0000000000461715
AUTHOR
Philippe Audra
An Overview of the Hypogene Caves of Sicily
Karst in Sicily develops in both Messinian gypsum and Mesozoic or Tertiary limestone rocks. Caves are also found in the basalts of Mount Etna. Except for some rare cases, until recently most caves developed in limestone were considered to be of epigenetic origin. The discovery of gypsum in some of these caves, and especially detailed morphological studies, have allowed defining a hypogenic origin for a dozen of caves up to now. In some of these, the hypogenic evidences are very clear, while others remain in doubt because of the widespread presence of well-developed condensation-corrosion morphologies not necessarily related to hydrothermal fluids. This paper reports the present knowledge of…
Acqua Fitusa cave: An example of inactive water-table sulphuric acid cave in Central Sicily
Description of the sulphuric acid cave in Sicily (see pdf attached)
L'impact méconnu des chauves-souris et du guano dans l'évolution morphologique tardive des cavernes
The little known impact of bats and bat guano in the late stages of cave morphogenesis. Bats are considered as symbolic caves inhabitants. The colonies, sometimes huge, may occupy caves through long periods. Large guano deposits were accumulated. Some have been mined for phosphates, either by hand or at the industrial scale. Bats impact is triple: breathing releases CO2, urine is corrosive, and guano mineralization releases acids (carbonic, nitric, sulfuric, and phosphoric). Such aggressive compounds have an effect on carbonate rock and flowstones, either by direct ground corrosion at the contact of the guano, or by condensation-corrosion on walls and ceilings. The speleogenetic impact of t…
Sulfuric acid speleogenesis (SAS) close to the water table: Examples from southern France, Austria, and Sicily
Caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate settings, from arid regions to mid-latitude and alpine areas. H2S is generally formed at depth by reduction of sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers. In tectonically disturbed areas major fractures eventually allow these H2S-bearing fluids to rise to the surface where oxidation processes can become active producing sulfuric acid. This extremely strong acid reacts with the carbonate bedrock creating caves, some of which are among the largest and most spectacular in the world. Production of sulfuric acid mostly occurs at or…
Guano-related phosphate-rich minerals in European caves
International audience; Guano is a typical deposit found in caves derived from the excretions of bats and in minor cases of birds. These organic deposits decompose and form a series of acid fluids and gases that can interact with the minerals, sediments, and rocks present in the cave. Over sixty phosphates are known and described from caves, but guano decay also often leads to the formation of nitrates and sulfates. In this study twenty-two European caves were investigated for their guano-related secondary minerals. Using various analytical techniques, seventeen phosphates, along with one sulfate (gypsum), were recognized as secondary products of guano decay. Among those minerals, some are …