IMPLICATIONS OF PETROGRAPHY AND GEOCHEMISTRY OF ATHINIOS METAMORPHIC UNITS USING PXRF AND GIS ANALYSES IN THERA (SANTORINI, GREECE).
Santorini metamorphic basement is part of the metamorphic complex known as Cycladic Massif, which was formed during the subduction of the Mediterranean lithosphere underneath the Aegean microplate. The two main components of the exposed basement are a complex of low-grade schists and phyllites, which are well exposed in Athinios harbour and overlaid by the crystalline limestones exposed in Mount Profitis Ilias and Mount Mesa Vouno. The Eocene and Miocene metamorphic units present evidence of dynamic metamorphism, and possibly are influenced by a granitic intrusion in Miocene. In this study, a new methodology was developed to study the two units exposed at Athinios. Structural data and rock samples were analysed using a Portable X-Ray fluorescence (PXRF) spectrometer analysis at Athinios and integrated in aGIS (Geographical Information System) software to understand the spatial geochemical variations in the area. PXRF results for the two metamorphic units showed similar geochemical patterns. However, a contour map of TiO2 (%) for the metamorphic rocks of the Athinios area presented intermittent zones of high and low TiO2 concentrations which could indicate hydrothermal remobilization of light elements and an enrichment in Ti. Petrography and geochemistry results suggest the local existence of a ductile-brittle shear zone between the two metamorphic units.