Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina

Jurassic volcanism in Patagonia is widespread. Although associated dyke swarms are conspicuous, they have been almost neglected in previous geologic studies of this region. Radiometric, paleomagnetic and magnetic anisotropy studies are reported from a Middle Jurassic basic to intermediate dyke swarm...

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Detalles Bibliográficos
Autores principales: Rapalini, A.E., Lopez De Luchi, M.
Formato: JOUR
Materias:
Dyke swarms
Jurassic
Magnetic fabric
Paleomagnetism
Patagonia
South America
dike
magnetic fabric
paleomagnetism
volcanism
Argentina
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00319201_v120_n1_p11_Rapalini
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00319201_v120_n1_p11_Rapalini2023-10-03T14:43:26Z Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina Rapalini, A.E. Lopez De Luchi, M. Dyke swarms Jurassic Magnetic fabric Paleomagnetism Patagonia South America dike Jurassic magnetic fabric paleomagnetism volcanism Argentina Jurassic volcanism in Patagonia is widespread. Although associated dyke swarms are conspicuous, they have been almost neglected in previous geologic studies of this region. Radiometric, paleomagnetic and magnetic anisotropy studies are reported from a Middle Jurassic basic to intermediate dyke swarm exposed in the Sierra de Mamil Choique (Western Patagonia) in an area of over 350 km2. Two whole-rock K/Ar determinations indicate that these dykes were intruded at around 170 Ma. An anisotropy of magnetic susceptibility (AMS) study on 15 dykes (74 block samples) shows that they carry different kinds of magnetic fabric (both normal and inverse), apparently governed by compositional differences. A paleomagnetic study of these samples suggests that Ti-poor titanomagnetite is the probable carrier to the characteristic remanence. Mean site characteristic directions pass a reversal test (grade C). A paleomagnetic pole, computed by averaging VGPs from each individual dyke, is situated at 70.2°S, 190.4°E (N = 13, α95 = 9.7°), not substantially apart from other Middle Jurassic poles from South America. Further refinement of the Jurassic South American apparent polar wander path is needed to establish whether or not the Mamil Choique dykes were affected by a small tectonic rotation. (C) 2000 Elsevier Science B.V. All rights reserved. Fil:Rapalini, A.E. 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_00319201_v120_n1_p11_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 Dyke swarms
Jurassic
Magnetic fabric
Paleomagnetism
Patagonia
South America
dike
Jurassic
magnetic fabric
paleomagnetism
volcanism
Argentina
spellingShingle Dyke swarms
Jurassic
Magnetic fabric
Paleomagnetism
Patagonia
South America
dike
Jurassic
magnetic fabric
paleomagnetism
volcanism
Argentina
Rapalini, A.E.
Lopez De Luchi, M.
Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina
topic_facet Dyke swarms
Jurassic
Magnetic fabric
Paleomagnetism
Patagonia
South America
dike
Jurassic
magnetic fabric
paleomagnetism
volcanism
Argentina
description Jurassic volcanism in Patagonia is widespread. Although associated dyke swarms are conspicuous, they have been almost neglected in previous geologic studies of this region. Radiometric, paleomagnetic and magnetic anisotropy studies are reported from a Middle Jurassic basic to intermediate dyke swarm exposed in the Sierra de Mamil Choique (Western Patagonia) in an area of over 350 km2. Two whole-rock K/Ar determinations indicate that these dykes were intruded at around 170 Ma. An anisotropy of magnetic susceptibility (AMS) study on 15 dykes (74 block samples) shows that they carry different kinds of magnetic fabric (both normal and inverse), apparently governed by compositional differences. A paleomagnetic study of these samples suggests that Ti-poor titanomagnetite is the probable carrier to the characteristic remanence. Mean site characteristic directions pass a reversal test (grade C). A paleomagnetic pole, computed by averaging VGPs from each individual dyke, is situated at 70.2°S, 190.4°E (N = 13, α95 = 9.7°), not substantially apart from other Middle Jurassic poles from South America. Further refinement of the Jurassic South American apparent polar wander path is needed to establish whether or not the Mamil Choique dykes were affected by a small tectonic rotation. (C) 2000 Elsevier Science B.V. All rights reserved.
format JOUR
author Rapalini, A.E.
Lopez De Luchi, M.
author_facet Rapalini, A.E.
Lopez De Luchi, M.
author_sort Rapalini, A.E.
title Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina
title_short Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina
title_full Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina
title_fullStr Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina
title_full_unstemmed Paleomagnetism and magnetic fabric of Middle Jurassic dykes from Western Patagonia, Argentina
title_sort paleomagnetism and magnetic fabric of middle jurassic dykes from western patagonia, argentina
url http://hdl.handle.net/20.500.12110/paper_00319201_v120_n1_p11_Rapalini
work_keys_str_mv AT rapaliniae paleomagnetismandmagneticfabricofmiddlejurassicdykesfromwesternpatagoniaargentina
AT lopezdeluchim paleomagnetismandmagneticfabricofmiddlejurassicdykesfromwesternpatagoniaargentina
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