Archaeomagnetism and Luminescence on Medieval kilns in Thessaloniki and Chalkidiki (N. Greece): Implications for geomagnetic field variations during the last two millennia

Abstract In the present study we report on archaeomagnetic and luminescence results from three ceramic kilns unearthed in a workshop during the subway (METRO) excavations in Thessaloniki (N. Greece) as well as from a small kiln at Ierissos (Chalkidiki). The first settlement is situated in the western part of the city where several similar workshops were excavated in the past. The archaeological information attributed a possible Ottoman age to these structures and placed their last use after the 14th century CE. The other small kiln is one of the rare “in situ” remains within the settlement reported as “Medieval Ierissos”. A total of fifty-five hand samples were retrieved from the four kilns and studied following established archaeomagnetic protocols in order to define the full vector of the magnetization. Additionally thermoluminescence (TL) experiments have been performed on the same material for the Thessaloniki kilns and the obtained ages converge and refine the archaeological ones. At Ierissos optically stimulated luminescence (OSL) experiments on five samples revealed the firing history of the structure. The combination of archaeological and/or TL-OSL information allowed to define four new full vector recordings for the improvement of the secular variation curves during the second millennium CE where intense variations of the Geomagnetic Field are reported from several places in Europe. The new data, together with recently published ones for the first millennium CE, allow to update the directional reference curves, poorly constrained for this period.