A 200 kyr record of cosmogenic radionuclide production rate and geomagnetic field intensity from Be-10 in globally stacked deep-sea sediments

The reconstruction of geomagnetic field intensity variations during the last 200 kyr from paleomagnetic data is at present the subject of numerous studies and major debate. There is currently no generally accepted record. Here we present a global stacked record of (Th-230(ex)-normalized) Be-10 deposition in marine sediments representing relative variations in Be-10 production rate which are translated into field intensity variations, The record shows major periods during which the field intensity was between 10% and 40% of the present day value; namely 30-42, 60-75, 85-110 and 180-192 kyr B.P. Our results are compared to independently derived paleomagnetic studies and Th/U calibrations of C-14 dates on corals. During most of the observed period the geomagnetic field intensity was weaker than today, resulting in an overall 30% reduced value for the last 200 kyr.