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
Marine Jouvent, Vit Peresty, Petr Jerabek, Ondrej Lexa, Andrew R. C. Kylander-Clark
Summary: The geochronology of metasediments in orogenic wedges reveals important information about the early evolution of collisional systems. This study focuses on the Variscan processes in the Saxothuringian orogenic wedge, showing the transition from oceanic to continental subduction and collision. By analyzing phyllites and micaschists in the Erzgebirge Crystalline Complex using in situ monazite U-Pb geochronology and Rare Earth Elements (REE) geochemistry, the researchers were able to link the ages and geochemical patterns to specific tectonometamorphic events. The results indicate a phase of accretion and inverted metamorphic field gradient followed by exhumation and final exhumation of the wedge.
Article
Geochemistry & Geophysics
Jiri Kvapil, Jaroslava Plomerova, Hana Kampfova Exnerova, Vladislav Babuska, Gyoergy Hetenyi
Summary: The study presents a regional-scale model of velocity distribution in the crust of the Bohemian Massif, revealing significant velocity variations between different geological units, especially remnants of tectonic activities from the Variscan period.
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
Geosciences, Multidisciplinary
Mengkui Li, Yu Wei, Tengfei Wu, Jinwu Li
Summary: Analysis of seismic wave data reveals significant lateral variations in crustal thickness and velocity ratio in the Qinling Orogenic Belt and its adjacent regions. The topography of Dabashan and central QOB is compensated by crustal thickness, while the western and eastern QOB may be in a non-Airy-type isostasy state.
Article
Geosciences, Multidisciplinary
Huilin Wang, Claire A. Currie
Summary: The outward growth of many mountain ranges is driven by the pulsed migration of the strain front. In the Central Andes, during the Cenozoic shortening, the strain front migrated abruptly eastward, isolating the plateau interior from deformation. Contrary to the traditional model, our numerical models show that the ductile lower crust plays a key role in orogen dynamics. As the orogen grows upward, the lower crust flows outward, causing stepwise expansion through landward-migrating deformation.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geology
Florent Cheval-Garabedian, Eric Marcoux, Hugues Raimbourg, Michel Faure
Summary: By studying the La Lucette deposit in the French Armorican Massif, the relationship between Sb-Au-W and the metallogenic processes of the deposit were revealed. The deposit is characterized by four ore deposition stages with different mineral assemblages. The formation of the deposit is closely related to the temperature and mixing processes of the fluids, and does not require significant burial or involvement of late magmatic events.
ORE GEOLOGY REVIEWS
(2023)
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
Veronique Gardien, Jean-Emmanuel Martelat, Philippe-Herve Leloup, Gweltaz Maheo, Benoit Bevillard, Pascal Allemand, Patrick Monie, Jean-Louis Paquette, Anne-Sabine Grosjean, Michel Faure, Cyril Chelle-Michou, Clementine Fellah
Summary: A leucogranite sill in the footwall of the extensional Pilat shear zone was emplaced and sheared between 301.8 +/- 3.1 and 303.0 +/- 1.6 Ma. The existence of a relief south of the shear zone and the filling of the St. Etienne Basin confirm the extensional phase. The rapid exhumation of the Velay dome was likely due to localized sub crustal lithospheric mantle dripping.
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
Geochemistry & Geophysics
Zhaoping Hu, Lingsen Zeng, Michael W. Forster, Linghao Zhao, Lie Gao, Huan Li, Yizeng Yang, Shuangqing Li
Summary: The alkaline mafic rocks from the southern Liaodong Peninsula in China are products of syn-exhumation magmatism during the continental collision between the South and North China blocks. They show shoshonitic affinities and are derived from recycled continental crust, indicating a metasomatic reaction of subducted continental crust-derived melts with the overlying subcontinental lithospheric mantle.
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
Geochemistry & Geophysics
Mariana Werle, Gary Stevens, Jean-Francois Moyen, Oscar Laurent, Chris Harris, Cristiano C. Lana, Philip E. Janney
Summary: The processes of crustal growth by addition of new mantle-derived material to the crust and recycling of crustal components remain poorly understood in collisional orogens due to the introduction of crustal components during subduction events. A study of lamprophyric-granitic composite dykes from the Variscan Aigoual granite in the French Massif Central reveals co-magmatic lamprophyres and granites with similar characteristics. The isotopic signatures of both rock types indicate a dual crust/mantle origin, suggesting partial melting of an enriched mantle metasomatised by subducted sediments.
Article
Geochemistry & Geophysics
Yuan-Hsi Lee, Timothy B. Byrne, Wei Lo, Shao-Jyun Wang, Shuh-Jong Tsao, Cheng-Hong Chen, Han-Cheng Yu, Xinbin Tan, Matthijs van Soest, Kip Hodges, Lucas Mesalles, Holden Robinson, Julie C. Fosdick
Summary: The Taiwan orogenic belt is a result of convergence between the Philippine Sea plate and Eurasia plate. This study provides evidence for a significant out-of-sequence thrust in the core of the Taiwan orogen through the integration of thermochronology and seismic tomography. The research reveals a phase of slow exhumation rate followed by a phase of rapid exhumation rate in the past 8 million years in Taiwan.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geography, Physical
Nezha Lazreq, Peter Koenigshof, Abderrahim Essaifi, Ali Bouari, Abdelhak Outigua
Summary: The Sarhlef Formation in the Moroccan Meseta region has been reevaluated to Late Devonian in age based on new biostratigraphic data, which is more compatible with the radiometric data of intrusive magmatic rocks in the region. This provides new insights into the geological evolution and stratigraphy of the area.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2021)
Article
Geochemistry & Geophysics
Ondrej Kryza, Ondrej Lexa, Karel Schulmann, Alexandra Guy, Denis Gapais, John Cosgrove, Wenjiao Xiao
Summary: This study presents a new analogue model of omclinal buckling based on the geological understanding of the Mongolian orocline, investigating the deformation patterns and lithospheric structure associated with the orocline development. The results suggest that oroclines with different materials exhibit varied geometries at different depths, contributing to our understanding of deep crustal structures in Mongolia.
Article
Geosciences, Multidisciplinary
Ben Hayes, Jeremie Lehmann, Grant M. Bybee, Trishya M. Owen-Smith
Summary: Evidence from the Mesoproterozoic K-feldspar megacrystic Red Granite at Oncocua Platform in southwestern Angola supports the theory of crystal transfer from magma to wallrock during syntectonic intrusion. The preservation of intrusive relations suggests that this process may be more common in granitoid plutons than previously believed. Additionally, the presence of similar crystals in both the intrusive Red Granite and wallrock tonalite indicates a possible transfer mechanism through collapsed magmatic conduits.
JOURNAL OF THE GEOLOGICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
L. Tajcmanova, Y. Podladchikov, E. Moulas, L. Khakimova
Summary: This study focuses on determining the appropriate thermodynamic formulation for petrological systems under gradients, comparing mass and molar approaches. It also highlights the importance of applying the positive entropy production principle as a necessary admissibility condition in understanding key processes in petrology.
SCIENTIFIC REPORTS
(2021)
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
Frantisek Hrouda, Jan Franek, Stuart Gilder, Martin Chadima, Josef Jezek, Stepanka Mrazova, Michal Ponavic, Martin Racek
Summary: Single crystals of graphite demonstrate strong crystalline anisotropy and diamagnetism, with magnetic susceptibility measured in alternating fields showing both in-phase and out-of-phase components. The study of anisotropy of magnetic susceptibility in graphite ore provides insight into the preferred orientation of graphite and the presence of paramagnetic and ferromagnetic minerals within the rock. The high opAMS degree and lineation perpendicular to metamorphic foliation suggest a significant LPO of graphite, likely formed during Variscan regional metamorphism.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Geochemistry & Geophysics
Jack James Percival, Jiri Konopasek, Robert Anczkiewicz, Morgan Ganerod, Jiri Slama, Roberto Sacks de Campos, Maria de Fatima Bitencourt
Summary: The Dom Feliciano Belt in southern Brazil and Uruguay represents the western half of a Neoproterozoic orogenic belt in the South Atlantic region. The nature of orogenesis in this belt has been debated due to limited geochronological data. In this study, metamorphosed rocks from the Brusque Complex in the northern Dom Feliciano Belt were analyzed, showing evidence of orogenic metamorphism and early crustal thickening. The results suggest that orogenesis in this belt was initiated by rift-basin inversion driven by far-field forces transmitted through the crust.
Article
Geosciences, Multidisciplinary
Igor Soejono, Karel Schulmann, Jiri Slama, Kristyna Hrdlickova, Pavel Hanzl, Jiri Konopasek, Stephen Collett, Jitka Mikova
Summary: This study investigates the U-Pb ages and Hf isotopic composition of detrital zircons from the Precambrian metasedimentary autochthon of the Brunovistulian Domain in the eastern Bohemian Massif. The results shed light on the pre-collisional evolution of the eastern periphery of the European Variscan belt. The detrital zircons show different age and isotopic characteristics depending on the Tonian and Ediacaran sequences, indicating distinct magma sources and geological processes. The findings challenge the existing hypotheses about the Rheic oceanic suture and propose an alternative pre-collisional model of the Bohemian Massif as a single Neoproterozoic crustal domain.
PRECAMBRIAN RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Petar Pongrac, Petr Jerabek, Holger Stuenitz, Hugues Raimbourg, Renee Heilbronner, Martin Racek, Lucille Negre
Summary: The effects of adding H2O on the deformation and recrystallization of quartz have been studied. H2O-added samples showed lower mean strengths compared to as-is samples. Deformation process involved plastic deformation, crack generation, and recrystallization, which were primarily achieved through cracking and grain boundary migration.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Geochemistry & Geophysics
T. Sukhbaatar, O. Lexa, K. Schulmann, C. Aguilar, P. Stipska, J. Wong, Y. Jiang, J. Mikova, D. Zhao
Summary: The Mongolian Altai Zone in the Central Asian Orogenic Belt is composed of a variety of metamorphic rocks and magmatic rocks, indicating different tectonic and magmatic activities during various periods. The study of the region reveals a complex tectonic history, with the fore-arc basin and core complex experiencing different compression and extension events during the Paleozoic and Mesozoic.
Editorial Material
Multidisciplinary Sciences
Karel Schulmann, Jean Bernard Edel, Ondrej Lexa, Wenjiao Xiao, D. Trebinova, Richard Spikings, Urs Schaltegger, Arkadiusz Derkowski, Marek Szczerba
NATIONAL SCIENCE REVIEW
(2023)
Article
Geochemistry & Geophysics
Marine Jouvent, Vit Peresty, Petr Jerabek, Ondrej Lexa, Andrew R. C. Kylander-Clark
Summary: The geochronology of metasediments in orogenic wedges reveals important information about the early evolution of collisional systems. This study focuses on the Variscan processes in the Saxothuringian orogenic wedge, showing the transition from oceanic to continental subduction and collision. By analyzing phyllites and micaschists in the Erzgebirge Crystalline Complex using in situ monazite U-Pb geochronology and Rare Earth Elements (REE) geochemistry, the researchers were able to link the ages and geochemical patterns to specific tectonometamorphic events. The results indicate a phase of accretion and inverted metamorphic field gradient followed by exhumation and final exhumation of the wedge.
Article
Geosciences, Multidisciplinary
Karel Schulmann, Petra Maierova, Petr Jerabek, Ondrej Lexa, Stanislav Ulrich, Bruce Hobbs, Alison Ord
Summary: This study investigates the deformation mechanism and rheological behavior of amphibolite facies marble and impure quartzite within an extensional shear zone. The microstructural analysis reveals three stages of deformation in both rock types, with different mechanisms dominating in each stage. The formation of stretching faults and embrittlement of the marble are attributed to the change in microstructure and fluid-induced drop in effective pressure. This study provides valuable insights into the deformation processes and mechanical properties of rocks.
JOURNAL OF STRUCTURAL GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Yazhou Miao, Jian Zhang, Karel Schulmann, Ondrej Lexa, Petr Jerabek, Min Sun, Yingde Jiang, Shuhui Zhang
Summary: Recent studies suggest that the Chinese Altai has undergone two major tectonothermal events in the Devonian and Permian, with their relationships still unclear. This study analyzes the structural features of Ordovician schists in the Chonghuer area of the Chinese Altai, revealing multiple metamorphic events and tectonic switches. The results provide important insights into the tectonic evolution of the region.
JOURNAL OF STRUCTURAL GEOLOGY
(2023)
Article
Geochemistry & Geophysics
Laurine Travers, Alain Chauvet, Jeremie Lehmann
Summary: This study investigates the structural controls of gold occurrences in the Barberton Greenstone Belt. Three major tectonic events have been identified, including regional schistosity, large-scale folding, and late barren hydrothermal quartz vein formation. The results suggest a model of regional deformation driven by E-W and NE-SW shortening directions.
Article
Geosciences, Multidisciplinary
Jeremie Lehmann, Alan M. Brower, Trishya M. Owen-Smith, Grant M. Bybee, Ben Hayes
Summary: This study characterizes the architecture of the Mesoproterozoic Kunene Complex anorthosite suite in Angola and Namibia using remote sensing and field observations, and reveals that the reflectance signature of the rocks is primarily influenced by the degree of metasomatism. This method can be applied to other anorthositic terrains.
GEOSCIENCE FRONTIERS
(2023)