How did the dipole axis vary during the first millennium BCE? New data from West Europe and analysis of the directional global database

• Published in: Physics of the Earth and Planetary Interiors
• Main Authors: Hervé, Gwenaël, Chauvin, Annick, Lanos, Philippe, Lhuillier, Florian, Boulud-Gazo, Sylvie, Denti, Mario, Macario, Raphaël
• Other Authors: IRAMAT-Centre de recherche en physique appliquée à l’archéologie (IRAMAT-CRP2A), Institut de Recherches sur les Archéomatériaux (IRAMAT), Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne (UBM)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne (UBM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Climat et Magnétisme (CLIMAG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Ludwig Maximilian University Munich = Ludwig Maximilians Universität München (LMU), Université de Nantes (UN), Centre de Recherche en Archéologie, Archéosciences, Histoire (CReAAH), Le Mans Université (UM)-Université de Rennes (UR)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN)-Ministère de la Culture (MC), Université de Rennes 2 (UR2), Hadès - Bureau d'Investigations Archéologiques, German Research Foundation (DFG) HE7343/1-1, Campus France PRESTIGE program PRESTIGE-2017-1-0002, ANR-15-CE31-0011,SVPIntMex,Variation séculaire et Paléointensité au Mexique pendant le Plio-Quaternaire(2015), ANR-10-LABX-0052,LaScArBx,Using the world in ancient societies : processes and forms of appropriation of space in Long Time(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Archaeomagnetism; Archaeointensity; Geomagnetic secular variation; First millennium BCE; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Geomagnetic Pole
• Online Access: https://insu.hal.science/insu-03203983; https://insu.hal.science/insu-03203983v2/document; https://insu.hal.science/insu-03203983v2/file/Herv%C3%A9%20et%20al.%20-%202021%20-%20How%20did%20the%20dipole%20axis%20vary%20during%20the%20first%20mill.pdf; https://doi.org/10.1016/j.pepi.2021.106712

International audience Despite progress in the knowledge of secular variation during the first millennium BCE in Europe, data coverage remains poor at the earliest periods, especially in some regions as in the Central Mediterranean area. This study presents three new directional and six new intensity data between the 13th and the 4th centuries BCE on archaeological kilns, pottery and baked clay fragments from South Italy and France. Archaeodirections were determined after thermal demagnetizations and archaeointensities using the Thellier-Thellier protocol with corrections for the anisotropy and cooling rate effects. The new data confirm the large deviation of the direction from a Geocentric Axial Dipole field, the high geomagnetic field strength and the fast secular variation observed in Europe during the earliest half of the first millennium BCE. Another characteristic of this period is a difference of ~25° between the longitudes of the virtual geomagnetic poles inferred from European and Middle East data. This unusual behaviour can be mainly related to the Levantine Iron Age anomaly (LIAA) and its expansion from the Middle East to Europe. However, the review of the global directional database shows that almost all virtual geomagnetic poles, 96% of them coming from Europe, the Middle East, East Asia, North America and Hawaii, are 10–25° away from the rotation axis towards North Russia between 1000 and 600 BCE. The calculation of a mean global VGP curve suggests that the North geomagnetic pole followed a clockwise motion during this period with a dipole tilt up to around 14°. This study shows that a dipole axis tilt may have played an important role in the rapid secular variation in western Eurasia, although part of this variation may also be related to non-dipole fields associated with the LIAA.