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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That unsaturated flow is 1. the movement of water in a porous medium in which the pore spaces are not filled to capacity with water [22]. 2. two phase flow through pores only partially filled with water and air [16].?

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Original article

UIS KHS Commission
Rates of condensation corrosion in speleothems of semi-arid northeastern Brazil
Abstract:

Condensation corrosion is a little studied, but important dissolutional process that occurs within caves in many karst settings around the world (for a review see Dublyansky and Dublyansky, 2000). Condensation corrosion occurs when air equilibrates with the cave atmosphere, becomes acidic and dissolves the bedrock and speleothems. It is a later vadose process that apparently depends on air circulation patterns, number of entrances and general configuration (vertical range, presence of ponded water, passage shape, etc) of the cave. Both bedrock and speleothems can be affected by the process, resulting in weathered outer surfaces. Condensation corrosion in speleogenesis has been regarded as responsible for dissolutional modification during later stages of cave development of coastal (Tarhule-Lips and Ford, 1998) and hypogenic caves (Hill, 1987; Palmer and Palmer, 2000).
Condensation corrosion is a little studied, but important dissolutional process that occurs within caves in many karst settings around the world (for a review see Dublyansky and Dublyansky, 2000). Condensation corrosion occurs when air equilibrates with the cave atmosphere, becomes acidic and dissolves the bedrock and speleothems. It is a later vadose process that apparently depends on air circulation patterns, number of entrances and general configuration (vertical range, presence of ponded water, passage shape, etc) of the cave. Both bedrock and speleothems can be affected by the process, resulting in weathered outer surfaces. Condensation corrosion in speleogenesis has been regarded as responsible for dissolutional modification during later stages of cave development of coastal (Tarhule-Lips and Ford, 1998) and hypogenic caves (Hill, 1987; Palmer and Palmer, 2000).
The Campo Formoso Karst area of northeastern Brazil holds very extensive cave systems, such as Southern Hemisphere’s longest cave, the 97 km long Toca da Boa Vista. These caves show remarkable features of condensation corrosion such as cupolas, weathered cave walls yielding dolomitic sand, “air scallops” and corroded speleothems. Weathering rinds up to 5 cm thick occur in both dolomite bedrock and speleothem surfaces. Unlike the dolomite, speleothems usually do not disintegrate but change to a milky white opaque porous calcite that is in marked contrast with the fresh crystalline calcite. The area is presently under semi-arid climate and the cave atmosphere is characterised by high internal temperatures (2729 °C) and low relative humidity (mean of 73% for sites away from entrances).
Despite being such a widespread process, rates of condensation corrosion have so far been reported only from caves in the coastal area of the Caribbean (Tarhule-Lips and Ford, 1998). In this study, rates of condensation corrosion in speleothems were derived by determining thickness of weathering rind and age of last unaltered calcite. These rates represent minimum rates because speleothem growth ceased later than age obtained, and also condensation corrosion may not be continuous in time. Due to variable thickness of weathering layer (usually thicker at the top and thinner at sides of stalagmites), maximum and minimum thickness were obtained for each sample. Dating was performed through the alpha spectrometric U-series method in the first unaltered calcite layer beyond the weathering rim. 
The rates obtained vary over two orders of magnitude. They appear to be highly site specific, and are probably heavily dependent on the local atmospheric conditions, although more sampling is needed to confirm this relationship. The data shows that rates are dependent primarily on thickness measured, as range of ages is quite small. Tarhule-Lips and Ford (1998), in the very different littoral caves of the Caribbean, have estimated condensation corrosion rates based on experiments using gypsum tablets. Their reported mean value of 24 mm/ka, much higher than observed in the Campo Formoso caves, suggest that the process may be episodic in the area, not occurring during speleothem growth phases associated with wetter periods.
Although the rates reported by Tarhule-Lips and Ford (1998) indicate that condensation corrosion may actually enlarge cave passages in the normal (10 4 – 10 6 ka) time range of speleogenesis, in the Campo Formoso caves the process appears to play a minor speleogenetic role, being responsible for later modification of cave walls and speleothems.