Institute of Geology AS CR, v. v. i.
Medium-sized research center which main purpose is to gain, interpret and integrate the knowledge of the Earth System.
Cryogenic cave carbonates – a new tool to estimate the minimum permafrost depth of the Last Glacial
Cryogenic cave carbonates can be identified in caves based on their characteristic mode of occurrence, typical shape, unique carbon and oxygen stable isotope compositions, and based on ages confirming their formation during the Glacial. Low-ventilation caves generally show temperature close to those of the surrounding rock. Cooling of such caves to freezing and/or subfreezing temperature is possible only due to evolution of permafrost (permafrost is the zone of soils and rocks having temperature 0 °C or lower for at least two subsequent years).
Within a project financed by the Czech Science Foundation data on occurrence of cryogenic cave carbonates have been collected in a large territory of several countries. The samples were dated by U-series method. The results show that the permafrost of the last Glacial started to develop in lowlands and highlands since 70 thousand years before present (ka BP). The permafrost depth oscillated and reached its maximum between 40 and 21 ka BP. The destruction of the permafrost (thawing) occurred between 17 and 12 ka BP. In the lowlands and highlands of Germany, Czech Republic and southern Poland a depth of 65 m was verified as a minimum permafrost depth of the last Glacial.
Reference: Žák, K. – Richter, D. K. – Filippi, M. – Živor, R. – Deininger, M. – Mangini, A. – Scholz, D.: Coarsely crystalline cryogenic cave carbonate – a new archive to estimate the Last Glacial minimum permafrost depth in Central Europe. Climate of the Past, roč. 8 (2012), s. 1821–1837.
Contact: Karel Žák, 233 087 215, zak
gli [dot] cas [dot] cz