New high precision full-vector archaeomagnetic data from a roman kiln in Mérida (Spain)

Abstract

This study presents new high precision age and full-vector archaeomagnetic data from a kiln excavated in the Roman archaeological site of Mitreo's house (Mérida, Badajoz, Spain). The age of the kiln was obtained by the stratigraphic method and by the ceramological study of the italic and sigillata pottery found with a very precise age date of 55 ± 15 years AD. Rock-magnetic experiments pointed towards magnetite as the main carrier of remanence and highly reversible thermomagnetic curves suggested that the studied samples were suitable for archaeoeointensity determinations.Paleomagnetic experiments including thermal and stepwise alternating field demagnetization yielded the following mean direction for the kiln: declination D = 0.6°; inclination I = 54.0°; (k = 481; α95 = 2.5°). Archaeointensityexperiments with the Thellier – Coe protocol on 28 samples yielded successful determinations in 27 cases. Anisotropy factors between 0.90 and 1.04 were obtained from anisotropy of thermoremanent magnetization (ATRM) experiments. A mean anisotropy-corrected archaeointensity value F = 56.3 ± 5.5 μT was obtained.

The geomagnetic model SHA.DIF.14 k was used for an archaeomagnetic dating yielding a chronological interval between 40 BCE and 150 CE. This low age resolution when compared with the pottery-based age data is related to the behavior of the geomagnetic field in the Iberian Peninsula during the Roman period, which does not allow to differentiate well between results corresponding to those centuries. However, it is also related to the fact that the Iberian archaeomagnetic dataset in the analysed time range is highly scattered. A high quality full-vector data with a very precise age have been obtained which contribute to improve the Iberian secular variation curve and geomagnetic databases.