From analysis of the hydrodynamic and hydrochemical responses of karst springs, it is possible to know the behaviour of the aquifers they drain. This manuscript aims to contribute to the characterization of infiltration process, and to determine the relative importance of the saturated zone and of the unsaturated zone in the hydrogeological functioning of carbonate aquifers, using natural hydrochemical tracers. Thus, chemical components together with temperature and electrical conductivity (both punctual and continuous records) have been monitored in three springs which drain Alta Cadena carbonate aquifer, Southern Spain. An evaluation of the percentage of the electrical conductivity frequency peaks determined for each of the three springs is linked to the chemical parameters that comprise the conductivity signal. One of these springs responds rapidly to precipitation (conduit flow system), due to the existence of a high degree of karstification in the unsaturated zone and in the saturated zone, both of which play a similar role in the functioning of the spring. Another spring responds to precipitation with small increases in water flow, somewhat lagged, because the aquifer has a low degree of karstification, even in the unsaturated zone, which seems to influence its functioning more strongly than does the saturated zone. The third spring drains a sector of the aquifer with a moderately developed degree of karstification, one that is intermediate between the other two, in which both the unsaturated zone and the saturated zone participate in the functioning of the spring, but with the latter zone having a stronger influence. These three springs show different hydrogeological functioning although they are in similar geological and climatic contexts, which show the heterogeneity of karst media and the importance of an adequate investigation for groundwater management and protection in karst areas.

Research highlights
- From analysis of the hydrodynamic and hydrochemical responses of karst springs. - Characterization of the relative importance of the saturated (SZ) and unsaturated (NSZ) zones - Villanueva del Rosario: NSZ and SZ play similar roles in the functioning of the system. ► Pita: NSZ seems to affect its functioning more than SZ. - Parroso: NSZ and SZ participate in the functioning of the system, but SZ is more active.

This investigation reports on the comparison between ICP-MS U-Th and AMS 14C ages of Phreatic Overgrowths on Speleothems (POS) from two different caves on the island of Mallorca (Spain). These speleothem encrustations form at the water table of coastal caves in a low-amplitude tide-controlled microenvironment and are used to reconstruct past sea level changes. The aim of this study is to evaluate if this particular type of speleothem is datable using 14C method and to investigate possible problems connected with the incorporation of dead carbon inherited from the dissolution of 14C-free limestone. The results show that 14C ages are strongly site dependent and appear related to local residence time of water infiltration through the soil and epikarst. When short transit time and limited interaction with soil and bedrock, as in Cova de Cala Varques A, the so-called “reservoir” effect is negligible and 14C and U-Th ages corresponds within the error range. When the residence time is longer, as in Cova des Pas de Vallgornera, 14C ages are steadily 2,300-2,400 years older than the U-Th data, as shown by the mean value (25%) of estimated percent dead carbon proportions and by higher and better correlated contents of major and trace elements in the vadose support of this speleothem encrustation. The potential use of this multi-method approach to paleoenvironmental studies is also suggested.

This investigation reports on the comparison between ICP-MS U-Th and AMS 14C ages of Phreatic Overgrowths on Speleothems (POS) from two different caves on the island of Mallorca (Spain). These speleothem encrustations form at the water table of coastal caves in a low-amplitude tide-controlled microenvironment and are used to reconstruct past sea level changes. The aim of this study is to evaluate if this particular type of speleothem is datable using 14C method and to investigate possible problems connected with the incorporation of dead carbon inherited from the dissolution of 14C-free limestone. The results show that 14C ages are strongly site dependent and appear related to local residence time of water infiltration through the soil and epikarst. When short transit time and limited interaction with soil and bedrock, as in Cova de Cala Varques A, the so-called “reservoir” effect is negligible and 14C and U-Th ages corresponds within the error range. When the residence time is longer, as in Cova des Pas de Vallgornera, 14C ages are steadily 2,300-2,400 years older than the U-Th data, as shown by the mean value (25%) of estimated percent dead carbon proportions and by higher and better correlated contents of major and trace elements in the vadose support of this speleothem encrustation. The potential use of this multi-method approach to paleoenvironmental studies is also suggested.

 Discovered in 1994, Ogof Draenen is currently the longest cave in Britain and among the thirty longest caves in the World, with a surveyed length in excess of 70km. Like other great caves, Ogof Draenen has had a complex multiphase history. This interpretation of the genesis of the cave is based on speleo-morphological observations throughout the system. Evidence of at least four phases of cave development can be identified, associated with major shifts in resurgence location and changes in flow direction of up to 180°. Joints have had a dominant influence on passage genesis. In particular joints have facilitated the development of maze networks and remarkably shallow horizontal phreatic conduits. The amplitude of these conduits is much shallower than predicted by models based on flow path length and stratal dip. Here, we suggest that presence of laterally extensive open joints, orientated perpendicular to the regional neo-tectonic principal stress field, determines the depth of flow in the aquifer, rather than fissure frequency per se as suggested in Ford’s Four State Model. We argue that the rate of base-level lowering, coupled with the depth of karstification determines whether a cave responds by phreatic capture or vadose incision. Maze cave networks within Ogof Draenen were probably initiated by bedrock-hosted sulphide oxidation and sulphuric acid speleogenesis.

(Note: Welsh terms used in this paper: Ogof = Cave; Afon = River; Cwm = Valley; Mynydd = Mountain).

The Planina Polje is located in the northwestern part of Notranjsko Podolje, Slovenia. Annual floods cover the flattened floor of the polje at elevation 445 m a.s.l. and reach the depth of approximately 8 meters. Loamy sediments which were found on surface and subsurface features from the inflow part of Planina Polje up to the elevations of about 495 m a.s.l., indirectly show that floods in the past must have been much more extensive than the recent ones. Radiocarbon dating of flowstone layer from side passage Tiha Jama in Planina Cave revealed that the last such extreme floods appeared around 5,706 ± 49 BP. The time frame of the flood roughly corresponds with the Altithermal (8,000–5,000 BP). More humid mid-Holocene climate might be the main cause for the high floods on Planina Polje.

The area of Niari-Nyanga, divided between Congo-Brazzaville and Gabon, corresponds to a Neoproterozoic synclinal whose schisto-limestones and dolomitic layers shelter many caves as well as vast underground karst systems that are hardly known. In a sub-equatorial climate characterized by sparse rainfall with very variable intensity, a dry season of five months and a savanna environment, the endokarst presents a vast array of forms with sometimes large, sometimes small dimensions. The caves are mostly horizontal and oriented along tectonic lines. Old fossil perched caves contrast with epiphreatic caves and drowned inaccessible systems. In current bioclimatic conditions, corrosion seems not very effective and not in equilibrium with some vast morphologies. The stacked levels, the presence of fossil speleothems and detritic material suggest a polyphase genesis in link with important paleoclimatic changes, where humid and dry periods alternate. Recent age dating with 14C on stalagmites show that the speleothemes are holocene and grew during the important rainfalls of this time, before drying up at the general chlimate change 3000 years before present. Thus, the endokarst of Niari-Nyanga as well as its neighbours is an archive of large importance.

The Crimean Piedmont stretches along the tectonic suture separating the fold-and-thrust structure of the Crimean Mountains from the Scythian Plate. It comprises two cuesta-like ridges whose structural slopes are built up of homoclinal limestone beds of the Paleocene- Eocene (the Inner Range), and the Neogene (the Outer Range) ages. Abundant relicts of the hypogene karst have been identified recently in steep cuesta cliffs of the Piedmont. The hypogene cavities formed in confined to semi-confined hydrological conditions due to interaction of the deep-seated waters, ascending along cross-formational fracture conduits, with the strata-bound lateral filtration flow. The ongoing geomorphological dissection of the stratified structure of the Piedmont com-monly follows the pre-formed hypogene conduits, resulting in the development of the pronounced cuesta relief with steep cliffs featuring massive exposure of the hypogene karst conduit paleo-walls with specific morphologies.
Movement of deep-seated fluids through carbonate wallrock may cause isotopic altera-tion of the later. We have studied isotopic composition of C and O along nine cores drilled into the walls of the cliffs decorated with hypogene solutional features, as well as in two hypogene caves. Data from all cores show the presence of a wide isotopic altera-tion halo, whose thickness exceeds the core length (max. 40 cm). In this zone, the rock is slightly depleted in δ18Î (ca. 1 -2 ‰) relative to the “pristine”, unchanged values of a given rock unit. In most cores the rock is also depleted in 13Ñ but two cores show high-er 13C values. In addition to this low-gradient alteration, most of the cores also show a narrow (4-50 mm) zone of the high-gradient alteration, across which δ18Î and δ13Ñ drop by respectively, 2.0–4.9 ‰ and 0.7–4.5 ‰. At three localities, the walls of the hypogene cavities were coated with phreatic calcite. Isotopic composition of this calcite corresponds to the lowermost values of the altered rock. In one core, the rock in the high-gradient alteration zone is depleted in 18Î but enriched in 13Ñ. In yet another core the rock is enriched in both 18Î and 13Ñ. The results corroborate the hypogenic origin of conduits and suggest that the wallrock was exposed to, and interacted with, geo-chemically different waters after the main volume of cavities had been created by disso-lution.

The Piei mine-cave (Lagnes, Vaucluse, France) locates at the contact of the Vaucluse Mounts and the Carpentras basin, close to the Fontaine de Vaucluse spring. It develops in Cretaceous limestone (Urgonian facies), close to a main regional lineament, the Salon-Cavaillon fault. The cave was mined in the XIXth Century, giving access to passages previously filled with diverse neogene sands and massive iron crusts. The exploitation mainly followed the natural passages. The origin of the cave is related to hypogenic flow rising from deep fissures or hydraulic breccias, with ferruginous deposition at the contact or on top of the neogene sands filling. Microbial activity was present during the cave activity, associated to the ferruginous deposits. This cave probably corresponds to the Neogene period, when the Vaucluse plateau was uplifted. The Piei mine-cave record the position of the corresponding base level and thus the progressive tilting of the massive, together with a range of similar caves located around the western edge of the Vaucluse Plateau

Germany currently features 20 caves in sulfate rocks (gypsum and anhydrite) longer than 200 m. Most of them occur either in the Werra-Anhydrite or in the Hauptanhydrite of the evaporitic Zechstein series (Upper Permian). One occurs in the Jurassic Münder Mergel and two in the Triassic Grundgips. The longest, the Wimmelburger Schlotten, is 2.8 km long with a floor area of 24,000 m2. All caves, except four, occur in the South Harz, where the Zechstein outcrop fringes the uplifted and tilted Variscian Harz. These caves can be divided into three general classes: (i) epigenic caves with lateral, turbulent water flow, and (ii) shallow or (iii) deep phreatic caves with slow convective density-driven dissolution. The latter were discovered during historic copper-shale mining and called “Schlotten” by the miners; most of them are not accessible any more. Shallow phreatic caves occur in several areas, most notably in the Nature Preserve of the Hainholz/Beierstein at Düna/Osterode/Lower Saxony. Here, we sampled all water bodies in May 1973 and monitored 31 stations between Nov. 23rd, 1974, and April 24th, 1976, with a total 933 samples, allowing us to characterize the provenance of these waters. These monitoring results were published only partially (PCO2 data, see Kempe, 1992). Here, I use the data set to show that the Jettenhöhle (the largest cave in the Hainholz) has been created by upward moving, carbonate-bearing, groundwater of high PCO2. Even though the cave has now only small cave ponds and essentially is a dry cave above the ground water level, it is a hypogene cave because of the upward movement “of the cave-forming agent” (sensu Klimchouk, 2012). Likewise, the Schlotten are created by water rising from the underlying carbonate aquifer, but under a deep phreatic setting

The Cova des Pas de Vallgornera is an important and protected coastal cave, located in the southern part of the island of Mallorca, that outstands due to its length and the complex processes involved in its speleogenesis. Although sediments are not the main topic of interest, their presence as well as their paleontological contents are valuable evidence for paleoclimatic and chronological reconstructions of the cave morphogenesis. The sedimentary infilling is characterized by a scarce presence of clastic sedimentation, mainly composed of silts and clays, which can only be found at some minor passages in the innermost parts of the cave. It corresponds to a clayey sedimentation mainly derived from the soil infiltration that can be found mixed with carbonate particles detached from the cave walls. A particularly different situation occurs in the northernmost end of the cave where an important sequence of silty sands are present, hosting a very rich paleontological deposit. The objective of this paper is to describe the detrital deposits present in the cave by means of the integration of sedimentological, chemical, and mineralogical data, which will aim to provide a better understanding of the processes that have occurred during the system’s speleogenetic evolution.

Porosity and permeability along fractured zones in carbonates could be significantly enhanced by ascending fluid flow, resulting in hypogene karst development. This work presents a detailed structural analysis of the longest cave system in South America to investigate the relationship between patterns of karst conduits and regional deformation. Our study area encompasses the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR) caves, which are ca. 107 km and 34 km long, respectively. This cave system occurs in Neoproterozoic carbonates of the Salitre Formation in the northern part of the São Francisco Craton, Brazil. The fold belts that are around and at the craton edges were deformed in a compressive setting during the Brasiliano orogeny between 750 and 540 Ma. Based on the integrated analysis of the folds and brittle deformation in the caves and in outcrops of the surrounding region, we show the following: (1) The caves occur in a tectonic transpressive corridor along a regional thrust belt; (2) major cave passages, at the middle storey of the system, considering both length and frequency, developed laterally along mainly (a) NE–SW to E–W and (b) N to S oriented anticline hinges; (3) conduitswere formed by dissolutional enlargement of subvertical joints,which present a high concentration along anticline hinges due to folding of competent grainstone layers; (4) the first folding event F1was previously documented in the region and corresponds with NW–SE- to N–S-trending compression, whereas the second event F2, documented for the first time in the present study, is related to E–Wcompression; and (5) both folding  еvents occurred during the Brasiliano orogeny. We conclude that fluid flow and related dissolution pathways have a close relationship with regional deformation events, thus enhancing our ability to predict karst patterns in layered carbonates.