PRINCIPAL FEATURES (MASTER CURVE) OF GEOMAGNETIC FIELD VARIATIONS IN BELORUSSIA DURING THE LAST 12 THOUSAND YEARS

Abstract

This paper presents the results of the paleomagnetic studies of the Naroch and Svir lake bottom deposits in Belorussia. The objects of study were nine columns of lake-floor sediments, totaling 6.50 m in thickness, collected using a special-type core sampler which did not disturb the structure of the sample material. The absolute dating of the sediments was performed by a radiocarbon method using the macroremains of the organic matter (grass). The columns of the sediments were correlated using their absolute ages, lithologies, and magnetic susceptibility values. All sedimentary rock columns showed a good agreement of the inclination and declination components of the natural remanent magnetization (ChRM) distinguished in all sedimentary rock columns using alternative magnetic field cleaning. The data obtained for all rock columns were summed up to produce the composite curves of ChRM declination and inclination variation for the sediments of these lakes. These data were compared with the archeomagnetic and limnomagnetic data available for Central and East Europe. All records of the paleosecular geomagnetic variations (PSV) showed a good agreement in terms of the morphology of the ChRM declination and inclination. At the same time the sediments of the Belorussian lakes showed a systematically older age and the lower magnitudes of the ChRM declination and inclination variations compared to the other PSV records available. These effects can be explained by the presence of some postdeposition remanent magnetization (PDRM) in the sediments of the Belorussian lakes and by the addition of some "aged'''' carbon (without 14C) to the lake from the surrounding carbonate rocks. The basic features of the geomagnetic field variations in Europe are discussed for the last 10-12 thousand years.