Geomagnetic field intensity changes in western Europe during the last millennia: new archeointensity data from Spanish potteries
Miriam Gomez-Paccard  1@  , María Luisa Osete  2@  , Annick Chauvin  3@  , Francisco Javier Pavón-Carrasco  4@  , Manuel Pérez-Asensio  5@  , Pedro Jiménez  6@  , Philippe Lanos  7, 8@  
1 : Géosciences-Rennes  (UMR-6118)
Université de Rennes I
Campus de Beaulieu, Bât. 15, 35000 Rennes -  France
2 : Departamento Física de la Tierra I, Facultad de Ciencias Físicas, Universidad Complutense
Ciudad Universitaria, 28040 Madrid -  Espagne
3 : Géosciences Rennes
CNRS : UMR6118
Campus de Beaulieu, 35042 Rennes cedex -  France
4 : Istituto Nazionale di Geofisica e Vulcanologia.
Via di Vigna Murata, 605 Roma -  Italie
5 : Archeologist
Granada -  Espagne
6 : Escuela de Estudios Árabes EEA-CSIC  (EEA-CSIC)
Frailes de la victoria, 1810 Granada -  Espagne
7 : Géosciences Rennes  (GR)  -  Site web
Universite de Rennes 1, Observatoire des Sciences de l'Univers de Rennes, INSU, CNRS : UMR6118
Bâtiment 15 - Université de Rennes 1 - Campus de Beaulieu - CS 74205 - 35042 Rennes Cedex - France -  France
8 : IRAMAT-CRPAA
CNRS : UMR5060
Esplanade des Antilles, 33607 Pessac cedex -  France

Over the last years new evidences of several intensity, short-lived, regional maxima of geomagnetic field intensity at various times and locations have been obtained. However, these features are not precisely described due to the limited number of high-quality archeointensity data. One of the main difficulties to obtain such a high-resolution reconstruction is the scarcity of precisely dated heated archeological materials. In this context, pottery fragments from superimposed strata covering long sequences of occupation provide a powerful tool to recover a clearer sequence of geomagnetic field intensity changes in the past. In this work we report the archeomagnetic study of several groups of ceramic fragments from southeastern Spain that belong to 14 stratigraphic levels corresponding to a surface no bigger than 3 m by 7 m. The ages of the pottery fragments studied range from the 8th to the11th centuries. The dates were established by three radiocarbon dates and by detailed archeological/historical constraints including typological comparisons and very well-controlled stratigraphic constraints. From classical Thellier and Thellier experiments including pTRM checks and TRM anisotropy and cooling rate corrections, height new high-quality mean intensities have been obtained. The new data obtained provide an improved description of the sharp abrupt intensity changes that took place in western Europe around 800 AD, one of the main geomagnetic features observed in Europe during the last millennia. Together with a selection of high-quality data for the last 2000 years, the new results confirm that several rapid intensity changes (of at least 10 µT/century) took place in western Europe during the recent history of the Earth.

 


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