Metamorphic evolution of the amphibolites from the polish part of Stare M sto Zone (Sudetes, SW Poland)

The Stare Mìsto Zone is the lowermost part of Lugicum, marking out the main boundarybetween the East and West Sudetes. Small part of the unit is exposed in Poland, in the vicinity of Bielicevillage. This area consists mainly of banded amphibolites, intruded by syntectonic granitoids. The bandedamphibolites are medium — to coarse grained. Main constituents are segregated into alternating, light —plagioclase rich, and dark—amphibole rich layers. Quartz and K-feldpars are subordinates. Accessories are:zircon, apatite, titanite, and locally garnet, biotite; secondary minerals are: chlorite and prehnite. Bandedamphibolites underwent progressive M1 amphibolite facies metamorphism, with PT peak conditions at650–720C and 8.0–9.5 kbar. This was followed by M2 and M3 regressive metamorphism, accompanied byrapid uplift, regional mylonitization and metamorphism under the greenschists and sub-greenschsits faciesconditions.