Establishing of the tectonic affinity and pre- Variscan evolution of the Brunovistulian microcontinent (Czech Republic) by U-Pb and Ar-Ar mineral dating of granitoid basement and cover sediments

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The Trans-European Suture Zone separates variscan Europe from the East European Craton margin of the palaeo-continent Baltica. It was formed during several major events lasting from the Cambrian to the Silurian. Due to poor exposure and a complex geological structure, many questions about its origin and evolution remain open.Our primary aim is to investigate the affinity and Early Palaeozoic, pre-Variscan evolution of the Brunovistulian microcontinent and its role in the Trans-European Suture Zone. Most of the Brunovistulian microcontinent basement is not exposed but covered by Neoproterozoic and Cambro-Ordovician sediments and few boreholes have reached crystalline basement. For this reason, we will focus on the southwestern part of the BVM around Brno in the Czech Republic, where basement and cover are well exposed, geological relations are clear and Variscan overprinting is limited.Magmatic zircon from several intrusive phases of I-type hornblende-bearing (grano)diorites and tonalites of the Slavkov Terrane basement will be dated to determine crystallization ages and reconstruct the intrusion history of the terrane. In addition, 40Ar/39Ar step-heating dating of magmatic amphibole and biotite from the same samples will be carried out to establish internally consistent cooling age histories. Magmatic zircons from deformed felsic tuff / ignimbrite layers in the Central Basic Belt basement will be dated to establish crystallization ages and elucidate the relation of the belt to the granitoid basement terranes to the west and east.Zircon and detrital white micas from Devonian clastic alluvial fan and alluvial sediments overlying the basement ("basal clastics") will be dated by in situ, single grain methods for as provenance study and establish their source. Conglomerate layers will be targeted as they contain abundant immature detritus derived from metamorphic and igneous rocks. Clasts of locally derived granitoids and exotic, muscovite-bearing granitoid clasts prove the close link between the conglomerates and the geology of the source areas and the erosional products hold an important key to the origin of the Brunovistulian microcontinent.