Article
Geosciences, Multidisciplinary
Stephen Collett, Karel Schulmann, Pierig Deiller, Pavla Stipska, Vit Peresty, Marc Ulrich, Yingde Jiang, Luc de Hoym de Marien, Jitka Mikova
Summary: This article investigates the high-pressure and high-temperature metamorphism during the Mid-Devonian period in the Variscan Orogeny, focusing on the geological characteristics of the Marianske Lazne Complex (MLC). The unique position of MLC at the base of its original upper plate is highlighted. The study reveals that both MLC and the upper plate developed above a relatively unaltered Neoproterozoic lithospheric mantle, which is important for reconstructing the original architecture of the Variscan terranes.
GEOSCIENCE FRONTIERS
(2022)
Article
Geochemistry & Geophysics
Johannes E. Pohlner, Afife El Korh, Reiner Klemd, Bernard Grobety, Thomas Pettke, Massimo Chiaradia
Summary: Eclogites, metagabbros, and paragneisses in the Variscan Munchberg Massif underwent a complex succession of igneous, hydrothermal, and metamorphic processes, with geochemical signatures revealing a varied history. The light and dark eclogites were likely formed from different parental magmas, with the former interpreted as plagioclase-rich cumulates and the latter as complementary differentiates. Metagabbros showed an enriched trace element signature and origin from a more enriched mantle source than the eclogites. The rocks experienced limited metamorphic fluid-rock interactions, possibly due to the lack of lawsonite dehydration.
Article
Geosciences, Multidisciplinary
Lukas Krmicek, Milan Novak, Robert B. Trumbull, Jan Cempirek, Stanislav Houzar
Summary: Various metacarbonate and calc-silicate rocks in the Bohemian Massif of the Variscan orogen contain tourmaline in different paragenetic settings, each showing distinctive compositional features. The presence of tourmaline with different B-isotope compositions in specific units suggests regional variations and possible metamorphic processes within the studied areas.
GEOSCIENCE FRONTIERS
(2021)
Correction
Geosciences, Multidisciplinary
Vojtech Janousek, Pavel Hanzl, Martin Svojtka, John M. Hora, Yulia V. Erban Kochergina, Petr Gadas, Frantisek V. Holub, Axel Gerdes, Krystof Verner, Kristyna Hrdlickova, J. Stephen Daly, David Burianek
Summary: The authors apologize for inadvertently providing an erroneous version of the recalculated titanite analyses data table.
INTERNATIONAL JOURNAL OF EARTH SCIENCES
(2021)
Article
Geology
Francisco J. Rubio Pascual, Luis M. Martin Parra, Ruben Diez Fernandez, Pablo Valverde-Vaquero, Alejandro Diez-Montes, Manuel P. Hacar Rodriguez, Justo Iglesias, Gloria Gallastegui, L. Roberto Rodriguez Fernandez, Aratz Beranoaguirre
Summary: This study examines the geological structures and metamorphic processes in the NW Iberian section of the Variscan Orogen. By analyzing the metamorphic record of tectonic slices, it reveals the transitional process between subduction and collision zones, providing important clues for understanding the construction of orogens.
INTERNATIONAL GEOLOGY REVIEW
(2022)
Article
Geosciences, Multidisciplinary
Matej Machek, Igor Soejono, Jiri Slama, Eliska Zackova
Summary: The high-grade metamorphic complexes along the northern Moldanubian periphery of the central Bohemian Massif provide a detailed structural record of the collisional evolution of the Variscan Orogeny. Multiple tectonic events were identified through the analysis of rock structures and microstructures, as well as geochronology.
JOURNAL OF THE GEOLOGICAL SOCIETY
(2022)
Review
Geosciences, Multidisciplinary
Wolfgang Franke, Andrzej Zelazniewicz
Summary: The Variscan Bohemian Massif provides evidence for two oceans and records various geological processes such as rifting, drift, convergence, and collision. It also confirms the emplacement and cooling of high-grade rocks from the asthenospheric mantle. The interaction between different tectonic units and the controversy surrounding the tectonic paths in the region are discussed.
Article
Geochemistry & Geophysics
Oscar Laurent, Simon Couzinie, Luc S. Doucet
Summary: The study reveals the timescales of lower crustal ultra-high temperature metamorphism and the production and transfer of granitic magmas. Zircon petrochronology of felsic and mafic granulite xenoliths from the Variscan eastern French Massif Central shows that these rocks underwent Variscan UHT peak metamorphism at 940-970°C and 8±2 kbar. The zircon U-Pb dates of the felsic granulites range from -315 to -265 Ma, indicating continuous crystallization of zircon upon cooling from the thermal peak. The emplacement of upper crustal granite started at 340 Ma and peaked at 313±3 Ma, reflecting melt extraction along the prograde path of the lower crust. The crystallization ages of mid-crustal migmatites (315-300 Ma) and lower crustal granulites (315-265 Ma) suggest slow cooling in the presence of melt.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Geochemistry & Geophysics
G. de Vicente, R. Diez Fernandez, A. Olaiz, A. Munoz-Martin
Summary: The Spanish-Portuguese Central System is a mountain range with a two-layer rheological structure, formed during the extensional collapse of the Variscan Orogen. It is controlled by thrusts and faults, with a unique structure in the eastern region. Crustal root and backthrusts suggest a delamination process, while shortening and subduction occurred due to structural inheritance in the crust.
Article
Geology
Jochen Roetzler, Martin J. Timmerman
Summary: The Saxon Granulite Massif is a key area for understanding the Palaeozoic Variscan orogeny, with a dome structure comprising high-P granulites and low-P metasedimentary rocks. New age and petrologic data suggest that the metaophiolites developed from early Cambrian protoliths and underwent high-P amphibolite facies metamorphism in the mid- to late-Devonian, followed by thermal overprinting by the exhuming hot granulite body in the early Carboniferous. The exhumation and cooling rates of the granulite body are estimated to be around 8 mm/year and 80 degrees C/Ma, with a significant drop in exhumation rate and a slight rise in cooling rate during the different stages of exhumation.
JOURNAL OF METAMORPHIC GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Stephen Collett, Pavla Stipska, Karel Schulmann, Jitka Mikova, Alfred Kroener
Summary: The study of the Velke Vrbno Dome eclogite provides evidence for the emplacement of eclogite protoliths in a transitional supra-subduction to continental-rift setting. Additionally, the discovery of a fragment of Palaeoproterozoic basement in the region suggests an earlier geological history.
JOURNAL OF THE GEOLOGICAL SOCIETY
(2021)
Article
Geology
Abderrahim Essaifi, Alicja M. Lacinska, Michel Corsini, Kathryn M. Goodenough, Amal EL Arbaoui, Rachid Zayane
Summary: In the Jebilet massif in Morocco, the Central Jebilet pluton is spatially associated with a regional shear zone and includes different eroded portions represented by intrusions like Tabouchent, Bramram, and Bamega. Mineralization occurs in the shear zones, with varying degrees of deformation observed in different intrusions.
ORE GEOLOGY REVIEWS
(2021)
Article
Geochemistry & Geophysics
Hans-Joachim Massonne, Botao Li
Summary: The study examined the pressure-temperature path of eclogite from Les Essarts high-pressure unit in western France and identified unusual atoll garnet. Through mineral chemistry characterization and thermodynamic modeling, the metamorphic evolution of eclogite was revealed. A geodynamic scenario was outlined to explain the formation and evolution of eclogite in two different geotectonic environments.
Article
Geology
Marine Jouvent, Ondrej Lexa, Vit Peresty, Petr Jerabek
Summary: The study focuses on the transition from low-grade phyllites to medium-grade micaschists in the surrounding metasediments, using thermodynamic modeling to determine the P-T conditions of four deformation fabric events. The evolution of Variscan orogenic processes from continental subduction to orogenic wedge formation is characterized by different metamorphic events with varying geothermal gradients. The Erzgebirge part of the Saxothuringian Domain displays an example of active margin evolution involving accretionary prism formation, orogenic wedge building through subducted continental crust accretion, and subsequent extensional collapse.
JOURNAL OF METAMORPHIC GEOLOGY
(2022)
Article
Geology
R. Arenas, I. Novo-Fernandez, A. Garcia-Casco, Fernandez R. Diez, J. M. Fuenlabrada, M. F. Pereira, J. Abati, Martinez S. Sanchez, F. J. Rubio Pascual
Summary: The Badajoz-Cordoba Unit is a Variscan high-P unit mainly composed of metapelites, metagreywackes, orthogneisses, Grt-amphibolites, and retrogressed eclogites. The unit underwent high-P metamorphism at around 377 Ma, forming rare metapelites with well-preserved high-P mineral assemblages. Pseudosection modelling suggests formation in blueschist facies under high pressure conditions, followed by exhumation and moderate heating, similar to other units in the Variscan Orogen.
INTERNATIONAL GEOLOGY REVIEW
(2021)
Article
Geography, Physical
Filip Scheiner, Martina Havelcova, Katarina Holcova, Nela Dolakova, Slavomir Nehyba, Lukas Ackerman, Jakub Trubac, Sarka Hladilova, Jan Rejsek, Torsten Utescher
Summary: In this study, the parastratotype section of the Karpatian stage at Hevlin quarry in the Czech Republic was analyzed to improve understanding of the palaeoenvironment and palaeoclimate during the Miocene Climate Optimum. The findings indicate a warm temperate to subtropical palaeoclimate with a mean annual temperature range of 17-19.5 degrees C and a high degree of seasonality. The annual precipitation range was 1050-1600 mm. The zonal vegetation cover was characterized as transitional between subtropical broad-leaved evergreen forest and warm-temperate to subtropical mixed mesophytic forest. These results agree with global trends and suggest widespread humid conditions in the region.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Lukas Ackerman, Jiri Zak, Vaclav Kachlik, Jan Pasava, Karel Zak, Andreas Pack, Frantisek Veselovsky, Ladislav Strnad
Summary: The Blovice accretionary complex in the Bohemian Massif contains abundant chert bodies that were formed on an oceanic plate during subduction beneath the northern margin of Gondwana. The characteristics and formation processes of the cherts reveal diverse depositional environments and positions on the oceanic plate. These cherts record a complex interplay between seafloor-related volcanic and sedimentary processes, hydrothermal activity, and subduction processes.
GEOSCIENCE FRONTIERS
(2023)
Article
Chemistry, Multidisciplinary
Jan Kucera, Katerina Pachnerova Brabcova, Mojmir Nemec, Jan Kamenik, Jakub Trubac, Veronika Brychova, Ivo Svetlik, Jan John, Roman Garba, Martin Dano
Summary: The first accelerator mass spectrometry (AMS) laboratory in the Czech Republic has been established and put into routine operation in February 2022. It is equipped with a 300 kV multi-isotope low-energy AMS system (MILEA) capable of analyzing various isotopes, including C-14. The laboratory has achieved successful separation and measurement of radionuclides and has presented results and procedures for sample preparation and measurement.
Article
Geology
Martin Kostak, Daniela Rehakova, Lucie Vankova, Martin Mazuch, Jakub Trubac, Rastislav Milovsky
Summary: Stable isotope data from bulk rock in the Jurassic-Cretaceous transition show stable values in many Tethyan carbonate sections, particularly those deposited in deeper-water marine conditions. The 813Ccarb curve at the J/K boundary interval does not provide significant value expressions for interregional correlation. However, a slight negative carbon isotopic excursion at the J/K boundary has been observed in well-calibrated sections, indicating a potential geochemical marker for stratigraphic correlation.
CRETACEOUS RESEARCH
(2023)
Article
Geochemistry & Geophysics
Michael A. Antonelli, Chris Yakymchuk, Edwin A. Schauble, John Foden, Vojtech Janousek, Jean-Francois Moyen, Jan Hoffmann, Frederic Moynier, Olivier Bachmann
Summary: Stable Ca isotopes are useful for understanding the formation of magmatic rocks, but Ca isotope fractionation in silicic continental crust is poorly understood.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Geology
Jiri Zak, Jiri Slama, Reza Syahputra, R. Damian Nance
Summary: The Bohemian Massif in Central Europe formed from lithospheric fragments at the northern margin of Gondwana. The key geodynamic process that shaped this margin was the Cambro-Ordovician rifting that opened the Rheic Ocean. The mechanism of this rifting is reconstructed based on new U-Pb zircon ages, and it is suggested that stretching of the lower lithosphere preceded upper lithospheric rifting, leading to the breakup of Gondwana.
INTERNATIONAL GEOLOGY REVIEW
(2023)
Article
Geochemistry & Geophysics
Vojtech Janousek, Luana Moreira Florisbal, Jiri Konopasek, Petr Jerabek, Maria de Fatima Bitencourt, Petr Gadas, Vojtech Erban, Veronika Kopackova-Strnadova
Summary: The Ediacaran syn-tectonic plutonic rocks in north-western Namibia belong to two compositionally similar, magnesian, transitional tholeiitic-calc-alkaline suites, the Older and the Younger. These suites are also found in southern Brazil and were separated during the opening of the southern Atlantic. The formation of these suites involved different magmatic processes, with the Older likely formed by fluid-present melting of metabasalts and metatonalites, and the Younger formed by dehydration melting of felsic lower crustal protoliths.
JOURNAL OF GEODYNAMICS
(2023)
Article
Environmental Sciences
Tomas Chuman, Marie Plasova, Nikola Derkova, Jakub Trubac
Summary: Studies found that stone quarries have the potential for carbon and nitrogen sequestration, but research in this area is limited. This study compared the carbon and nitrogen pools and sequestration rates of stone quarries with other mining sites. It was found that carbon and nitrogen naturally accumulate in the soil during the natural succession of stone quarries, and the sequestration rates decrease over time.
LAND DEGRADATION & DEVELOPMENT
(2023)
Article
Paleontology
Marta Kerkhoff, Katarina Holcova, Katalin Baldi, Natalia Hudackova, Martin Racek, Jakub Trubac, Adam Culka
Summary: Microbial activity in carbonate hardgrounds can be expressed through various structures including boring structures, biofilmlike subproducts, and framboidal pyrite precipitates. These structures, found in foraminifera tests, can serve as paleoenvironmental markers for paleobathymetry, oxygenation, and environmental stress. The study focuses on microendolithic structures in foraminifera tests from dysphotic to aphotic, shelf to upper bathyal hypoxic environment, and investigates microbial traces such as microborings, framboidal pyrite bacterial subproducts, and probable biofilms. It also examines oxygen depletion levels using Benthic Foraminifera Oxygen index (BFOI) and infers the bacterial origin of pyrite through morphology and isotopic analysis.
MARINE MICROPALEONTOLOGY
(2023)
Article
Paleontology
Yuliia V. Vernyhorova, Katarina Holcova, Nela Dolakova, Bettina Reichenbacher, Filip Scheiner, Lukas Ackerman, Jan Rejsek, Lorenzo De Bortoli, Jakub Trubac, Torsten Utescher
Summary: The Miocene Climate Optimum and Climate Transition have significant implications for the biotic, environmental, and geologic events in the Black-Caspian Sea region. The study area showed open shelf conditions, variable water column stratification, and changing vegetation from humid to arid conditions. The Eastern Paratethys experienced climate change slightly earlier than the Central Paratethys, possibly due to the presence of the flat Eurasian continent.
MARINE MICROPALEONTOLOGY
(2023)
Article
Geochemistry & Geophysics
Jan Pasava, Lukas Ackerman, Jiri Zak, Martin Svojtka, Tomas Magna, Ondrej Pour, Jakub Trubac, Frantisek Veselovsky
Summary: Black shales in the Ediacaran trench-slope in the Czech Republic were found to have an unusual type of gold mineralization, which is related to the formation of quartz-sulfide vein systems. The gold enrichment is a result of the precipitation of native gold from silica and low-temperature hydrothermal colloidal solutions. This study provides a new genetic model for the exploration of gold in other terrains underlain by a rifted Cadomian basement.
MINERALIUM DEPOSITA
(2023)
Article
Geochemistry & Geophysics
Vladislav Rapprich, Vojtech Janousek, Tomas Hroch, Jitka Mikova, Vojtech Erban, Firdawok Legesa, Zoltan Pecskay, Patricie Halodova
Summary: A group of pyroclastic cones is scattered in the North Chamo Volcanic Field, with different eruption styles and complex magmatic evolution. The cones on the Nech Sar plains displayed a simple Strombolian eruptive style, while those in the northern part of Chamo Lake had a more complex history with a transition from Surtseyan-style eruption to Strombolian style. The magmas parental to the North Chamo alkaline volcanic rocks evolved through closed-system fractionation of olivine, followed by assimilation of country-rock felsic igneous material.
JOURNAL OF GEOSCIENCES
(2023)
Article
Geochemistry & Geophysics
Pavel Hanzl, Vojtech Janousek, Kristyna Hrdlickova, David Burianek, Ochir Gerel, Battushig Altanbaatar, John M. Hora, Petr Coupek
Summary: The Trans-Altai Zone in southern Central Asia is made up of preserved Early Paleozoic oceanic crust and igneous arcs. Late Paleozoic plutons intruded the Edren and Baaran subzones, while Mississippian plutons intruded Devonian and Carboniferous volcano-sedimentary sequences in two magmatic pulses.
JOURNAL OF GEOSCIENCES
(2023)
Article
Geosciences, Multidisciplinary
Igor Soejono, Vojtech Janousek, Vit Peresty, Karel Schulmann, Martin Svojtka, Pavel Hanzl, John M. Hora, Jitka Mikova, Pavla Stipska, Alexandra Guy, Stephen Collett, Dorjsuren Otgonbaatar
Summary: A study on the magmatic record in the Zavkhan Block, part of the Mongolian Collage in the Central Asian Orogenic Belt, revealed two distinct magmatic events in the region, Late Tonian (c. 840-800 Ma) and Cambro-Ordovician (c. 510-470 Ma). These events represent different sources and evolution processes of the crust, indicating the breakup of Rodinia and the development of a continental magmatic-arc system during the Cambro-Ordovician.
Article
Geosciences, Multidisciplinary
Jiri Zak, Martin Svojtka, Jiri Slama, Filip Tomek, Vaclav Kachlik, Lukas Ackerman, Frantisek Vacek, Jakub Trubac
Summary: This paper presents new U-Pb zircon ages obtained using laser ablation ICP-MS from various plutonic units that intruded along the southern margin of the Bienville domain, a Neoarchean magmatic arc in Quebec, Canada. The U-Pb ages indicate episodic emplacement of the arc plutons between ca. 2745 Ma and ca. 2697 Ma, synchronous with regional deformation. The observed intra-pluton age variations suggest incremental growth of the Radisson pluton over at least 15 My through successive emplacement of elongated, sheet-like magma batches.
PRECAMBRIAN RESEARCH
(2023)
