International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Volume 73 no. 5 / October 2022

Volume 73 no. 5 / October 2022

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Articles in this issue

  • Multi-method field detection of map-scale faults and their parameters: Case study from the Vikartovce fault (Western Carpathians)

    Abstract: This research tests multi-method field survey for detecting fault parameters in a known fault structure interpreted on geological maps. The research was focused on detecting the Vikartovce fault and its inclination which is crucial for its genetic and kinematic interpretation. The chosen Vikartovce fault is a genetically related dislocation to the Sub-Tatras fault which is a major boundary fault in the Vysoké Tatry Mts. asymmetric horst. The Vikartovce fault can serve as a proxy for the evolution and physical and structural parameters of the Sub-Tatras fault which is difficult to study in the field because of thick Quaternary glaci-fluvial deposition cover. We applied a multi-method approach based on geophysical field surveys to detect the Vikartovce fault´s parameters. We combined ten field geophysical survey methods with soil and indoor radon emanometry and mercurometry along five profiles crosscutting the fault trace. These methods confirmed the presence of a fault between the Kozie chrbty ridge and the Paleogene sediments of the Hornád depression, described as the Vikartovce fault, and provided precise data on its geometry. This fault interface is represented by two major tightly spaced parallel north dipping reverse faults, tilted to almost a vertical position with an approximately 8 to 30 m wide fault damage zone and at least 1.5 km confirmed depth range.
  • Pressure–temperature–time constraints on the evolution of epidote-bearing albite granite from Mt. Medvednica (Croatia): Further evidence of the Middle Triassic opening of the Neotethys Ocean

    Abstract: Albite granite from Mt. Medvednica in northern Croatia is the only known surface appearance of granite in the complex Zagorje-Mid-Transdanubian zone. This granite contains almost pure albite (An01, ~50‒55 vol. %), quartz (~20‒25 vol. %), epidote (~1 vol. %), phengite (5‒12 vol. %), and secondary chlorite (~10‒15 vol. %) and calcite (~5 vol. %). Accessories are zircon, apatite, and ilmenite. The granite has a calc-alkaline geochemical signature with a metaluminous and high-Na character. CaO, MgO, and FeO contents are relatively low. Normalised contents of rare-earth elements (REE) show a relatively flat distribution of those that are heavy, suggesting a magma source in the lower continental crust. The modelled empirical relationship for average crustal thickness based on Sr/Y ratio and contents of REE indicates a 34 km thick continental crust. Zircon typology is characterised by the predominance of {100} prisms and {101} bipyramids. This typology, zircon chemistry, zircon saturation temperature (775 °C), and Ti-in-zircon temperature (mean 785 °C) also suggest a deep-seated magma source. Epidote and perhaps phengite crystallised at a pressure around 1.0 GPa from the melt according to thermodynamic modelling. Temperatures were 650 °C or more at this stage. A U–Pb concordia age of 242.9±4.0 Ma (2σ) was determined on zircon coinciding with the Middle Triassic peak of magmatic activity in the Dinarides, but also in the Southern Alps and Western Carpathians. The age is interpreted as marking the beginning of the fragmentation of continental lithosphere and the onset of rifting processes, which was followed by the broadening of the newly-formed Neotethys Ocean.
  • Updated calpionellid zonation around the Jurassic–Cretaceous boundary in NE Algeria (“Ravin Bleu” site, Batna Mountains): A potential regional stratotype for the North Africa Maghrebian Ranges

    Abstract: In NE Algeria and the Tunisia–Algeria border chains, detailed stratigraphic investigations across the Jurassic– Cretaceous boundary (JKB) are scarce and this important stratigraphic interval remains poorly known. This work attempts fulfilling this gap of our knowledge on the JKB successions in this area. It represents unpublished data on calpionellid zonations, based on bed-by-bed sampling, of two sections from the “Ravin Bleu” site of Batna Mountains. In the Jebel Kasserou and J. Bou Merzoug study sections, most of the standard Upper Tithonian–lowermost Valanginian calpionellid zones and subzones are first identified here. Their limits correspond to main calpionellid bioevents allowing to recognize a new Alpelliptica Subzone of the Calpionella Zone in the Lower–Middle Berriasian; subsidiary bioevents being useful to delimit six horizons in the Upper Tithonian Crassicollaria Zone and two others in the Middle Berriasian Elliptica Subzone. All these biostratigraphic units are correlated with their lateral equivalents in other Tethyan sections, mainly from Morocco, Tunisia, SE France, Spain, the Carpathian Ranges and the Balkanides. Chitinoidellid and most of the calpionellid species from Eastern Algeria are first illustrated here. In addition to their easy access and good outcrops, the continuous, complete and thick marine study successions are devoid of strong diagenetic alteration, synsedimentary features and tectonic effects. The “Ravin Bleu” site is proposed herein as a potential reference section for the JKB interval in the North Africa Maghrebian Ranges of the SW Tethys Margin.
  • Transpression-driven deformations of the Chočské vrchy Mountains (Western Carpathians): Insights from magnetic fabric

    Abstract: The Chočské vrchy Mts. are a part of the Tatra–Fatra Belt located in the Central Western Carpathians (Slovakia). We characterize the main Late Cretaceous–Cenozoic deformation events and the changing strain that formed the geological setting of the Chočské vrchy Mts. by applying the Anisotropy of Magnetic Susceptibility coupled with the Anisotropy of Anhysteretic Remanent Magnetization and complemented by petromagnetic analyses. We analyse Lower Cretaceous marly limestones of the Mraznica Formation (Fm.), which is a part of the Krížna nappe, and the “post-thrusting” Eocene–Oligocene Huty Fm. Petromagnetic experiments reveal that paramagnetic minerals control the magnetic susceptibility, although a distinct contribution of ferromagnetics (magnetite, hematite and likely pyrrhotite) is also documented. The magnetic fabric in both the Mraznica and Huty fms. is generally sedimentary with minor tectonic imprint. The NNE–SSW orientation of the magnetic lineation in most of the Mraznica Fm. sites corresponds well with the local bedding strike as well as the calculated regional statistical fold axis for the Krížna nappe, but it deflects from the expected orientation considering the regional Cretaceous thrusting direction. Similarly oriented magnetic lineation is also documented in some Huty Fm. sites. Magnetic and structural results reveal the dip of the post-trusting Paleogene strata covering the Chočské vrchy Mts. horst block differs from both the dip of magnetic lineation and the dip of statistical fold axis from the Krížna nappe within this uplifted block, suggesting complex uplift-related deformations. We conclude that Krížna nappe folds together with AMS lineation, both formed during Late Cretaceous thrusting, have been later rotated by an angle of 20° as an effect of Neogene transpression, which also affected the magnetic fabric of the post-thrusting cover.
  • Influence of fluid flows on low-temperature thermochronology: An example from the Podhale Basin, Internal Western Carpathians, Poland

    Abstract: A novel approach that couples hydrological and thermochronological modelling is tested in a well-known hydrothermal system, the Inner Western Carpathians, providing insights of the yet-unexplained Apatite Fission Track (AFT) ages of the Podhale Basin. Our new model improves previous ones by incorporating the effects of fluid circulation, by considering compaction, smectite dehydration and meteoric water as sources of fluid. Rock properties such as thermal diffusivity, porosity and permeability, are dependent on lithology and the effective-stress state of the system, making our calculations depart from previous efforts on thermochronological modelling. Particularly, we examined young (around 12 Ma) apatite fission track ages from Oligocene strata of the Podhale wild flysch, which suggest the occurrence of either substantial burial or an elevated basal thermal paleogradient, even though none of the above have been documented in the area. Such problem is addressed on this contribution, since by reproducing previous numerical experiments but adding groundwater circulation this time, improved thermally-reset AFT ages of the Podhale Basin are obtained. Thermal, hydrological and mineralogical observations are successfully reproduced, putting forward the calibration and validity of the model here proposed. Furthermore, our findings not only unveil the linking between the hydrological and thermal phenomena present in the study region, but also, trigger new questions on the processes that should be taken into account when thermochronological calculations are concerned.
  • Seasonal study of calcite-water oxygen isotope fractionation at recent freshwater tufa sites in Hungary

    Abstract: Recent fluvial tufa carbonates were investigated from the Szalajka Valley (Bükk Mts., Hungary) and Malom Valley (Balaton Uplands, Hungary) to (1) study the suitability of the published oxygen isotope-based palaeothermometers for tufa deposits, (2) find the most appropriate (closest to equilibrium) places downstream for temperature calculation. A good correlation was observed between 1000lnα and the temperature of the water from which the tufa precipitated close to the spring orifice in the Szalajka and Malom Valleys. Large differences between calculated and measured temperature values were seen in areas where the seasonal water temperature increased and decreased by several degrees during our studied period. The stable isotope composition of the measured Hungarian tufas represents intermediate values between the western and eastern parts of Europe, reflecting increasing continentality in climate from west to east.