Coarsely crystalline cryogenic cave carbonate – a new archive to estimate the Last Glacial minimum permafrost depth in Central Europe

Abstract

Abstract. Cryogenic cave carbonate (CCC) represents a specific type of speleothem whose precipitation is triggered by freezing of mineralized karst water. Coarsely crystalline CCC, which formed during slow freezing of water in cave pools, has been reported from 20 Central European caves located in Germany, the Czech Republic, Slovakia and Poland. All these caves are situated in an area which was glacier-free during the Weichselian. Whereas the formation of usual types of speleothems in caves of this region usually ceased during the glacials, coarsely crystalline CCC precipitation was restricted to glacial periods. Since this carbonate type represents a novel, useful paleoclimate proxy, data from its Weichselian occurrences in caves in Central Europe were collected, including their C and O stable isotope values, U-series ages and depth below the surface. When using only the CCC data from caves with limited cave ventilation, the permafrost depths of the Weichselian can be estimated to be at least 65 m in the lowlands and uplands. An isolated CCC find indicates that Weichselian permafrost penetrated to a depth of at least 285 m in the High Tatra mountains, Slovakia. A model of the formation of coarsely crystalline CCC assumes its formation especially during periods of permafrost thawing. U-series data confirm that permafrost depth changed and CCC precipitation in deep caves occurred repeatedly in the studied area during marine isotope stages 4, 3 and 2. One important phase of coarsely crystalline CCC formation related to permafrost thawing occurred between 40 and 21 ka BP, and the last phase of its formation was related to the final permafrost destruction between 17 and 12 ka BP.

Holocene climate change, permafrost and cryogenic carbonate formation: insights from a recently deglaciated, high-elevation cave in the Austrian Alps

“…Although the main descending gallery in the MSK Cave until very recently contained ice several meters thick, CCC coarse only formed in two side chambers far from the entrance; these were obviously also ice-filled at some point allowing the formation of these cryogenic minerals. This is consistent with observations from other caves where CCC coarse typically also formed in the deep interior (Žák et al, 2012;Richter et al, 2009), where ventilation was very limited and stable thermal conditions prevailed. once the ice was completely gone and the calcite crystals were released the ice did not regrow.…”

“…CCC coarse has never been observed in statu nascendi and most dated occurrences in central European caves are from the last glacial period (Žák et al, 2012;Richter et al, 2013;Orvošová et al, 2014). Interestingly, the youngest currently known occurrence is from a cave in the Swiss Alps located at the threshold of modern permafrost and dates from the medieval period .…”

Deep structures of slopes connected with sandstone crags in the upland area of the Świętokrzyskie (Holy Cross) Mountains, Central Poland

“…Climatic fluctuations resulting in permafrost oscillations in the older Vistulian were recorded by palaeontological, lithological and other records, e.g. interstadial soils, which were formed 80-75, 55-50 and 32-28 ka ago (Maruszczak, 1986;Dybova-Jachowicz and Sadowska, 2003;Lindner and Marks, 2008;Žák et al, 2012). However, the development or initiation of these structures during the glaciations of the Middle Polish Complex (= Saalian) is also possible.…”

Speleothem Stable Isotope Records from Eastern Europe & Turkey

“…Coarsely crystalline cryogenic cave carbonates (CCCcoarse) from Central Europe represent a novel archive to study the extent of permafrost in the past (e.g. [102][103][104][105] CCCcoarse deposits are formed because permafrost thawing allows water starts to percolate through the epikarst and penetrate into the still-frozen cave system where it slowly freezes, becoming increasingly enriched in ions until the solution is supersaturated and carbonate precipitates [102]. Cryogenic carbonate has a very specific isotope composition [105,106].…”