Pre-conference field trip: Assembly of the Variscan Orogenic Wedge

Ondrej Lexa, Petr Jeřábek & Stephen Collett

The excursion will demonstrate key aspects of tectono-metamorphic evolution of the Erzgebirge including its early history, subduction related UHP metamorphism and later two stage exhumation. During the excursion we will focus on structural, metamorphic and geochronological record in rocks with contrasting metamorphic grade starting from phyllite (Stop 1), to micaschist, orthogneiss, mafic eclogite (Stops 2,4 and 5) and UHP orthogneiss (Stop 3). The protoliths of these rocks and their earlier pre-Variscan evolution will be discussed at Stop 2. General architecture and evolution of the Erzgebirge orogenic wedge will be discussed throughout the excursion.

Post-conference field trip: Quaternary geodynamics of the seismoactive Cheb basin

Petra Štěpančíková, Tomáš Fischer & Miroslav Coubal

The excursion will show several sites with Quaternary tectonic and volcanic activity and the present-day geodynamic features in the Cheb basin, which is a western part of Cenozoic Eger rift. The Cheb basin is famous by Pleistocene volcanoes and maars, mantle-derived CO2 emanation and by present-day fluid-driven earthquake swarms. During the excursion we will visit Kopanina site (Stop 1), where paleoseismic trenches (already closed) revealed late Quaternary (up to Holocene) surface-rupturing earthquakes.  At Stop 2 Skalná we will visit a gallery monitoring site with seismic stations and other monitoring instruments. Stop 3 will bring us to mid-Pleistocene volcano Komorní hůrka, where stress field conditions and changes were recorded within the basaltic lava flows. Stop 4 represents SOOS national natural reserve with active bubbling mofettes (cold CO2 gas vents), mineral springs and diatomite deposits. Stop 5 will then show natural mantle-derived CO2 emanation and its monitoring in the floodplain of Plesná river.