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
Geosciences, Multidisciplinary
Reza Syahputra, Jiri Zak, Filip Tomek, Vaclav Kachlik
Summary: The late Ediacaran to Cambrian end of the Cadomian accretionary orogeny was a complex cascade of events that led to the opening of the Rheic Ocean and formation of a passive margin along the northern Gondwana periphery. The emplacement and tectonic setting of the ca. 524-523 Ma Kdyne gabbro to diorite pluton suggest that it was formed through magma wedging and magmatic stoping in an extensional stepover between two dextral transtensional zones. The rapid heat input into the base of the accretionary wedge may have been caused by slab break-off. The high-temperature events following Cadomian accretion indicate that magmatism may have played a key role in the rifting of northern Gondwana during the Cambro-Ordovician period.
PRECAMBRIAN RESEARCH
(2023)
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
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
Geology
Ruben Diez Fernandez, Ricardo Arenas, Esther Rojo-Perez, Sonia Sanchez Martinez, Jose Manuel Fuenlabrada
Summary: The Neoproterozoic and Palaeozoic rocks of the Merida Massif in SW Iberia have been grouped into tectonostratigraphic units, separated by crustal-scale thrusts and/or extensional detachments. This tectonic setting was formed during the Cadomian Orogeny and later modified by the Variscan Orogeny, resulting in the juxtaposition of different units and the formation of folds and thrusts. The Merida Ophiolite represents a Cadomian suture zone exposure in the Gondwanan realm, reflecting inland transference of allochthonous terranes onto mainland Gondwana during different geological periods.
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)
Article
Geology
Isak Yilmaz, Sabah Yilmaz Sahin, Namik Aysal, Yildirim Gungor, Alper Akgunduz, Ugur Can Bayhan
Summary: The Cadomian magmatic rocks in the Istranca Massif range from peraluminous to slightly metaluminous, exhibiting calc-alkaline and high-K calc-alkaline compositions. Zircon U-Pb crystallization ages fall between 525.3 +/- 3.5 Ma and 548.7 +/- 2.3 Ma, indicating a subduction-related magmatic arc setting during the Late Precambrian-Early Palaeozoic period.
INTERNATIONAL GEOLOGY REVIEW
(2022)
Article
Geochemistry & Geophysics
Diana Moreno-Martin, Ruben Diez Fernandez, Ricardo Arenas, Esther Rojo-Perez, Irene Novo-Fernandez, Sonia Sanchez Martinez
Summary: The Cadomian Orogeny created a subduction-related mountain range along the periphery of Gondwana and formed the basement of the Iberian Massif. Detailed analysis in SW Iberia has identified three deformation phases and provided insights into the building and dismantling processes of the Cadomian Orogen. The first phase involved tabular plutons during the formation of a continental arc, the second phase produced folding and thickening of the crust, and the third phase resulted in an orogen-parallel dome with extensional flow. The formation of the Cadomian Orogen was associated with ongoing subduction, while its dismantling during the Early Paleozoic was driven by oblique convergence.
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)
Article
Geosciences, Multidisciplinary
S. Siegesmund, S. Oriolo, B. Schulz, T. Heinrichs, M. A. S. Basei, B. Lammerer
Summary: The study of metasedimentary rocks in the Austroalpine, South Alpine and Penninic basement domains reveals their pre-Variscan tectonic evolution. The research suggests a continuum of tectonosedimentary processes from Late Ediacaran to Carboniferous periods, with detrital zircon samples mainly originating from the northeastern Saharan Metacraton and the Sinai basement. The Alpine basement, comprising Pan-African metasedimentary and subordinate metaigneous rocks, underwent significant reworking during the Paleozoic orogenic evolution.
INTERNATIONAL JOURNAL OF EARTH SCIENCES
(2021)
Article
Geosciences, Multidisciplinary
Pierig Deiller, Pavla Stipska, Marc Ulrich, Karel Schulmann, Stephen Collett, Vit Peresty, Bradley Hacker, Andrew Kylander-Clark, Hubert Whitechurch, Ondrej Lexa, Eric Pelt, Jitka Mikova
Summary: The study examined previously unrecognized mafic and felsic plutonic rocks, as well as a possible upper-crustal equivalent, in the Bohemian Massif. The rocks exhibited evidence of active margin magmatism and Mid-Devonian magmatism, with a three-stage geodynamic model proposed to explain their formation. The magmatic rocks recorded a Mid-Devonian magmatic arc related to the subduction wedge beneath the upper plate.
Article
Geochemistry & Geophysics
Jakub Kryl, Petr Jerabek, Ondrej Lexa
Summary: The study of the Erzgebirge dome reveals different microstructural types associated with continuous deformation and decompression processes, shedding light on the formation mechanism of the orogenic wedge.
Article
Geochemistry & Geophysics
Prokop Zavada, Pavia Stipska, Pavlina Hasalova, Martin Racek, Petr Jerabek, Karel Schulmann, Andrew Kylander-Clark, Robert Holder
Summary: The study conducted on a sequence of samples from a (U)HP crustal section in the Eger Crystalline Complex revealed important insights into the process of crustal metamorphism and melt percolation, indicating a 15+/-3 Ma period of monazite (re)crystallization. Age and trace element distribution of monazite grains provided valuable information on the complex geological processes involved in Variscan continental subduction.
Article
Geosciences, Multidisciplinary
Jose Manuel Fuenlabrada, Ricardo Arenas, Manuel Francisco Pereira, Esther Rojo Perez, Sonia Sanchez Martinez, Ruben Diez Fernandez
Summary: The Cadomian Orogeny involved the opening and closing of oceanic domains and associated sedimentary basins in the northern margin of Gondwana. These basins are found within autochthonous and allochthonous terranes of the Variscan Orogen in the Iberian Massif. Nd isotope data supports the idea of varying sources along the North Gondwanan margin during the Early Paleozoic.
PRECAMBRIAN RESEARCH
(2023)
Article
Geosciences, Multidisciplinary
Ulf Linnemann, Mandy Hofmann, Andreas Gaertner, Jessica Gaertner, Johannes Zieger, Rita Krause, Robert Haenel, Katja Mende, Maria Ovtcharova, Urs Schaltegger, Pat Vickers-Rich
Summary: Recent studies in the Armorican Massif of Normandy, France, have described glacigenic sedimentary deposits from the late Ediacaran period. Combined with data from other regions, it appears that these deposits represent an Upper Ediacaran Glacial Period in northern peri-Gondwana.
GEOLOGICAL MAGAZINE
(2022)
Article
Geology
Jiri Zak, Martin Svojtka, Ianko Gerdjikov, Alexandre Kounov, Dian A. Vangelov
Summary: The study focuses on analyzing four lithotectonic units in the Balkans using detrital zircon U-Pb geochronology to understand their formation and origins. Through statistical comparison and multidimensional scaling, the Balkan terranes are compared with other terranes from the Eastern Alps to Iran, revealing their paleogeographic positions and significant dextral strike-slip displacements.
INTERNATIONAL GEOLOGY REVIEW
(2022)
Article
Geology
Fritz Finger, David Schiller, Martin Lindner, Christoph Hauzenberger, Krystof Verner, Jiri Zak
Summary: Comprehensive zircon thermometry was used to study the thermal evolution of the Variscan South Bohemian batholith and the emplacement temperature of its granitic rocks. The study found that the early stages of batholith formation were characterized by low to medium temperature melting driven by isothermal exhuma-tion, while later stages saw the intrusion of high to ultrahigh temperature granites, possibly linked to a hidden mafic intrusion.
Article
Geosciences, Multidisciplinary
Reza Syahputra, Jiri Zak, R. Damian Nance
Summary: The diachronous opening of the Rheic Ocean and the separation of Avalonian-Cadomian terranes from Gondwana during the late Ediacaran to early Cambrian period remains poorly understood. The Pribram-Jince basin in the Bohemian Massif is studied as a case example to better understand Cambrian rifting. The study provides insights into the sources of sedimentary deposits and the tectonic evolution of the basin.
Article
Geosciences, Multidisciplinary
Andreas Gaertner, Mandy Hofmann, Johannes Zieger, Anja Sagawe, Rita Krause, Marika Stutzriemer, Subani Gesang, Axel Gerdes, Linda Marko, Cristiano Lana, Ulf Linnemann
Summary: Extensive morphological and age studies on detrital zircon grains from modern sands of Namibia reveal complex mechanisms of sediment transport. A large Southern Namibian Sediment Vortex and a modified model of the Orange River sand highway are hypothesized based on the results of this study. The potential impact of spatial variations of erosion rates on sediment movements towards the interior of the continent is also highlighted. Additionally, detrital zircon morphology and large geo-databases are identified as valuable tools for provenance analysis.
INTERNATIONAL JOURNAL OF EARTH SCIENCES
(2022)
Article
Geology
Bidyananda Maibam, Richard M. Palin, Axel Gerdes, Richard W. White, Stephen Foley
Summary: The tectonic significance of blueschist-facies rocks associated with the Indo-Myanmar ophiolite belt is uncertain due to the lack of detailed petrological study and reliable age data. This study presents new petrological and geochronological data from the Nagaland complex, northeast India, which provide constraints on the pressure-temperature conditions and ages of metamorphism. The results suggest that the region experienced high-pressure prograde-to-peak metamorphism followed by lower-pressure retrograde metamorphism, with peak metamorphism dated at approximately 95 Ma and retrograde metamorphism at approximately 90 Ma. The study also indicates an exhumation rate of approximately 1 cm/year, consistent with Phanerozoic plate tectonic rates.
INTERNATIONAL GEOLOGY REVIEW
(2023)
Article
Geosciences, Multidisciplinary
Lukas Ackerman, Jiri Zak, Karel Zak, Jan Pasava, Vaclav Kachlik, John Hora, Frantisek Veselovsky, Jaroslava Hajna
Summary: The Ediacaran to early Cambrian limestones in the Blovice accretionary wedge demonstrate how paleooceanographic and palaeoenvironmental conditions at active plate margins can be recorded by isotopic composition. Different types of limestones provide insights into various depositional conditions and are linked with paleooceanic and paleogeographic interpretations. Additionally, carbonate-bearing silicate rocks with different elemental and isotopic compositions suggest their common origin at active margins and some of them may have formed through hydrothermal activity.
PRECAMBRIAN RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Lukas Ackerman, Jiri Zak, Vaclav Kachlik, Martin Svojtka, Filip Tomek, Vaclav Santolik, Jiri Slama, Jakub Trubac, Ladislav Strnad, Frantisek Vacek
Summary: This study presents new geochemical and geochronological data for different lithotectonic units in the northeastern part of the Superior Province in Canada, providing insights into crustal growth and tectonic regime during the late Archean. The results suggest a transition from plume-dominated to plate-tectonic regime, representing a significant crustal growth event.
PRECAMBRIAN RESEARCH
(2022)
Article
Geochemistry & Geophysics
Vaclav Santolik, Lukas Ackerman, Vaclav Kachlik, Jiri Slama, Noemi Meszarosova
Summary: The processes leading to the formation of siliceous magmatic rocks from juvenile sources within intra-oceanic island arcs play a significant role in the formation and growth of continental crust. The study reveals that low-pressure intra-oceanic arc granitoids can form in a nearly closed system with little assimilation of older crustal material.
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
Multidisciplinary Sciences
Daniel Munoz-Lopez, David Cruset, Jaume Verges, Irene Cantarero, Antonio Benedicto, Vinyet Baques, Xavier Mangenot, Richard Albert, Axel Gerdes, Aratz Beranoaguirre, Anna Trave
Summary: This study applies U-Pb dating and geochemical analysis to fracture-filling calcite veins and host carbonates from the Boixols-Sant Corneli anticline in the Southern Pyrenees. The analysis provides insights into the absolute timing of fracturing and mineralization, the age and duration of fold evolution, and the variations and implications of fluid behavior across the anticline.
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
Geosciences, Multidisciplinary
Jiri Zak, Martin Svojtka, Ianko Gerdjikov, Dian A. Vangelov, Alexandre Kounov, Jiri Slama, Vaclav Kachlik
Summary: This paper attempts to locate the unknown provenance of pre-Darriwillian basement slivers along the boundary of the Avalonian-type Moesia microplate attached to the southeastern margin of Baltica and the Balkan fold-and-thrust belt in Bulgaria. The U-Pb detrital zircon ages analysis suggests that the pre-Darriwillian units were deposited in an accretionary wedge/forearc basin setting or in an incipient rift superposed on the Cadomian forearc/arc region, while the overlying formations indicate sustained delivery of cratonic detritus. The detrital zircon ages possibly define the Rheic suture and imply the possibility of Cadomian terranes remaining attached to Gondwana during the Early Paleozoic.