Terrestrial radioisotopes in black shale hosted Mn-carbonate deposit (Úrkút, Hungary)

Previously, little attention has been paid to terrestrial radioisotopes (U, Th, ⁴⁰K) occurring in manganese ores, despite the fact that the biogeochemical relationship between Mn and U is versatile. Occurrence of terrestrial radioisotopes in great amounts during mining on a long-term causes significant radiation exposure. It is important to inspect black shale-hosted manganese ores from this aspect, as black shales are typically potential U-rich formations. Despite the increased radon concentration in the mine, based on the detailed major elements, trace elements and gamma spectroscopy inspection of the rock types of deposit, the U, Th enrichment was undetectable. However, the U and Th content of about average terrestrial abundance of the great ore amount may be in the background of the increased radon concentration level. This Mn-carbonate ore deposit in spite of the low U content exhibit potential radon danger for miners, which can be eliminated with intensive air change only.     

In-mine geoelectric investigations for detecting tectonic disturbances in coal seam structures

The methods of in-mine seam-sounding and transillumination (geoelectric tomography) for the detection of tectonic disturbances of coal seams were developed by the Department of Geophysics of the University of Miskolc in the 1970–80’s with the effective support of the former “Borsod” Coal Mines Ltd. The paper gives an overview about the theory of seam-sounding and a special geoelectric tomographic inversion, and introduces the in-mine geoelectric seam-sounding and transillumination measurement systems using vertical electrode dipoles. In the second part the paper, the results of an in-mine geoelectric measurement are presented, which was carried out in order to detect tectonic disturbances of the Miocene aged coal seams situated in Slovakia. As results of the geophysical investigation, the authors forecasted the tectonic features in the coal seam. The company confirmed the results by independent information about seam disturbances and tectonic features arising from the excavation of the investigated area.     

Till fabric and grain-size analysis of glacial sequences in the Upper Sil River Basin,Cantabrian Mountains,NW Spain

Fabric and grain-size analysis of eight deposits present in the Upper Sil River Basin palaeoglacial system of northwest Spain were used to interpret till types and to reconstruct the glacial paleoprocess history of this region. They are represented by lodgement, deformation, and melt-out tills. The first, representative of glacial advance stages, present cluster fabrics and are generally composed of poorly sorted and finer sediments. Melt-out and deformation tills, representative of stages of glacial stability followed by fast recession, present transitional to girdle fabrics and are composed of poorly sorted coarser sediments. In any case, multiple criteria, including lithological, clast-shape, or structural data, support these directional and grain-size observations. These sequences, most of them located in the snout area of the Sil palaeoglacier, are important in the reconstruction of glacial dynamics due to poor preservation of landforms related to the maximum glacial advance. This palaeoglacial system was formed by multiple tributaries and had an extension of over 450 km², with the Sil paleoglacier being 51 km long during its maximum glacial advance.     

A new sediment slicer for rapid sectioning of the uppermost sediment cores from marine and freshwater habitats

The new sediment slicer described herein provides an easy and time-efficient way of sectioning cores of varying length, diameter, and composition from a wide range of habitats and sediment types. It is designed to process sediments collected by means of any soft-sediment core sampler with the core tube detachable from the sampler head and trigger unit. It is useful for sectioning core samples that include both the undisturbed sediment/water interface and highly consolidated sediments. The slicer is composed of three parts: (1) a supporting block, (2) a gliding block with the incorporated 10 cm sub-sampler holder designed to glide freely in the grooves along the supporting block, and (3) a metal blade for sediment slicing.     

Analysing the positional accuracy of GNSS multi-tracks obtained from VGI sources to generate improved 3D mean axes

ABSTRACT

The sharing of Global Navigation Satellite System (GNSS) tracks on the Internet is increasing enormously. Every day a great number of users capture routes using different devices and share these data. Individually these tracks present a poor positional accuracy because these devices obtain positions with accuracy of about 5-10 metres. In addition, they are usually captured for navigation and not for surveying. However, we can take advantage of the great quantity of tracks of the same linear element in order to obtain a more accurate solution. This study analyses this possibility using a wide set of tracks obtained in known conditions. We emulated those tracks obtained by Volunteered Geographic Information (VGI) users and we compared the mean axis obtained using all tracks with others obtained from a more accurate source. Additionally, we analyse the displacement of other axes obtained by varying several parameters such as the number of tracks and their length or by dividing the route into sections in function of sinuosity, etc. The results have shown an improved 3D mean axis and the viability of the method proposed in this study in order to use axes obtained from several tracks in maps at certain scales.     

Imprints of hydrocarbon-bearing basinal fluids on a karst system: mineralogical and fluid inclusion studies from the Buda Hills,Hungary

Calcite veins and related sulphate–sulphide mineralisation are common in the Buda Hills. Also, abundant hypogenic caves are found along fractures filled with these minerals pointing to the fact that young cave-forming fluids migrated along the same fractures as the older mineralising fluids did. The studied vein-filling paragenesis consists of calcite, barite, fluorite and sulphides. The strike of fractures is consistent—NNW–SSE—concluding a latest Early Miocene maximum age for the formation of fracture-filling minerals. Calcite crystals contain coeval primary, hydrocarbon-bearing- and aqueous inclusions indicating that also hydrocarbons have migrated together with the mineralising fluids. Hydrocarbon inclusions are described here for the first time from the Buda Hills. Mixed inclusions, i.e., petroleum with ‘water-tail’, were also detected, indicating that transcrystalline water migration took place. The coexistence of aqueous and petroleum inclusions permitted to establish the entrapment temperature (80°C) and pressure (85 bar) of the fluid and thus also the thickness of sediments, having been eroded since latest Early Miocene times, was calculated (800 m). Low salinity of the fluids (<1.7 NaCl eq. wt%) implies that hydrocarbon-bearing fluids were diluted by regional karst water. FT-IR investigations revealed that CO₂ and CH₄ are associated with hydrocarbons. Groundwater also contains small amounts of HC and related gases on the basin side even today. Based on the location of the paleo- and recent hydrocarbon indications, identical migration pathways were reconstructed for both systems. Hydrocarbon-bearing fluids are supposed to have migrated north-westward from the basin east to the Buda Hills from the Miocene on.     

Rockfalls detached from a lateral moraine during spring season. 2010 and 2011 events observed at the Rebaixader debris-flow monitoring site (Central Pyrenees, Spain)

Instability processes at glacial deposits represent an important hazard in mountainous areas. During the spring seasons of 2010 and 2011, two falls of large boulders (18 and 55? m³) initiated in a lateral moraine in the Rebaixader catchment (Central Pyrenees, Spain). Detailed information was gathered due to the debris-flow monitoring system installed along the torrent. Meteorological data showed that the two rockfalls were triggered without important rainfall amounts. Field surveys, ground vibration acquired at geophones and the movie recorded with a video camera provided unique information on the rockfall occurrence and dynamics. In addition, the information gave an excellent opportunity to show the importance of monitored data for the calibration of model parameters for runout simulations. The analysis focussed on the 2011 event and showed that the boulder passed rolling and bouncing through the monitored torrent reach. The velocity estimates in this reach range from 3 to 9 ?m/s. The 2011 rockfall was also back-analysed by a two-dimensional physically based model, which was fitted by the monitored and field data. The results of the simulation coincided well with recorded measurements, although the output could be improved by the application of a three-dimensional model.     

Lithosphere thermal structure at the eastern margin of the Bohemian Massif: a case petrological and geophysical study of the Nied?wied? amphibolite massif (SW Poland)

The crustal section beneath amphibolite Nied?wied? Massif (Fore-Sudetic Block in NE Bohemian Massif), modelled on the basis of geological and seismic data, is dominated by gneisses with subordinate granites (upper and middle crust) and melagabbros (lower crust). The geotherm was calculated based on the chemical analyses of the heat-producing elements in the rocks forming the crust and the measurements of their density and heat conductivity. The results were verified by heat flow calculations based on temperature measurements from 1,600?m deep well in the Nied?wied? Massif and by temperature–depth estimates in mantle xenoliths coming from the nearby ca. 4.5?My basanite plug in Lutynia. The paleoclimate-corrected heat flow in the Nied?wied? Massif is 69.5?mW?m^?2, and the mantle heat flow is 28?mW?m^?2. The mantle beneath the Massif was located marginally relative to the areas of intense Cenozoic thermal rejuvenation connected with alkaline volcanism. This results in geotherm which is representative for lithosphere parts located at the margins of zones of continental alkaline volcanism and at its waning stages. The lithosphere–asthenosphere boundary (LAB) beneath Nied?wied? is located between 90 and 100?km depth and supposedly the rheological change at LAB is not related to the appearance of melt.     

Generation and emplacement of shear-related highly mobile crustal melts: the synkinematic leucogranites from the Variscan Tormes Dome, Western Spain

The Tormes dome consists of S-type granites that intruded into Ordovician augen gneisses and Neoproterozoic–Lower Cambrian metapelites/metagreywackes at different extents of migmatization. S-type granites are mainly equigranular two-mica granites, occurring as: (1) enclave-laden subvertical feeder dykes, (2) small external sill-like bodies with size and shape relations indicative for self-similar pluton growth, and (3) as large pluton bodies, emplaced at higher levels than the external ones. These magmas were highly mobile as it is inferred from the high contents of fluxing components, the disintegration and alignment of pelitic xenoliths in feeder dykes and at the bottom of some sill-like bodies. Field relations relate this 311?Ma magmatism (U–Pb monazite) to the regional shearing of the D₃ Variscan event. Partial melting modeling and the relatively high estimated liquidus temperatures indicate biotite-dehydration partial melting (800–840°C and 400–650?MPa) rather than water-fluxed melting, implying that there was no partial melting triggered by externally derived fluids in the shear zones. Instead, the subvertical shear zones favored extraction of melts that formed during the regional migmatization event around 320?Ma. Nd isotope variation among the granites might reflect disequilibrium partial melting or different protoliths. Mass-balance and trace element partial melting modeling strongly suggest two kinds of fertile crustal protoliths: augen gneisses and metapelites. Slight compositional variation among the leucogranites does not reflect different extent of protolith melting but is related to a small amount of fractional crystallization (<13% for the equigranular granites), which is generally more pronounced in shallower batholitic leucogranites than in the small and homogeneous sill-like bodies. The lower extent of fractional crystallization and the higher-pressure emplacement conditions of the sill-like bodies support a more restricted movement through the crust than for batholitic leucogranites.     

Determination of Fluoride Ions in Iron Ores by UV–VIS Spectrophotometry after Matrix Removal Using Diphonix® Resin

A modification of the spectrophotometric method for the determination of fluoride ions in iron‐rich materials is proposed. In this method the iron matrix was successfully removed using Diphonix^® resin. The studied sample was a ferruginous mineral which contained about 38% of iron. The Euronorm certified reference material (ECRM) 676‐1 (Iron Ore Sinter), as a commercially available material having a similar matrix (39.76% w/w Fe) and fluoride level (0.1% w/w), was used to validate the method. After partial digestion in concentrated hydrochloric acid the samples were diluted and passed through Diphonix^® resin. The concentration of fluoride ions was determined by a spectrophotometric method using a Zr:ER complex (λ = 540 nm). The result obtained for the ECRM was in good agreement with the certificate specification and thus proved the method to be applicable for the determination of fluoride ions in iron‐rich materials. Due to the easy digestion step and simple requirements for equipment, this method can be used in most laboratories.