Evidence for multiple paleomagnetic intensity lows between 30 and 50Â ka BP from a western Equatorial Pacific sedimentary sequence

A paleomagnetic study was carried out on the radiocarbon dated MD97-2134 core located in the western Equatorial Pacific (Southern Papua New Guinea margin). Rock magnetic investigations revealed changes of the magnetic mineralogy along the hemi-pelagic sedimentary sequence but the reconstruction of past direction and relative paleointensity variations of the geomagnetic field remained feasible. Four successive paleointensity drops are recorded between 30 and 50 ka BP. The largest one is associated with an abrupt swing of declination and inclination interpreted as a smoothed signature of the Laschamp excursion (∼41 ka BP). The succession of four events of weak intensity between 30 and 50 ka BP introduces a complex behaviour of the geomagnetic field in the time interval spanning over the Laschamp and the Mono Lake excursions.