Hypogene Caves Research Articles

Ferruginous accumulations in hypogene karst conduits of Crimean Piedmont: Evidence for a deep iron source for the Kerch-Taman iron-ore province, north Black Sea region

This study documents ferruginous accumulations in hypogene karst cavities in the Eocene limestones of central-eastern Crimean Piedmont, including unusual quartz-goethite tubes in Tavrida Cave, and aims to reveal their origin and significance to the problem of iron source for the adjacent Kerch-Taman iron ore province. We employed speleological, petrographic, mineralogical, and geochemical (including REE analysis) methods. Ferruginous materials dominated by goethite precipitated in open cavities, although metasomatic replacement of the host rock also occurred. Although the formation of conduits/cavities enclosing ferruginous materials clearly predated the main phase of hypogene speleogenesis in Tavrida Cave, both speleogenetic phases were controlled by the same cross-formational flow paths. Geochemical characteristics of the studied materials in all sites are largely similar, pointing to their genetic affinity. REEY patterns in most of the samples are remarkably similar to those found in iron formations worldwide, for which significant hydrothermal contribution is established. We show that these accumulations had been formed from acidic, reduced, hydrothermal fluids rising from a deep source and intruding oxidizing environment of the karstified Eocene aquifer, where goethite had been precipitated at the boundary of the iron reduction/oxidation zone. This mechanism is consistent with the hypogene origin of host karst conduits. These findings have implications to the origin of iron ores in the adjacent Kerch-Taman province, where deposits are closely associated with mud volcanoes operating there since at least the Middle Miocene. Although the marine sedimentary (hydrogenetic) origin of these deposits is universally accepted, the source of iron is a matter of debate. Revealing of the deep fluid source of iron for the ferruginous accumulations in hypogene caves in Piedmont suggests that the deep fluid system associated with mud volcanism in the Kerch-Taman region could have been a significant, if not the major, supplier of iron for ore deposits in the Cimmerian basin.

Multi-method geochemical characterization of groundwater from a hypogene karst system

An approach, combining several geochemical methods, was used to determine the groundwater properties and components of a hypogene karst system, where sampling is restricted only to the spring sites, and with a limited number of available sampling locations. Radiogenic isotopes (3H, 14C) were used to constrain the groundwater mean residence time and separate different groundwater components. Noble gases, stable isotopes of water (δ18O, δ2H), dissolved inorganic carbon (δ13C) and dissolved sulfate (δ34S, δ18O), and major ion and trace element composition were used to identify the source of water, its chemical evolution and water–rock interactions, as well as to identify the contribution and composition of endogenic gases. This approach was applied to three low-temperature thermal springs located in Mariovo (North Macedonia) associated with fossil hypogene caves, previously identified by morphological and geochemical studies of caves and cave deposits. Based on the obtained results, the main studied springs represent an output part of a regional hypogene karst groundwater system with a deep-circulating (~1 km), old (~15 ka), thermal (≥60 °C) water, which mixes with young (<50 years), cold (<14 °C) and shallow epigene karst groundwater. The output parts are structurally controlled, at the interception of low topography and deep faults, along which the groundwater interacts with deep-seated gases, dominantly CO2 of metamorphic origin (δ13C of +4.5‰ VPDB), with some contribution of mantle helium. The thermal karst groundwater interacts at depth with volcanic rocks from the nearby Neogene-Quaternary volcanic complex, as well as with metamorphic basement rocks and granitoids.

Szemelvények az elmúlt két évtized ELTE-n végzett, medenceléptékű hidrogeológiai kutatásaiból

Az Eötvös Loránd Tudományegyetem (ELTE) Általános és Alkalmazott Földtani Tanszékének hidrogeológiai kutató és oktatócsoportja (Tóth József és Erzsébet Hidrogeológia Professzúra) tevékenységének középpontjában a felszínalatti vízáramlásoknak és kapcsolódó jelenségeknek a hidraulikus folytonosság alaptételére épülő medenceléptékű és rendszer szemléletű megközelítése áll. A jelen tanulmány e megközelítést történeti felvezetéssel és a korábbi, rétegtani (hidrosztratigráfiai) alapú „artézi” paradigmával szembeállítva mutatja be. A folyamatosan fejlesztett medenceléptékű hidrogeológiai kutatási módszertant röviden tárgyaljuk, a technikai részletek helyett kiemelve az alkalmazott módszertani megközelítések magyarázatát. Ezek közül legnagyobb jelentőséggel a kutakban mérhető hidraulikai adatok medenceléptékű, azaz medencehidraulikai elemzése bír, amelynek eredménye a „valós vízáramlási rendszermodell” felállítása. Ennek megfelelően kutatás történetünkből a medenceléptékű és különösen a medencehidraulikai eredményeket szemlézzük a továbbiakban, említve az ezekáltal összefüggésrendszerbe helyezett és egyéb módszerekkel vizsgált jelenségeket is. Az ország területének nagyrészét lefedő kutatásaink domborzattól és kőzettípustól (sziliciklasztos vagy karbonátos) függetlenül kimutatták a kőzetváz hidraulikus folytonosságát és a gravitáció vezérelte regionális felszínalatti vízáramlási rendszerek jelenlétét. Ezek medenceléptékben fedetlen, csapadékvízből utánpótlódó és közel hidrosztatikus nyomásrezsimű tartománya alatt a mélymedencékben abnormális nyomásrezsimek (túlnyomásos vagy alulnyomásos) fedett, és nem vagy csak korlátozottan utánpótlódó tartományai találhatók. E komplex hidraulikai helyzettel és a felszínalatti víz áramlások földtani és környezeti hatótényező szerepével számos felszíni (szikesedés, felszín alatti víztől függő ökoszisztémák, FAVÖKO-k stb.), és felszín alatti (hipogénbarlangképződés, szénhidrogén csapdázódás stb.) jelenség és folyamat nyert magyarázatot.

Supergene sulphuric acid speleogenesis and the origin of hypogene caves: evidence from the Northern Pennines, UK

AbstractThe maze caves of the Northern Pennines are rectilinear joint‐controlled networks of predominantly tall vertical rifts developed on one level towards the top of a ~20 m thick limestone bed; they were all intersected by underground mines and have no relationship to the present landscape. Passage walls commonly have large, non‐directional scallops; speleothems are uncommon. The caves were previously identified as hypogene in origin, i.e. formed by groundwater ascending from depth, but reassessment of their origin using published data shows that they lack diagnostic hypogene features (rising wall channels, ceiling channels, ceiling cupolas and dome‐pits), and the low permeability strata above and below the limestone bed greatly restrict vertical groundwater flow through the caves. Instead the maze caves were dissolved by the sulphuric acid released by oxidation of iron sulphides (and perhaps chalcopyrite) in the mineralized veins adjacent to all these caves; passage sizes decrease away from the veins and gypsum encrusts the walls of one cave. The maze caves were not formed by vertical groundwater flow, and dissolution was focussed in a relatively small area of limestone beneath an impermeable confining layer. The caves began to form when river incision due to the probably Late Cenozoic uplift of northern England exposed the iron sulphides to weathering and oxidation.The process that formed the maze caves is here termed supergene sulphuric acid speleogenesis, because generation of the acidity was due to near‐surface supergene sulphide oxidation, and differentiated from hypogene sulphuric acid speleogenesis, where the source is at depth beneath the cave.To clarify usage of the term hypogene, it should be restricted to Palmer's geochemical definition (Speleogenesis: Evolution of Karst Aquifers, eds Klimchouk et al., National Speleological Society: Huntsville, AL, 2000; 77–90): dissolution by a deep‐seated source of acidity. Caves dissolved by ascending groundwater containing carbonic acid with a near‐surface origin, e.g. on the rising limb of a phreatic loop, are better identified as epigene. © 2020 John Wiley &amp; Sons Ltd

The Morro Vermelho hypogenic karst system (Brazil): Stratigraphy, fractures, and flow in a carbonate strike-slip fault zone with implications for carbonate reservoirs

The Morro Vermelho Cave (MVC) (Brazil) developed within the Morro Vermelho karst system, which affected Neoproterozoic limestones (Salitre Formation). The MVC experienced little interactions with meteoric processes and is an example of a hypogenic cave formed during strike-slip deformation. The Salitre carbonates in the MVC experienced distributed deformation along an elongated domain overlying a buried strike-slip fault. Gently dipping, semiductile shear zones formed with decimeter-scale (3.9 in.) dolomitic veins. In our model, Mg-rich fluids flowing along the Salitre aquifer caused at the same time extensive dolomitization of the body of rock (100-m [328-ft] scale) experiencing distributed deformation. With progressive displacement, the deep strike-slip fault propagated upward causing the development of an anticline pop-up, steepening sedimentary layers, and steep 1–10-m-long (3.3–33.8-ft) fractures, which served as pathways for upward fluid flow. These steep extensional fractures made it possible for fluids flowing in lower, quartzitic aquifers to enter the carbonate aquifer causing silica deposition in rock cavities and in fractures and fault planes. Following the main stage of speleogenesis, silica deposition took over again depositing on the cave walls a continuous silica crust, rarely observed in other settings worldwide. The interplay between regional bedding-parallel flow and focused circulation of fluids along steep faults and dipping layers, and the associated rock–fluid interactions are not unique to the contractional settings presented but can also occur in association with similar faults in rifted continental margins.

Characterization of the regional groundwater flow systems in south Transdanubia (Hungary) to understand karst evolution and development of hydrocarbon and geothermal resources

In South Transdanubia (Hungary), the remarkable geothermal and hydrocarbon resources in the Drava Basin and the hypogene caves at the margin of outcropping carbonate hills were usually investigated separately and their interactions were hitherto neglected. The aim of this study is to give all these groundwater-related resources and phenomena a common framework applying the concept of regional hydraulic continuity, and to complete the regional (i.e., basin-scale) hydraulic assessment of the area based on preproduction archival measured data. Pressure-elevation profiles, tomographic fluid-potential maps and hydraulic cross-sections were constructed to determine the vertical and horizontal fluid-flow conditions. As a result, two kinds of fluid flow systems could be identified. Within the gravitational flow systems, horizontal flow conditions are dominant and the regional flow direction tends toward the S–SE. In deeper basin regions, an overpressured flow system is prevalent, where fluids are driven laterally from the deeper sub-basins towards their margins. Based on the regional-scale evaluation of fluid flow systems, conclusions could be drawn regarding the geothermal and hydrocarbon potential of the area. Additionally, local-scale phenomena could be explained, particularly in the southern foreland of the Villány Hills. Cave formation cannot be related to the present-day flow systems here. In the Harkány area, groundwater chemistry could be explained by fluid contribution from the Drava Basin. A comparison with the marginal Buda Thermal Karst area allows for generalized conclusions regarding the connections between marginal karst reservoirs and the Pannonian Basin.

Biologically mediated release of endogenous N2O and NO2 gases in a hydrothermal, hypoxic subterranean environment

The migration of geogenic gases in continental areas with geothermal activity and active faults is an important process releasing greenhouse gases (GHG) to the lower troposphere. In this respect, caves in hypogenic environments are natural laboratories to study the compositional evolution of deep-endogenous fluids through the Critical Zone. Vapour Cave (Alhama, Murcia, Spain) is a hypogenic cave formed by the upwelling of hydrothermal CO2-rich fluids. Anomalous concentrations of N2O and NO2 were registered in the cave's subterranean atmosphere, averaging ten and five times the typical atmospheric backgrounds, respectively. We characterised the thermal conditions, gaseous compositions, sediments, and microbial communities at different depths in the cave. We did so to understand the relation between N-cycling microbial groups and the production and transformation of nitrogenous gases, as well as their coupled evolution with CO2 and CH4 during their migration through the Critical Zone to the lower troposphere. Our results showed an evident vertical stratification of selected microbial groups (Archaea and Bacteria) depending on the environmental parameters, including O2, temperature, and GHG concentration. Both the N2O isotope ratios and the predicted ecological functions of bacterial and archaeal communities suggest that N2O and NO2 emissions mainly depend on the nitrification by ammonia-oxidising microorganisms. Denitrification and abiotic reactions of the reactive intermediates NH2OH, NO, and NO2− are also plausible according to the results of the phylogenetic analyses of the microbial communities. Nitrite-dependent anaerobic methane oxidation by denitrifying methanotrophs of the NC10 phylum was also identified as a post-genetic process during migration of this gas to the surface. To the best of our knowledge, our report provides, for the first time, evidence of a niche densely populated by Micrarchaeia, which represents more than 50% of the total archaeal abundance. This raises many questions on the metabolic behaviour of this and other archaeal phyla.

Sulfuric acid speleogenesis in the North Caucasus: Sharo-Argun valley Caves (Chechen Republic, Russia)

Geological and hydrogeological conditions in the North Caucasian monocline allow ascending cross-formational flow and discharge of artesian waters from Upper Jurassic and Lower Cretaceous strata, thus enabling hypogene karst. The presence of evaporites (gypsum and anhydrite) in the deep-seated Mesozoic deposits promotes the sulfate-reduction processes, which supply H2S in the waters, thus enabling the sulfuric acid speleogenesis (SAS). Here we report on four hypogene caves of the Sharo-Argun valley. Three caves, Sheki, Magomed, and Kamila are presently active; H2S waters discharge through them. The fourth cave, Said-Emin is in the fossilized state. The active caves are characterized by high H2S contents in the air (up to 60 ppmv), high acidity of condensation solutions (pH 0.5–3.0) and abundant bacterial biofilms and mats dominated by sulfur-oxidizing bacteria. Morphological features of the caves (feeders, condensation-corrosion domes, horizontal water table notches and slots, gypsum replacement pockets, etc.) and mineral deposits (replacement gypsum, native sulfur, minerals of the alunite group) are typical of the cases formed by SAS. Sulfates and native sulfur of the caves have ‘light’ δ34S isotope compositions, consistent with sulfate-reduction in deep seated conditions and subsequent H2S oxidation in the near-surface conditions.

Influence of fracture stratigraphy on hypogene cave development and fluid flow anisotropy in layered carbonates, NE Brazil

Abstract Fractured and karstified carbonates are often major aquifers and hydrocarbon reservoirs. The Toca da Boa Vista (TBV) and Toca da Barriguda (TBR) caves in NE Brazil, which form the longest cave system in South America, developed in a gently folded, layered and fractured Neoproterozoic carbonate sequence made of different lithological units (limestones versus siliciclastic rocks and marls) with variable bed properties (bed thickness, surface roughness of bed-to-bed interlayers) and fracture attributes (spacing, height). The functional organization of the hypogenic cave system has been recently revealed, with subdivision in three speleo-stratigraphic storeys which, from bottom to top, acted as recharge, lateral redistribution and outflow components of the rising fluid flow system, respectively. Structural analysis and new fracture data from TBV and TBR indicate that the stratigraphic setting controlled the fracture pattern development during two tectonic phases, which determined the fluid flow anisotropy during speleogenesis. We found that mechanical and fracture stratigraphy, in conjunction with bed thickness and bed-to-bed interlayer characteristics, controlled the spacing and height of fractures and, as a result, strongly influenced the fluid flow pattern and functional organization of the cave system. In particular, bed-normal rising fluids localized along m-to tens of m-spaced throughgoing fractures developed in the lower and upper storeys, whereas horizontal and bed-parallel fluid flow was focused in a package of thin carbonates, siliciclastics and marls with cm-spaced, strata-bound fractures. This fluid flow anisotropy is attained also due to the presence of rough-walled, bedding-parallel interlayers (i.e., burial stylolites) in the lower massive grainstone which hampered bed-parallel flow, and smooth, planar bedding-parallel interlayers which enhanced lateral fluid movements in the well-layered and fractured middle storey units. Therefore, we conclude that in heterolithic layered carbonate packages, the intricate hypogenic karst pattern is related to heterogeneous fluid flow behaviour associated with the structural complexity imparted by the mechanical versus fracture stratigraphy.

Sulfuric acid caves in Calabria (South Italy): Cave morphology and sulfate deposits

Research on karst in the Calabria region recognized three different hypogenic cave systems, all related to sulfidic thermal springs. Cave morphology, the depositional setting and isotopic characteristics of gypsum deposits reveal that the main process for cave formation was the oxidation of H2S to sulfuric acid. This process, known as sulfuric acid speleogenesis, was induced by thermal water rising towards the oxidizing zone in tectonic windows where dolomitic or limestone rocks outcrop. The δ34S values of most gypsum deposits prove they originated from sulfuric acid produced by H2S oxidation in the cave atmospheres. Most gypsum deposits in the Calabrian caves, in fact, exhibit δ34S values very similar to those of H2S, not to those of sulfate in the groundwater. On the contrary, the barite and part of the gypsum in the Terme Luigiane have δ34S values similar to those for sulfate in the water, implying that the sulfate minerals precipitated in a subaqueous environment. A large-scale deposition of replacement gypsum occurred only in the water table caves of Cassano, where subaerial corrosion greatly influenced cave morphology and the typical passage cross-sections. In the Terme Luigiane and Mount Sellaro cave systems, these subaerial processes caused only minor changes in inclined passages that had evolved mainly in subaqueous conditions.

The conduit-seal system of hypogene karst in Neoproterozoic carbonates in northeastern Brazil

Abstract Karst processes are of primary importance for the generation of secondary porosity and permeability in carbonate reservoirs and aquifers. The topic investigated in this study are the effects of the facies and stratigraphy of different layers on the vertical distribution of solution cavities formed by hypogenic fluids in a carbonate sequence. This work uses the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR) caves as analogues of carbonate reservoirs that are affected by karst processes. These are two different caves that are 400 m apart but exhibit the same geological characteristics and occur in the Neoproterozoic Salitre Formation (700-560 Ma), Sao Francisco Craton, Brazil. These caves form the longest cave system in South America, with conduits of lengths ∼107 km (TBV) and ∼34 km (TBR). Previous studies of these caves indicated their hypogene origins. These caves developed by an ascending fluid flow, mainly along fractures. The fluid then flowed laterally and was influenced by the following five stratigraphic units, from the bottom to the top: (1) cross-bedded oolitic grainstone, (2) fine grainstone with chert nodules, (3) microbial carbonate, (4) interbedded fine siliciclastics and marls, and (5) crystalline grainstone interfingered with chert layers. Units 4 and 5 formed a stratigraphic seal. Units 1, 2, and 3 below the seal supported the lateral redistribution of flow and respective conduit development. Therefore, these units exhibit a high degree of karstification. Veins related to the first fluid phases that compose a hydrothermal mineral assemblage cut across these units. We conclude that stratigraphic control is important for determining the architecture of the hypogenic cave system at the local scale.

Unconfined hypogene evaporite karst: West Texas and southeastern New Mexico, USA

Diverse karst phenomena occur throughout the Gypsum Plain where the Castile Formation crops out over ~1800 km2 in West Texas and southeastern New Mexico. Hypergene karst is extensive and widespread, while traditional hypogene karst manifestations (both caves and intrastratal dissolution) occur in high frequency in the western outcrop region where surface denudation has been the greatest so as to induce surficial breaching. Unconfined hypogene karst occurrences have been recently identified, including two general variations: 1) artesian-like discharge features; and 2) venting structures. Artesian-like discharge features arise at surficially-breached hypogene caves and through high permeability regions on the margins of breccia pipes; these occur when aquifer pressures within the underlying Bell Canyon siliciclastics are sufficiently elevated subsequent to anomalously high precipitation events. Venting structures associated with condensation corrosion-like processes coupled with ascending moisture-rich vapor occur as fracture vents and hydration buckles; fracture vents develop along near-vertical joint sets and hydration buckles form at intermittent zones of high permeability within the core regions of breccia pipes. All venting structures form highly porous, low density, secondary sulfate mineralization at the land surface, creating local topographic highs decimeters to a meter in scale that preclude interception of meteoric waters into these unconfined hypogene karst features. The Gypsum Plain hosts complex karst phenomena that present unique engineering challenges as variable geohazard occurrences ranging from shallow, hypergene caves to deep, complex, hypogene features both formed in semi-confined and unconfined speleogenetic conditions.

New insights on secondary minerals from Italian sulfuric acid caves

Sulfuric acid minerals are important clues to identify the speleogenetic phases of hypogene caves. Italy hosts ~25% of the known worldwide sulfuric acid speleogenetic (SAS) systems, including the famous well-studied Frasassi, Monte Cucco, and Acquasanta Terme caves. Nevertheless, other underground environments have been analyzed, and interesting mineralogical assemblages were found associated with peculiar geomorphological features such as cupolas, replacement pockets, feeders, sulfuric notches, and sub-horizontal levels. In this paper, we focused on 15 cave systems located along the Apennine Chain, in Apulia, in Sicily, and in Sardinia, where copious SAS minerals were observed. Some of the studied systems (e.g., Porretta Terme, Capo Palinuro, Cassano allo Ionio, Cerchiara di Calabria, Santa Cesarea Terme) are still active, and mainly used as spas for human treatments. The most interesting and diversified mineralogical associations have been documented in Monte Cucco (Umbria) and Cavallone-Bove (Abruzzo) caves, in which the common gypsum is associated with alunite-jarosite minerals, but also with baryte, celestine, fluorite, and authigenic rutile-ilmenite-titanite. In addition, the core of alunite and jarosite, from these two systems, results enriched in PO43-, clearly suggesting hypogene hydrothermal origin. Santa Cesarea Terme, Capo Palinuro, and Acqua Mintina caves show important native sulfur deposits, which abundantly cover walls, ceilings, and speleothems. Abundant copiapite, pickeringite, tamarugite, hexahydrate assemblages have been observed in the Calabrian systems; their association with pyrite and hematite would suggest they formed in very acidic conditions with pH ranging between 0 and 4.

Old and recent processes in a warm and humid desert hypogene cave: ‘A’rak Na‘asane, Israel

Old and recent processes in a warm and humid desert hypogene cave: ‘A’rak Na‘asane, Israel

Biofilm forming bacteria and archaea in thermal karst springs of Gellért Hill discharge area (Hungary).

The Buda Thermal Karst System (BTKS) is an extensive active hypogenic cave system located beneath the residential area of the Hungarian capital. At the river Danube, several thermal springs discharge forming spring caves. To reveal and compare the morphological structure and prokaryotic diversity of reddish-brown biofilms developed on the carbonate rock surfaces of the springs, scanning electron microscopy (SEM), and molecular cloning were applied. Microbial networks formed by filamentous bacteria and other cells with mineral crystals embedded in extracellular polymeric substances were observed in the SEM images. Biofilms were dominated by prokaryotes belonging to phyla Proteobacteria, Chloroflexi and Nitrospirae (Bacteria) and Thaumarchaeota (Archaea) but their abundance showed differences according to the type of the host rock, geographic distance, and different water exchange. In addition, representatives of phyla Acidobacteria, Actinobacteria, Caldithrix, Cyanobacteria, Firmicutes Gemmatimonadetes, and several candidate divisions of Bacteria as well as Crenarchaeota and Euryarchaeota were detected in sample-dependent higher abundance. The results indicate that thermophilic, anaerobic sulfur-, sulfate-, nitrate-, and iron(III)-reducing chemoorganotrophic as well as sulfur-, ammonia-, and nitrite-oxidizing chemolithotrophic prokaryotes can interact in the studied biofilms adapted to the unique and extreme circumstances (e.g., aphotic and nearly anoxic conditions, oligotrophy, and radionuclide accumulation) in the thermal karst springs.

Sulphuric acid geofluid contribution on thermal carbonate coastal springs (Italy)

Hypogenic caves, developed by sulphuric acid speleogenesis, are known all over the world among which the Santa Cesarea Terme caves have been included. They are four submerged caves, located along a coastal carbonate sector in Southern Italy and hosting the outflow of coastal springs of thermal mixed waters (from 21 to 33 °C). These waters derive from the mixing of three water end members: the fresh pure groundwater of a wide karstic aquifer, the deep sulphur thermal water and the seawater. This cave system represents an almost unique case of hypogenic sea caves in carbonate environment. The thermal mixed waters have a different effect on the surrounding rocks of the caves, influencing the sulphuric acid speleogenetic process within the whole cave system. To understand the complex and overlapping natural processes acting on the development of these coastal caves, a multidisciplinary study has been carried out. This study has integrated all the data resulting from different methods and technologies, merging morphology, structural geology, hydrogeology, hydrogeochemistry and mineralogy. This multidisciplinary study has allowed to define the main geochemical processes acting within these caves, including the cave development and the formation of the mineral concretions. After the introduction of H2S in the thermal waters, formed by the reduction of sulphates in the sedimentary deposits crossed at depth in the offshore, the oxidation occurs within the caves, producing sulphuric acid. Favoured by upwelling deep-seated thermal flows, this acid dissolves the limestone, with condensation corrosion process that involve replacement of limestone rock with gypsum. This process has resulted to be more active and remarkable within the Gattulla Cave, one of the Santa Cesarea Terme sea caves.

Az utóbbi 20 év barlangkutatási eredményei a Budai-hegységben (különös tekintettel a Rózsadomb környékére)

A Földtani Közlöny 125. 3-4. számában jelent meg összefoglaló a Budai-hegység barlangjairól (Leél-Őssy Sz. 1995). Az azóta eltelt időszakban (elsősorban a kutatási módszerek fejlődésének, és a megszaporodott hegyvidéki építkezéseknek köszönhetően) nemcsak új feltárások történtek (elsősorban a Rózsadomb térségében, ahol az 1995-ben ismert 30 km-es járathossz csaknem a duplájára, 55 km-re növekedett), hanem az itteni hipogén barlangok genetikájával, ásványvilágával kapcsolatban is számos új eredmény született. A keletkezéssel kapcsolatos új elméletek közül az elváltozott (kovás) zónákkal kapcsolatosakat, és a barlangot kioldó aszcendens termálvizek eredetével és keveredésével kapcsolatos új eredményeket kell kiemelnünk. Az akkor a Budai-hegységben ismert barlangi ásványfajok száma 15-ről 31-re emelkedett. Ebben az időszakban születtek az első konkrét eredményeket tartalmazó korhatározások is. Ezek közül több részben publikálásra került Mindszenty Andrea szerkesztette Budapest: Földtani értékek és az ember c. 2013-as könyvben. Az egész Budai-hegységben ma 239 barlangot ismerünk. Budapesten (a Pilishez tartozó Róka-hegyen lévőkkel együtt) 176 barlang található. A Rózsadomb térségében 102 barlangot kataszterizáltak az Országos Barlangnyilvántartásban. Az elmúlt 20 évben legfontosabb barlangfelfedezések a víz alatti Molnár János-barlangban, a Hideglyuk- és Harcsaszájú, valamint a Pál-völgyi-barlangban történtek: az utóbbi három barlang és a Mátyás-hegyi-barlang közötti összekötő járatok feltárásának köszönhetően, közel 31 km-es hosszával a Pál-völgyi-barlangrendszer lett Magyarország leghosszabb barlangja, megelőzve az Aggtelek-jósvafői Baradla-barlangot (beleértve a Baradla szlovákiai részét, a Domica-barlangot is). Nagy eredmény az eddig csak felszín közeli járatairól ismert Ferenc-hegyi-barlangban a Mélyszint megtalálása. Három új kisbarlang: a Citadella-kristálybarlang, a Királylaki-barlang és a József-hegyi 4. sz. barlang felfedezése pedig különösen értékes ásványkiválásai, ill. nagyon perspektivikus továbbkutatási lehetőségei miatt nagyon jelentős. Ezen kívül további 32 kisbarlangot találtak a kutatók az elmúlt 20 évben a Budai-hegységben, elsősorban a Rózsadomb térségében (1. ábra, 1. táblázat).

Deep geoelectrical investigation to bound a coastal thermal outflow area

The coastal carbonate Apulian aquifers, located in southern Italy, feed several coastal fresh springs and constitute the main local source of high quality water. The Santa Cesarea Terme cave system is almost unique case of hypogenic coastal spring caves, located along the Adriatic Sea coastline and hosting spring coastal outflow of mixed groundwater (from 22°C to 33°C) mainly of thermal groundwater due to infiltration offshore, in the sea bottom, and pure fresh groundwater due rainfall infiltration. Thermal springs and the outflow system are strictly controlled by both the discontinuity network and the karst processes involving the foreland environment. Detailed geoelectrical prospecting were carried out to bound the upflow continental area of this system, considering the geoelectrical effects of deep water mixing with different salinity and temperature close the Adriatic coast.

A new species of stygobiont freshwater planarian (Platyhelminthes, Tricladida) from a chemoautotrophic ecosystem: the Frasassi karst in Italy

In this paper we report a new species of Dendrocoelum from the chemoautotrophic ecosystem of the Frasassi hypogenic cave complex in the northeastern Apennines of Italy. Dendrocoelum leporii Stocchino &amp; Sluys, sp. nov. is characterized by the presence of a muscular atrial valve, which is unique within the genus. Moreover, the new species is characterized also by a penis papilla with a pseudoflagellum, numerous testes situated in the ventral, dorsal and median body regions with the follicles extending to the far posterior end of the body, and a large adenodactyl with the so-called Balkan type of musculature. The new species represents the twelfth dendrocoelid species recorded for Italy. A summary is provided of the species of the family Dendrocoelidae Hallez, 1892 thus far reported for the mainland and the isles of Italy.

Palaeokarst Deposits in Caves: Examples from Eastern Australia and Central Europe

Palaeokarst deposits are most commonly found in excavations, drill holes and naturally exposed at the Earth’s surface. Some caves however intersect palaeokarst deposits. This occurs in large hypogene caves in the USA, thermal caves in Hungary and in many caves in eastern Australia. Palaeokarst deposits in caves respond to cave forming processes in the same way as hostrock: the palaeokarst deposits form cave walls. A range of palaeokarst deposits is exposed in caves including; filled tubes, walls composed of flowstone, large-scale bodies, breccia pipes, dykes, volcaniclastic palaeokarst and crystalline palaeokarst. As well as being exposed in cave walls, palaeokarst deposits can wholly or partly form speleogens (speleogens made from palaeokarst). Records of geological events not preserved elsewhere can occur in palaeokarst deposits in caves. These can be difficult to correlate with conventional geological histories. It is important to be able to distinguish between palaeokarst deposits, relict sediments and phantom rock (in-situ weathered rock, also called ghost rock; Vergari & Quinif 1997). Relict sediments can be distinguished from palaeokarst deposits because the cave walls bound relict sediments while palaeokarst deposits form the cave walls. Palaeokarst can be distinguished from phantom rock, as palaeokarst is unconformable with the hostrock, with structures in the hostrock not continuing across the boundary into the palaeokarst. Hostrock structures and textures do continue across the boundary between unaltered hostrock and phantom rock. Similarly, cave sediments are unconformable or disconformable with the hostrock while phantom rock is conformable with hostrock containing hostrock structures and textures. It has been difficult to explain why palaeokarst occurs in some caves and not others. One explanation worth considering is that palaeokarst deposits are not intersected by caves or sections of caves that contain large perennial streams and/or have undergone large-scale vadose fluvial development capable of escaping from the bounds of structural guidance, such as the caves in the Classical Karst. Key words: palaeokarst, caves, Australia, relict sediments, phantom rock.