Proweniencja ludności pochowanej na cmentarzysku oraz form odlewniczych z późnej epoki brązu na podstawie analizy izotopów strontu i neodymu / Provenance of the individuals buried at the Late Bronze Age cemetery and of the casting moulds in light of analyses of strontium and neodymium isotopes
1 – Laboratorium Izotopowe, Uniwersytet im. Adama Mickiewicza, ul. Krygowskiego 10, 61-680 Poznań
In: E. Tomczak, A. Szczepanek, P. Jarosz 2021. Gogolin-Strzebniów, stanowisko 12. Cmentarzysko kultury łużyckiej na Wyżynie Śląskiej, Ocalone Dziedzictwo Archeologiczne 11, Pękowice: Stowarzyszenie Archeologów Terenowych „Stater”, Wydawnictwo Profil-Archeo, p. 125-130.
Summary: Strontium isotope ratios (87Sr/86Sr) were applied to investigate provenance of the Bronze Age population buried at cemetery in Gogolin-Strzebniów. The study used 12 samples: two human enamel samples from inhumation graves and ten samples of petrous part of temporal bone from cremation burials. Baseline information on the local Sr isotope composition was established on geological data. The human samples of ten individuals yielded a quite narrow range of Sr isotope signatures, from 0.7112 to 0.7121 (Table 1; Fig. 1). The obtained results indicate that these individuals have 87Sr/86Sr values which fits well within the range of Sr isotope signatures established for the local area. Signatures of two individuals are outside this range. The bone remains from grave 59 have a lower value of 87Sr/86Sr (0.7107), and a molar tooth of an individual from grave 63 – has a higher value (0.7128). These two individuals have been recognized as non-local. Moreover, the isotopic composition of neodymium (143Nd/144Nd) was analysed for three casting moulds found in grave 24 (Fig. 2; Table 2). The isotopes of this element are the best indicators of the origin of rocks, sediments and related materials (e.g. ceramics) so they allow not only for estimation of the geographical origin of samples, but also for determining their geological age. Because of these advantages, neodymium isotopes are the most frequently used indicator of provenance in geological research. In this method, we obtain several parameters (ratio 143Nd/144Nd, neodymium epsilon eNd, ratio 147Sm/144Nd, value of the model age TDM) for each analysed sample, which together allow for a very precise identification of the raw material origin. Mould No. 8 is made of clay. This material is characterised by an epsilon value of -12.3 and the value of model age TDM = 1.77 Ga, indicating the possibility of the local origin of the material used for the production of this tool. Mould No. 1 is made of sandstone with a model age value TDM = 2.06 Ga. In Europe, such high TDM values are associated with rocks of the East European Platform, which covers the area of Scandinavia (without Denmark), Russia, Ukraine and north-eastern Poland. During the spread of the Scandinavian ice sheet during the Pleistocene period, erratic “Scandinavian” material was transported to Central Europe. In Poland, post-glacial sediments, often containing various erratics, are common in the area of nearly 90% of the territory. Therefore, it is very likely that the sandstone used to produce mould No. 1 was obtained from local Scandinavian materials. Mould No. 3 was made of sandstone, which has similar values of eNd and a similar 143Nd/144Nd ratio as mould No. 1. It cannot therefore be ruled out that this sandstone is also derived from the Scandinavian materials. However, a fully reliable interpretation of this artefact is impossible, because the rock has an unnaturally low of 147Sm/144Nd ratio and therefore its model age is also low (TDM = 1.25). Although rocks of this model age are known from other areas of the world, in Europe they are found only in Scotland. Therefore, it is very probable that the low ratio of 147Sm/144Nd is the result of the secondary removal of the samarium from this rock, most likely during the interaction with hot metal (bronze).