A6: Late Pennsylvanian paleoclimate and depositional systems of Central and Western Bohemian Basin

1 day, 22 June, Czech Republic; Trip leaders: R. Lojka1, S. Opluštil2
1Czech Geological Survey, Czech Republic; 2Charles University, Czech Republic
Contact: richard.lojka@geology.cz
Price: 80 EUR
 
Transportation: bus; Participants: Minimum 13, Maximum 20
Departure: Prague, Hotel Diplomat (7:30); Return: Prague, Hotel Diplomat
Includes: field trip guidebook, transportation, lunch packet.
Degree of physical difficulty: Intermediate level of physical fitness is required. The trip will include short walks (trekking shoes are recommended). Hard hats will be provided.
 
The Central and Western Bohemian basin is a complex of intermontane basins formed on top of the collapsed plateau in the Variscan orogen's interior. They share a similar sedimentary record and stratigraphy and thus likely comprise several once interconnected depocenters. Individual basins developed as grabens and half-grabens filled by fluvial to lacustrine successions, intercalated with several ash-fall tuff horizons between c.314 and 297 Ma (latest Duckmantian to middle to late Autunian). During this 1-day field trip, architectures and facies of different fluvial styles will be examined. Controls on development of fining upward fluvial cycles and paleoclimate record in associated clastic paleosols will be discussed. In one locality, fine-grained, organic- rich clastics of a relatively deep-water lacustrine system with prodelta turbidites and lobes will be demonstrated. The excursion will end with a tour of the Pilsner Urquell brewery that uses water from Pennsylvanian arcose aquifers for brewing its world-class beer.
 
 
Left: Alluvial red beds comprise series of floodplain channels, crevasse splays and levee deposits cut by ribbon sandstone of trunk channel. Kryry brick pit, Líňě Formation, lowermost Permian (Asselian); Right: Fining upward fluvial cycle comprise basal conglomerate sheets and lenses of thalweg fills, overlaid by sandy cross beds of barforms that are capped by silty bar top deposits or abandoned channel fills. Kaznějov kaoline quarry, Kladno Formation, Middle – Upper Pennsylvanian boundary.
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