New archaeomagnetic directions from Portugal and evolution of the geomagnetic field in Iberia from Late Bronze Age to Roman Times

Palencia-Ortas, A., Osete, M.L., Campuzano, S., McIntosh, G., Larrazabal, J., Sastre, J. and Rodriguez-Aranda, J. (2017) New archaeomagnetic directions from Portugal and evolution of the geomagnetic field in Iberia from Late Bronze Age to Roman Times. Physics of the Earth and Planetary Interiors, 270. pp. 183-194. ISSN 0031-9201.

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Abstract

This study presents new archaeomagnetic results from 33 combustion structures (kilns and hearths) from the archaeological sites of Castelinho, Crestelos, Olival Poço da Barca and Fonte do Milho in NE Portugal. The age of the investigated structures ranges from 1210 BC to 200 AD according to calibrated radiocarbon dating, thermoluminescence dating and archaeological constraints. Stepwise thermal and alternating field demagnetization isolate a single, stable, characteristic remanence component with very well defined directions. Rock magnetic analyses suggest low-Ti titanomagnetite/maghemite as the main magnetic carrier of the remanence. Mean directions are well grouped in most structures. The effect of thermoremanent anisotropy on mean directions has been evaluated and was found to be important. Inclination increases of between 2° and 13° after applying the anisotropy correction at specimen level. This highlights the requirement of evaluating this effect on the directions of small and flattened thin kilns and hearths. The 31 new directional data improve both the temporal and spatial distribution of the Iberian archaeomagnetic dataset from Late Bronze Age to Roman Times.

Finally, a new directional palaeosecular variation curve for Iberia for the last twelve centuries BC is proposed. The curve has been computed using the bootstrap method and includes data coming from sites within 900 km of Madrid. The new palaeodirectional secular variation curve for Iberia is consistent with the Western European palaeosecular variation curve and with the prediction of regional European models.

Item Type: Article
Additional Information: This manuscript version is made available under the CC-BY-NC-ND- 4.0 License.
Subjects: C Auxiliary Sciences of History > CC Archaeology
Q Science > QC Physics > QC0501 Electricity and magnetism
Q Science > QC Physics > QC0811 Geomagnetism
Divisions: Faculty of Social and Applied Sciences > School of Human and Life Sciences
Depositing User: Gregg McIntosh
Date Deposited: 06 Dec 2017 14:28
Last Modified: 06 Dec 2017 14:32
URI: https://create.canterbury.ac.uk/id/eprint/16582

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Last edited: 29/06/2016 12:23:00