Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)

The Early Cretaceous may be considered a key period for understanding the evolution of the Earth's magnetic field. Some still unsolved problems are related to the mode of paleosecular variation (PSV) of the Earth's magnetic field before and during the Cretaceous Normal Superchron. We repor...

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Detalles Bibliográficos
Autores principales: Mena, M., Goguitchaichvili, A., Solano, M.C., Vilas, J.F.
Formato: JOUR
Materias:
Argentina
Early Cretaceous
paleomagnetic poles
paleosecular variation
Paraná Magmatic Province
Posadas Formation
Cretaceous
geomagnetic field
magnetic intensity
magnetic reversal
paleolatitude
paleomagnetism
secular variation
thermoremanent magnetization
virtual geomagnetic pole
Misiones [Argentina]
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00393169_v55_n2_p279_Mena
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00393169_v55_n2_p279_Mena
record_format dspace
spelling todo:paper_00393169_v55_n2_p279_Mena2023-10-03T14:49:37Z Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina) Mena, M. Goguitchaichvili, A. Solano, M.C. Vilas, J.F. Argentina Early Cretaceous paleomagnetic poles paleosecular variation Paraná Magmatic Province Posadas Formation Cretaceous geomagnetic field magnetic intensity magnetic reversal paleolatitude paleomagnetism secular variation thermoremanent magnetization virtual geomagnetic pole Argentina Misiones [Argentina] The Early Cretaceous may be considered a key period for understanding the evolution of the Earth's magnetic field. Some still unsolved problems are related to the mode of paleosecular variation (PSV) of the Earth's magnetic field before and during the Cretaceous Normal Superchron. We report here a detailed rock-magnetic, paleomagnetic and paleointensity investigation from 28 lava flows (331 standard paleomagnetic cores) collected in the Argentinean part of the Parana Flood Basalts (Formation Posadas) in order to contribute to the study of PSV during the early Cretaceous and to obtain precise Cretaceous paleomagnetic pole positions for stable South America. The average paleofield direction is precisely determined from 26 sites, which show small within-site dispersion and high directional stability. Five sites show evidences for the self-reversal of thermoremanent magnetization. 23 sites yielded normal polarity magnetization and only 3 are reversely magnetized. Moving windows averages were used to analyze the sequential variation of virtual geomagnetic pole's (VGP) axial positions. Interestingly, the axial average VGP path traces an almost complete cycle around the geographical pole and passes near the location of all previously published Paraná Magmatic Province poles. Both paleomagnetic poles and average VGP paths are significantly different from the pole position suggested by fixed hotspot reconstructions, which may be due to true polar wander or the hotspot motion itself. Only 15 samples from 5 individual basaltic lava flows, yielded acceptable paleointensity estimates. The site mean paleointensities range from 25.2 ± 2.2 to 44.0 ± 2.2 μT. The virtual dipole moments (VDMs) range from 4.8 to 9.9 × 1022 Am2. This correspond to a mean value of 7.7 ± 2.1 × 1022 Am2 which is 96% of the present day geomagnetic field strength. These intensities agree with the relatively high values already reported for Early Cretaceous, which are consistent with some inferences from computer simulations previously published. © 2011 Institute of Geophysics of the ASCR, v.v.i. Fil:Mena, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Vilas, J.F. 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_00393169_v55_n2_p279_Mena
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
Early Cretaceous
paleomagnetic poles
paleosecular variation
Paraná Magmatic Province
Posadas Formation
Cretaceous
geomagnetic field
magnetic intensity
magnetic reversal
paleolatitude
paleomagnetism
secular variation
thermoremanent magnetization
virtual geomagnetic pole
Argentina
Misiones [Argentina]
spellingShingle Argentina
Early Cretaceous
paleomagnetic poles
paleosecular variation
Paraná Magmatic Province
Posadas Formation
Cretaceous
geomagnetic field
magnetic intensity
magnetic reversal
paleolatitude
paleomagnetism
secular variation
thermoremanent magnetization
virtual geomagnetic pole
Argentina
Misiones [Argentina]
Mena, M.
Goguitchaichvili, A.
Solano, M.C.
Vilas, J.F.
Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)
topic_facet Argentina
Early Cretaceous
paleomagnetic poles
paleosecular variation
Paraná Magmatic Province
Posadas Formation
Cretaceous
geomagnetic field
magnetic intensity
magnetic reversal
paleolatitude
paleomagnetism
secular variation
thermoremanent magnetization
virtual geomagnetic pole
Argentina
Misiones [Argentina]
description The Early Cretaceous may be considered a key period for understanding the evolution of the Earth's magnetic field. Some still unsolved problems are related to the mode of paleosecular variation (PSV) of the Earth's magnetic field before and during the Cretaceous Normal Superchron. We report here a detailed rock-magnetic, paleomagnetic and paleointensity investigation from 28 lava flows (331 standard paleomagnetic cores) collected in the Argentinean part of the Parana Flood Basalts (Formation Posadas) in order to contribute to the study of PSV during the early Cretaceous and to obtain precise Cretaceous paleomagnetic pole positions for stable South America. The average paleofield direction is precisely determined from 26 sites, which show small within-site dispersion and high directional stability. Five sites show evidences for the self-reversal of thermoremanent magnetization. 23 sites yielded normal polarity magnetization and only 3 are reversely magnetized. Moving windows averages were used to analyze the sequential variation of virtual geomagnetic pole's (VGP) axial positions. Interestingly, the axial average VGP path traces an almost complete cycle around the geographical pole and passes near the location of all previously published Paraná Magmatic Province poles. Both paleomagnetic poles and average VGP paths are significantly different from the pole position suggested by fixed hotspot reconstructions, which may be due to true polar wander or the hotspot motion itself. Only 15 samples from 5 individual basaltic lava flows, yielded acceptable paleointensity estimates. The site mean paleointensities range from 25.2 ± 2.2 to 44.0 ± 2.2 μT. The virtual dipole moments (VDMs) range from 4.8 to 9.9 × 1022 Am2. This correspond to a mean value of 7.7 ± 2.1 × 1022 Am2 which is 96% of the present day geomagnetic field strength. These intensities agree with the relatively high values already reported for Early Cretaceous, which are consistent with some inferences from computer simulations previously published. © 2011 Institute of Geophysics of the ASCR, v.v.i.
format JOUR
author Mena, M.
Goguitchaichvili, A.
Solano, M.C.
Vilas, J.F.
author_facet Mena, M.
Goguitchaichvili, A.
Solano, M.C.
Vilas, J.F.
author_sort Mena, M.
title Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)
title_short Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)
title_full Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)
title_fullStr Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)
title_full_unstemmed Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)
title_sort paleosecular variation and absolute geomagnetic paleointensity records retrieved from the early cretaceous posadas formation (misiones, argentina)
url http://hdl.handle.net/20.500.12110/paper_00393169_v55_n2_p279_Mena
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AT solanomc paleosecularvariationandabsolutegeomagneticpaleointensityrecordsretrievedfromtheearlycretaceousposadasformationmisionesargentina
AT vilasjf paleosecularvariationandabsolutegeomagneticpaleointensityrecordsretrievedfromtheearlycretaceousposadasformationmisionesargentina
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