New archaeomagnetic secular variation data from Central Europe, I: Directions

Abstract

Summary Archaeomagnetic directions of one hundred and forty-one archaeological structures have been studied from 21 sites in Austria, 31 sites in Germany and one site in Switzerland. Characteristic remanent magnetisation directions obtained from alternating field and thermal demagnetisations provided 82 and 78 new or updated (12 and 10 per cent) directions of Austria and Germany, respectively. Nine of the directions are not reliable for certain reasons (e.g. displacement) while three of the features are not well dated. Apart from this some updated age information for the published databases is provided. Rock magnetic experiments revealed magnetite as main magnetic carrier of the remanences. The new data agree well with existing secular variation reference curves. The extended data set covers now the past 3500 years and a lot of progress were made to cover times BC with data. Here enhanced secular variation is observed manifested in declinations with values up to 70°. The new data will allow for recalculation of archaeomagnetic calibration curves for Central Europe from mid Bronze Age until today.

SCHA.DIF.4k: 4,000 Years of Paleomagnetic Reconstruction for Europe and Its Application for Dating

“…According to the Hovmöller diagram (Figure 8c, left) and the animated maps of the supporting information, the eastern maximum around 1000 BC is observed around 800 BC in Western Europe characterized by higher eastern declinations. This maximum is well‐constrained by new declination data from West‐Central Europe (Osete et al., 2020; Schnepp et al., 2020). In the first millennium AD there is a noticeable sharp minimum in the eastern curve around 600 AD that expands to west up to 10°E of longitudes.…”

New Italian directional and intensity archaeomagnetic reference curves for the past 3000 years: Insights on secular variation and implications on dating

“…A very similar trend is also seen in Central Europe, based on recently published directional data from Germany and Austria (Schnepp et al . 2020). The very high‐intensity value of 85 μT observed in Italy around 800–700 bce is in good agreement with the LIAA high intensity reported in Israel at the beginning of the eighth century bce (Shaar et al .…”

An updated archeomagnetic directional variation curve for France over the past two millennia, following 25 years of additional data acquisition

“…The latter DSV curve does not show the directions with inclinations as low as ~55° between ~1200/1300 and ~1400 AD that are present in both the French and Iberian curves. However, it should be noted that such data are now present in the recently updated archeomagnetic database (Schnepp et al, 2020). Figure 12 highlights, in a simple and very general way, the need to homogenize the methods used to estimate regional DSV curves.…”

“…Numerous studies have led to a better understanding of the temporal variations of the geomagnetic field in different parts of the world, although these data still mainly concern the European area (e.g. Schnepp and Lanos, 2005;Gómez-Paccard et al, 2006;Martón and Ferencz, 2006;Tema et al, 2006;Batt et al, 2017;Molina-Cardín et al, 2018;Shaar et al, 2018;Schnepp et al, 2020). For metropolitan France, in particular, the last two decades have been marked by significant progress in the knowledge of directional variations during the first millennium BC (e.g.…”

“…Another reason for the recent spurt of development in archeomagnetism is its ability to provide original dating constraints for archeologically poorly-dated structures (e.g. Le Pavón-Carrasco et al, 2011;Rouzeau et al, 2015;Tema et al, 2019;Schnepp et al, 2020) , as well as for a better understanding of the history of volcanoes (e.g. Tanguy et al, 2007;2011).…”