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| Titel |
Cryogenic cave carbonates as an archive of Late Pleistocene permafrost in the Ural Mountains: preliminary results |
| VerfasserIn |
Yuri Dublyansky, Olga Kadebskaya, Hai Cheng, Mark Luetscher, Christoph Spötl |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104667
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| Publikation (Nr.) |
 EGU/EGU2015-4095.pdf |
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| Zusammenfassung |
| A specific type of cave deposits, cryogenic cave carbonates (CCCs), was discovered in the
late 1980s in several caves of Central Europe. Unlike “common” speleothems that form
primarily due to degassing of CO2 from Ca2+ and HCO3- -rich waters, CCCs form by
freezing-induced segregation (Žák et al., 2004). The formation of CCCs, hence, requires the
presence of both liquid water and freezing temperatures. The latter combination
may occur in caves in two situations: (1) freezing-thawing cycles in cave entrance
zones; and (2) degrading permafrost conditions, when the active layer reaches the
cave ceiling, whilst the deeper parts of the cave remain frozen. The latter situation
is associated with a particular type of CCCs, which can be used as a marker for
permafrost conditions. Because cave carbonates can be accurately dated using the U/Th
method, CCCs may be used to identify events of (degrading) palaeo-permafrost
conditions.
In this study, CCCs were identified and sampled in four caves, located along a 1000
km-long transect from the northern to the southern Ural Associating the CCCs to permafrost
conditions was possible on the basis of field observations (locations deep inside the cave, far
from entrance zones) and stable isotope properties (strongly depleted δ18O values, inverse
correlation between δ18O and δ13C).
Chaikovskiy et al. (2014) reported five U/Th analyses of CCC from three caves: 16.7 ka
and 104.8 ka (Divja Cave, northern Ural); and 13.4 ka, 86.5 ka and 125.3 ka (Rossijskaya and
Usvinskaya Caves, central Ural). In this study we report 25 additional U/Th ages from
northern and central Ural, as well as the first CCC age from southern Ural (Shulgan-Tash
Cave).
Most of the younger ages ( |
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