On the reliability of Mesozoic Dipole Low: New absolute paleointensity results from Paraná Flood Basalts (Brazil)

Abstract

Thellier paleointensity experiments were carried out on Early Cretaceous Paraná Flood Basalts. Forty-two samples from 11 lava flows yielded apparently reliable absolute intensity determinations. The mean paleointensity values per flow obtained in this study are ranging from 19.4 ± 4.0 to 46.7 ± 7.0 μT and the corresponding Virtual Dipole Moments are ranging from 4.0 ± 0.6 to 10.5 ± 1.1 (1022 Am2). These yield a mean value of 7.2 ± 2.3 x 1022 Am2, which is about 92% of the present geomagnetic axial dipole. Our results in conjunction with Tarduno et al.'s [2001] data suggest that the paleostrength during early Cretaceous period might be comparable or even much higher than recent field intensity and not 'anomalousely low' as previously suggested. Thus, the Mesozoic Dipole Low (MDL) may probably be considered as unreliable.