HR: 14:30h
AN: GP43A-03    [Abstracts]
TI: Early Cretaceous absolute geomagnetic paleointensities from Arapey Formation (Uruguay)
AU: * Cejudo, R
EM: ruben@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria, S/N, Mexico, 04510, Mexico
AU: Gogichaishvili, A
EM: avto@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria, S/N, Mexico, 04510, Mexico
AU: Sánchez Bettucci, L
EM: leda@fcien.edu.uy
AF: Laboratorio de Geofísica-Geotectónica Departamento de Geología Área de Geología y Paleontología Facultad de Ciencias - Universidad de la República , Iguá 4225, Montevideo, 11400, Uruguay
AU: Alva Valdivia, L
EM: lalva@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria, S/N, Mexico, 04510, Mexico
AB: Absolute paleointensity determinations before and during CNS are still scarce and of variable qualities. In this study, we report new paleointensity data from Arapey Formation (part of the Paraná-Etendeka large igneous province) which have several advantages: (1) they are widely distributed in a large volcanic province and easy to access; (2) they record faithfully the magnetic field that existed at the time of their eruption; (3) Most of them are fresh for isotopic dating and have already yielded reliable K-Ar and Ar-Ar ages. 56 samples from 11 individual flows yielded acceptable paleointensity estimates. The mean paleointensity values per flow are ranging from 47.5 to 21.6 microT and the corresponding Virtual Dipole Moments (VDMs) are ranging from 8.9 to 4.3 (1022 Am2). This correspond to the mean value of 6.8 (1.7) x 1022 Am2, which is only slightly lower with respect to the present geomagnetic axial dipole. Currently available selected paleointensity data from 140 to 70 Ma suggest that geomagnetic field strength frequently fluctuated before and during the Cretaceous Normal Superchron while the magnetic polarity maintained stable.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1519 Magnetic mineralogy and petrology
DE: 1521 Paleointensity
DE: 1532 Reference fields: regional, global
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly