Comparative Analysis of the Archaeointensity of the Geomagnetic Field Recorded in Brick Fragments from a Roman Kiln (Village of Dragovishtitsa, Western Bulgaria)

Abstract—This paper is devoted to the study of the features of thermoremanent magnetization (TRM) acquisition in brick fragments from a Roman kiln, uncovered by archeological excavations near the village of Dragovishtitsa (Western Bulgaria), in experiments using the Thellier method as modified by Coe. The aim was to determine the magnitude of the geomagnetic field in ~300 CE. Initially, petromagnetic and archeomagnetic studies were carried out at the paleomagnetic laboratory of the National Institute of Geophysics, Geodesy, and Geography, Bulgarian Academy of Sciences. Then experiments using the Thellier–Coe procedure at two sample cooling rates taking into account the TRM anisotropy were carried out at the laboratory of the main geomagnetic field and petromagnetism of the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. Based on 18 archaeointensity determinations, the average weighted value of the magnetic field was obtained: Bsр= 56.5 ± 0.8 μT, which corresponds to an archeological age of 260 ± 20 CE. The dating obtained using the archeomagnetic method, 281–342 CE, is consistent with the archeological estimate of the time of operation of the kiln. The calculated archaeointensity satisfactorily corresponds to the reference values of the magnetic field for Bulgaria and confirms its decrease in the time interval ~200–300 CE.