Investigating the expected archaeomagnetic dating precision in Europe: A temporal and spatial analysis based on the SCHA.DIF.3K geomagnetic field model

Abstract

Archaeomagnetic dating is a chronometric dating technique, based on the ability of baked clay archaeological structures and artifacts to acquire a thermal remanent magnetization (TRM) when heated at high temperatures and cooled in the presence of the Earth's magnetic field. The precision of archaeomagnetic dating depends on several factors, among others the availability of a detailed reference secular variation (SV) curve for a given territory. In this study, we investigate the precision that archaeomagnetic dating can reach in Europe. We used the SCHA.DIF.3K European geomagnetic field model to calculate the dating uncertainties for the last 3000 years, taking into consideration only the uncertainties depending on the change rate of the geomagnetic field in the past and the reference SV curve's uncertainty envelope. Such uncertainties were calculated both in time and space, they are usually asymmetrically distributed around the considered year and it have been represented as dynamic maps of uncertainties. The obtained results show that archaeomagnetic dating based solely on directional data (declination and inclination) can be very precise for the last four centuries, with total uncertainties being almost always lower than 100 years all around Europe. Inherent dating uncertainties are also low for the last millennium, with values ranging from 50 to 300 years. These results underline the great potential of archaeomagnetism on dating baked clays belonging to the last 1000 years. For older periods, the uncertainty maps show that the dating precision may importantly vary from place to place, but with local non-symmetric uncertainty ranges generally below 400 years. The obtained maps also show that adding the intensity to the computation of the inherent uncertainties does not always reduce the uncertainty. The temporal and spatial analysis presented here does not give the total dating imprecision of archaeomagnetic dating (that definitely depends on numerous, often uncontrollable, factors), but aims at offering a useful tool to archaeomagnetic and archaeological research to check the feasibility of archaeomagnetic dating for determining the age of an archaeological structure below a desired precision.