groundwater- and river water-level variations (e.g., Schnellmann et al. 2010 ; Mentes 2017b ) on river bank stability. However, to date, the direct effect of hydrological processes on movements and deformations of high river banks (e.g., Uchimura et
Stone masonry arch bridges in North Hungary represent cultural heritage values. For the maintenance and preservation of these bridges detailed mapping of lithologies and weathering forms are required. The purpose of this paper is to present the identified lithotypes, their conditions (weathering grade) and their petrophysical properties by using in situ lithological mapping, documentation of weathering forms, non-destructive tests and laboratory analyses. Furthermore these analyses demonstrate the difficulties of characterization and diagnostics of the historical construction materials. Additionally the results of condition assessments and the properties of the four different dimension stones from four different sites provide examples for the large dissimilarities regarding the strength parameters. The above-listed parameters are required as input data for stability calculations and modeling of these structures.
Following a short historical survey of the Hungarian geodetic control networks the author analyses four Hungarian networks measured after the introduction of the Schreiber angle measurement method (1878), namely those measured by the Milit\ärgeographisches Institut Wien (1878-1899), the first order network in Transdanubia measured in 1901-1908, the new triangulation network measured in 1925-1942 and the network HD72 started in 1950. The presented results are Ferrero's mean square angular errors (Table I), comparison of the form of the networks, determination of the co-ordinate differences of the point transfers (Table II), then for identical points the comparison of direction measurements from the station adjustment (Tables III-VIII). The conclusion of this study is that historical Hungarian triangulation measurements are not applicable for the detection of exact point movements.
Recently, due to population increase in urban areas, underground excavations increasingly influenced the development of cities, parallel with traffic organization. One of the best examples is Eger in North Hungary: several kilometer-long wine-cellars were dug over the centuries beneath the city, which influences further construction; sometimes they present a danger due to the increased weight of surface vehicles as well. Therefore, nowadays the prediction of the stability of these cellars is a question of utmost importance here. The goal of this paper is to statistically analyze the results of strength investigations of the excavated rocks, in order to predict their strength (both compressive and tensile) and Young's modulus. The results of 19 sample blocks are statistically analyzed here in different petrophysical states (air-dry, semi-saturated and fully saturated). The relationships between the different petrophysical constants are also determined and analyzed in this paper. On the basis of these correlations prediction of rock strength has become easier and faster.
Authors:István Marsi, Ildikó Selmeczi, László Koloszár, József Vatai, Ildikó Szentpétery, Árpád Magyari, and László Róth
The authors carried out geologic investigations in the Kolontár area in connection with the red mud catastrophe of 4 October 2010, and have acquired more detailed knowledge using geologic mapping methods. This study is an evaluation on the basis of the immediate analyses that were made after the accident and are published in this paper.
Based on their research results the authors find that the alluvial deposits of the Torna Brook are highly inhomogeneous, which is manifested in the variability of stability and bearing capacity. Based on the morphology in the area of Kolontár a small, rhombus-shaped pull-apart basin can be outlined, which can be interpreted as a neotectonic event characterized by a right-lateral fault. However, further detailed research is needed in order to understand what kind of role the geologic environment played in the development of the situation that led to the dam failure.
Authors:Péter Árkai, Kenneth J. T. Livi, and Péter Horváth
Metamorphic mineral assemblages in low-temperature metaclastic rocks often contain paragonite and/or its precursor metastable phase (mixed K-Na-white mica). Relationships between the bulk rock major element chemistries and the formation of paragonite at seven localities from Central and SE-Europe were studied, comparing the bulk chemical characteristics with mineral assemblage, mineral chemical and metamorphic petrological data. Considerable overlaps between the projection fields of bulk chemistries of the Pg-free and Pg-bearing metaclastic rocks indicate significant differences between the actual (as analyzed) and effective bulk chemical compositions. Where inherited, clastic, inert phases/constituents were excluded, it was found that a decrease in Na/(Na+Al*) and in K/(K+Al*) ratios of rocks favors the formation and occurrence of Pg and its precursor phases (Al* denotes here the atomic quantity of aluminum in feldspars, white micas and “pure” hydrous or anhydrous aluminosilicates). In contrast to earlier suggestions, enrichment in Na and/or an increase in Na/K ratio by themselves do not lead to formation of paragonite. Bulk rock chemistries favorable to formation of paragonite and its precursor phases are characterized by enrichment in Al and depletion in Na, K, Ca (and also, Mg and Fe2+). Such bulk rock chemistries are characteristic of chemically “mature” (strongly weathered) source rocks of the pelites and may also be formed by synand post-sedimentary magmatism-related hydrothermal (leaching) activity. What part of the whole rock is active in determining the effective bulk chemistry was investigated by textural examination of diagenetic and anchizone-grade samples. It is hypothesized that although solid phases act as local sources and sinks, transport of elements such as Na through the grain boundaries have much larger communication distances. Sodium-rich white micas nucleate heterogeneously using existing phyllosilicates as templates and are distributed widely on the thin section scale. The results of modeling by THERMOCALC suggest that paragonite preferably forms at higher pressures in low-T metapelites. The stability fields of Pg-bearing assemblages increase, the Pg-in reaction line is shifted towards lower pressures, while the stability field of the Chl-Ms-Ab-Qtz assemblage decreases and is shifted towards higher temperatures with increasing Al* content and decreasing Na/(Na+Al*) and K/(K+Al*) ratios.
Authors:Éva Jankovics, Szabolcs Harangi, and Theodoros Ntaflos
The alkaline basalt of the Füzes-tó scoria cone is the youngest volcanic product of the Bakony-Balaton Highland Volcanic Field. The bombs and massive lava fragments are rich in various crystals, such as mantle-derived xenocrysts (olivine, orthopyroxene, clinopyroxene, spinel), high-pressure mineral phases (clinopyroxene) and phenocrysts (olivine, clinopyroxene). Peridotite xenoliths are also common. Ratios of incompatible trace elements (Zr/Nb and Nb/Y) suggest that the primary magma was formed in the transitional spinel-garnet stability field, at the uppermost part of the asthenosphere. Magmatic spinel inclusions with low-Cr# (22–35) in olivine phenocrysts can reflect a fertile peridotite source. The olivine, orthopyroxene, colourless clinopyroxene and spinel xenocrysts are derived from different depths of the subcontinental lithospheric mantle and their compositions resemble the mineral phases of the ultramafic xenoliths found in this region. The rarer green clinopyroxene cores of clinopyroxene phenocrysts could represent high-pressure products of crystallization from a more evolved melt than the host magma, or they could be derived from mafic lower crustal rocks. Crystallization of the basaltic magma resulted in olivine and clinopyroxene phenocrysts. Their compositions reflect polybaric crystallization with a final, strongly oxidized stage. The Füzes-tó basalt does not represent a certain magma composition, but a mixture of mineral phases having various origin and mantle-derived basaltic melt.
Authors:Stephen Fityus, Ákos Török, and John Gibson
This paper presents a case study to illustrate the role played by geologic structures in the design and construction of major transportation infrastructure, in a setting of moderately deformed Paleozoic sedimentary rocks in eastern Australia. It describes a complex development of folding, faulting and jointing that has resulted in significant inclination of beds, juxtaposition of strata and affected the weathering characteristics of a wide range of rock types. The sequence, which displays an upward transition from marine to terrestrial sediments, comprises an interbedded succession of conglomerate, sandstone, shale and erratic volcanics and crystal tuff. Unfavorable relationships between major excavation faces, inclined beds and jointing have resulted in problems with the stability of road cuttings. Also, the presence of faults and dykes at various scales has had a significant effect on weathering and rock strength. The paper demonstrates the importance of the choice of alignment at design stage, and how a basis of good structural interpretation and geologic mapping can be used to avoid problems during construction and issues with ongoing maintenance.