SILCRETE AND CHERT AS SOURCE ROCKS OF EARLY PREHISTORIC ARTIFACTS: THE CASE OF CENTRAL EVIA (GREECE)

Abstract

Silcrete and chert were used for the manufacture of stone tools in early prehistoric (Middle / Late Palaeolithic and Mesolithic) times in Central Evia island. We have undertaken an analysis of visual characteristics of pre-historic artifacts and the potential source rocks exposed in the area to provide evidence of use of locally avail-able raw material. Field geological surveys indicate that silcrete, chert nodules in limestones, and varicolored cherts within siliceous mudstones and sandstones in the area were potential raw materials for prehistoric knappers. Geological mapping and detailed studies of the mineralogy, texture and geochemistry of critical rock types demonstrate extensive use of different silcrete facies associated with weathered ultramafic ophio-litic rocks and chert nodules occurring within Upper Cretaceous limestones. SEM, XRF, XRD and ICP-MS analytical methods were employed. The hard, massive, buff reddish-brown variety of silcrete triggered the main interest of prehistoric knappers. Provenancing of lithic tools made of silcrete is facilitated by the presence of disseminated grains of relictic chromite/spinel and serpentine, and the high Cr, Ni, Fe, Mg, Co, V contents. Chert nodules are depleted in almost all the major, minor and REE elements, except for silica and Ca. It is concluded that the chemistry of cherts alone is not considered a reliable approach to resolve the critical prob-lem of sourcing of chert artifacts, with detailed field surveys in neighboring areas and petrographic analysis needed for compelling source to artifact correlations.