P–T paths and modeling the evolution of metapelitic mineral assemblages in the MnNCKFMASH system: A case of Northern Ladoga area

Phase equilibria in medium-grade metapelites of the Northern Ladoga area are calculated with the pseudosection method and Theriak/Domono software on the basis of zoning in garnets. It is shown that garnet in the staurolite-bearing parageneses crystallized at 520–600°C against the background of a pressure release from 7.0 to 3.5–4.0 kbar. The evolution of the mineral composition of rocks in the course of porphyroblast formation is discussed, placing special emphasis on the comparative analysis of P–T paths of garnet growth under decompression conditions.