2019/04/17 by C. Matthias Hüls, C Matthias Hüls, John Meadows +1
Social Sciences · Earth and Planetary Sciences · #Metallurgy and Cultural Artifacts #Archaeology and ancient environmental studies
paper · pdf · doi:10.1017/rdc.2019.15
ABSTRACT Radiocarbon ( 14 C) ages were determined for 10 iron samples from the war booty offering site in the Nydam peat bog (SE Denmark), and compared to archaeologically inferred periods of deposition. Additional 14 C measurements were carried out for modern iron standards made with charcoal of known isotopic composition to evaluate possible effects of handling. Modern iron standards give depleted 14 C concentrations, compared to the initial charcoal 14 C composition, and may indicate carbon fractionation effects during carbon dissolution in the iron lattice. Further studies are needed to verify if this is a common effect during iron production. 14 C dating of two swords and one ax head are in comparatively good agreement with expected deposition times and indicate only small old-wood effects. In contrast, 14 C dating of iron rivets from the Nydam (B) oak boat proved difficult due to corrosion with siderite (FeCO 3 ) and conservation with wax. A step-combustion procedure was applied, using a low (∼570–600°C) temperature prior to the high (∼970–1000°C) combustion temperature for carbon extraction, aiming to remove siderite and wax before collecting the original carbon dissolved in the iron lattice. Nevertheless, measured 14 C ages of the iron rivets differ by about 200–300 years from the dendro-date of the Nydam (B) oak boat they belong to, indicating persisting aging effects (e.g. old-wood, contamination with fossil carbon added during iron making and/or handling prior 14 C dating). Also, a possible recycling of older iron cannot be excluded.