Geomagnetic field intensity variations in Northwestern-Central Russia between the 12th and 19th century AD

We will present a synthesis of the archeointensity data spanning the past millennium that we recently acquired in the European part of Russia. These data were principally obtained from groups of architectural brick fragments sampled in the Novgorod, Moscow and Yaroslavl areas that are precisely dated between the 12th and the 19th century thanks to archives and archeological constraints. All intensity measurements were carried out using the experimental protocol developed for the Triaxe magnetometer. The reliability of the data is attested through the use of stringent selection criteria on the Triaxe data, rock magnetic experiments and by the use of two different cooling rates for laboratory thermoremanent magnetization acquisition. Altogether the new data show a progressive decrease of the geomagnetic field intensities in Northwestern-Central Russia over the past millennium. They do not exhibit large and rapid fluctuations, as those previously reported from the Balkan archeointensity dataset. They further allow us to constrain the dipole moment evolution over the past four centuries. Finally, we will discuss the consistency of the geomagnetic field intensity variations during the second millennium AD at the entire European scale. The research was supported by RSF (project No. 16-17-10097)