Paleointensity across the Réunion event in Ethiopia

Abstract

Paleointensity experiments have been conducted on a volcanic series of 33 flows which recorded the geomagnetic Réunion event. Successive determinations of absolute paleointensity from 20 flows indicate that the Réunion event would actually be characterized by two successive periods of low field intensity, with a total duration not in excess of 30 kyr. The first period has a mean paleointensity of 12 μT and shows significant deviations from initial reverse polarity but no signs of fully normal polarity. It is followed by field recovery, then a decrease prior to the second directional episode. The second period has a mean paleointensity of 17 μT and is associated with full normal directions, and thus likely a dominantly dipolar configuration. These results are compatible with a simple `earthlike' magnetic field model with a large decrease in dipole field strength which yields local emergence of relatively stronger non-dipole components. Field characteristics from this configuration would be different at different locations and could explain the variability of the paleomagnetic records collected around the world. We propose that the absence of field recovery following the event is responsible for not leading to a durable polarity interval.