Paleointensity of the Earth's magnetic field and K‐Ar dating of the Louchadiere volcanic flow (central France): New evidence for the Laschamp excursion

Abstract

We report paleointensity results of the Earth's magnetic field from a Late Pleistocene lava flow (Louchadière, Central France), which recorded an intermediate geomagnetic field direction (5 sites, mean declination=114.1°, inclination=58.2°, k=130, α95=6.7°). New K‐Ar age determinations confirm that this flow is contemporaneous with the Laschamp and Olby flows, and that this excursion occurred around 45ka ago. Using the Thellier double heating method, reliable paleointensities have been obtained for ten samples from three different sites, providing an average field strength of 12.9 µT (±3.3). This low value and previous results of the Laschamp excursion from France and Iceland confirm that the Earth's magnetic field was in an intermediate state during the Laschamp excursion.