Variations of the geomagnetic field during the Cretaceous

Abstract

This study provides a compilation of the paleointensity records for the Cretaceous period derived from sediments of the Russian Plate and adjacent areas. The paleoinetensity values were calibrated using the laboratory redeposition experiments. Remarkable differences in the relative paleointensity variations were detected at the Berriasian–Early Barremian, Late Barremian–Santonian and Early–Late Maastrichtian boundaries. In the Berriasian–Early Barremian interval, the paleointensity varied stochastically, with the amplitude of about 1Ho and the mean value of 0.63Ho (Ho is the present-day geomagnetic field intensity assumed to be 40 μT). The records for the Barremian–Santonian give a picture of the geomagnetic field with alternating high- and low-amplitude features. The mean paleointensities remain constantly high (being on average 0.87Ho), and intervals of low-amplitude variation alternate with the pronounced bursts (3.5Ho). The Late Maastrichtian interval is characterized by high-amplitude paleointensity variations (4Ho) and a sharp drop towards the end of the interval. All records show remarkable similarities near the boundaries between geological time intervals, which are an increase in the amplitude and mean values of intensity at the end of intervals followed by a decrease towards the beginning of the subsequent interval.

Behavior of paleointensity during the Paleogene

“…4b). Earlier, we studied these deposits on the example of the Crimea deposits (Kurazhkovskii et al, 2012). The study by described in Kurazhkovskii et al (2012) as well as the present study it revealed that significant bursts of paleointensity took place in the end of the Maastrichtian.…”

“…Earlier, we studied these deposits on the example of the Crimea deposits (Kurazhkovskii et al, 2012). The study by described in Kurazhkovskii et al (2012) as well as the present study it revealed that significant bursts of paleointensity took place in the end of the Maastrichtian. In addition, the burst of the paleointensity in the end of the Selandian was detected both on sediments of borehole and on the deposits of lower Volga (Fig.…”