The speleogenetic role of air flow caused by convection. 1st contribution

Abstract

In the past some authors described the speleogenetic role of convection in phreatic conditions. Similar effects exist also in the air-filled part of vadose passages of caves as a consequence of an air circulation due to a relevant temperature gradient; the effects can be enhanced by the presence of some acids as, e.g., H2S, H2S04, etc. In this paper the conditions matching convection and condensation which produce typical forms, very similar to those found under phreatic conditions, are discussed both for limestone and gypsum caves. RIASSUNTOIn passato vari autori han no descritto il ruolo speleogenerico di fenomeni convettivi in regime freatico. Effetti analoghi si verificano anche nelle zone emerse di livelli vadosi in conseguenza di una circolazione d' aria provocata dalla presenza di notevoli gradienti termici in atmosfera; questi effetti possono essere esaltati dalla presenza di acidi come, per esempio, H2S, H2S04, ecc. In questo lavoro vengono prese in considerazione, sia per grotte nel calcare che nei gessi, Ie condizioni che possono ponare a convenzione e condensazione provocando COS! forme molto simili a quelle che si riscontrano in condizioni freatiche.

The role and importance of cave microclimate in the sustainable use and management of show caves

“…Condensation in caves �as been addressed in t�e researc� literature, suc� as by Cigna and Forti (1986) and more recently by Dublyansky and Dublyansky (2000), Dreybrodt et al (2005), Auler and Smart (2004) and de Sc�mekal (2003, 2006). The results are also relevant to aspects of tourist cave management.…”

Diagenesis of a drapery speleothem from Castañar Cave: from dissolution to dolomitization

“…Condensation processes are governed by the type and amount of heat transfers in the cave (Dreybrodt et al, 2005). They can be quite intense above thermal lakes where the thermal gradient is high (Audra et al, 2007;Cigna & Forti, 1986) or close to cave entrances, where diurnal or seasonal variations of the air temperature are active (Tarhule-Lips & Ford, 1998). In other situations, cave air temperature and condensation is mainly determined by outside air temperature and cave ventilation rate, which is itself a function of outside air temperature (de Freitas & Schmekal, 2006).…”

Evaporite karst in Italy: a review

“…Also the role of CO 2 in the dissolution mechanisms of gypsum and the deposition of carbonate speleothems in these caves is based on observations in this area (Forti & Rabbi, 1981), as is the importance of condensation waters (Cigna & Forti, 1986). Furthermore, the possibility to use the deviation of speleothems' growth axes as indicators of past earthquakes, first detected in speleothems from Frasassi cave (in limestone, Marche), were also studied in a stalagmite of a gypsum cave (Buco dei Buoi) near Bologna (Forti & Postpischl, 1980).…”