THE EARTH’S MAGNETIC FIELD HISTORY FOR THE PAST 400 MYR
A.Yu. Kurazhkovskiia, N.A. Kurazhkovskayaa, B.I. Klaina, and V.Yu. Braginb
a Borok Geophysical Observatory, Filial of Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Borok, Yaroslavl region, 152742, Russia
b A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Paleointensity, frequency of reversals, tectonic events
Pages: 380-386
Abstract
Published and new data on the Earth’s past magnetic field have been interpreted in terms of its links with the frequency of magnetic polarity reversals and with tectonic events such as plume-related eruptions and rifting. The paleointensity and reversal frequency variations show an antiphase correlation between 0 and 160 Ma, and the same tendency, likely, holds for the past 400 Myr. The geomagnetic field intensity averaged over geological ages (stages) appears to evolve in a linearly increasing trend, while its variations increase proportionally in amplitude and change in structure. Both paleointensity and reversal frequency patterns correlate with rifting and eruption events. In periods of high rifting activity, the geomagnetic field increases (15 to 30%), and the reversals become about 40% less frequent. Large eruption events between 0 and 150 Ma have been preceded by notable changes in magnetic intensity, which decreases and then increases, the lead being most often within a few million years.
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