Hranice Abyss and Hranice Karst; half-day field trip
With its 404 m of depth, the Hranice Abyss (Hranická propast) is currently the deepest underwater cave in the world. It is located in a small karst area, developed in Devonian carbonate rocks, which however underwent a long and interesting history of karstification. Water filling the abyss is strongly enriched in endogenic CO2, which is at least partially sourced from Earth´s mantle and which finds its pathway to the Earth surface along deep-seated faults. This carbon dioxide is primarily responsible for karstification in the Hranice Karst, making it a unique example of so-called hypogenic karst. Nearby located hills, however provide evidence of much older karstification. Geophysical surveying and drilling works demonstrate that before mid-Miocene, the Hranice Karst developed as a tropical cockpit (mogote) karst leaving behind mogotes with >50 m height and ~100 m diameter, which were later buried by mid-Miocene marine mudstones. This field trip will include visit to the main karst features near Hranice, including the Hranice Abyss and the Zbrašov Aragonite Cave with CO2 pools, and discussion of the karts features directly in the field. This easy field trip is appropriate for the broad masses of participants and accompanying persons. Stay one day more in Olomouc and enjoy geological beauty of its surrondings!
Route plan: Olomouc – Teplice nad Bečvou – Zbrašov – Lipník nad Bečvou (Helfštýn castle, optional) – Olomouc.
Leaders: Ondřej Bábek, Ondřej Šráček
Price: to be announced
Where the Variscan and Alpine orogens meet: Cainozoic evolution of the Upper Morava Graben; one-day field trip.
Constituting a system of linear basins, about 80 x 20 km in dimensions, the Upper Morava Graben represents a distinct crustal structure of the NE Bohemian Massif developed in foreland of the Western Carpathians´ orogenic front. Delimited by NW–SE-striking faults, this crustal domain is characterised by Late Cainozoic volcanic activity, present-day seismicity, evidence of palaeoseismicity and increased CO2 fluxes. The faults, which lend the entire area a conspicuous horst-and-graben morphology, can be traced in geophysical image, in particular as steep gradients on gravity maps and in shallow resistivity surveying. The Upper Morava Graben developed by Cainozoic rejuvenation of faults of the Elbe Fault System in response to the tectonic loading by thrust sheets of the Western Carpathians, representing a unique example of foreland tectonics comparable, to a certain extent, to the European Cainozoic Rift System. The tectonic processes resulted in varied geological and geomorphological features. During the field trip, we will visit several outcrops to see the geological evidence of Late Cainozoic volcanism and sedimentation in the graben, as well as some important viewpoints to observe the morphology of the basin. Moreover, geophysical and drilling data will be demonstrated and discussed in the field. This field trip it designed for participants deeper interested in geology of Olomouc region. Discover places you would not expect to find somewhere in Middle Europe!
Route plan: Olomouc – Svatý Kopeček – Šternberk – Uhlířský vrch u Bruntálu – Mezina – Razová – Těšíkov – Olomouc.
Leaders: Ondřej Bábek, Daniel Šimíček
Price: to be announced