Geomagnetic Intensity and Direction for the Last 14 ka Recorded in the Core from the Bering Sea

Abstract

AbstractPaleomagnetic and rock magnetic studies were conducted on the cores from the borehole B5‐4 in a continental slope of the Bering Sea to determine intensity and direction of the geomagnetic field. The results show that the magnetic properties are uniform except the finer magnetic grain size on the upper 0∼0.44 m. The relative paleointensity in the core is highly consistent with that of ODP983. According to the correlation between relative paleointensity in the borehole B5‐4 and ODP983 and an AMS 14C dating of foraminifera at 4.54∼4.56 m, three correlation points can be further determined, thus an age model for the borehole B5‐4 was obtained. The declination and inclination in B5‐4 agree highly with that of high latitude regions, such as the Lake Baikal, North America and Europe and the spherical harmonic model of local geomagnetic field, which provide additional tie points for the age model and a nearly linear sedimentation for the last 14 ka was revealed. The inclination correlation between B5‐4 and two cores from the China East Sea suggests the two discrete sections of shallow inclinations in B5‐4 are likely record of the Gothenburg event, but affected by the early diagenesis or smoothing effect. The above results prove that both relative paleointensity and direction can be obtained in appropriate sediments of the Bering Sea that serve as a time marker. This is very helpful in paleoenvironmental and paleoceanographic study in the Arctic and subarctic areas considering the awful scarcity of age information due to the shortage of calcareous tests and shells.