TRM anisotropy correction: An essential requirement to assess past geomagnetic field strength from ancient potteries. Evidence from new archeointensity data from NW Argentina

Abstract

Trabajo presentado en la International Conference on Rock Magnetism, celebrada en Utrech (Países Bajos) del 10 al 14 de julio de 2017Improving geomagnetic field reconstructions clearly poses a high-priority challenge in Earth Sciences today. A better characterization of the variation of the geomagnetic field strength at centennial to millennial time scales in the southern hemisphere is particularly crucial to disentangle the long-term evolution of the Earth's dipole moment, a global characteristic of our planet. Here we present new high-quality archeointensities obtained from the study of four collections of well-dated pottery fragments from La Puna (Northwest Argentina). The classical Thellier method including regular partial thermoremanent magnetization (pTRM) checks and TRM anisotropy and cooling rate corrections has been used for archeointensity determination. The new data obtained shed new light on the past fluctuation of geomagnetic field strength in South America, a rather poorly known region in terms of geomagnetic field intensity fluctuations. In addition, the results confirm that TRM anisotropy corrections are an essential requirement when studying past geomagnetic field strength from the archeomagnetic study of pottery fragments. Future geomagnetic field reconstructions do well to have the TRM anisotropy requirement in mind when trying to unravel geomagnetic field variations from pottery-based archeointensity data, both at regional or global scales.Peer reviewe