Lead isotope and geochemical analyses of copper-based metal artefacts from the Iron Age water burial in Levänluhta, Western Finland

Abstract

This article presents the results of the first-ever lead isotope (LI) analysis of copper-based archaeological artefacts found in the region of Finland. Eight metal objects recovered from the Iron Age water burial site of Levänluhta in western Finland were analysed via multi collector inductively coupled plasma mass spectrometry (MC-ICP-MS) and portable X-ray fluorescence spectrometry (pXRF) in order to attain geochemical and LI data. The majority of the objects are Merovingian period (ca. 550–800 CE) jewellery, displaying domestic Iron Age artefact styles, and were probably cast by local workshops in Finland. Until recently, the copper exploited in Bronze and Iron Age metallurgy in Finland had been linked to Scandinavian ores. However, this provenance scenario seems implausible in the light of recent LI studies demonstrating that Scandinavian Bronze Age artisans in fact relied on long-distance metal transport. Comparisons between the LI data of the analysed objects and published ore databases exclude the possibility of a domestic or Scandinavian copper source for the metals. Instead, it appears likely that the copper originated from southern European ores. The low arsenic and antimony levels in the copper alloys provide indication of long recycling patterns of the metals used in the Iron Age workshops in Finland. It is possible that the Iron Age artefacts contain recycled copper-alloys already acquired in the Bronze Age. The metals were transported for long distances, and it appears that the pan-European metal circulation network also crossed the Baltic Sea to reach coastal Finland.