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Abstract

The laboratory micro X-ray diffraction (μ-XRD) technique is a suitable method to study minerals in-situ in whole-rock specimens without any sample preparation or in polished thin sections, and even in small amounts in powdered form. The micro X-ray diffraction method uses the conventional, closed-tube X-ray generator, but modifications were needed in the diffraction column, sample holder and detector in order to achieve μ-XRD capability.

In this paper, we present a case study of the capillary method used in µ-XRD on hydrothermal clay mineral assemblages that formed in the Velence Mts (Hungary). The capillary method in µ-XRD has many advantages in the investigation of small amounts of clay minerals: (1) easy and rapid preparation of randomly oriented, powdered samples; (2) rapid measurements; (3) accurate diffraction patterns. By using the capillary method, the formation of preferred orientation can be eliminated; thus the (hkl) reflection of the clay minerals can be precisely measured. Illite polytype quantification and the investigation of (060) reflection of clay minerals can be used satisfactorily in µ-XRD.

Hydrothermal clay mineral assemblages are indicative of temperature and pH. Their examination can determine the physicochemical parameters of the hydrothermal fluids that interacted with the host granite in the Velence Mts. The analyzed hydrothermal clay minerals from the western part of the mountains suggest lower temperatures (150–200 °C) and intermediate pH conditions. In contrast, the clay mineral assemblages' characteristics for the eastern part of the mountains indicate more intense argillization and higher temperatures (∼220 °C) and intermediate pH conditions.

Open access

Abstract

Permian felsic volcanic rocks were encountered in petroleum exploration boreholes in SE Hungary (eastern Pannonian Basin, Tisza Mega-unit, Békés–Codru Unit) during the second half of the 20th century. They were considered to be predominantly lavas (the so-called “Battonya quartz-porphyry”) and were genetically connected to the underlying “Battonya granite.” New petrographic observations, however, showed that the presumed lavas are crystal-poor (8–20 vol%) rhyolitic ignimbrites near Battonya and resedimented pyroclastic or volcanogenic sedimentary rocks in the Tótkomlós and the Biharugra areas, respectively. The studied ignimbrites are usually massive, matrix-supported, fiamme-bearing lapilli tuffs with eutaxitic texture as a result of welding processes. Some samples lack vitroclastic matrix and show low crystal breakage, but consist of oriented, devitrified fiammes as well. Textural features suggest that the latter are high-grade rheomorphic ignimbrites.

Felsic volcanic rocks in SE Hungary belong to the Permian volcanic system of the Tisza Mega-unit; however, they show remarkable petrographic differences as compared to the other Permian felsic volcanic rocks of the mega-unit. In contrast to the crystal-poor rhyolitic ignimbrites of SE Hungary with rare biotite, the predominantly rhyodacitic–dacitic pyroclastic rocks of the Tisza Mega-unit are crystal-rich (40–45 vol%) and often contain biotite, pyroxene, and garnet. Additionally, some geochemical and geochronological differences between them were also observed by previous studies. Therefore, the Permian felsic volcanic rocks in SE Hungary might represent the most evolved, crystal-poor rhyolitic melt of a large-volume felsic (rhyodacitic–dacitic) volcanic system.

The Permian volcanic rocks of the studied area do not show any evident correlations with either the Permian felsic ignimbrites in the Finiş Nappe (Apuseni Mts, Romania), as was supposed so far, or the similar rocks in any nappe of the Codru Nappe System. Moreover, no relevant plutonic–volcanic connection was found between the studied samples and the underlying “Battonya granite.”

Open access

Abstract

Permian felsic volcanic rocks were encountered in petroleum exploration boreholes in SE Hungary (eastern Pannonian Basin, Tisza Mega-unit, Békés–Codru Unit) during the second half of the 20th century. They were considered to be predominantly lavas (the so-called “Battonya quartz-porphyry”) and were genetically connected to the underlying “Battonya granite.” New petrographic observations, however, showed that the presumed lavas are crystal-poor (8–20 vol%) rhyolitic ignimbrites near Battonya and resedimented pyroclastic or volcanogenic sedimentary rocks in the Tótkomlós and the Biharugra areas, respectively. The studied ignimbrites are usually massive, matrix-supported, fiamme-bearing lapilli tuffs with eutaxitic texture as a result of welding processes. Some samples lack vitroclastic matrix and show low crystal breakage, but consist of oriented, devitrified fiammes as well. Textural features suggest that the latter are high-grade rheomorphic ignimbrites.

Felsic volcanic rocks in SE Hungary belong to the Permian volcanic system of the Tisza Mega-unit; however, they show remarkable petrographic differences as compared to the other Permian felsic volcanic rocks of the mega-unit. In contrast to the crystal-poor rhyolitic ignimbrites of SE Hungary with rare biotite, the predominantly rhyodacitic–dacitic pyroclastic rocks of the Tisza Mega-unit are crystal-rich (40–45 vol%) and often contain biotite, pyroxene, and garnet. Additionally, some geochemical and geochronological differences between them were also observed by previous studies. Therefore, the Permian felsic volcanic rocks in SE Hungary might represent the most evolved, crystal-poor rhyolitic melt of a large-volume felsic (rhyodacitic–dacitic) volcanic system.

The Permian volcanic rocks of the studied area do not show any evident correlations with either the Permian felsic ignimbrites in the Finiş Nappe (Apuseni Mts, Romania), as was supposed so far, or the similar rocks in any nappe of the Codru Nappe System. Moreover, no relevant plutonic–volcanic connection was found between the studied samples and the underlying “Battonya granite.”

Open access

Abstract

The fuzzy clustering technique is one of the ways of organizing data that presents special patterns using algorithms and based on the similarity level of data. In this study, in order to cluster the resulting data from the Babakoohi Anticline joints, located north of Shiraz, K-means and genetic algorithms are applied. The K-means algorithm is one of the clustering algorithms easily implemented and of fast performance; however, sometimes this algorithm is located in the local optimal trap and cannot respond with an optimal answer, due to the sensitivity of this algorithm to the centers of the primary cluster. In addition, it has some basic disadvantages, such as its inappropriateness for complicated forms and also the dependency of the final result upon the primary cluster. Therefore, in order to perform the study more accurately and to obtain more reliable results, the genetic algorithm is used for categorizing the data of joints of the studied area. Applying this algorithm for leaving the local optimal points is an effective way. The results of clustering of the aforementioned data using the two above techniques represent two clusters in the Babakoohi Anticline. Furthermore, for validity and surveying of the results of the suggested techniques, various mathematical and statistical techniques, including ICC, Vw, VMPC, and VPMBF, are applied, which supports the similarity of the obtained results and the data clustering process in two algorithms.

Open access

Abstract

The fuzzy clustering technique is one of the ways of organizing data that presents special patterns using algorithms and based on the similarity level of data. In this study, in order to cluster the resulting data from the Babakoohi Anticline joints, located north of Shiraz, K-means and genetic algorithms are applied. The K-means algorithm is one of the clustering algorithms easily implemented and of fast performance; however, sometimes this algorithm is located in the local optimal trap and cannot respond with an optimal answer, due to the sensitivity of this algorithm to the centers of the primary cluster. In addition, it has some basic disadvantages, such as its inappropriateness for complicated forms and also the dependency of the final result upon the primary cluster. Therefore, in order to perform the study more accurately and to obtain more reliable results, the genetic algorithm is used for categorizing the data of joints of the studied area. Applying this algorithm for leaving the local optimal points is an effective way. The results of clustering of the aforementioned data using the two above techniques represent two clusters in the Babakoohi Anticline. Furthermore, for validity and surveying of the results of the suggested techniques, various mathematical and statistical techniques, including ICC, Vw, VMPC, and VPMBF, are applied, which supports the similarity of the obtained results and the data clustering process in two algorithms.

Open access

Abstract

In June 2017 a new sauropod trackway locality was discovered in the central part of the Adriatic–Dinaric Carbonate Platform (ADCP), on the island of Hvar (Croatia). The track site is situated on the northern shore of the western edge (Pelegrin) of the island in the upper Turonian – lower Coniacian limestone series. The track site contains altogether 13 footprints arranged in four possible trackways. The largest footprints have a diameter up to 80 cm. In some places the limestone surface is strongly karstified and the tracks are partly eroded, which has certainly modified the original shape and size of the footprints. Microfossil assemblage from the track-bearing beds suggest an early Coniacian age for the tracks. The new trackways on Hvar Island further strengthen the earlier hypothesis that sauropods were present in the western Tethyan archipelago during the late Cenomanian–late Campanian period. In addition, the new tracks, together with those from the Žukova Cove of Hvar, represent two, possibly slightly different stratigraphic horizons close to the Turonian–Coniacian boundary, and suggest that the occurrence of sauropods on the ADCP and possibly also on other parts of the Apulian microplate was not accidental, but rather periodical and more frequent than previously thought.

Open access

Abstract

In June 2017 a new sauropod trackway locality was discovered in the central part of the Adriatic–Dinaric Carbonate Platform (ADCP), on the island of Hvar (Croatia). The track site is situated on the northern shore of the western edge (Pelegrin) of the island in the upper Turonian – lower Coniacian limestone series. The track site contains altogether 13 footprints arranged in four possible trackways. The largest footprints have a diameter up to 80 cm. In some places the limestone surface is strongly karstified and the tracks are partly eroded, which has certainly modified the original shape and size of the footprints. Microfossil assemblage from the track-bearing beds suggest an early Coniacian age for the tracks. The new trackways on Hvar Island further strengthen the earlier hypothesis that sauropods were present in the western Tethyan archipelago during the late Cenomanian–late Campanian period. In addition, the new tracks, together with those from the Žukova Cove of Hvar, represent two, possibly slightly different stratigraphic horizons close to the Turonian–Coniacian boundary, and suggest that the occurrence of sauropods on the ADCP and possibly also on other parts of the Apulian microplate was not accidental, but rather periodical and more frequent than previously thought.

Open access

Abstract

With the introduction of the Water Framework Directive, the relative importance of smaller waterways increased. This statement is particularly true for Hungary, where water-quality monitoring of most smaller rivers only began 12 years ago. Due to their large number, and the lack of historical data concerning their state, systematic monitoring is a challenge.

In the current study, 101 creeks are characterized on the one hand by 13 physico-chemical quality parameters (pH, electric conductivity, chloride ion concentration, dissolved oxygen, oxygen saturation, biochemical oxygen demand, chemical oxygen demand, total organic carbon, ammonium nitrogen, total inorganic nitrogen, total nitrogen, orthophosphate and total phosphorus), on the other hand by their watershed's relief, land use, and point sources' pollution indicators. Euclidean distance between water bodies (henceforth WBs) is calculated according to normalized physico-chemical monitoring values. They are grouped into clusters using the hierarchical clustering method. Watershed characteristics are used to explain the clustering via linear discriminant analysis.

The investigation revealed that the main driver of cluster group creation is related to human impact: diffuse agricultural and point-source pollution. The first of the three clusters involved water bodies with low or no human impact; the second cluster contained those with medium-level anthropogenic disturbance, while waters with high pollution values formed the third cluster. Mean distance between heavily polluted waters was 1.5 times higher than that between those showing no or low disturbance, meaning that pristine waters are more similar to one another than polluted ones. The current number of samples per river is twice as high in cluster 1 as in cluster 3, revealing that there is room for optimization of the monitoring system. This contribution uses Hungary as a case study.

Open access

Abstract

With the introduction of the Water Framework Directive, the relative importance of smaller waterways increased. This statement is particularly true for Hungary, where water-quality monitoring of most smaller rivers only began 12 years ago. Due to their large number, and the lack of historical data concerning their state, systematic monitoring is a challenge.

In the current study, 101 creeks are characterized on the one hand by 13 physico-chemical quality parameters (pH, electric conductivity, chloride ion concentration, dissolved oxygen, oxygen saturation, biochemical oxygen demand, chemical oxygen demand, total organic carbon, ammonium nitrogen, total inorganic nitrogen, total nitrogen, orthophosphate and total phosphorus), on the other hand by their watershed's relief, land use, and point sources' pollution indicators. Euclidean distance between water bodies (henceforth WBs) is calculated according to normalized physico-chemical monitoring values. They are grouped into clusters using the hierarchical clustering method. Watershed characteristics are used to explain the clustering via linear discriminant analysis.

The investigation revealed that the main driver of cluster group creation is related to human impact: diffuse agricultural and point-source pollution. The first of the three clusters involved water bodies with low or no human impact; the second cluster contained those with medium-level anthropogenic disturbance, while waters with high pollution values formed the third cluster. Mean distance between heavily polluted waters was 1.5 times higher than that between those showing no or low disturbance, meaning that pristine waters are more similar to one another than polluted ones. The current number of samples per river is twice as high in cluster 1 as in cluster 3, revealing that there is room for optimization of the monitoring system. This contribution uses Hungary as a case study.

Open access
Central European Geology
Authors: Ildikó Gyollai, Ákos Kereszturi and Elias Chatzitheodoridis

The study of shock-metamorphic features of the Zagami meteorite revealed pseudotachylite-like melt veins with inhomogeneous chemistry and schlieren structure of silica-glass and alkali feldspar melt glass. The feldspar occurs as diaplectic glass in the interstitial area indicating short-time (few seconds) quenching of shock pressure during the impact event, with post-shock annealing. At several locations, apatite needles were identified, which are formed by fluids (cold water with dissolved ions) after the crystallization of cumulate magmatic minerals. Phosphates also could form in impact melts due to circulation of fluids after the impact event. The other signature for the high shock temperature is the presence of Ca–Ti-rich pyroxenes and titanomagnetite, which indicate temperature above 1,200 °C. The formation of silica-rich melt in interstitial area has two scenarios: (a) fractional melting of the Martian crust or (b) formation by pseudotachylite-like impact melting. According to textural observations (schlieren pattern), we propose an impact origin of the large amount of silica-rich melt in this meteorite. Pseudotachylite-like textures were mentioned earlier in terrestrial impact craters; however, we first propose them to form in a Martian meteorite based on their similarity of texture with terrestrial pseudotachylites.

Open access