A 2000 year geomagnetic field record from the Gulf of Papua

Abstract

A high resolution Holocene record of geomagnetic field direction and intensity in the Gulf of Papua was constructed using paleomagnetic data from eight piston cores collected in the region. The chronology of the cores was based largely on radiocarbon dates from benthic foraminifera. Correlation of seismic reflectors imaged in subbottom data between nearby cores was consistent with the chronostratigraphic framework based on radiocarbon dates and provided additional confidence of the age model. In other regions, where cores sampled different depositional settings associated with the three-dimensional prograding lobes, reflectors could not be confidently correlated between cores. Furthermore, radiocarbon ages from the bottoms of trigger cores and tops of co-located piston cores revealed varying amounts of overpenetration of the piston core below the seafloor. The relative paleointensity, and a general eastward trend in the declination and steepening of the inclination in our new record are generally compatible with the closest (>4300 km) existing records. Our record does not agree well with global field models CALS3k and pfm9k, likely reflecting the lack of existing data contributing to field models in the region.