The provenance study of archaeological materials is an important step in understanding the cultural and economic life of ancient human communities. One of the most popular approaches in provenance studies is to obtain the chemical composition of material and process it with chemometric methods. In this paper, we describe a combination of the total-reflection X-ray fluorescence (TXRF) method and chemometric techniques (PCA, k-means cluster analysis, and SVM) to study Neolithic ceramic samples from eastern Siberia (Baikal region). A database of ceramic samples was created and included 10 elements/indicators for classification by geographical origin and ornamentation type. This study shows that PCA cannot be used as the primary method for provenance purposes, but can show some patterns in the data. SVM and k-means cluster analysis classified most of the ceramic samples by archaeological site and type with high accuracy. The application of chemometric techniques also showed the similarity of some samples found at sites located close to each other. A database created and processed by SVM or k-means cluster analysis methods can be supplemented with new samples and automatically classified.

In this study, the assessment of uncertainties introduced at different stages of the elemental analysis of archaeological ceramics has been described using the example of the Neolithic pottery sherds from Popovsky Lug (eastern Siberia). To evaluate the uncertainty introduced by sampling due to ceramic heterogeneity, three original sherds were cut into small subsamples. Powdered subsamples (250–350 mg) were analyzed using wavelength-dispersive X-ray fluorescence and inductively coupled plasma mass spectrometry methods, and the variations between analytical results for independent subsamples were compared with the variations introduced during the analytical process (measurement and sample preparation). It was shown that 250–350 mg of ceramic is sufficient to obtain good reproducibility (2–15%) between separate subsamples for most major and trace elements, even for the heterogeneous Neolithic ceramics included in this study. The differing behavior of concentration variations in some elements was explained by measuring the ceramic cross-sections by scanning electron microscopy and micro-X-ray fluorescence spectrometry, as well as by the theoretic modeling of the sampling error. The described workflow can be useful in finding uncertainties in elemental analysis results, which may affect the interpretation of bulk chemical composition in ceramic provenance studies.

Wavelength-dispersive X-ray fluorescence analysis (WDXRF) and total-reflection X-ray fluorescence (TXRF) analysis were applied to study the elemental composition of the Late Neolithic ancient ceramics collected at the Popovsky Lug burial site (Kachug, Upper Lena river, Russia). Semi-quantitative non-destructive analysis of ceramic pieces showed that measurements of the upper and lower sides of the ceramic are less informative than the measurement of its cut. Various sample preparation techniques for the low quantity of crushed ceramics such as fusion, pressing and preparation of suspensions were compared to preserve the material. Samples were prepared as 150 mg fused beads and 250 mg pressed pellets for WDXRF, and as suspensions of 20 mg sample based on the aqueous solution of the Triton X-100 surfactant for TXRF. Certified methods were used to validate the obtained contents of rock-forming oxides and inductively coupled plasma mass spectrometry was used to confirm the results of trace elements determination. Based on the carried-out studies, a combination of the wavelength-dispersive X-ray fluorescence analysis (glass) and total-reflection X-ray fluorescence analysis (suspension) methods was chosen to obtain the data on the elemental bulk composition of archaeological ceramics. The proposed combination allowed the quantitative determination of Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe, V, Cr, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Pb, and Ba from the sample of crushed ceramics weighing only about 170 mg.