Novel insights on the geomagnetic field in West Africa from a new intensity reference curve (0-2000 AD)

Kapper, Lisa; Serneels, Vincent; Panovska, Sanja; Ruíz, Rafael García; Hellio, Gabrielle; Groot, Lennart de; Goguitchaichvili, Avto; Morales, Juan; Ruíz, Rubén Cejudo

doi:10.1038/s41598-020-57611-9

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Novel insights on the geomagnetic field in West Africa from a new intensity reference curve (0-2000 AD)

Kapper, Lisa National Archeomagnetic Service, Institute of Geophysics, Campus Morelia, Universidad Nacional Autónoma de México (UNAM), Morelia, 58190, Mexico
Serneels, Vincent Department of Geosciences, University of Fribourg, Fribourg, 1700, Switzerland
Panovska, Sanja Deutsches GeoForschungsZentrum GFZ, Helmholtz Zentrum Potsdam, Telegrafenberg, 14473, Potsdam, Germany
Ruíz, Rafael García National Archeomagnetic Service, Institute of Geophysics, Campus Morelia, Universidad Nacional Autónoma de México (UNAM), Morelia, 58190, Mexico
Hellio, Gabrielle Laboratory of Planetology and Geodynamics, Nantes University, Nantes, 44322, France
Groot, Lennart de Paleomagnetic laboratory Fort Hoofddijk, Utrecht University, Utrecht, 3584 CD, The Netherlands
Goguitchaichvili, Avto National Archeomagnetic Service, Institute of Geophysics, Campus Morelia, Universidad Nacional Autónoma de México (UNAM), Morelia, 58190, Mexico
Morales, Juan National Archeomagnetic Service, Institute of Geophysics, Campus Morelia, Universidad Nacional Autónoma de México (UNAM), Morelia, 58190, Mexico
Ruíz, Rubén Cejudo National Archeomagnetic Service, Institute of Geophysics, Campus Morelia, Universidad Nacional Autónoma de México (UNAM), Morelia, 58190, Mexico

24.01.2020

Published in:

Scientific Reports. - 2020, vol. 10, no. 1, p. 1121

English The geomagnetic field variations on the continent of Africa are still largely undeciphered for the past two millennia. In spite of archaeological artefacts being reliable recorders of the ancient geomagnetic field strength, only few data have been reported for this continent so far. Here we use the Thellier-Coe and calibrated pseudo- Thellier methods to recover archaeointensity data from Burkina Faso and Ivory Coast (West Africa) from well-dated archaeological artefacts. By combining our 18 new data with previously published data from West Africa, we construct a reference curve for West Africa for the past 2000 years. To obtain a reliable curve of the archaeointensity variation, we evaluate a penalized smoothing spline fit and a stochastic modelling method, both combined with a bootstrap approach. Both intensity curves agree well, supporting the confidence in our proposed intensity variation during this time span, and small differences arise from the different methodologies of treating data and uncertainties. Two prominent peaks at around 740 AD and 1050 AD appear to be common in ours and several reference curves from other locations, indicating a general westward movement from China to Hawaii of a rather stable feature of the geomagnetic field. However, independent smaller peaks that do not correlate in different locations may hint to localized expressions of the geomagnetic field as a result of temporarily varying non-dipole sources.

Faculty

Faculté des sciences et de médecine

Department

Département de Géosciences

Language