the Tunas Formation. The sections sampled are exposed in the eastern parts of th...

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Autores principales: Tomezzoli, R.N., Vilas, J.F.
Formato: JOUR
Materias:
Argentina
Gondwana
Palaeomagnetism
Palaeozoic
Sierras Australes
South America
Tectonics
deformation
fold and thrust belt
geochronology
paleomagnetism
Permian
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_0956540X_v138_n3_p857_Tomezzoli
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_0956540X_v138_n3_p857_Tomezzoli2023-10-03T15:52:03Z Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina Tomezzoli, R.N. Vilas, J.F. Argentina Gondwana Palaeomagnetism Palaeozoic Sierras Australes South America Tectonics deformation fold and thrust belt geochronology Gondwana paleomagnetism Permian Argentina A palaeomagnetic study has been carried out on late Palaeozoic rocks exposed in the Sierras Australes thrust and fold belt of Buenos Aires province (Argentina), in the early Permian red sandstones and clay siltstones of the Tunas Formation. The sections sampled are exposed in the eastern parts of the belt, in Sierra de las Tunas (north) and Sierra de Pillahuinco (south). More than 300 specimens were collected from 25 sites, in three localities with different structural attitudes. Demagnetization at high temperatures isolated a characteristic remanence at 20 sites. All the localities have a reverse characteristic remanence, suggesting that the magnetization was acquired during the Kiaman interval. Stepwise tectonic tilt correction suggests that the Tunas Formation in these localities acquired its magnetization during folding in early Permian times. Palaeomagnetic poles were computed for each locality based on partial tilt-corrected remanence directions. Taking into account the fact that these localities are close to one another and that the rocks are all of reverse polarity, a group syntectonic palaeomagnetic pole called Tunas was calculated: longitude: 13.9°E, latitude: 63.0°S; A95 = 5.4°, K = 39.7, N = 19. This pole is consistent with previously calculated poles from South America assigned to the early Permian. In age it corresponds to the early Permian San Rafaelic tectonic phase of the Sierras Australes. Independent geological evidence indicates that the Tunas Formation underwent syndepositional deformation. We conclude that the Tunas Formation was deposited, deformed and remagnetized, all during the early Permian. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0956540X_v138_n3_p857_Tomezzoli
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Argentina
Gondwana
Palaeomagnetism
Palaeozoic
Sierras Australes
South America
Tectonics
deformation
fold and thrust belt
geochronology
Gondwana
paleomagnetism
Permian
Argentina
spellingShingle Argentina
Gondwana
Palaeomagnetism
Palaeozoic
Sierras Australes
South America
Tectonics
deformation
fold and thrust belt
geochronology
Gondwana
paleomagnetism
Permian
Argentina
Tomezzoli, R.N.
Vilas, J.F.
Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina
topic_facet Argentina
Gondwana
Palaeomagnetism
Palaeozoic
Sierras Australes
South America
Tectonics
deformation
fold and thrust belt
geochronology
Gondwana
paleomagnetism
Permian
Argentina
description A palaeomagnetic study has been carried out on late Palaeozoic rocks exposed in the Sierras Australes thrust and fold belt of Buenos Aires province (Argentina), in the early Permian red sandstones and clay siltstones of the Tunas Formation. The sections sampled are exposed in the eastern parts of the belt, in Sierra de las Tunas (north) and Sierra de Pillahuinco (south). More than 300 specimens were collected from 25 sites, in three localities with different structural attitudes. Demagnetization at high temperatures isolated a characteristic remanence at 20 sites. All the localities have a reverse characteristic remanence, suggesting that the magnetization was acquired during the Kiaman interval. Stepwise tectonic tilt correction suggests that the Tunas Formation in these localities acquired its magnetization during folding in early Permian times. Palaeomagnetic poles were computed for each locality based on partial tilt-corrected remanence directions. Taking into account the fact that these localities are close to one another and that the rocks are all of reverse polarity, a group syntectonic palaeomagnetic pole called Tunas was calculated: longitude: 13.9°E, latitude: 63.0°S; A95 = 5.4°, K = 39.7, N = 19. This pole is consistent with previously calculated poles from South America assigned to the early Permian. In age it corresponds to the early Permian San Rafaelic tectonic phase of the Sierras Australes. Independent geological evidence indicates that the Tunas Formation underwent syndepositional deformation. We conclude that the Tunas Formation was deposited, deformed and remagnetized, all during the early Permian.
format JOUR
author Tomezzoli, R.N.
Vilas, J.F.
author_facet Tomezzoli, R.N.
Vilas, J.F.
author_sort Tomezzoli, R.N.
title Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina
title_short Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina
title_full Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina
title_fullStr Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina
title_full_unstemmed Palaeomagnetic constraints on the age of deformation of the Sierras Australes thrust and fold belt, Argentina
title_sort palaeomagnetic constraints on the age of deformation of the sierras australes thrust and fold belt, argentina
url http://hdl.handle.net/20.500.12110/paper_0956540X_v138_n3_p857_Tomezzoli
work_keys_str_mv AT tomezzolirn palaeomagneticconstraintsontheageofdeformationofthesierrasaustralesthrustandfoldbeltargentina
AT vilasjf palaeomagneticconstraintsontheageofdeformationofthesierrasaustralesthrustandfoldbeltargentina
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