Abstract :
By Korzhinsky and Schrienemakers, methods, phase relations of Mn-Al-Ca-silicates and other minerals in highly oxidized quartzites and schists of blueschist type metamorphism have been discussed. Because, such rocks were extensively studied in central Shikoku of Japan and in Andros and Evvia islands of Greece, they have been considered as thermodynamic system for discussion. The system contains piemontite, braunite, surssasite, spessartine, pumpellyite, phlogopite, clinochlore, talc and kyanite with excess muscovite, quartz and water. System components include Al2O3, Mn2O3, MnO, CaO, MgO and K2O with excess SiO2 and H2O. Application of Korzhinsky and Schrienemakers, methods into the system gives three independent petrogenetic girds. Considering the chemographic relationships in the petrogenetic gird of [Su]-[Tlc]-[Pi], it can vividly be concluded that highly oxidized Mn-bearing quartzites or schists in blueschist facies divided to low temperature assemblage (Su + Pmp + Clin + Pi), medium temperature assemblage (Clin + Sps + Bru + Pi) and high temperature assemblage (Tlc + Sps + Br + Pi). Application to natural assemblages, show correspondence between different natural assemblages in response to variable physical conditions and their relative stability predicted from Korzhinsky and Schrienemakers, methods.
