2005 Volume 114 Issue 2 Pages 201-211
Paleomagnetism has been applied to tectonics studies on the basis of the geocentric axial dipole (GAD) field hypothesis. However, the applicability of the GAD hypothesis is still under investigation in the paleomagnetic community. It is directly connected to the precision of the tectonic movements derived from paleomagnetism, so that the the morphology of the geomagnetic field should draw wide attention among Earth scientists. The morphology of the long term geomagnetic features is often represented by the time-averaged field (TAF) and the paleosecular variation (PSV). They are extracted from the paleodirections of lavas erupted during the past 5 My.
The recent TAF and PSV models indicate following; (1) the GAD hypothesis is not strictly accurate, (2) the geocentric axial quadupole (g02) field exists in the TAF and it cannot be neglected, and (3) the inclination anomaly calculated from the averaged paleomagnetic data consists also of the apparent effect of the PSV, which additionally cannot be ignored. These components should be paid close attentions to specially in the case of detailed tectonics such as highresolution plate motion. The inclination anomaly due to g02 in the TAF and the effect of the PSV would produce a mistake of the paleolatitude, which becomes totally up to several degrees.
