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The north-western part of Brunovistulicum was shaped by polyphase Variscan deformations, metamorphism and multiple westward thusting. Metavolcanic rocks as amphibolites, quartz-amphibole rocks, greenstones and granitoids are present within metasediments of the Proterozoic Desna Series (that consists of biotitic paragneisses, migmatites and mylonites), covered by quartzites, marbles, mica and quartzite schists of the Early and Middle Devonian Vrbno Series which is followed by the Andelska Hora Formation (Late Devonian-Early Carboniferous) of a flysch character. The youngest flysch sediments in the Opava Mts with presence of greywackes consist of the Horni Beneszov Formation, which is Early Carboniffeous in age.
Metamorphic zonation of progressive character from south towards north is confirmed by mineral assemblage of the rocks and plagioclase composition within amphibolites. Temperature calculated on pairs of neighbouring amphibole and plagioclase grains which recorded progressive character of metamorphism is lower at the south of the Opava Mts. Big amphibole crystals, which reveal differences in chemical composition of cores and rims, grew during increase of temperature. Small, uniform amphibole crystals reveal temperatures of their forming similar to the outer parts of the big ones. Field examination, relicts of an ophiolitic texture and geochemistry of amphibolites and greenstones indicate their igneous origin. The protoliths of the investigated rocks must have been tholeitiic basalts.
Six stages of tectonic evolution of the north-western edge of Brunovistulicum were established: stage (1) Late Devonian rifting; stages (2 & 3) which probably started in Middle Visean in condition of dextral transpression causing thrusting displacements of NNE-SSW direction (top towards SSW). Both stages were connected with Early Carboniferous oblique undertrusting of the Brunovistulicum terrane under Moldanubicum terrane together with continental accretionary wedge formation. Stage (4) deformations took place after Namurian A under sinistral transpression causing westward trusting and NE-SW folding. Stage (5) proceeded in dextral transpression conditions forming NE, ENE or E thrusting, probably after Westphalian B, and stage (6) deformations took place in Late Carboniferous time, revealing multiphase thrusting toward NE.
Wedge eduction and Late Carboniferous transpression lasted from stage (4) up to stage (6). Extensional regime within described area with magmatic episodes proceeded in stage (1) and after stages (3), (4) and (5).
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