Geochemistry and Petrogenesis of Post-Collision Pangeon Granitoids in Central Macedonia, Northern Greece

Abstract

Abstract The Pangeon granitoids in northern Greece are intrusive into metamorphic rocks of the Lower Tectonic Unit of the Rhodope Massif. They are characterized by two distinct petrological types: A medium- to coarse-grained porphyritic, hornblende-biotite bearing tonalite to granodiorite (PTG), and a fine- to medium-grained biotite granodiorite to two-mica granite (MGG). Biotite-hornblende bearing mafic microgranular enclaves of monzodioritic composition (MME) are present in the PTG rocks. The granitoids have characteristics of high-K calc-alkaline metaluminous (PTG) to slightly peraluminous (MGG) rocks. The sharp contacts between the two types and the different compositional trends shown by them indicate the existence of two magma pulses. It is considered that partial melting of the same source rock, but under different P-T conditions, produced the magma pulses. These conditions were slightly higher for the PTG rocks than the MGG ones. The chemical variations within each group suggest a major crystal fractionation, accompanied by contamination. The Pangeon granitoids are enriched in K, Rb, Ba and Th relative to Nb, Zr, Sm and resemble post-collisional granites.