Paleointensity data from Early Cretaceous Ponta Grossa dikes (Brazil) using a multisample method
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
19/10/2012
19/10/2012
2009
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Resumo |
Definition of the long-term variation of the geomagnetic virtual dipole moment requires more reliable paleointensity results. Here, we applied a multisample protocol to the study of the 130.5 Ma Ponta Grossa basaltic dikes (southern Brazil) that carry a very stable dual-polarity magnetic component. The magnetic stability of the samples wits checked using thermomagnetic curves and by monitoring the magnetic Susceptibility evolution through the paleointensity experiments. Twelve sites containing the least alterable samples were chosen for the paleointensity measurements. Although these rocks failed stepwise double-heating experiments, they yielded coherent results in the multisample method for all sites but one. The coherent sites show low to moderate field intensities between 5.7 +/- 0.2 and 26.4 +/- 0.7 mu T (average 13.4 +/- 1.9 mu T). Virtual dipole moments for these sites range from 1.3 +/- 0.04 to 6.0 +/- 0.2 x 10(22) A m(2) (average 2.9 +/- 0.5 x 10(22) A m(2)). Our results agree with the tendency for low dipole moments during the Early Cretaceous, immediately prior to the Cretaceous Normal Superchron (CNS). The available paleointensity database shows a strong variability of the field between 80 and 160 Ma. There seems to be no firm evidence for a Mesozoic Dipole Low, but a long-term tendency does emerge from the data with the highest dipole moments Occurring at the middle of the CNS. CNPq FAPESP[05/57782-4] |
Identificador |
EARTH PLANETS AND SPACE, v.61, n.1, p.41-49, 2009 1343-8832 |
Idioma(s) |
eng |
Publicador |
TERRA SCIENTIFIC PUBL CO |
Relação |
Earth Planets and Space |
Direitos |
restrictedAccess Copyright TERRA SCIENTIFIC PUBL CO |
Palavras-Chave | #Mesozoic Dipole Low #Cretaceous #paleointensity #Parana basin #EARTHS MAGNETIC-FIELD #PARANA MAGMATIC PROVINCE #MESOZOIC DIPOLE LOW #GEOMAGNETIC PALEOINTENSITIES #NORTHEASTERN CHINA #LIAONING PROVINCE #AGE-DETERMINATION #NORMAL SUPERCHRON #FLOOD VOLCANISM #SOUTHERN BRAZIL #Geosciences, Multidisciplinary |
Tipo |
article original article publishedVersion |