Corrosion of carbonate speleothems by an allogenic river inferred from petrography and a weight loss experiment : a case study from the Demänová Cave System, Slovakia

The crystallization of speleothems can be interrupted by the invasion of allogenic water into cave passages. These interruptions were studied, both in speleothems currently submerged in an underground river and in speleothem sections, which were found at the lowermost fluvially active passage level of the Demänová Cave System. The interaction between speleothems and allogenic water, undersaturated with respect to calcite, is manifested in the presence of siliciclastic material and the corrosion of calcite crystals. The progressive development of corrosion features depends on the duration of the interaction of calcite crystals with allogenic water. Moreover, the movement of the water and siliciclastic deposition over the speleothems can influence the corrosion process. The estimated rate of corrosion, caused by the underground Demänovka River and measured by the weight loss of experimental tablets, is up to 0.029 mm/y. U-series dating indicated that the interaction of speleothems with allogenic water occurred during the Vistulian (Weichselian). The identification of corrosion episodes, caused by allogenic water, is a step towards understanding the origin of hiatuses and establishing criteria for recognition of them.