A new model for the Neoproterozoic to Cambrian growth of the West Gondwana margin
Our latest study uses detrital zircon geochronology to reveal details of the late Neoproterozoic to early Cambrian expansion of the accretionary margin of West Gondwana. The detrital zircon ages indicate a pulsed continental growth where non-accretionary periods alternated with periods of strongly accretionary behavior. Furthermore, the zircon ages also trace peaks and lulls in volcanic arc aktivity and suggest many similarities with modern continental-margin arcs.
Hajná J, Žák J, Dörr W (2017)
Time scales and mechanisms of growth of active margins of Gondwana: a model based on detrital zircon ages from the Neoproterozoic to Cambrian Blovice accretionary complex, Bohemian Massif
Gondwana Research 42: 63–83
A special issue of Journal of Geosciences „Advances in petrology of magmatic rocks of the Bohemian Massif“ published as a tribute to František V. Holub
This special issue coedited and involving contributions by our group was published to pay hommage to František V. Holub, our colleague and friend who passed away in summer 2015. František took part in many of our research projects and coauthored a number of our publications.
Žák J, Rapprich G (2016)
Foreword to the special issue „Advances in petrology of magmatic rocks of the Bohemian Massif: a tribute to František V. Holub“
Journal of Geosciences 61, issue 4
International workshop Orogenic processes in the Bohemian Massif
Our group co-organized an international field trip and workshop Orogenic processes in the Bohemian Massif held in Hotel Annín near Sušice. The meeting brought together scientists from the Czech Republic, Austria, Germany, and Slovakia and has witnessed a range of interesting contributions and fruitful discussions on the development of the Variscan orogenic belt.
Exhumation of a mid-crustal granite–migmatite dome with (U)HP rocks
The Podolsko complex, Bohemian Massif, has long been interpreted as part of a large hot nappe rooted in an important suture within the Variscan orogenic belt. Our new structural, geochronologic, and petrologic data challenge this view and indicate that the complex developed as a granite–migmatite dome during upper-crustal collapse. The (U)HP rocks record a more complex P–T path but were incorporated into the dome before normal shearing.
Žák J, Sláma J, Burjak M (2016)
Rapid extensional unroofing of a granite–migmatite dome with relics of high-pressure rocks, the Podolsko complex, Bohemian Massif
Geological Magazine in press
Faryad SW, Žák J (2016)
High-pressure granulites of the Podolsko complex, Bohemian Massif: an example of crustal rocks that were subducted to mantle depths and survived a pervasive mid-crustal high-temperature overprint
Lithos 246–247: 246–260
Kryštof Verner defended habilitation thesis
On February, 11th Kryštof Verner successfully defended his habilitation thesis entitled ‚Fabrics and emplacement of granitoid plutons: implications for geodynamic evolution of Central Europe and the Wallowa Mts. in the northwestern United States‘. Congratulations!
Magnetic fabric data from three Miocene andesite lava domes in the Štiavnica volcano–plutonic complex, Western Carpathians, suggest that the domes were emplaced coevally as a lava coulée, a single dome, and a composite dome along a caldera ring fault. We developed a new general model of how various emplacement mechanisms of extrusive domes may directly record trap-door, piston, and piecemeal stages of collapse of the underlying calderas.
Tomek F, Žák J, Holub FV, Chlupáčová M, Verner K (2016)
Growth of intra-caldera lava domes controlled by various modes of caldera collapse, the Štiavnica volcano–plutonic complex, Western Carpathians
Journal of Volcanology and Geothermal Research 311: 183–197
Our group received support for a big multidisciplinary 3-year project „Sedimentary record and mechanics of collapse of orogenic belts“. The project will address mechanisms of decay of orogenic belts, with a particular emphasis on the develoment of sedimentary basins, paleotopography, and thermal-mechanical evolution of the lithosphere. The research will also include collaboration with the Department of Mechanics, Czech Technical University in Prague.
Jakub Trubač and Filip Tomek received Faculty of Science Dean´s awards
On a scientific conference of our Faculty, Jakub Trubač and Filip Tomek received Faculty of Science Dean´s awards for the best young researcher and for the best Ph.D. thesis, respectively. Congratulations!
Oroclinal rotation of the North American Cordillera reconsidered
Displacements and possible rotations of exotic terranes along the North American craton margin have long been one of the most puzzling issues in Cordilleran geology. Based on a magnetic fabric study of Early Cretaceous arc plutons, we contribute to the debate and put forward a new model of oroclinal rotation and terrane accretion in the Blue Mountains province, northeastern Oregon.
Žák J, Verner K, Tomek F, Holub FV, Johnson K, Schwartz JJ (2015)
Simultaneous batholith emplacement, terrane/continent collision, and oroclinal bending in the Blue Mountains Province, North American Cordillera
Tectonics 34: 1107–1128
On September, 11th Jakub Trubač successfully defended his comprehensive Ph.D. thesis entitled „The origin of compositional and textural zonation in shallow-level granitoid plutons“. Congratulations!
Filip Tomek successfully defended his Ph.D. thesis
On September, 3rd Filip Tomek has completed a 4-year research project and successfully defended his Ph.D. thesis entitled „Magnetic fabric, magma flow and deformation in volcano-plutonic systems“. Congratulations!
Filip Tomek received Radek Melka Prize for the best paper
Emplacement of granite sheeted complexes during syn-convergent transtension
Late Devonian arc-related orthogneisses in the center of the Bohemian Massif have long represented an enigmatic magmatic event during early stages of the Variscan orogeny. As opposed to the previously assumed thrust-controlled emplacement, our latest research shows that they were emplaced as a stack of sheeted sills during early-orogenic syn-convergent transtension. In combination with our previous studies, we demonstrate a complex three-dimensional deformation of an upper crustal wedge during Variscan collisions.
Tomek F, Žák J, Chadima M (2015)
Granitic magma emplacement and deformation during early-orogenic syn-convergent transtension: the Staré Sedlo complex, Bohemian Massif
Journal of Geodynamics 87: 50–66
New insights into (U)HP metamorphism during early Variscan orogenic history of the Bohemian Massif
As a contribution to the recent hot debate on polarity of Variscan subductions in the Bohemian Massif, Faryad, Kachlík, and others present new petrologic data and U–Pb zircon ages from a metatroctolite in the high-grade core of the Variscan orogen. The proposed tectonic model invokes a westward subduction of the Moldanubian plate followed by thermal reequilibration of earlier (U)HP assemblages due to slab break-off and astenosphere upwelling.
Faryad SW, Kachlík V, Sláma J, Hoinkes G (2015)
Implication of corona formation in a metatroctolite to the granulite facies overprint of HP–UHP rocks in the Moldanubian Zone (Bohemian Massif)
Journal of Metamorphic Geology 33: 295–310
Eurogranites 2015 international field meeting will be held in the Bohemian Massif
After 20 years, the Eurogranites international field meeting will be held again in the Czech Republic, co-organized by our group. The five-days tour across the Bohemian Massif will provide a comprehensive overview of Variscan plutonism and will follow the orogen’s tectonic development: we will start off with the early arc-related calc-alkaline tonalites to granodiorites, continue to examine ultrapotassic plutons in close association with granulites, and end up in late-orogenic S-type crustally-derived granites. Apart from its specialized leading theme, each day of the trip will offer beautiful landscapes, historic sights, as well as great Czech beer and cuisine in the evenings. Check the Eurogranites website for more info!
A special issue of Journal of Geosciences devoted to the Variscan orogeny
Stemming from a lively special session on the joint meeting of the Czech and German geological societies held in Pilsen in September 2013 (GEOPilsen 2013), co-organized by our group, this special issue brings together a selection of papers dealing with various aspects of the intriguing tectonic history of the Bohemian Massif and its correlatives in the Variscan belt.
Žák J, Finger F, Zulauf G (2014)
Foreword to the special issue ’Recent advances in unraveling Variscan orogeny in the Bohemian Massif’
Journal of Geosciences 59, issue 4
Kryštof Verner received an international research project
In a strong international competition, Kryštof Verner was awarded a three-year project from the Austrian Science Fund FWF. The project will support an extensive research into petrogenesis, timing, and geodynamic causes of late-orogenic magmatism in the Bohemian Massif and will also enhance collaboration between our group and research team of Prof. Fritz Finger, University of Salzburg in Austria. Congratulations!
Complex magma flow beneath caldera volcanoes
Detailed magnetic fabric analysis by Tomek et al. reveals rather complex magma flow patterns in a shallow-level granodioritic pluton inside a large Miocene Štiavnica caldera, Western Carpathians. The pluton formed first as a thin sill and then thickened via piecemeal downdrop of its faulted floor, providing a particularly informative example of how magma chambers are built beneath large caldera stratovolcanoes.
Tomek F, Žák J, Chadima M (2014)
Magma flow paths and strain patterns in magma chambers growing by floor subsidence: a model based on magnetic fabric study of shallow-level plutons in the Štiavnica volcano–plutonic complex, Western Carpathians
Bulletin of Volcanology 76, Article No. 873
This special publication summarizes about fifteen years of research of our group on Variscan plutons in the Bohemian Massif. The structural and AMS data are integrated with a thorough overview of U–Pb zircon geochronology to constrain the Variscan tectonic evolution of the Bohemian Massif from Late Devonian microplate convergence to late Carboniferous destruction of the orogen.
Žák J, Verner K, Janoušek V, Holub FV, Kachlík V, Finger F, Hajná J, Tomek F, Vondrovic L, Trubač J (2014)
A plate-kinematic model for the assembly of the Bohemian Massif constrained by structural relations around granitoid plutons
In: Schulmann K, Oggiano G, Lardeaux JM, Janoušek V, Martínez Catalán JR (Eds), The Variscan orogeny: extent, timescale and the formation of the European crust
Geological Society, London, Special Publications 405: 169–196
For the first time, Jakub Trubač and others tested a quantitative method of inverse strain estimation from magnetic fabric (AMS) using the Matlab software SUSIE. In the Melechov pluton, Bohemian Massif, the calculations reveal that the internal fabric, though very weak in intensity, records a strain gradient fitting surprisingly well the theoretical models of crystal-poor, Newtonian magmatic diapirs.
Trubač J, Žák J, Chlupáčová M, Janoušek V (2014)
Magnetic fabric and modeled strain distribution in the head of a nested granite diapir, the Melechov pluton, Bohemian Massif
Journal of Structural Geology 66: 271–283
A recent study by Jaroslava Hajná and colleagues examines fascinating evolution of a late Neoproterozoic accretionary wedge in the Bohemian Massif. The tectonic history of this wedge is interpreted as resulting from several cycles of smooth-slab subduction interrupted by arrival of linear seamount chains. The latter triggers extensive disruption of basaltic ocean floor and its incorporation into chaotic mélanges.
Hajná J, Žák J, Kachlík V (2014)
Growth of accretionary wedges and pulsed ophiolitic mélange formation by successive subduction of trench-parallel volcanic elevations
Terra Nova 26: 322–329
The geodynamic causes of high heat flow and generation of large post-collisional batholiths has been a matter of longstanding controversy. Kryštof Verner and others newly define one of the largest granite–migmatite core complexes in the Variscan belt and propose this dome formed as an isostatic accommodation structure along an underthrust continental microplate due to lateral variations in temperature, lithology, and crustal strength.
Verner K, Žák J, Šrámek J, Paclíková J, Zavřelová A, Machek M, Finger F, Johnson K (2014)
Formation of elongated granite–migmatite domes as isostatic accommodation structures in collisional orogens
Journal of Geodynamics 73: 100–117
Jaroslava Hajná received postdoctoral grant by the Grant Agency of the Czech Republic
Jaroslava Hajná received a three-year postdoctoral grant focused on the dynamics of Precambrian accretionary wedges. This project will support a number of detailed analytical studies in the Blovice accretionary complex, Bohemian Massif, including anisotropy of magnetic susceptibility, U–Pb and K–Ar geochronology, and geochemistry. Congratulations!