Five hypogenic-origin caves from Southern France are presented. Investigations using XRD, SEM and Raman spectroscopy, reveal the presence of uncommon cave minerals. Oilloki Cave is a small lead ore mine-cave containing galena, cerussite, and bismuth (present as native element or as sulfide).La Baume Cave is a hydrothermal breccia-pipe, filled with colorful (red, green, white) clays. Some of the clay minerals (clinochlore se-piolite), could originate from hydrothermal weathering of clastic material. The Mala-coste Quarry, harbors a hydrothermal chimney with enlarged vugs lined with calcite spar and filled with iron oxyhydroxides poolfingers (goethite-hematite) and manganese oxides (birnessite, todorokite). Deposition of iron and manganese oxides results of the pH-Eh evolution along the hydrothermal chimney. Pigette Cave is a hydrothermal ver-tical maze with calcite lining and small iron oxyhydroxides and manganese oxides mass-es. The hydrothermal weathering of the walls deposited grains of lithiophorite, barite, and celadonite, which could originate from glauconite. Baume Galinière Cave is a small horizontal maze originating from the oxidation of sulfide masses of pyrite. Beside the common byproducts (gypsum, goethite, sulfur), the six members of the jarosite sub-group are present: jarosite, ammoniojarosite, argentojarosite, hydronium jarosite, natro-jarosite, plumbojarosite, together with fibroferrite. In these caves, three minerals are new cave minerals (bismuth, celadonite, argentojarosite); some others have been men-tioned before only in a few caves worldwide (clinochlore, lithiophorite, ammoniojaro-site, hydronium jarosite, natrojarosite, plumbojarosite, fibroferrite). The mineralogene-sis involves different processes: (i) Deposition in mixing zone from species carried by rising deep flow (barite, galena, bismuth, birnessite, todorokite, lithiophorite); (ii) Hy-drothermal weathering of clay minerals contained in host rock or present as clastic sediments (clinochlore, sepiolite, celadonite); (iii) Oxidation of sulfide masses (goethite, cerussite, jarosite subgroup minerals, fibroferrite).

The Botovskaya Cave is a typical example of a two-dimensional maze with a total length of explored passages exceeding 60 km, which represents the longest limestone cave system in the Russian Federation. The clastic cave sediments filling the cave passages differ in both mineral and mineral magnetic properties and were deposited under different hydrological conditions. The older portion of the clastic cave fills was derived from overlying sandstones, whereas the properties of younger cave sediments show closer affinity to the soils and weathering products originating on the sandstone plateau above the cave. The cave sediments underwent repeated periods of deposition and erosion during the Tertiary and Pleistocene.

The leading role in the geomorphic development of the Crimean fore-mountain region is played by the processes of dismemberment of “shielding” limestone layers of the monoclinal stratified structure through valley entrenchment, and by further retreat of vertical rocky outcrops via block-toppling mechanism. These processes are guided by the presense of hypogene karst structures, whose formation preceded the modern relief. Karstified fracture-karst zones, 100 to 400 m wide, in the Cretaceous-Paleogene strata controlled the entrenchment of valleys in the limestone layers. The basic elements of hypogenic karst structures, which form their spatial framework, are sub-vertical fracture-karst conduits (karst “rifts”). Denudational opening of vertical fracture-karst rift conduits in limestone layers set the cliff-like shape of valleys slopes, and presence of such rift conduits in the rear of cliffs of already incised valleys determines the block-toppling mechanisms of slope retreat. This maintains the verticality of cliff segments in the cuesta ridge and controls their position. Hypogenic sculptural morphology is extensively displayed in the exposed walls of cliffs (former conduit walls), which determines the originality and nomenclature of morphology of limestone cliffs of the Inner Ridge. In those areas of slopes where position of cliffs has stabilized for considerable time due to absence of new lines of block detachment in the rear, weathering becomes a significant process in the morphogenesis of surfaces. The abundance, outstanding expression, preservation and accessibility of relict hypogene karst features in the extensive cuesta cliffs of the Inner Ridge makes the region the foremost one for studying regularities of hypogene solution porosity development, the process currently ongoing in the adjacent artesian basin of the Plain Crimea.

Caves evolve due to various geomorphological processes which can be used to develop a classification scheme. We adapted existing genetic classifications and focused on the main genetic process which we defined as the one that was responsible for most of the cave volume. This scheme was applied to the 4,849 known caves of Lower Austria and some neighbouring areas. It turned out that more than half of the caves have developed due to weathering and erosion and only 45 % are karstic ones.

The Diana Cave in SW Romania develops along a fault line at the contact between Late Jurassic limestones and Early Cretaceous marls. It formed through corrosion of bedrock (limestone and marls) by sulphuric acid-rich steam condensate resulted after oxidation/hydrolysis of H2S escaping from the thermo-mineral water emerging from depth in the cave. The sulfuric acid causes a strong acid sulfate weathering of the bedrock generating a sulfate-dominated secondary cave-mineral assemblage that includes gypsum, anhydrite, bassanite, epsomite, alunite, and halotrichite group minerals. Closely associated with these minerals are two rare sulfate species, namely rapidcreekite and tamarugite that represent new occurrences in limestone caves. Traditional X-ray diffraction and single crystal analyses were used along with scanning electron microscope (SEM), stable isotope, and electron microprobe investigations to fully characterize the primary and secondary speleogenetic by-products of Diana Cave.

The Diana Cave in SW Romania develops along a fault line and hosts a spring of hot (Tavg = 51 °C), sulfate-rich, sodium-calcium-chloride bearing water of near-neutral pH. Abundant steam and H2S rises from the thermal water to condensate on the walls and ceiling of the cave. The sulfuric acid produced by H2S oxidation/hydrolysis causes a strong acid-sulfate weathering of the cave bedrock generating a sulfate-dominated mineral assemblage that includes rapidcreekite, Ca2(SO4)(CO3)•4H2O closely associated with gypsum and halotrichite group minerals. Rapidcreekite forms bundles of colorless tabular orthorhombic crystals elongated along [001] and reaching up to 1.5 mm in length. For verifying the hydrogen bond scheme and obtaining crystal-chemical details of the carbonate group a single-crystal structure refinement of rapidcreekite was performed. Its unit-cell parameters are: a = 15.524(2), b = 19.218(3), c = 6.161(1) Å; V = 1838.1(5) Å3, Z = 8, space group Pcnb. Chemi¬cal composition (wt%): CaO 35.65, SO3 24.97, CO2 13.7, H2O 23.9, Na2O 0.291, MgO 0.173, Al2O3 0.07, total 98.75%. The empirical formula, based on 7 non-water O atoms pfu, is: Ca1.98Na0.029Mg0.013 Al0.004(S0.971 O4)(C0.97O3)•4.13H2O. The d34S and d18O values of rapidcreekite and other cave sulfates range from 18 to 19.5‰ CDT and from –9.7 to 7.8‰ SMOW, respectively, indicating that the source of sulfur is a marine evaporite and that during hydration of the minerals it has been an abundant 18O exchange with percolating water but almost no oxygen is derived from O2(aq). This is the first descrip¬tion of rapidcreekite from a cave environment and one of the very few natural occurrences worldwide. We also report on the mineral stability and solubility, parameters considered critical to understand the co-precipitation of carbonates and sulfates, a process that has wide applications in cement industry and scaling prevention.

In the recent work of Aubrecht et al. (2011) the presence of “unlithified or poorly-lithified beds” of sands in the   quartz-sandstone stratigraphic succession is proposed as a key factor for speleogenesis in the Venezuelan tepuis.   In this comment we observe that in the cited work the geologic history of the region, in terms of sedimentation   environment, diagenesis and low grade burial metamorphism, has not been considered. Furthermore, the   peculiar “pillar flow” columns that Aubrecht et al. describe as a proof of the unlithification are lacking in   many other different cave systems in the same area.   Four critical points are discussed: the burial metamorphism of the Mataui Formation, the significance of the   Schmidt Hammer measurements, the cave morphologies and the role of SiO2 dissolution. Finally we suggest   that weathering, in its wider significance, is probably the triggering process in speleogenesis, and there is no   need to invoke a differential diagenesis of the sandstone beds

Many quarries for the extraction of gypsum are located in the hills of the Monferrato area (central eastern Piedmont). Close to the village of Moncalvo, Asti Province, a subterranean quarry of more than 20 km long is present. During the excavations a fracture from which water gushed at a pressure of 3 atm has been intercepted in 2005. The underground works have been suspended immediately and, after only a few hours a water flow comprised between 3000 and 4000 Ls-1 has flooded the quarry tunnels filling a volume of over 60,000 m3. After more than one month of pumping the flooded areas have been made accessible again, revealing a thin rock diaphragm that separated the quarry tunnel from a natural cave, which failed under the high hydraulic pressure. Through this small gap it has been possible to access an extensive karst network that previously was completely submerged. During the following quarry operations a second natural cave has been encountered, belonging to the same system but physically divided from the first cave by some metres of sediments. The total development of this cave system is around 1 km. The exploration of these caves has allowed to gather an interesting set of observations that have contributed to elaborating a speleogenetic model. The first information regards the impressive

amount of snottites present along the walls of the caves, and the overall thickness of gypsum rock subdued to weathering, reaching up to 30 cm. There are many morphologies that clearly demonstrate the caves being formed in phreatic conditions, such as pendants and corrosion cupola, but also flat corrosion bevels and V-shaped cross-sections, further evidences of formation in saturate conditions. The stratigraphic asset of the area surely has played a fundamental role in the formation of these karst systems. From bottom to top there is a thick shale sequence, and a thin discontinuous and extremely well karstified marly limestone bed that seemed to have enhanced the hydrological flow in the above lying gypsum beds. The principal cave systems are formed in between the first and second bed of gypsum, along a shaly finely stratified interbed rich in organic material. On the floor of the main passage there are many rather small subvertical conduits that develop up to the underlying limestone bed thus favoring the upward movement of water and the dissolution of the gypsum rocks. The subterranean excavations also have intercepted other caves, most of them of much smaller size, often reaching some cubic metres in size and partially filled with large gypsum crystals, grown by the continuous but slow feeding of slightly supersaturated waters.

The Salman Farsi dam project is constructed on the Ghareh Agahaj River about 140km south of Shiraz city in the Zagros Mountains of southwestern Iran. This tectonic province of southwestern Iran is characterized by a simple folded sedimentary sequence. The dam foundation rocks compose of the Asmari Formation of Oligo-miocene and generally comprise of a variety of karstified carbonate rocks varying from strong to weak rocks. Most of the rocks exposed at the dam site show a primary porosity due to incomplete diagenetic recrystallization and compaction. In addition to these primary dispositions to weathering, layering conditions (frequency and orientation of bedding) and the subvertical tectonic discontinuities channeled preferably the infiltrating by deep-sited hydrothermal solutions. Consequently the porosity results to be enlarged by dissolution and the rocks are expected to be karstified and to develop cavities in correspondence of bedding, major joint planes and fault zones. This kind of karsts is named hypogenic karsts which associated to the ascendant warm solutions. Field observations indicate strong karstification and vuggy intercalations especially in the middle part of the Asmari succession. The biggest karst in the dam axis which identified by speleological investigations is Golshany Cave with volume of about 150,000 m3. The tendency of the Asmari limestone for strong dissolution can alert about the seepage from the reservoir and area of the dam locality

The Salman Farsi dam project is constructed on the Ghareh Agahaj River about 140km south of Shiraz city in the Zagros Mountains of southwestern Iran. This tectonic province of southwestern Iran is characterized by a simple folded sedimentary sequence. The dam foundation rocks compose of the Asmari Formation of Oligo-miocene and generally comprise of a variety of karstified carbonate rocks varying from strong to weak rocks. Most of the rocks exposed at the dam site show a primary porosity due to incomplete diagenetic recrystallization and compaction. In addition to these primary dispositions to weathering, layering conditions (frequency and orientation of bedding) and the subvertical tectonic discontinuities channeled preferably the infiltrating by deep-sited hydrothermal solutions. Consequently the porosity results to be enlarged by dissolution and the rocks are expected to be karstified and to develop cavities in correspondence of bedding, major joint planes and fault zones. This kind of karsts is named hypogenic karsts which associated to the ascendant warm solutions. Field observations indicate strong karstification and vuggy intercalations especially in the middle part of the Asmari succession. The biggest karst in the dam axis which identified by speleological investigations is Golshany Cave with volume of about 150,000 m3. The tendency of the Asmari limestone for strong dissolution can alert about the seepage from the reservoir and area of the dam locality.

This paper focuses on the evolution and patterns of microscale weathering forms and dissolution rates of “standard” (Lipica) limestone tablets. Analysis of carbonate weathering using combination of methods (quantitative analysis by the weight loss of "standard" tablets, and qualitative analysis of the weathered surfaces by stained acetate peels and SEM imaging) showed that dissolution takes place not only at the surface of limestone tablets, but also along voids and cavities in limestone tablets which makes total weathering surface larger than the area of the tablet surface. Dissolution is more pronounced on the micritic calcite surfaces (due to different dissolution kinetics of carbonate minerals), resulting in lowering of the surface (calcite matrix) which causes gradual unburial and removal of authigenic dolomite grains.

Epikarst is a weathered zone of enhanced porosity on or near the surface or at the soil/bedrock contact of many karst landscapes. The epikarst is essentially the upper boundary of a karst system but is also a reaction chamber where many organics accumulate and react with the percolating water. The epikarst stores and directs percolating recharge waters to the underlying karst aquifers. Epikarst permeability decreases with depth below the surface. The epikarst may function as a perched aquifer with a saturated zone that transmits water laterally for some distance until it drains slowly through fractures or rapidly at shaft drains or dolines. Stress-release and physical weathering as well as chemical dissolution play a role in epikarst development. Epikarst may be found on freshly exposed carbonates although epikarst that develops below a soil cover should form at a faster rate due to increased carbon dioxide produced by vegetation. The accumulation of soil within the fractures may create plugs that retard the downward movement of percolating water and creates a reservoir rich in organic material. The thickness of the epikarst zone typically ranges from a few meters to 15 meters, but vertical weathering of joints may be much deeper and lead to a “stone forest” type of landscape. Some dolines are hydrologically connected directly to the epikarst while other dolines may drain more directly to the deeper conduit aquifer and represent a “hole” in the epikarst. water stored in the epikarst may be lost to evapotranspiration, move rapidly down vertical shafts or larger joints, or drain out slowly through the soil infillings and small fractures. Much of the water pushed from the epikarst during storms is older water from storage that is displaced by the new event water.

The Salman Farsi dam project is constructed on the Ghareh Agahaj River about 140km south of Shiraz city in the Zagros Mountains of southwestern Iran. This tectonic province of southwestern Iran is characterized by a simple folded sedimentary sequence. The dam foundation rocks compose of the Asmari Formation of Oligo-miocene and generally comprise of a variety of karstified carbonate rocks varying from strong to weak rocks. Most of the rocks exposed at the dam site show a primary porosity due to incomplete diagenetic recrystallization and compaction. In addition to these primary dispositions to weathering, layering conditions (frequency and orientation of bedding) and the subvertical tectonic discontinuities channeled preferably the infiltrating by deep-sited hydrothermal solutions. Consequently the porosity results to be enlarged by dissolution and the rocks are expected to be karstified and to develop cavities in correspondence of bedding, major joint planes and fault zones. This kind of karsts is named hypogenic karsts which associated to the ascendant warm solutions. Field observations indicate strong karstification and vuggy intercalations especially in the middle part of the Asmari succession. The biggest karst in the dam axis which identified by speleological investigations is Golshany Cave with volume of about 150,000 m3. The tendency of the Asmari limestone for strong dissolution can alert about the seepage from the reservoir and area of the dam locality

The Carboniferous Limestone at Bullslaughter Bay hosts some of the most notable examples of deep weathering in  the British Isles as well as two members of an enigmatic suite of breccias known as the Gash Breccias. The weathered limestone has  been investigated thoroughly in order to identify the process responsible for the weathering. In this paper it is demonstrated that the  weathering is isovolumetric but the weathering profile is not characterised by a vertical gradient and its depth suggests that meteoric  waters did not contribute significantly to the weathering process. The weathered limestone has lost significant amounts of calcium and  parts are virtually decalcified. It is seen that the dominant primary minerals of illite and quartz have been preserved while secondary  clay minerals are generally absent. The weathered limestone cannot be a saprolite sensu stricto as it has been subjected to only restricted  chemical processes. It is, therefore, interpreted as a “ghost-rock”. This type of weathering results from chemical dissolution by slow  moving waters in the saturated zone. It is suggested that the weathering may have taken place during periods of emergence in the  Carboniferous, at the same time as the cyclothem tops were exposed to subaerial modification, as evidenced by omission surfaces and  palaeokarstic solution features. This is the first time that ghost-rock weathering has been reported from the British Isles.