Anita Erőss

ABSTRACT Unconformities and related karst systems are studied worldwide. A unique red calcite generation, which fills fractures/cavities, is hosted by Mesozoic carbonates in the Transdanubian Range, Hungary. Solid inclusions are located along growth zones of calcite. Hematite, the most abundant solid inclusion, gives the red colour of it. Outcrop-scale geometry, mineralogical features and detrital mineral assemblage (hematite, gibbsite, goethite, kaolinite, smectite, illite, Cr-spinel, monazite, xenotime, zircon, apatite, and Ti-oxide) of calcite precipitates suggest strong correlation between the calcite and nearby karst bauxite deposits. Fluid inclusion petrography and microthermometry (T<50 °C; salinity from 0 to 0.17 NaCl eq. w%) of primary fluid inclusions, and the stable isotope trend of the calcite, following the meteoric water line, clearly indicate vadose and phreatic meteoric origin in a near-surface karst system.The late Cretaceous to mid-Eocene unconformity-related cavity-filling deposits occur close to the surface; indicating that the most recent Quaternary exhumation re-exposed those surfaces that existed at the time of calcite mineralization. Thus red calcite precipitates are interpreted as being speleothems, vestiges of the subterranean part of the pre-Middle Eocene karst. The infiltrated, fine bauxite particles enclosed by the calcite are the witnesses of the once areally extensive pre-Middle Eocene bauxitic blanket that became partially eroded by the time of the deposition of the cover beds.Red calcite when found in core samples may provide good evidence on bauxite formation associated with the overlying unconformity, even if it was later removed by erosion. Therefore, presence or absence of red calcite may be used as distinguishing criteria between karst episodes with or without bauxite formation.This article is protected by copyright. All rights reserved.

Europe's largest naturally flowing thermal water system can be found in Budapest. The springs and wells that supply the famous baths of Budapest discharge from a regional Triassic carbonate rock aquifer system. As the result of the interaction of discharging waters and carbonate rocks, extensive cave systems has developed and still developing today. These caves belong to the group of hypogenic caves, and their special morphology and peculiar minerals make Budapest, beside the city of spas, also "the capital of caves". According to the recent developments in the speleogenetic theories, hypogenic karsts and caves are viewed in flow system context, and can thus be considered as the manifestations of flowing groundwater. Being a marginal area at the boundary of uplifted carbonates and a sedimentary basin, the Buda Thermal Karst serves as a discharge zone of the regional fluid flow. This implies that it may receive fluid components (karstic and basinal) from several sources...

ABSTRACT Unconformities and related karst systems are studied worldwide. A unique red calcite generation, which fills fractures/cavities, is hosted by Mesozoic carbonates in the Transdanubian Range, Hungary. Solid inclusions are located along growth zones of calcite. Hematite, the most abundant solid inclusion, gives the red colour of it. Outcrop-scale geometry, mineralogical features and detrital mineral assemblage (hematite, gibbsite, goethite, kaolinite, smectite, illite, Cr-spinel, monazite, xenotime, zircon, apatite, and Ti-oxide) of calcite precipitates suggest strong correlation between the calcite and nearby karst bauxite deposits. Fluid inclusion petrography and microthermometry (T<50 °C; salinity from 0 to 0.17 NaCl eq. w%) of primary fluid inclusions, and the stable isotope trend of the calcite, following the meteoric water line, clearly indicate vadose and phreatic meteoric origin in a near-surface karst system.The late Cretaceous to mid-Eocene unconformity-related cavity-filling deposits occur close to the surface; indicating that the most recent Quaternary exhumation re-exposed those surfaces that existed at the time of calcite mineralization. Thus red calcite precipitates are interpreted as being speleothems, vestiges of the subterranean part of the pre-Middle Eocene karst. The infiltrated, fine bauxite particles enclosed by the calcite are the witnesses of the once areally extensive pre-Middle Eocene bauxitic blanket that became partially eroded by the time of the deposition of the cover beds.Red calcite when found in core samples may provide good evidence on bauxite formation associated with the overlying unconformity, even if it was later removed by erosion. Therefore, presence or absence of red calcite may be used as distinguishing criteria between karst episodes with or without bauxite formation.This article is protected by copyright. All rights reserved.

To prove the hydraulic connection between the urban R?zsadomb recharge area (Buda Thermal Karst System, Budapest, Hungary) ? through its hydrothermal inactive caves ? and the springs at the foothills has been an important question since the 1980s. These cold and lukewarm springs have been utilized as thermal baths since Roman times, and in modern times, occasionally, chemical and bacterial

The Buda Thermal Karst System is an active hypogenic karst area that offers possibility for the analysis of biogenic cave formation. The aim of the present study was to gain information about morphological structure and genetic diversity of bacterial communities inhabiting the Diana-Hygieia Thermal Spring (DHTS). Using scanning electron microscopy, metal accumulating and unusual reticulated filaments were detected in large numbers in the DHTS biofilm samples. The phyla Actinobacteria, Firmicutes and Proteobacteria were represented by both bacterial strains and molecular clones but phyla Acidobacteria, Chlorobi, Chlorofexi, Gemmatimonadetes, Nitrospirae and Thermotogae only by molecular clones which showed the highest similarity to uncultured clone sequences originating from different environmental sources. The biofilm bacterial community proved to be somewhat more diverse than that of the water sample and the distribution of the dominant bacterial clones was different between biofilm and water samples. The majority of biofilm clones was affiliated with Deltaproteobacteria and Nitrospirae while the largest group of water clones was related to Betaproteobacteria. Considering the metabolic properties of known species related to the strains and molecular clones from DHTS, it can be assumed that these bacterial communities may participate in the local sulphur and iron cycles, and contribute to biogenic cave formation.

ABSTRACT Unconformities and related karst systems are studied worldwide. A unique red calcite generation, which fills fractures/cavities, is hosted by Mesozoic carbonates in the Transdanubian Range, Hungary. Solid inclusions are located along growth zones of calcite. Hematite, the most abundant solid inclusion, gives the red colour of it. Outcrop-scale geometry, mineralogical features and detrital mineral assemblage (hematite, gibbsite, goethite, kaolinite, smectite, illite, Cr-spinel, monazite, xenotime, zircon, apatite, and Ti-oxide) of calcite precipitates suggest strong correlation between the calcite and nearby karst bauxite deposits. Fluid inclusion petrography and microthermometry (T<50 °C; salinity from 0 to 0.17 NaCl eq. w%) of primary fluid inclusions, and the stable isotope trend of the calcite, following the meteoric water line, clearly indicate vadose and phreatic meteoric origin in a near-surface karst system.The late Cretaceous to mid-Eocene unconformity-related cavity-filling deposits occur close to the surface; indicating that the most recent Quaternary exhumation re-exposed those surfaces that existed at the time of calcite mineralization. Thus red calcite precipitates are interpreted as being speleothems, vestiges of the subterranean part of the pre-Middle Eocene karst. The infiltrated, fine bauxite particles enclosed by the calcite are the witnesses of the once areally extensive pre-Middle Eocene bauxitic blanket that became partially eroded by the time of the deposition of the cover beds.Red calcite when found in core samples may provide good evidence on bauxite formation associated with the overlying unconformity, even if it was later removed by erosion. Therefore, presence or absence of red calcite may be used as distinguishing criteria between karst episodes with or without bauxite formation.This article is protected by copyright. All rights reserved.

The Buda Thermal Karst System is located under the densely populated hills of Budapest. One of its caves (Pál-völgy Cave System) is the longest cave of Hungary with 30.1 km. The research was done in this area as a methodological study to estimate karst porosity parameters of aquifers or hydrocarbon reservoirs. In this study two modeling methods are demonstrated. The volumetric modeling method was primarily aimed to determine the macro-scale (>0.5 m) conduit porosity (referred as macroporosity) of the study area as percentage of the incorporating limestone and marl. This method is based on archive survey data (maps and records). Through this method, morphometric parameters and the approximate sizes of the unexplored cave parts were also calculated. The porosity modeling was aimed at the estimation of the meso-scale (0.02–0.5 m) and macro-scale conduit porosity. It is based on rock face measurements near the Pál-völgy Cave System and image analysis. The matching macroporosity estimations of the two methods suggest that the map-based volumetric modeling method can be a useful tool for karstologists and modeling experts to extract as much information as possible from existing cave maps, even if the records of the original survey were lost or scanty. With the matrix porosity data published earlier from this area, and the conduit porosity calculated from the models, hydrological models of the area can be completed.