Inclination flattening effect in highly anisotropic archaeological structures from Iberia. Influence on archaeomagnetic dating

Abstract : In directional archaeomagnetic studies, it is rarely analysed whether the combustion structures display anisotropy of their thermoremanent magnetization (ATRM). It has been observed that, in specific cases like thin baked clays from the base of small hearths, archaeomagnetic directions can also be disturbed by the ATRM. We re-examine data from 56 combustion structures from Iberia and use them to analyse the ATRM effect on their archaeomagnetic directions. Flattening of inclinations up to 13 degrees has been found in highly anisotropic structures that can be adequately corrected by the ATRM tensors. We show how the lack of anisotropy corrections on directional values can dramatically deteriorate the ages obtained from archaeomagnetic dating, highlighting the importance of systematically analysing this property in future archaeomagnetic studies.