Cryogenic carbonates and cryogenic speleothem damage in the Za Hájovnou Cave (Javoříčko Karst, Czech Republic)

Abstract

As so ci ate ed i tor: Tadeusz M. Peryt A new lo cal ity of coarse-grained cryo genic cave car bon ates has been found in the Za Hájovnou Cave in Javoøíèko Karst in Cen tral Moravia, Czech Re pub lic. Crys tals and crys tal ag gre gates, usu ally up to 15 mm in size, form typ i cal loose ac cu mu lations on the sur face of large fallen lime stone blocks and clays cov er ing the bot toms of sev eral cave cham bers dis tant from the cave en trance. The cryo genic or i gin of the car bon ates is sup ported by their mode of oc cur rence, spe cific crys tal and aggre gate mor phol ogy, and C and O sta ble iso tope data. Use ries dat ing of one sam ple of cryo genic car bon ate (age 29.5 ±0.1 ka) in di cated that a pe riod of karst wa ter freez ing oc curred in ma rine iso tope stage (MIS) 3, within the Weichselian. The cave also hosts nu mer ous ex am ples of speleothem dam age. As shown in this pa per, some of these are clearly con nected with freez ing con di tions and cave ice ac tion.

Increased autumn and winter precipitation during the Last Glacial Maximum in the European Alps

“…CCC thus document that perennial ice close to the melting point was wide-spread in the Obir caves during the LGM. This is consistent with the occurrence of detached stalagmites in the same rooms and galleries, a deformation feature known from caves that were located in the permafrost zone during the last glacial period and where ice movement has caused wide-spread damage of older stalagmite generations 28 , 29 . Mapping of CCC and detached stalagmites, however, only provides a minimum estimate of the former extent of ice in these caves.…”

“…Petrographic studies reveal the presence of only one type of CCC in some places and of two or three types in others, an observation also commonly made in other caves hosting CCC 29 , 30 . The ages of different CCC types within individual heaps commonly differ by up to several hundred years.…”

Damaged Speleothems and Collapsed Karst Chambers Indicate Paleoseismicity of the NE Bohemian Massif (Niedźwiedzia Cave, Poland)

“…Žák et al. (2019) suggest permafrost thickness >50 m in Central Moravia (Czechia) during the Pleistocene (south of the study area). Concerning the present‐day morphology, the in‐cave sampling sites are located 60–115 m from the slope surface, measured vertically, and from 75 to more than 150 m measured horizontally.…”

“…However, U‐Th‐documented speleothem growth during cold periods implies the long‐term presence of unfrozen percolating water inside the cave (Figure 8), which would contradict deep (>50 m) permafrost existence. Notably, one of the known problems with testing the "creeping ice theory” (e.g., Kempe, 2004; Žák et al., 2019) is that ice cover inside caves grows for hundreds of years (Hercman et al., 2010), and it can disappear abruptly in just a few decades. For this reason, when dating old speleothems (>150 ka), short‐term episodes of ice growth and disappearance can be unrecorded.…”

“…(2015) postulated an earthquake origin, while Žak et al. (2019) stated that the caves were also affected by ice. Furthermore, other causes of speleothem deformation, such as clastic substratum movements (compaction, soil creep, gravitational mass movement or liquefaction), floods, mud and debris flows, and human or animal impacts, are also possible.…”