Metamorphic evolution of mica-schists and their tectonic position in the Polička Crystalline ComplexArticle PDF
Metamorphic evolution of mica-schists and their tectonic position in the Polička Crystalline Complex
The Polička Crystalline Complex is situated in the eastern part of the Bohemian Massif. This metamorphosed volcano-sedimentary complex is composed mainly of biotite to two mica gneisses. Micaschists are present only as small lenses or bodies within gneisses, which represent typical rocks of the Polička Crystalline Complex. Based on the geological position, two types of mica-schists were recognized: (i) Mica-schists with mineral assemblage Qtz+Ms+Bt+Grt±Pl±Sill are situated along the contact with the Svratka Crystalline Complex (W boundary Polička Crystalline Complex). These mica-schists yield PT conditions of 642 ±124 °C and 8 ±2 kbar. (ii) Mica-schists with mineral assemblage Qtz+Ms+Bt±Pl±St±Grt±Pl±Ky form several N-S oriented stripes between villages Stašov, Hamry and Jedlová on NE margin of the Polička Crystalline Complex. Mica-schists in this part of the Polička krystalline Complex indicate peak P–T conditions of ~650 °C and ~8 kbar and younger decrease of pressure to about 7 kbar and 660 °C, related to thrusting of the Letovice Crystalline Complex over the Polička Crystalline Complex. According theirs mineralogy and geological position can be the mica schists interpreted as tectonic slice rocks from surrounding units (Svratka and Letovice Crystalline Complex) incorporated into the volcano-sedimentary complex of the Polička Crystalline Complex during Variscan orogeny.
David Buriánek, Czech Geological Survey, Leitnerova 23, Brno, e-mail: firstname.lastname@example.org