Janos Hun-haas - Academia.edu (original) (raw)
Papers by Janos Hun-haas
The organic-rich late Triassic KoÈ ssen Formation (Hungary) was deposited in a shallow basin, sit... more The organic-rich late Triassic KoÈ ssen Formation (Hungary) was deposited in a shallow basin, situated between a carbonate platform and the continent. A large number (107) of samples of a 240 m thick, steeply dipping core section of the KoÈ ssen Fm., built up of mostly non-bioturbated sediments have been analysed by Rock-Eval pyrolysis. Organic petrographic studies, sulphur and iron speciation (total sulphur, HCl-soluble sulphate sulphur, pyrite iron and HClsoluble iron) and CO 2 measurements have been carried out on smaller sample sets. According to Rock-Eval pyrolysis and organic petrography the immature organic matter (OM) is of dominantly marine origin throughout the section. Unicellular planktonic algae are remains of the most important organic constituents but microbial-algal mat material is also of importance. The carbonate and TOC contents and HI values display much scatter and upward decreasing trends. Type II-S OM is common in the lower third of the section and it occurs in its middle interval, too. The marked downward decrease of T max values is explained by the downward increase of the OM sulphur content. The original organic carbon content (TOC or) was calculated. The degree of OM preservation, expressed in term of TOC/TOC or , varies between 0.36 to 0.89 and shows an upward decreasing trend, interrupted by high values around the middle of the section. This strengthening of the degradation during the black shale event was the result of the parallel decreasing rate of sedimentation and OM deposition. The high TOC/TOC or values found around the middle of the section are mostly the result of a temporary acceleration of OM deposition. Sulphur richness of the OM shows no positive correlation with the degree of organic preservation. Sulphur partitioning between pyrite and OM was controlled by the ratio of reactive iron to OM. Average rates of planktonic productivity (C prod) vary between 6±9 and 60±88 t C org /m 2 /Ma. The rough covariance of the degree of preservation and C prod suggests that variations in planktonic productivity exerted a strong control on preservation in the suboxic, low to medium productivity KoÈ ssen Formation.
Central European Geology, 2009
For comparative studies of Upper Triassic cyclic platform carbonates, the Transdanubian Range (Hu... more For comparative studies of Upper Triassic cyclic platform carbonates, the Transdanubian Range (Hungary) and the Pelagonian Zone (Greece) were chosen. Paleogeographically they represent two distant segments of the passive margin of the Neotethys Ocean. During the Late Triassic, on this wide margin a very extensive tropical carbonate platform domain was developed, referred to as the Dachstein-type carbonate platform system. The Transdanubian Range (TR) represents a segment of a continent-encroaching platform system, whereas the Pelagonian-Subpelagonian Zone (PG) may have been a large isolated platform, surrounded by deep-water basins. The discussed Upper Triassic thick platform carbonates (Fõdolomit/Hauptdolomit Formation and Dachstein Limestone in the TR, and Pantokrator Formation in the PG) are made up of cyclically arranged facies deposited under similar environmental conditions in the interior zones of carbonate platforms. Three characteristic major facies types can be distinguished: shallow subtidal-lagoonal, intertidal and supratidal-pedogenic, which correspond to the three typical lithofacies (members C, B and A) of Fischer's (1964) Lofer-cycle. The cycles are usually bounded by discontinuity surfaces related to subaerial exposure and pedogenic alteration. The meter-scale (Lofer) cyclicity is predominant throughout the successions. However, various stacking patterns including symmetric complete, truncated, incomplete, and condensed cycles or even alternating peritidal and subtidal facies without any disconformity are recognized in both areas studied. Pervasive or partial early diagenetic dolomitization affected some parts of the cyclic successions in both areas. However, age-dependence of the early dolomitization was clearly demonstrated only in the TR, where the older part of the platform carbonate succession was subject to pervasive dolomitization, whereas the younger part is non-dolomitized and there is a transitional unit between them. This trend is attributed to the climate changing from semiarid to more humid. The Upper Triassic platform carbonates of the TR and PG show strikingly similar features concerning the litho-and biofacies, the stacking pattern and the thickness of the elementary cycles, despite their distant and different paleogeographic setting within the western Neotethys realm.
Acta Geologica Hungarica, 2006
Facies patterns of the Upper Permian and Triassic formations within the Transdanubian Range are p... more Facies patterns of the Upper Permian and Triassic formations within the Transdanubian Range are presented. Based on surface and subsurface data, facies maps were compiled for six time slices which served as a basis of the paleogeographic reconstructions. Considering the entire Late Permian-Triassic interval, the Transdanubian Range unit shows a definite polarity: its northeastern part represents the seaward (internal) side, whereas its southwestern part represents the landward (external) side. A remarkable part of facies units of the Transdanubian Range could be correlated with time equivalent facies in the Southern Alps and the Upper Austroalpine nappes, providing an effective tool for the reconstruction of the original position of the displaced Transdanubian Range Unit.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2016
The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, ... more The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, (7) yellowish, mottled (hydromorphic) paleosols. The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels. The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site is interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.
World Geomorphological Landscapes, 2015
The Pannonian region (the Pannonian or Carpathian Basin and the surrounding mountain ranges) is p... more The Pannonian region (the Pannonian or Carpathian Basin and the surrounding mountain ranges) is part of the Mediterranean Mountain System, which was formed during the last platetectonic cycle since the latest Paleozoic times. In Europe it is an about 300-800 km wide belt (Neo-Europe) accreted to the previously consolidated parts of Europe (Hercynian/Variscan Europe or Meso-Europe) as a result of the Alpine orogeny caused by convergence of the European (Eurasian) and African Plates. The present-day geological structure of the region is mostly determined by the evolution of the Tethys and Atlantic Ocean systems, i.e. the dismembering of the European and African continental plate margins during the early evolutionary stages and their tectonic deformation and uplifting as consequences of plate and microplate collisions. Plate-tectonic processes led to the formation of the large Pannonian Basin in the Late Cenozoic times. Hungary lies in the central part of the Pannonian Basin that is actually a system of several basins separated by isolated ranges of Palaeozoic and Mesozoic, sedimentary, magmatic and metamorphic formations and Cenozoic sedimentary and igneous rocks.
Central European Geology, 2017
The 1,200-m-deep Budaörs-1 borehole provided important data for our understanding of the stratigr... more The 1,200-m-deep Budaörs-1 borehole provided important data for our understanding of the stratigraphy and tectonic setting of the southern part of the Buda Hills. Although previous reports contained valid observations and interpretations, a number of open questions remained. The importance of this borehole and the unsolved problems motivated us to revisit the archived core. The new studies confirmed the existing stratigraphic assignment for the upper dolomite unit (Budaörs Dolomite Formation) as the dasycladalean alga flora proved its late Anisian to Ladinian age assignment. An andesite dike was intersected within the Budaörs Dolomite. U-Pb age determination performed on zircon crystals revealed a Carnian age (~233 Ma), and settled the long-lasting dispute on the age of this dike, proving the existence of a Carnian volcanic activity in this area after the deposition of the Budaörs Dolomite. Palynostratigraphic studies provided evidence for a late Carnian to early Norian age of the upper part of the lower unit (Mátyáshegy Formation). This result verified an earlier assumption and reinforced the significance of the tectonic contact between the upper unit (Budaörs Formation) and the lower unit (Mátyáshegy Formation). Based on structural observations and construction of cross sections, two alternative models are presented for the structural style and kinematics of the contact zone between the Budaörs and Mátyáshegy Formations. Model A suggests a Cretaceous age for the juxtaposition, along an E-W striking sinistral transpressional fault. In contrast, model B postulates dextral transpression and an Eocene age for the deformation. The latter one is better supported by the scattered dip data; however, both scenarios are considered in this paper as possible models.
International Journal of Earth Sciences, 2021
In the Transdanubian Range (Hungary), a wide spectrum of Triassic dolomites is known. Mechanism o... more In the Transdanubian Range (Hungary), a wide spectrum of Triassic dolomites is known. Mechanism of dolomitization of the platform carbonate successions was subject of a number of studies but the study of dolomitization of basinal carbonates is very limited. Petrographical and isotope–geochemical characteristics of the Upper Triassic dolomitized carbonate deposits, formed in a fault-controlled intraplatform basin, and interpretation of the dolomite-forming processes are presented in the current paper. From the latest Carnian to Middle Norian under semi-arid climatic conditions density-driven flux of seawater derived mesohaline fluids was the dominant mechanism of the near-surface pervasive dolomitization of the thick platform carbonate succession. In the late Middle Norian incipient rifting of the Alpine Tethys led to establishment of an extensional structural regime and onset of the formation of the Kössen Basin. In the study area, above the dolomitized platform carbonate succession...
Central European Geology, 2014
Partial and pervasive dolomitization of foreslope and toe-of-slope deposits of an early Carnian c... more Partial and pervasive dolomitization of foreslope and toe-of-slope deposits of an early Carnian carbonate platform was investigated for understanding the process and mechanism of dolomitization. Based on petrographic observations and C and O isotope data, the dolomitization took place in near surface to shallow burial setting and seawater of slightly elevated salinity was likely the dolomitizing fluid. The circulation system was maintained by reflux of evaporated sea water and geothermal heating of cold seawater derived from the surrounding deeper basin. The dolomitization was mostly controlled by the permeability of the platform-derived calcareous sediments.
IYPE activities of various geo-science associations, universities, research institutes and privat... more IYPE activities of various geo-science associations, universities, research institutes and private companies in Hungary (www.foldev.hu) have been successfully coordinated by the Hungarian National Committee, which was established by the Hungarian Academy of Sciences, the UNESCO- and the IUGS National Committees. The National Launch Event (April 17, 2008) was followed with a four-days long "Earth Science Fair" at the Hungarian Natural History Museum in Budapest. The IYPE was even briefly reviewed in the Hungarian Parliament. The Science Festival, organized annually by the Hungarian Academy of Sciences, in 2008 had a special IYPE-inspired slogan: "Science for the Habitable Earth", where lectures were held about the modern content of the Greek Classical Elements ("earth", "water", "air" and "fire", that is energy) and about the Humanity. In 2008/2009 numerous publications (including the Hungarian version of the IYPE booklet series, under the title GEO-FIFIKA, the Természet Világa special issue in February 2009, the IYPE number of Földrajzi Közlemények (Geographical Communications), and the "Geological Map of Hungary for Tourists" were produced. Throughout the country, symposia (e.g. HUNGEO 2008, ELGI 100, MÁFI 140, Geotourism Symposium in October 2009), several contests (Hungarian Television "Delta", Élet és Tudomány on the occasion of the UN year, and the annual contests starting in 2007 at Miskolc University), film shows (e.g., the movie "Another Planet") and other performances (e.g. End of the Ice Age in Hungarian Natural History Museum) were organized, with modest but increasing media coverage. The worldwide premier of the Planet Earth TV took place in Hungary, on the occasion of the IAGA 11th Scientific Assembly (August 23-30, 2009, www.iaga2009sopron.hu). One of our conferences ("Earth and Heaven - Geology and Theology") pointed out that there should be no conflict between science and religion, either in the fields of Earth's history or evolution. Science (and only science) is able to give reliable knowledge how Nature works, and the investigation of the "ultimate Why" (i.e. the "Primordial Cause") should be left to religions and philosophy. At the same time, there are antagonistic conflicts between science and pseudo-science, and also between religions and pseudo-religions. Among the scientific programmes the activity of Geological Institute of Hungary in the OneGeology initiative should be at first mentioned. In 2007/2008, among the main environmental challenges, it was exclusively the so-called "global warming" in the focal point of public interest in Hungary. By now, the importance of soil, groundwater and energy have been also recognized, largely (or at least partly) due to IYPE. This is perhaps the largest result of the IYPE in Hungary.
Sedimentary Geology, Apr 1, 2015
ABSTRACT Dolomite most commonly forms via replacement of precursor carbonate minerals. For this r... more ABSTRACT Dolomite most commonly forms via replacement of precursor carbonate minerals. For this reason, diagnosing primarily precipitated organogenic dolomite in microbial mat deposits from the rock record is not straightforward, even though the deposits exhibit microbial fabric. Single and multiple dolomite crusts exhibiting microbial fabric occur in a pervasively dolomitized Middle Triassic platform succession. Two sections were studied in detail in the north-eastern part of the Transdanubian Range (north-central Hungary). In both sections, thin layer-couplets of two fabric types occur in the upper part of the metre-scale cycles. Microbial boundstone (fabric type 1)––characterised by clusters of dolomite microcrystals which display diagnostic microbial features, such as calcimicrobes, clotted–spherular aggregates and globules––composes the upper layer of couplets. The lower layer of the couplets is different in the two studied sections. In Section 1, it is micritic dolomite (fabric type 2) that is characterised by predominantly fine crystals and contains obscured microbial components. In Section 2, it is bioclastic dolomite (fabric type 3) that is rich in reworked dasycladalean fragments and consists of dolomite crystals of wide size-range from fine to coarse. The precipitation of the microcrystalline dolomite phase, which process is the focus of this study, is interpreted as being facilitated by mats and biofilms favouring/tolerating increasing frequency of subaerial conditions in the upper intertidal setting. Petrographic analyses revealed that organogenic calcite was also precipitated, especially in mat deposits rich in bioclasts. Synsedimentary dolomitization, resulting in fine crystals, was coupled with aragonite dissolution. Moreover, it postdated the organogenic precipitation and fibrous calcite cementation. Synsedimentary replacive dolomitization took place only in the peritidal caps of the shallowing-upward depositional units. Petrographic analyses provide circumstantial evidence constraining that microcrystalline dolomite did not form via mimetic replacement. Accordingly the microcrystalline dolomite, which shows microbial microfabrics in the studied samples, is interpreted as organogenic primary precipitate. Both peritidal processes, dolomite precipitation and replacement, were likely controlled by the environmental factors in a semi-arid climate. Those components of the platform succession that were not dolomitized in the peritidal environment were replaced and cemented by medium and coarsely crystalline dolomite during further burial at elevated temperature, as shown by fluid inclusion homogenisation temperature (62 to 83 °C) and negative stable oxygen isotope values. Thus, the majority of the studied formation consists of fabric-destructive dolomite (fabric type 4).
Acta Geologica Hungarica, Mar 13, 2015
ABSTRACT
Central European Geology, 2010
Acta Geologica Hungarica, 2006
The basement of the Pannonian Basin is made up of tectonostratigraphic terranes of varying origin... more The basement of the Pannonian Basin is made up of tectonostratigraphic terranes of varying origin. They gradually amalgamated to form the large Alcapa and Tisza-Dacia composite terranes that were juxtaposed during the Tertiary. In North Hungary, in the basement of the Tertiary volcanic complex of the Mátra Mts and in the western part of the Bükk Mts, remnants of a Jurassic accretionary wedge were encountered. Ore exploration boreholes encountered several hundred-meter thick carbonate and siliceous shale-radiolarite successions in the basement of the Mátra Mts (Darnó Complex). Based on detailed studies of Core Recsk-109, the carbonate succession consists predominantly of grainstone with packstone-wackestone intercalations. Peloidal bioclastic grainstone is the most common texture type but sand-sized intraclasts and oncoid and ooid grains also occur locally. The most spectacular feature is the large amount of coarse to medium sand-sized fragments of calcified cyanobacteria ("Porostromata"). Platform-derived foraminifera and fragments of crinoids are also common. Gravity flows transported the carbonate detritus to the site of deposition at the lower foreslope and proximal toe-of-slope. Based on foraminifera the succession is Aalenian? or Early Bajocian in age.
Acta Geologica Hungarica, 2005
... Geologija, 31/32, pp. 415435, Ljubljana. 128 S. Kovács et al. Acta Geologica Hungarica 48, 2... more ... Geologija, 31/32, pp. 415435, Ljubljana. 128 S. Kovács et al. Acta Geologica Hungarica 48, 2005 Page 7. ... Poseb. izd. Geologija, 32, 172 p., Ljubljana. Pamic, J., V. Marci 1990: Petrologija amfibolitskih stijena slavonskih planina (sjev. Hrvatska). Geol. vjesn., 43, pp. ...
Sedimentary Geology, 1999
Toe-of-slope megabreccia deposits of an Upper Cretaceous rudist platform were studied in the Bako... more Toe-of-slope megabreccia deposits of an Upper Cretaceous rudist platform were studied in the Bakony Mountains. During the Turonian-early Senonian tectogenesis an articulated basin came into being in the area of the Bakony; depressions and highs were formed roughly parallel with the structural strike of the mountains. Inundation of the highs led to the evolution of carbonate platforms. The investigated platform shows an asymmetric architecture. In contrast to its gentle northern slope a steep erosional slope bounded the platform to the south with large, low-angle aprons, the site of deposition of megabreccias. The breccia accumulation occurred within a single 3rd-order cycle commencing in the early highstand and reaching its climax in the late highstand.
Sedimentary Geology, 2002
In the Late Triassic, a large carbonate platform system came into existence in the Transdanubian ... more In the Late Triassic, a large carbonate platform system came into existence in the Transdanubian Range (TR) producing a 1.5-to 2-km-thick carbonate succession. The lower part of the platform carbonate series is made up of cyclic peritidal dolomite (Main Dolomite Formation), while the upper one consists of cyclic peritidal limestone (Dachstein Limestone Formation). However, there is a transitional member of remarkable thickness between them consisting of partially dolomitised limestone and calcitic dolomite. This study focuses on the transitional member where the process of early dolomitisation was halted at various stages. In the investigated sections the early dolomitisation was controlled by the climate and high-frequency sea-level oscillation, which led to periodic subaerial exposure of large areas and palaeo-hydrological conditions. Increasing humidity and gradual extension of the permanently inundated outer platform led to cessation of early dolomitisation in the Middle to Late Norian. D
The organic-rich late Triassic KoÈ ssen Formation (Hungary) was deposited in a shallow basin, sit... more The organic-rich late Triassic KoÈ ssen Formation (Hungary) was deposited in a shallow basin, situated between a carbonate platform and the continent. A large number (107) of samples of a 240 m thick, steeply dipping core section of the KoÈ ssen Fm., built up of mostly non-bioturbated sediments have been analysed by Rock-Eval pyrolysis. Organic petrographic studies, sulphur and iron speciation (total sulphur, HCl-soluble sulphate sulphur, pyrite iron and HClsoluble iron) and CO 2 measurements have been carried out on smaller sample sets. According to Rock-Eval pyrolysis and organic petrography the immature organic matter (OM) is of dominantly marine origin throughout the section. Unicellular planktonic algae are remains of the most important organic constituents but microbial-algal mat material is also of importance. The carbonate and TOC contents and HI values display much scatter and upward decreasing trends. Type II-S OM is common in the lower third of the section and it occurs in its middle interval, too. The marked downward decrease of T max values is explained by the downward increase of the OM sulphur content. The original organic carbon content (TOC or) was calculated. The degree of OM preservation, expressed in term of TOC/TOC or , varies between 0.36 to 0.89 and shows an upward decreasing trend, interrupted by high values around the middle of the section. This strengthening of the degradation during the black shale event was the result of the parallel decreasing rate of sedimentation and OM deposition. The high TOC/TOC or values found around the middle of the section are mostly the result of a temporary acceleration of OM deposition. Sulphur richness of the OM shows no positive correlation with the degree of organic preservation. Sulphur partitioning between pyrite and OM was controlled by the ratio of reactive iron to OM. Average rates of planktonic productivity (C prod) vary between 6±9 and 60±88 t C org /m 2 /Ma. The rough covariance of the degree of preservation and C prod suggests that variations in planktonic productivity exerted a strong control on preservation in the suboxic, low to medium productivity KoÈ ssen Formation.
Central European Geology, 2009
For comparative studies of Upper Triassic cyclic platform carbonates, the Transdanubian Range (Hu... more For comparative studies of Upper Triassic cyclic platform carbonates, the Transdanubian Range (Hungary) and the Pelagonian Zone (Greece) were chosen. Paleogeographically they represent two distant segments of the passive margin of the Neotethys Ocean. During the Late Triassic, on this wide margin a very extensive tropical carbonate platform domain was developed, referred to as the Dachstein-type carbonate platform system. The Transdanubian Range (TR) represents a segment of a continent-encroaching platform system, whereas the Pelagonian-Subpelagonian Zone (PG) may have been a large isolated platform, surrounded by deep-water basins. The discussed Upper Triassic thick platform carbonates (Fõdolomit/Hauptdolomit Formation and Dachstein Limestone in the TR, and Pantokrator Formation in the PG) are made up of cyclically arranged facies deposited under similar environmental conditions in the interior zones of carbonate platforms. Three characteristic major facies types can be distinguished: shallow subtidal-lagoonal, intertidal and supratidal-pedogenic, which correspond to the three typical lithofacies (members C, B and A) of Fischer's (1964) Lofer-cycle. The cycles are usually bounded by discontinuity surfaces related to subaerial exposure and pedogenic alteration. The meter-scale (Lofer) cyclicity is predominant throughout the successions. However, various stacking patterns including symmetric complete, truncated, incomplete, and condensed cycles or even alternating peritidal and subtidal facies without any disconformity are recognized in both areas studied. Pervasive or partial early diagenetic dolomitization affected some parts of the cyclic successions in both areas. However, age-dependence of the early dolomitization was clearly demonstrated only in the TR, where the older part of the platform carbonate succession was subject to pervasive dolomitization, whereas the younger part is non-dolomitized and there is a transitional unit between them. This trend is attributed to the climate changing from semiarid to more humid. The Upper Triassic platform carbonates of the TR and PG show strikingly similar features concerning the litho-and biofacies, the stacking pattern and the thickness of the elementary cycles, despite their distant and different paleogeographic setting within the western Neotethys realm.
Acta Geologica Hungarica, 2006
Facies patterns of the Upper Permian and Triassic formations within the Transdanubian Range are p... more Facies patterns of the Upper Permian and Triassic formations within the Transdanubian Range are presented. Based on surface and subsurface data, facies maps were compiled for six time slices which served as a basis of the paleogeographic reconstructions. Considering the entire Late Permian-Triassic interval, the Transdanubian Range unit shows a definite polarity: its northeastern part represents the seaward (internal) side, whereas its southwestern part represents the landward (external) side. A remarkable part of facies units of the Transdanubian Range could be correlated with time equivalent facies in the Southern Alps and the Upper Austroalpine nappes, providing an effective tool for the reconstruction of the original position of the displaced Transdanubian Range Unit.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2016
The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, ... more The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, (7) yellowish, mottled (hydromorphic) paleosols. The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels. The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site is interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.
World Geomorphological Landscapes, 2015
The Pannonian region (the Pannonian or Carpathian Basin and the surrounding mountain ranges) is p... more The Pannonian region (the Pannonian or Carpathian Basin and the surrounding mountain ranges) is part of the Mediterranean Mountain System, which was formed during the last platetectonic cycle since the latest Paleozoic times. In Europe it is an about 300-800 km wide belt (Neo-Europe) accreted to the previously consolidated parts of Europe (Hercynian/Variscan Europe or Meso-Europe) as a result of the Alpine orogeny caused by convergence of the European (Eurasian) and African Plates. The present-day geological structure of the region is mostly determined by the evolution of the Tethys and Atlantic Ocean systems, i.e. the dismembering of the European and African continental plate margins during the early evolutionary stages and their tectonic deformation and uplifting as consequences of plate and microplate collisions. Plate-tectonic processes led to the formation of the large Pannonian Basin in the Late Cenozoic times. Hungary lies in the central part of the Pannonian Basin that is actually a system of several basins separated by isolated ranges of Palaeozoic and Mesozoic, sedimentary, magmatic and metamorphic formations and Cenozoic sedimentary and igneous rocks.
Central European Geology, 2017
The 1,200-m-deep Budaörs-1 borehole provided important data for our understanding of the stratigr... more The 1,200-m-deep Budaörs-1 borehole provided important data for our understanding of the stratigraphy and tectonic setting of the southern part of the Buda Hills. Although previous reports contained valid observations and interpretations, a number of open questions remained. The importance of this borehole and the unsolved problems motivated us to revisit the archived core. The new studies confirmed the existing stratigraphic assignment for the upper dolomite unit (Budaörs Dolomite Formation) as the dasycladalean alga flora proved its late Anisian to Ladinian age assignment. An andesite dike was intersected within the Budaörs Dolomite. U-Pb age determination performed on zircon crystals revealed a Carnian age (~233 Ma), and settled the long-lasting dispute on the age of this dike, proving the existence of a Carnian volcanic activity in this area after the deposition of the Budaörs Dolomite. Palynostratigraphic studies provided evidence for a late Carnian to early Norian age of the upper part of the lower unit (Mátyáshegy Formation). This result verified an earlier assumption and reinforced the significance of the tectonic contact between the upper unit (Budaörs Formation) and the lower unit (Mátyáshegy Formation). Based on structural observations and construction of cross sections, two alternative models are presented for the structural style and kinematics of the contact zone between the Budaörs and Mátyáshegy Formations. Model A suggests a Cretaceous age for the juxtaposition, along an E-W striking sinistral transpressional fault. In contrast, model B postulates dextral transpression and an Eocene age for the deformation. The latter one is better supported by the scattered dip data; however, both scenarios are considered in this paper as possible models.
International Journal of Earth Sciences, 2021
In the Transdanubian Range (Hungary), a wide spectrum of Triassic dolomites is known. Mechanism o... more In the Transdanubian Range (Hungary), a wide spectrum of Triassic dolomites is known. Mechanism of dolomitization of the platform carbonate successions was subject of a number of studies but the study of dolomitization of basinal carbonates is very limited. Petrographical and isotope–geochemical characteristics of the Upper Triassic dolomitized carbonate deposits, formed in a fault-controlled intraplatform basin, and interpretation of the dolomite-forming processes are presented in the current paper. From the latest Carnian to Middle Norian under semi-arid climatic conditions density-driven flux of seawater derived mesohaline fluids was the dominant mechanism of the near-surface pervasive dolomitization of the thick platform carbonate succession. In the late Middle Norian incipient rifting of the Alpine Tethys led to establishment of an extensional structural regime and onset of the formation of the Kössen Basin. In the study area, above the dolomitized platform carbonate succession...
Central European Geology, 2014
Partial and pervasive dolomitization of foreslope and toe-of-slope deposits of an early Carnian c... more Partial and pervasive dolomitization of foreslope and toe-of-slope deposits of an early Carnian carbonate platform was investigated for understanding the process and mechanism of dolomitization. Based on petrographic observations and C and O isotope data, the dolomitization took place in near surface to shallow burial setting and seawater of slightly elevated salinity was likely the dolomitizing fluid. The circulation system was maintained by reflux of evaporated sea water and geothermal heating of cold seawater derived from the surrounding deeper basin. The dolomitization was mostly controlled by the permeability of the platform-derived calcareous sediments.
IYPE activities of various geo-science associations, universities, research institutes and privat... more IYPE activities of various geo-science associations, universities, research institutes and private companies in Hungary (www.foldev.hu) have been successfully coordinated by the Hungarian National Committee, which was established by the Hungarian Academy of Sciences, the UNESCO- and the IUGS National Committees. The National Launch Event (April 17, 2008) was followed with a four-days long "Earth Science Fair" at the Hungarian Natural History Museum in Budapest. The IYPE was even briefly reviewed in the Hungarian Parliament. The Science Festival, organized annually by the Hungarian Academy of Sciences, in 2008 had a special IYPE-inspired slogan: "Science for the Habitable Earth", where lectures were held about the modern content of the Greek Classical Elements ("earth", "water", "air" and "fire", that is energy) and about the Humanity. In 2008/2009 numerous publications (including the Hungarian version of the IYPE booklet series, under the title GEO-FIFIKA, the Természet Világa special issue in February 2009, the IYPE number of Földrajzi Közlemények (Geographical Communications), and the "Geological Map of Hungary for Tourists" were produced. Throughout the country, symposia (e.g. HUNGEO 2008, ELGI 100, MÁFI 140, Geotourism Symposium in October 2009), several contests (Hungarian Television "Delta", Élet és Tudomány on the occasion of the UN year, and the annual contests starting in 2007 at Miskolc University), film shows (e.g., the movie "Another Planet") and other performances (e.g. End of the Ice Age in Hungarian Natural History Museum) were organized, with modest but increasing media coverage. The worldwide premier of the Planet Earth TV took place in Hungary, on the occasion of the IAGA 11th Scientific Assembly (August 23-30, 2009, www.iaga2009sopron.hu). One of our conferences ("Earth and Heaven - Geology and Theology") pointed out that there should be no conflict between science and religion, either in the fields of Earth's history or evolution. Science (and only science) is able to give reliable knowledge how Nature works, and the investigation of the "ultimate Why" (i.e. the "Primordial Cause") should be left to religions and philosophy. At the same time, there are antagonistic conflicts between science and pseudo-science, and also between religions and pseudo-religions. Among the scientific programmes the activity of Geological Institute of Hungary in the OneGeology initiative should be at first mentioned. In 2007/2008, among the main environmental challenges, it was exclusively the so-called "global warming" in the focal point of public interest in Hungary. By now, the importance of soil, groundwater and energy have been also recognized, largely (or at least partly) due to IYPE. This is perhaps the largest result of the IYPE in Hungary.
Sedimentary Geology, Apr 1, 2015
ABSTRACT Dolomite most commonly forms via replacement of precursor carbonate minerals. For this r... more ABSTRACT Dolomite most commonly forms via replacement of precursor carbonate minerals. For this reason, diagnosing primarily precipitated organogenic dolomite in microbial mat deposits from the rock record is not straightforward, even though the deposits exhibit microbial fabric. Single and multiple dolomite crusts exhibiting microbial fabric occur in a pervasively dolomitized Middle Triassic platform succession. Two sections were studied in detail in the north-eastern part of the Transdanubian Range (north-central Hungary). In both sections, thin layer-couplets of two fabric types occur in the upper part of the metre-scale cycles. Microbial boundstone (fabric type 1)––characterised by clusters of dolomite microcrystals which display diagnostic microbial features, such as calcimicrobes, clotted–spherular aggregates and globules––composes the upper layer of couplets. The lower layer of the couplets is different in the two studied sections. In Section 1, it is micritic dolomite (fabric type 2) that is characterised by predominantly fine crystals and contains obscured microbial components. In Section 2, it is bioclastic dolomite (fabric type 3) that is rich in reworked dasycladalean fragments and consists of dolomite crystals of wide size-range from fine to coarse. The precipitation of the microcrystalline dolomite phase, which process is the focus of this study, is interpreted as being facilitated by mats and biofilms favouring/tolerating increasing frequency of subaerial conditions in the upper intertidal setting. Petrographic analyses revealed that organogenic calcite was also precipitated, especially in mat deposits rich in bioclasts. Synsedimentary dolomitization, resulting in fine crystals, was coupled with aragonite dissolution. Moreover, it postdated the organogenic precipitation and fibrous calcite cementation. Synsedimentary replacive dolomitization took place only in the peritidal caps of the shallowing-upward depositional units. Petrographic analyses provide circumstantial evidence constraining that microcrystalline dolomite did not form via mimetic replacement. Accordingly the microcrystalline dolomite, which shows microbial microfabrics in the studied samples, is interpreted as organogenic primary precipitate. Both peritidal processes, dolomite precipitation and replacement, were likely controlled by the environmental factors in a semi-arid climate. Those components of the platform succession that were not dolomitized in the peritidal environment were replaced and cemented by medium and coarsely crystalline dolomite during further burial at elevated temperature, as shown by fluid inclusion homogenisation temperature (62 to 83 °C) and negative stable oxygen isotope values. Thus, the majority of the studied formation consists of fabric-destructive dolomite (fabric type 4).
Acta Geologica Hungarica, Mar 13, 2015
ABSTRACT
Central European Geology, 2010
Acta Geologica Hungarica, 2006
The basement of the Pannonian Basin is made up of tectonostratigraphic terranes of varying origin... more The basement of the Pannonian Basin is made up of tectonostratigraphic terranes of varying origin. They gradually amalgamated to form the large Alcapa and Tisza-Dacia composite terranes that were juxtaposed during the Tertiary. In North Hungary, in the basement of the Tertiary volcanic complex of the Mátra Mts and in the western part of the Bükk Mts, remnants of a Jurassic accretionary wedge were encountered. Ore exploration boreholes encountered several hundred-meter thick carbonate and siliceous shale-radiolarite successions in the basement of the Mátra Mts (Darnó Complex). Based on detailed studies of Core Recsk-109, the carbonate succession consists predominantly of grainstone with packstone-wackestone intercalations. Peloidal bioclastic grainstone is the most common texture type but sand-sized intraclasts and oncoid and ooid grains also occur locally. The most spectacular feature is the large amount of coarse to medium sand-sized fragments of calcified cyanobacteria ("Porostromata"). Platform-derived foraminifera and fragments of crinoids are also common. Gravity flows transported the carbonate detritus to the site of deposition at the lower foreslope and proximal toe-of-slope. Based on foraminifera the succession is Aalenian? or Early Bajocian in age.
Acta Geologica Hungarica, 2005
... Geologija, 31/32, pp. 415435, Ljubljana. 128 S. Kovács et al. Acta Geologica Hungarica 48, 2... more ... Geologija, 31/32, pp. 415435, Ljubljana. 128 S. Kovács et al. Acta Geologica Hungarica 48, 2005 Page 7. ... Poseb. izd. Geologija, 32, 172 p., Ljubljana. Pamic, J., V. Marci 1990: Petrologija amfibolitskih stijena slavonskih planina (sjev. Hrvatska). Geol. vjesn., 43, pp. ...
Sedimentary Geology, 1999
Toe-of-slope megabreccia deposits of an Upper Cretaceous rudist platform were studied in the Bako... more Toe-of-slope megabreccia deposits of an Upper Cretaceous rudist platform were studied in the Bakony Mountains. During the Turonian-early Senonian tectogenesis an articulated basin came into being in the area of the Bakony; depressions and highs were formed roughly parallel with the structural strike of the mountains. Inundation of the highs led to the evolution of carbonate platforms. The investigated platform shows an asymmetric architecture. In contrast to its gentle northern slope a steep erosional slope bounded the platform to the south with large, low-angle aprons, the site of deposition of megabreccias. The breccia accumulation occurred within a single 3rd-order cycle commencing in the early highstand and reaching its climax in the late highstand.
Sedimentary Geology, 2002
In the Late Triassic, a large carbonate platform system came into existence in the Transdanubian ... more In the Late Triassic, a large carbonate platform system came into existence in the Transdanubian Range (TR) producing a 1.5-to 2-km-thick carbonate succession. The lower part of the platform carbonate series is made up of cyclic peritidal dolomite (Main Dolomite Formation), while the upper one consists of cyclic peritidal limestone (Dachstein Limestone Formation). However, there is a transitional member of remarkable thickness between them consisting of partially dolomitised limestone and calcitic dolomite. This study focuses on the transitional member where the process of early dolomitisation was halted at various stages. In the investigated sections the early dolomitisation was controlled by the climate and high-frequency sea-level oscillation, which led to periodic subaerial exposure of large areas and palaeo-hydrological conditions. Increasing humidity and gradual extension of the permanently inundated outer platform led to cessation of early dolomitisation in the Middle to Late Norian. D