Chemical Weathering of Limestones and Dolomites in A Cave Environment, 2003, Zupan Hajna, N.

The weathered parts of carbonate bedrock on cave walls are a consequence of its incomplete chemical dissolution. The phenomenon is expressed in parts of the caves where walls are in contact with clastic fluvial sediments, wetted by percolation water or wetted by condensation water, and not rinsed by flowing or dripping water. The temperature in the cave is not an important parameter of weathered zone formation. Incomplete dissolution is characteristic both of Alpine and of Mediterranean caves. Limestone or dolomite are dissolved by corrosive moisture; the dissolution is distinctly selective and it go as on at intervals depending on inflow of new aggressive water. The weathered zone of limestone or dolomite is almost identical to the parent rocks in its chemical and mineral composition yet it is much more porous. During chemical weathering the amount of Mg, Sr and U is decreased, these components being leached out of limestone and dolomite. The amount of insoluble residue is usually higher in weathered limestones and in some other cases in fresh limestones which is not very common but it may occur.

Condensation on cave walls: Implications for cave enlargement and sulfuric acid speleogenesis, 2003, Engel As, Stern La, Bennett Pc,

Rates of condensation corrosion in speleothems of semi-arid northeastern Brazil, 2004, Auler A. S. , Smart P. L.

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.

High-accuracy graphic representation of underground karst features and formations during cave mapping, 2004, Szunyogh Gá, Bor

We attempt to develop a new method of cave mapping, which would be superior in terms of the amount and quality of the documented information, relative to the "standard" methods of cave survey. The method envisages that everything that can be seen in the cave which is being surveyed, e.g., corrosional features, cave formations, water bodies, fallen rock blocks, fractures in cave walls, artificial (engineering) structures, etc., must be represented on the map. The method employs the traditional system of map symbols; the accuracy of the produced map, however, approaches the accuracy of the engineering survey maps. The maps accurately render positions, shapes and dimensions of cave features: for example all stalagmites with diameters greater than ca. 10 cm, and all rock blocks with linear sizes exceeding 0.5 m are shown on the maps individually. In the report we will elaborate on the most important aspects of this mapping method, including stages of survey and mapping, system of drawing, map symbols.

Weathering of cave walls in Krempljak, SW Slovenia, 2005, Zupanhajna, Nadja

Condensation corrosion: a theoretical approach, 2005, Dreybrodt W. , Gabrovšek F. , Perne M.

Condensation of water from warm, humid air to cold rock walls in caves is regarded to play a significant role in speleogenesis.
The water condensing to the cave walls quickly attains equilibrium with the carbon dioxide in the surrounding air, and consequentlydissolves limestone or gypsum forming various types of macro- ,meso-, and micromorphologies. In this paper we present the basic physical principles of condensation and give equations, which allow a satisfactory estimation of condensation rates. Water condensing to a cooler wall releases heat of condensation, which raises the temperature of the wall thus reducing the temperature
difference ΔT between the warm air and the cave wall. Furthermore one has to take into account the heat flux from the air to the cave wall. This defines the boundary conditions for the equation of heat conduction. For a constant temperature of the air initial condensation rates are high but then drop down rapidly by orders of magnitude during the first few days. Finally constant condensation rates are attained, when the heat flux into the rock is fully transmitted to the surface of the karst plateau. For spherical and cylindrical conduits these can be obtained as a function of the depth Z below the surface. When diurnal or seasonal variations of
the air temperature are active as is the case close to cave entrances, condensation rates can become quite significant, up to about 10-6 m/year. The theoretical results are applied also to corrosion of speleothems and the formation of »röhrenkarren« as described by Simms (2003). To convert condensation rates into retreat of bedrock the saturation state of the solution must be known. In the appendix we present experiments, which prove that in any case the solution flowing off the rock is saturated with respect to limestone or gypsum, respectively

Condensation corrosion: A theoretical approach, 2005, Dreybrodt Wolfgang, Gabrovš, Ek Franci, Perne Matija

Condensation of water from warm, humid air to cold rock walls in caves is regarded to play a significant role in speleogenesis. The water condensing to the cave walls quickly attains equilibrium with the carbon dioxide in the surrounding air, and consequently dissolves limestone or gypsum forming various types of macro- ,meso-, and micromorphologies. In this paper we present the basic physical principles of condensation and give equations, which allow a satisfactory estimation of condensation rates. Water condensing to a cooler wall releases heat of condensation, which raises the temperature of the wall thus reducing the temperature difference (T between the warm air and the cave wall. Furthermore one has to take into account the heat flux from the air to the cave wall. This defines the boundary conditions for the equation of heat conduction. For a constant temperature of the air initial condensation rates are high but then drop down rapidly by orders of magnitude during the first few days. Finally constant condensation rates are attained, when the heat flux into the rock is fully transmitted to the surface of the karst plateau. For spherical and cylindrical conduits these can be obtained as a function of the depth Z below the surface. When diurnal or seasonal variations of the air temperature are active as is the case close to cave entrances, condensation rates can become quite significant, up to about 10-6 m/year. The theoretical results are applied also to corrosion of speleothems and the formation of "röhrenkarren" as described by Simms (2003). To convert condensation rates into retreat of bedrock the saturation state of the solution must be known. In the appendix we present experiments, which prove that in any case the solution flowing off the rock is saturated with respect to limestone or gypsum, respectively.

Extremely acidic, pendulous cave wall biofilms from the Frasassi cave system, Italy, 2007, Jennifer L. Macalady, * Daniel S. Jones And Ezra H. Lyon

The sulfide-rich Frasassi cave system hosts an aphotic, subsurface microbial ecosystem including extremely acidic (pH 0?1), viscous biofilms (snottites) hanging from the cave walls. We investigated the diversity and population structure of snottites from three locations in the cave system using full cycle rRNA methods and culturing. The snottites were composed primarily of bacteria related to Acidithiobacillus species. Other populations present in the snottites included Thermoplasmata group archaea, bacteria related to Sulfobacillus, Acidimicrobium, and the proposed bacterial lineage TM6, protists, and filamentous fungi. Based on fluorescence in situ hybridization population counts, Acidithiobacillus are key members of the snottite communities, accompanied in some cases by smaller numbers of archaea related to Ferroplasma and other Thermoplasmata. Diversity estimates show that the Frasassi snottites are among the lowestdiversity natural microbial communities known, with one to six prokaryotic phylotypes observed depending on the sample. This study represents the first in-depth molecular survey of cave snottite microbial diversity and population structure, and contributes to understanding of rapid limestone dissolution and cave formation by microbially mediated sulfuric acid speleogenesis.

THE MINERALOGICAL STUDY ON THE CUEVA DE LAS VELAS (NAICA, MEXICO), 2007, Forti P. , Galli E. , Rossi A.

The Cueva de las Velas is the last cave unveiled at -290 level within the Naica Mine; the cavity has been intercepted by a mine gallery at the beginning of 2005. One of its peculiarities is the widespread thick deposits of diagenetic minerals deposited over the cave walls before the beginning of the evolution of the giant gypsum crystals. These deposits consist of complex, often scarcely crystalline iron-manganese-lead oxides-hydroxides, but carbonates, sulphates and silicates are also present. Other minerals, mainly sulphates, started developing just after this area of the mine was dewatered some 20 years ago. Presently 17 different minerals have been observed, 5 of which (orientite, starkeyite, szmolnokite, szmikite and woodruffite) are completely new for the cavern environment. The study of these minerals, together with the presence of a completely new type of gypsum crystals, allowed to improve the knowledge on the speleogenetic evolution of this cave, which seems to be by far more complex than that of the other cavity of the -290 level. Its complexity is reflected by the activity of a larger number of different speleogenetic mechanisms. Among them are worth of mention the thermal corrosion/dissolution, the anhydrite- gypsum disequilibrium, the acid aggression, and the capillary migration and evaporation.

Sulfidic ground-water chemistry in the Frasassi Caves, Italy, 2008, Galdenzi S. , Cocchioni M. , Moricheui L. , Amici V. , And Scud S.

A year-long study of the sulfidic aquifer in the Frasassi caves (central Ita ly) employed chemical analysis of the water and measurements of its level, as well as assessments of the concentration of H2S, CO2, and O2 in the cave air. Bica rbonate water seepage derives from diffuse infiltration of meteoric water into the karst surface, and contributes to sulfidic ground-water dilution, with a percentage that varies between 30% and 60% during the year. Even less diluted sulfidic ground water was found in a localized area of the cave between Lago Verde and nearby springs . This water rises from a deeper phreatic zone , and its chemistry changes only slightly with the seasons with a contribution of seepage water that does not exceed 20'10 . In order to understand how the H2S oxidation, which is considered the main cave forming process, is influenced by the seasonal changes in the cave hydrology, the sulfide/total sulfur ratio was related to ground-water dilution and air composition. The data suggest that in the upper phreatic zone, limestone corrosion due to H2S oxidation is prominent in the wet season because of the high recharge of Oj-rich seepage water, while in the dry season, the H2S content increases, but the extent of oxidation is lower. In the cave atmosphere, the low H2S content in ground water during the wet season inhibits the release of this gas, but the H2S concentration increases in the dry season, favoring its oxidation in the air and the replacement of limestone with gypsum on the cave walls.

, 2008, Jones O. S. , Lyon E. H. , And Macalady J. L.

Su lfid ic cave walls host abundant, rapid ly-growing micro bia l communities that display a variety o f mo rphologies previously described for verrn iculations. Here we present molecular, microscopic, isotopic, and geochemical data describing the geomicrobiology o f these biovennic ulations from the Frasassi cave system, Italy. The biove rm iculations are compo sed of densely packed prokaryo tic and funga l cells in a mineral-organ ic matrix co ntaining 5 to 25% o rganic carbon. The carbon and nitrogen isoto pe compositions o f the biovermiculations (ti 13e = - 35 to - 43%0, and til 5N = 4 to - 270/00. respectively) indicate that with in sulfidic zo nes, the o rga nic matter o rigina tes from chemolithotrophic bacterial primary productivity. Based on 165 rRNA gene cloning (n=67). the bioverrn ... iculation communitv is extrernelv diverse, incl uding 48 . ~ . ... representative phylotypes (>98% identity) from at least 15 major bacterial lineages. Important lineages include the Betaproteobacteria (1 9.5% of clones). Gammaproteobacteria (1 8%). Acidobacteria (1 0.5%). Nitrospirae (7.5%). and Planctomyces (7.5%). The most abundant phylotype, comprising over 100/0 of the 16S rRNA gene sequences. groups in an unnamed clade within the Gammaproteobacteria. Based on phylogenetic analysis, we have identified potential sulfur- and nitrite-oxidizing bacte ria. as well as both auto- and heterotrophic members of the biovermiculation community. Additionally. many of the clones a re representatives of deeply branching bacterial lineages with no cultivated representatives. The geochemistry and microbial composition of the biovermicula tions suggest that they play a role in acid production and carbonate disso lution. thereby contributing to cave formation.

Geomicrobiology of biovermiculations from the Frasassi Cave System, Italy, 2008, D. S. Jones, E. H. Lyon, And J. L. Macalady

Sulfidic cave walls host abundant, rapidly-growing microbial communities that display a variety of morphologies previously described for vermiculations. Here we present molecular, microscopic, isotopic, and geochemical data describing the geomicrobiology of these biovermiculations from the Frasassi cave system, Italy. The biovermiculations are composed of densely packed prokaryotic and fungal cells in a mineral-organic matrix containing 5 to 25% organic carbon. The carbon and nitrogen isotope compositions of the biovermiculations (d13C 5 235 to 243%, and d15N 5 4 to 227%, respectively) indicate that within sulfidic zones, the organic matter originates from chemolithotrophic bacterial primary productivity. Based on 16S rRNA gene cloning (n567), the biovermiculation community is extremely diverse, including 48 representative phylotypes (.98% identity) from at least 15 major bacterial lineages. Important lineages include the Betaproteobacteria (19.5% of clones), Gammaproteobacteria (18%), Acidobacteria (10.5%), Nitrospirae (7.5%), and Planctomyces (7.5%). The most abundant phylotype, comprising over 10% of the 16S rRNA gene sequences, groups in an unnamed clade within the Gammaproteobacteria. Based on phylogenetic analysis, we have identified potential sulfur- and nitrite-oxidizing bacteria, as well as both auto- and heterotrophic members of the biovermiculation community. Additionally, many of the clones are representatives of deeply branching bacterial lineages with no cultivated representatives. The geochemistry and microbial composition of the biovermiculations suggest that they play a role in acid production and carbonate dissolution, thereby contributing to cave formation.

Present-day sedimentary facies in the coastal karst caves of Mallorca island (western Mediterranean), 2009, Fornós J. J. , Ginés J. , And Gràcia F.

In spite of the increasing number of papers on cave sediments published during the last few decades, no one has focused from a sedimentological point of view on the processes that take place specifically within the coastal karst areas of carbonate islands. The objective of the present investigations is to deal with the sedimentary processes that take place inside two littoral caves of Mallorca (western Mediterranean), characterizing the different facies existing in the particular geological, geochemical, and hydrological setting that represents this very specific cave sedimentary environment. The recent exploration of extensive underwater galleries and chambers into some outstanding coastal caves of the island, has permitted the recognition of important accumulations of present-day sedimentary infillings in their drowned passages. Both the Pirata-Pont- Piqueta cave system and the Cova de sa Gleda have floors covered by muddy and/or sandy sediments which, in a wide sense, fit into two well-differentiated categories. On one hand we have allochthonous reddish mud sediments (mainly siliciclastic) and on the other hand autochthonous yellowish carbonate mud or sands. The mixing of both materials is also frequent as well as the accumulation of large blocks and debris due to the breakdown of roof and cave walls. A series of 21 manual cores was obtainedby scuba-divers in both caves, in order to collect the full thickness of sedimentary fill. Soil samples at the entrance of the two caves, as well as rock samples of the walls of both sites, were also obtained for a later comparison. Several sedimentary facies can be distinguished, which include coarse-grained deposits (entrance facies and breakdown blocks), fine-grained siliceous sediments (silts and muddy deposits with very variable organic matter content), carbonate deposits composed of calcite raft accumulations and/ or weathering-released limestone grains, and mixed facies including diverse proportions of the other sediment types. There are also some relict deposits composed of siliceous red silts, which are affected by polygonal desiccation cracks. In all the cases, the siliciclastic elements (quartz and feldspars, mainly) are related to rain events supplying dust of Saharan origin. The deposits and facies described herein correspond to different sedimentary environments that can be individualized inside the caves (collapse entrances, breakdown chambers, fully drowned passages and chambers, pools with free water surface…), and reflect very specific hydrological, geochemical, and mechanical processes related to the coastal nature of the studied karst caves.

A spreadsheet program (Scallopex) to calculate paleovelocities from cave wall scallops, 2009, Woodward Emily, Sasowsky Ira D.

The determination of paleovelocities through analysis of scal-lops on cave walls is an important part of paleohydrologic analysis. The linked equations that must be solved to do this are cumbersome, though. This paper presents a spreadsheet program that simplifies the process. The user enters scallop lengths, paleotemperatures, and passage dimensions; and the program returns velocities.

HYPOGENE CAVES IN DEFORMED (FOLD BELT) STRATA: OBSERVATIONS FROM EASTERN AUSTRALIA AND CENTRAL EUROPE, 2009, Osborne R.

While there is a well-established general theory for the mechanism of excavation of hypogene caves in artesian basins, the same cannot be said for hypogene caves in deformed strata. A few active thermal caves, several dormant hypogene caves and many extinct hypogene caves and extinct hypogene sections of complex multiprocess caves are developed in impounded karsts along the whole length of the Tasman Fold Belt System in eastern Australia. The active caves are related to warm springs with temperatures (20°-28°C) only a few degrees above the annual average (17°C) and are often cooler than the external summer temperature. The origins of these waters have not been investigated, but most active, dormant, extinct and suspect ancient hypogene caves occur in close proximity to faults, frequently to large regional faults. If and how water from these faults is transmitted to the propagation planes in the caves is not known. While hypogene speleothems occur in the active and dormant caves, these are absent from the older suspect hypogene caves, some of which have probably been thermally dormant for hundreds of millions of years. The older caves are characterized by cave pattern, the presence of hypogene speleogens and poor relationship with surrounding hydrology. Two processes that are signi?cant in the development of the older complex caves are integration, which leads to formerly separate cavities joining to form larger caves and renovation, which smoothes cave walls, obliterating boxwork, etching and lithologically selective solution.