Climate-induced changes in Holocene calcareous tufa formations, Bohemian Karst, Czech Republic
2002; Elsevier BV; Volume: 91; Issue: 1 Linguagem: Inglês
10.1016/s1040-6182(01)00107-0
ISSN1873-4553
AutoresKarel Žák, Vojen Ložek, Jaroslav Kadlec, Jana Hladı́ková, Václav Cı́lek,
Tópico(s)Geological formations and processes
ResumoAbout 70 localities where Holocene calcareous tufa is formed recently and/or was formed in the past are known in the Bohemian Karst, a small karst area located SW of Prague. All known tufa accumulations display a very similar pattern of lithological and biostratigraphic evolution, reflecting climatic changes, erosion events and biota succession. A 17 m thick tufa accumulation at Svatý Jan pod Skalou was selected and thoroughly studied as a typical, well developed representative of local tufa deposits. Tufa formation started at about 9500 BP, on a flat fluvial gravel terrace of Late Glacial/Early Holocene age. Deposition of lithologically uniform, pure hard porous tufa continued until about 6500 BP. From that time, a more unstable climate with several dry periods and erosion events produced a lithologically varied complex of loose tufa alternating with embedded soils and scree layers. Termination of the tufa deposition occurred about 2500 BP, and was followed by partial erosion connected with relocation of the spring below the tufa body. Holocene climatic changes were recorded in lithology, molluscan assemblages, and oscillations of oxygen and carbon stable isotope ratios in carbonate. The observed patterns are in good agreement with the evolution of calcareous tufa deposits throughout Central Europe.
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