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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ftunibueairesbd:paper:paper_00393169_v55_n2_p279_Mena 2023-05-15T16:19:41+02:00 Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina) Mena, Mabel Vilas, Juan Francisco A. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00393169_v55_n2_p279_Mena https://hdl.handle.net/20.500.12110/paper_00393169_v55_n2_p279_Mena unknown https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00393169_v55_n2_p279_Mena http://hdl.handle.net/20.500.12110/paper_00393169_v55_n2_p279_Mena 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] 2011 ftunibueairesbd https://doi.org/20.500.12110/paper_00393169_v55_n2_p279_Mena 2023-02-16T01:54:55Z 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 ... Other/Unknown Material Geomagnetic Pole Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires) Argentina Misiones ENVELOPE(-63.900,-63.900,-64.450,-64.450) |
institution |
Open Polar |
collection |
Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires) |
op_collection_id |
ftunibueairesbd |
language |
unknown |
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 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 Misiones [Argentina] Mena, Mabel Vilas, Juan Francisco A. 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 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 ... |
author |
Mena, Mabel Vilas, Juan Francisco A. |
author_facet |
Mena, Mabel Vilas, Juan Francisco A. |
author_sort |
Mena, Mabel |
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) |
publishDate |
2011 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00393169_v55_n2_p279_Mena https://hdl.handle.net/20.500.12110/paper_00393169_v55_n2_p279_Mena |
long_lat |
ENVELOPE(-63.900,-63.900,-64.450,-64.450) |
geographic |
Argentina Misiones |
geographic_facet |
Argentina Misiones |
genre |
Geomagnetic Pole |
genre_facet |
Geomagnetic Pole |
op_relation |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00393169_v55_n2_p279_Mena http://hdl.handle.net/20.500.12110/paper_00393169_v55_n2_p279_Mena |
op_doi |
https://doi.org/20.500.12110/paper_00393169_v55_n2_p279_Mena |
_version_ |
1766006101206106112 |