Behavior of paleointensity during the Paleogene

• Behavior of the paleointensity during the Paleogene was studied using the sediments.
• The paleointensity bursts were revealed in the interval of Danian to Ypresian.
• The paleointensity in the Paleogene are in antiphase with the frequency of reversals.
• The bursts were found only during reverse polarity of the geomagnetic field.

Behavior of the intensity of geomagnetic field in the Paleogene was studied by the analysis of the sedimentary rocks of the Russian Plate. It is revealed that in the beginning of the Paleogene the variations of little-amplitude paleointensity (about 0.5H0, where H0 is the value of modern geomagnetic field taken as 40 μT) were alternating with bursts of large amplitude (up to 5H0). By the end of the Paleogene only the paleointensity variations with a little amplitude were revealed.The relation between behavior of the paleointensity and the polarity regime is analyzed. On the basis of the behavior of the reversal frequency and asymmetry of the polarity and according to Molostovskii et al. (2007) the Paleogene was divided into two hyperchrons. In the first hyperchron (66–40) Ma the polarity of the geomagnetic field was predominantly reverse. In the second hyperchron (40–22) Ma the intervals of normal and reverse polarity alternated. The bursts of the paleointensity were revealed only in the beginning of the first hyperchron. In addition, during the first hyperchron both the average values (for the geological age) and the amplitude of the paleointensity variations decreased; within the interval of (40–22) Ma both the amplitude and its mean values were changing inconsiderably.