Polymetamorphic greenschists with Al-rich green spinels (the Western Carpathian Mts.)

Abstract

During the course of the UNESCO/IGCP project nr. 442 (1999–2001) the present author, along with several colleagues, has described rare raw material types, used in the Neolithic/Aeneolithic, for the construction of stone implements. A metamorphic rock-type (greenschist) containing a substantial amount of Al-rich green spinels, is of special interest. This raw material type is characterized in this contribution.The rocks, which are the object of the present study, are metamorphic rocks of the greenschist association (containing monoclinic as well as rhombic amphiboles, and Al-rich green spinels in a substantial (5–20 vol. %) amount). Accessory mineralsnot necessarily encountered in each thin section, are olivine, orthopyroxene, corundum, clinozoisite, muscovite, cordierite, various plagioclases (albite and anorthite included), phlogopite, ilmenite, magnetite and sphene. The results of microprobe analyses for individual rock-forming minerals are presented. The genesis of the described rock-types is complicated; they are product of three metamorphic events (M1, M2, M3).