Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength

We report a detailed rock magnetic and Thellier paleointensity study from 130.5 Ma Ponta Grossa Dike Swarms in Southern Brazil. Twenty-nine samples from seven cooling units were pre-selected for paleointensity experiments based on their low viscosity index, stable remanent magnetization and close to...

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Detalles Bibliográficos
Autores: R. Cejudo Ruiz, A. Goguitchaichvili, J. Morales, R. I. F. Trindade, L. M. Alva Valdivia, J. Urrutia-Fucugauchi
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2009
País:México
Institución:Universidad Nacional Autónoma de México
Repositorio:Redalyc-UNAM
OAI Identifier:oai:redalyc.org:56813223007
Acceso en línea:https://www.redalyc.org/articulo.oa?id=56813223007
Access Level:acceso abierto
Palabra clave:Ciencias de la Tierra
Brazil
Paraná basin
paleointensity
rock magnetism
Early Cretaceous
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spelling Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strengthR. Cejudo RuizA. GoguitchaichviliJ. MoralesR. I. F. TrindadeL. M. Alva ValdiviaJ. Urrutia-FucugauchiCiencias de la TierraBrazilParaná basinpaleointensityrock magnetismEarly CretaceousWe report a detailed rock magnetic and Thellier paleointensity study from 130.5 Ma Ponta Grossa Dike Swarms in Southern Brazil. Twenty-nine samples from seven cooling units were pre-selected for paleointensity experiments based on their low viscosity index, stable remanent magnetization and close to reversible continuous thermomagnetic curves. 19 samples characterized by negative pTRM tests, Arai concave-up curves or positive pTRM tests with NRM loss uncorrelated with TRM acquisition were rejected. High quality reliable paleointensity determinations are determined from detailed evaluation criteria, with 10 samples belonging to three dikes passing the tests. The site-mean paleointensity values obtained in this study range from 25.6 ± 4.3 to 11.3 ± 2.1 uT and the corresponding VDMs range from 5.7 ± 0.9 to 2.5 ± 0.5 (10(22) Am2). These data yield a VDM mean value of 4.1 ± 1.6 x 10(22) Am2. Significant variability of Earths magnetic field strength is observed for Ponta Grossa Dikes with the mean value being significantly lower as compared to the mean VDM obtained from the nearby Paraná Magmatic Province. The paleointensities for the Ponta Grossa Dikes are in agreement with absolute paleointensities retrieved from the submarine basaltic glasses from 130 to 120 Ma. It seems that a relatively low field prevailed just before the Cretaceous Normal Superchron.Universidad Nacional Autónoma de México2009info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdf0016-7169https://www.redalyc.org/articulo.oa?id=56813223007Geofísica Internacional (México) Num.2 Vol.48reponame:Redalyc-UNAMinstname:Universidad Nacional Autónoma de Méxicoinstacron:UNAMenhttp://www.redalyc.org/revista.oa?id=568Geofísica Internacionalinfo:eu-repo/semantics/openAccessoai:redalyc.org:568132230072025-09-03T18:06:23Z
dc.title.none.fl_str_mv Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
title Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
spellingShingle Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
R. Cejudo Ruiz
Ciencias de la Tierra
Brazil
Paraná basin
paleointensity
rock magnetism
Early Cretaceous
title_short Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
title_full Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
title_fullStr Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
title_full_unstemmed Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
title_sort Absolute Thellier paleointensities from Ponta Grossa dikes (southern Brazil) and the early Cretaceous geomagnetic field strength
dc.creator.none.fl_str_mv R. Cejudo Ruiz
A. Goguitchaichvili
J. Morales
R. I. F. Trindade
L. M. Alva Valdivia
J. Urrutia-Fucugauchi
author R. Cejudo Ruiz
author_facet R. Cejudo Ruiz
A. Goguitchaichvili
J. Morales
R. I. F. Trindade
L. M. Alva Valdivia
J. Urrutia-Fucugauchi
author_role author
author2 A. Goguitchaichvili
J. Morales
R. I. F. Trindade
L. M. Alva Valdivia
J. Urrutia-Fucugauchi
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv Ciencias de la Tierra
Brazil
Paraná basin
paleointensity
rock magnetism
Early Cretaceous
topic Ciencias de la Tierra
Brazil
Paraná basin
paleointensity
rock magnetism
Early Cretaceous
description We report a detailed rock magnetic and Thellier paleointensity study from 130.5 Ma Ponta Grossa Dike Swarms in Southern Brazil. Twenty-nine samples from seven cooling units were pre-selected for paleointensity experiments based on their low viscosity index, stable remanent magnetization and close to reversible continuous thermomagnetic curves. 19 samples characterized by negative pTRM tests, Arai concave-up curves or positive pTRM tests with NRM loss uncorrelated with TRM acquisition were rejected. High quality reliable paleointensity determinations are determined from detailed evaluation criteria, with 10 samples belonging to three dikes passing the tests. The site-mean paleointensity values obtained in this study range from 25.6 ± 4.3 to 11.3 ± 2.1 uT and the corresponding VDMs range from 5.7 ± 0.9 to 2.5 ± 0.5 (10(22) Am2). These data yield a VDM mean value of 4.1 ± 1.6 x 10(22) Am2. Significant variability of Earths magnetic field strength is observed for Ponta Grossa Dikes with the mean value being significantly lower as compared to the mean VDM obtained from the nearby Paraná Magmatic Province. The paleointensities for the Ponta Grossa Dikes are in agreement with absolute paleointensities retrieved from the submarine basaltic glasses from 130 to 120 Ma. It seems that a relatively low field prevailed just before the Cretaceous Normal Superchron.
publishDate 2009
dc.date.none.fl_str_mv 2009
dc.type.none.fl_str_mv info:eu-repo/semantics/publishedVersion
info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv 0016-7169
https://www.redalyc.org/articulo.oa?id=56813223007
identifier_str_mv 0016-7169
url https://www.redalyc.org/articulo.oa?id=56813223007
dc.language.none.fl_str_mv en
language_invalid_str_mv en
dc.relation.none.fl_str_mv http://www.redalyc.org/revista.oa?id=568
dc.rights.none.fl_str_mv Geofísica Internacional
info:eu-repo/semantics/openAccess
rights_invalid_str_mv Geofísica Internacional
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Universidad Nacional Autónoma de México
publisher.none.fl_str_mv Universidad Nacional Autónoma de México
dc.source.none.fl_str_mv Geofísica Internacional (México) Num.2 Vol.48
reponame:Redalyc-UNAM
instname:Universidad Nacional Autónoma de México
instacron:UNAM
instname_str Universidad Nacional Autónoma de México
instacron_str UNAM
institution UNAM
reponame_str Redalyc-UNAM
collection Redalyc-UNAM
repository.name.fl_str_mv
repository.mail.fl_str_mv
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