Isotope geochemistry in the archaeomertical ceramic analysis

Farkas Pintér

State Center for the Restoration and Conservation of Historic Monuments, Scientific Laboratory

pinterfarkas@yahoo.com

Abstract

The radiogenic isotope geochemistry is a widely used analytical method among the geochemical analyses. Radiogenic isotopes (e.g. ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, etc.) are mostly used for absolute dating of minerals and rocks, or they can also be used as tracers in the characterization of geological regimes, rocks and areas. According to the analyses of the magmatic and metamorphic rocks, the radiogenic isotopes were successfully applied in the research of siliciclastic sediments. The main results of these researches can be concluded in the following:

• the averaged radiogenic isotopie composition of the material of the sedimentary basin reflects the averaged isotopic composition of the source area of the sediments
• sedimentation, burial and higher temperature do not effect the initial isotopic composition of the materials
• siliciclastic sediments belonging to the same geological formation have homogenous isotopic composition.

Until the mid 90ties the radiogenic isotopes have not been used as tracers in the archaeometrical pottery analyses. The first successful attempt to use this method for ceramics and comparative sediments was at the University of Tübingen (Germany). The method seems to be well-applicable, however due to its high costs it cannot be regarded as a wide-spread analytical method in the pottery analysis yet.

The benefits of the method are:

• very small amount of sample
• radiogenic isotopes are inert for secondary (burial, firing, etc.) effects
• results are direct comparable with geological or with locally produced ceramic samples

Notwithstanding these benefits, the radiogenic isotopes cannot substitute for petrographic and other chemical methods; only the combined use of these methods can give effective provenance. In addition to this, the accurate knowledge of the geology of the potential raw materials and the place of find of the sherds is also necessary. Especially the presence of deliberately added temper (e.g. volcanites, magmatites, sand, etc.) from crushed rocks or from another geological formation can hard influence the bulk isotopic composition of the analysed sample. In case of fine wares this effect is negligible.