Metapelite from the high? to ultrahigh?pressure terrane of the Eastern Alps (Pohorje Mountains, Slovenia)—New pressure, temperature and time constraints on a polymetamorphic rock

The Austroalpine nappe stack of the Pohorje Mountains (Mts.) in northeastern Slovenia comprises a suite eclogite facies metamorphic rocks that were partially assigned to Eo-Alpine ultrahigh-pressure metamorphism (UHPM). We selected micaschist, which was previously related this metamorphism, for detailed study including chemical zonation garnet and potassic white mica, identification mineral inclusion assemblages, pseudosection modelling with PERPLE_X, monazite in-situ dating electron microprobe. Polymetamorphism revealed by (at least) two generations phengite four populations yielding ages 283.6 ± 6.1 (2?), 94.1 3.7, 47.9 10.8 26.2 2.8 Ma. Permian population is characterized relatively high Y contents (~1.15 wt% Y) low La/Gd mass ratios (8.7) indicating its formation before growth porphyroblastic garnet. population, however, grew synchronously based on (~0.05 wt%) (21.4). older Tertiary (48 Ma) shows also (1.1 (10.6) whereas younger contents. P–T conditions 7.5–10 kbar at 600–650°C obtained using assemblage staurolite+rutile+biotite High pressure (HP) but no UHPM reconstructed both coarse (Si = 3.22 per formula unit pfu) small garnet+fine-grained 3.27 peak pressures ~16 18.5–23 respectively. Maximum temperatures close 650°C likely reached during HP event, those event probably ~580°C. These events suggest Mts. experienced an subduction–exhumation history, latter mainly reported underlying Penninic nappes so far.