QUANTIFICATION OF MICROSTRUCTURAL FEATURES THROUGH IMAGE ANALYSIS IN THE MESOLITHIC AND NEOLITHIC POTTERY FROM AL KHIDAY (KHARTOUM, SUDAN)

摘要

The main aims of archaeometric analysis on archaeological pottery usually are the characterisation of the production technology and the provenance of raw materials. In this study, Mesolithic (Ⅶth millennium BC) and Neolithic (Ⅴth millennium BC) potsherds (212 samples) from Al Khiday 1 and 10-W-4 sites (Khartoum, Sudan) have been analyzed in order to define a model for the production technology. Minero-petrographic composition and quantification of inclusions, in terms of absolute abundance within the ceramic paste, grain-size distribution and shape were defined for the most representative potsherds (25 samples), one for each of the petrographic groups microscopically defined, in order to quantify the differences in the ceramic pastes, and, therefore, to define the different production recipes. Quantitative description of the microstructural features, particularly inclusions, of pottery samples was obtained by image analysis (IA), a powerful tool to extract meaningful information from two-dimensional images by means of image processing techniques. IA was performed on backscattered electrons images (SEM-BSE images) and elemental chemical maps, acquired with a CamScan MX 2500 microscope, equipped with a LaB_6 cathode. The result of IA, represented by a segmented image where all the textural features can be separately analyzed, was used to obtain a binary image for each feature. Particle analysis was performed on binary images in order to quantify different parameters that describe inclusions shape, size and quantity; results obtained were compared through statistical software. Significant differences were observed between the production recipes of Mesolithic and Neolithic pottery and also within Mesolithic repertoire, suggesting that the great variability in the Mesolithic production can be related to a low grade of standardization in the production processes, while the decrease of variability in the Neolithic pottery may be due to changes in the society organization, leading to a higher grade of production standardisation.