Relation between geomagnetic field intensity and peculiarities of its variations with inversion frequency

Abstract

The assumption that the variation of the ancient geomagnetic field (GF) is governed by processes in the Earth’s core is usually accepted without question. Numerical modeling of the evolution of αω -dynamo showed that change in the characteristics of the GF (paleointensity variations and inversion frequency) should correlate [1, 2]. However, the search for the correlation of paleointensity and inversion frequency has not been successful up to the present time owing to the lack of paleomagnetic data [3, 4]. Our reconstructions of paleointensity in the Jurassic and Cretaceous based on sedimentary rocks widened significantly the information dataset about this characteristic of the geomagnetic field. The summary of the author’s data on paleointensity obtained for the sedimentary rocks and world data based on thermomagnetized rocks provided a new basis for constructing the dynamics of the GF intensity and investigating the correlation between the characteristics of the magnetic field. Reconstruction of the fragments of GF intensity was based on the analysis of sedimentary rock collections gathered on the Russian Plate and adjacent territories [5, 6]. Previously, these collections were used for constructing the Middle Jurassic‐Cretaceous regional magnetostratigraphic scale [7]. The results of determinations of paleointensity based on thermomagnetized rocks were taken from the database (DB) at http://www. brk.adm.yar.ru/palmag/index.html. The information about inversions is mainly taken from [8]. The Albian‐ Coniacian interval is an exception. The frequency of the Albian‐Coniacian inversions was plotted from the more complete data in [7].