PIXE analysis and provenance study of archaeological potsherds from West Africa

Abstract

The present work is part of an archaeometrical programme dealing with prospection and analytical studies of sites contemporaneous with the West-African Empires during the Middle Ages. The measurement of the chemical composition of archaeological potsherds has been undertaken using PIXE analysis in order to characterize the production areas and to investigate commercial and cultural exchanges in the Inland Niger Delta (Mali). Samples consist of thick clay pellets pressed without binding material. Irradiations were performed in the proton beam of a 4 MV Van de Graaff accelerator. Experimental conditions were the same as those suggested in a previous work. The analysis of a standard pottery has shown that the concentration of more than twenty elements, heavier than aluminium, can be measured with good reproducibility and sufficient accuracy. Experiments were carried out in two steps, a 1 MeV irradiation for detection of elements ranging from aluminium to iron, and then irradition by 3 MeV protons for elements heavier than iron. Five archaeological sites have been considered and especially the megalithic sites of Tondidarou and Dabi, both on the shores of the Tagadji lake, in the South-West of Tombouctou. The results are discussed using statistical treatment and cluster analysis. The typical composition of the clay from this region is then presented.