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  • 2010-2014  (14)
  • 1
    Publication Date: 2019-07-17
    Description: In 2004 and 2005 a passive seismic experiment was carried out in the northern and northeastern part of the Bohemian Massif (Sudetes) to study the lithospheric structure. We present results from Ps and Sp receiver function analyses. With one exception, Moho depth at stations in the northwestern part of the study area varies between 28 and 32 km. Thicker crust up to 35 km was mapped toward the south (Moldanubian unit) and toward the east (Moravo–Silesian and Brunovistulian units) confirming results from previous active seismic measurements. There exists a relatively sharp step in Moho depth between units of the central Sudetes (~ 30 km) and the Moravo–Silesian unit (~ 35 km). The vp/vs ratios inverted from primary and multiple Moho Ps conversions hint for different crustal compositions of the units. Toward the Carpathian thrust we have no clear indications for any crustal root or slab beneath the western Carpathians. However, our data suggests a deepening of the Moho or at least a complicated crust–mantle transition in this area. Additional Ps phases were observed between 6 and 10 s delay time in the Sudetes. These phases cannot be explained by Moho reverberations, but are most probably caused by low velocity zones in the middle crust or lithospheric mantle as shown by modeling of theoretical receiver functions. The stations showing these abnormal phases are located in the area of Permo-Carboniferous basins on probably Teplá–Barrandian crust. Therefore we assume that the phases hint at a mid-crustal low velocity zone between 16 and 20 km depth, which is interpreted as a felsic solidified magma reservoir of the Permo-Carboniferous volcanism beneath the Sudetic Basins. Sp receiver functions show phases with negative polarity at 9 to 12 s lead time on average, which we interpret as lithosphere–asthenosphere boundary at about 80 to 110 km depth.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 2
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 3
    Publication Date: 2013-10-16
    Description: The Lithosphere–Asthenosphere Boundary (LAB) is a fundamental boundary in the plate tectonic paradigm — it is the most pervasive on the planet, yet comparatively it is one we know little about. Defined initially on the basis of the mechanical response of the Earth to loading, its usage has become ubiquitous across the geosciences but the natural differences in its definition, due to differences in thermal, physical and chemical parameters, cause confusion. To advance this debate, comparisons are made both qualitatively and quantitatively, between the delineation of the LAB for Europe based on Seismological and electromagnetic observations. We examine statistically, using robust methods, the LABs derived from independent datasets and methods. Essentially, all definitions of the LAB, as an impedance contrast from receiver functions (sLABrf), a seismic anisotropy change (sLABa) and an increase in conductivity from magnetotellurics (eLAB), are consistent with a deeper LAB beneath Precambrian Europe, and a shallower LAB beneath Phanerozoic Europe, with some exceptionally deep regions in Phanerozoic Europe, such as the Alps. All three LABs increase in depth significantly and rapidly at a location consistent with the surface expression of the Trans-European Suture Zone (TESZ) which separates Precambrian Europe to the north and east from Phanerozoic Europe in the centre. Two of the definitions, sLABrf and eLAB, are consistent for Phanerozoic Europe with mean values of 90–100 km, compared to an average sLABrf of 135 km. A different two, sLABa and sLABrf, are consistent for Precambrian Europe with mean values of 170–180 km compared to an eLAB mean of 250 km. The deeper eLAB depths for Precambrian Europe are more consistent with body wave and surface wave tomography models than are the sLABa and sLABrf ones, suggesting that the lower lithosphere beneath Precambrian Europe between 170 to 250 km is responding to shearing on the base of the lithosphere from plate driving forces. Taken together the definitions provide strong constraints on the nature of the LAB. For example, the electrical eLAB beneath the TESZ is anomalously thick, to possibly the transition zone, whereas sLABa and sLABrf seismological definitions would place it at far shallower depths. Given the sensitivity of electrical conductivity to partial melt and water content, the thick eLAB beneath the TESZ excludes interpretation of the seismic LAB in that location in terms of a thermal structure that would induce partial melting or hydration.
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 4
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    In:  Geophysical Journal International ; Year: 2012 ; Volume: 188 ; Issue: 2 ; Pages: 600-612
    Publication Date: 2017-03-06
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 5
    Publication Date: 2018-03-16
    Description: In 2004 and 2005 a passive seismic experiment was carried out in the northern and northeastern part of the Bohemian Massif (Sudetes) to study the lithospheric structure. We present results from Ps and Sp receiver function analyses. With one exception, Moho depth at stations in the northwestern part of the study area varies between 28 and 32 km. Thicker crust up to 35 km was mapped toward the south (Moldanubian unit) and toward the east (Moravo–Silesian and Brunovistulian units) confirming results from previous active seismic measurements. There exists a relatively sharp step in Moho depth between units of the central Sudetes (~ 30 km) and the Moravo–Silesian unit (~ 35 km). The vp/vs ratios inverted from primary and multiple Moho Ps conversions hint for different crustal compositions of the units. Toward the Carpathian thrust we have no clear indications for any crustal root or slab beneath the western Carpathians. However, our data suggests a deepening of the Moho or at least a complicated crust–mantle transition in this area. Additional Ps phases were observed between 6 and 10 s delay time in the Sudetes. These phases cannot be explained by Moho reverberations, but are most probably caused by low velocity zones in the middle crust or lithospheric mantle as shown by modeling of theoretical receiver functions. The stations showing these abnormal phases are located in the area of Permo-Carboniferous basins on probably Teplá–Barrandian crust. Therefore we assume that the phases hint at a mid-crustal low velocity zone between 16 and 20 km depth, which is interpreted as a felsic solidified magma reservoir of the Permo-Carboniferous volcanism beneath the Sudetic Basins. Sp receiver functions show phases with negative polarity at 9 to 12 s lead time on average, which we interpret as lithosphere–asthenosphere boundary at about 80 to 110 km depth.
    Language: English
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 6
    Publication Date: 2013-10-17
    Type: http://purl.org/eprint/type/ConferencePaper
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  • 7
    Publication Date: 2013-07-05
    Description: We present a new velocity-perturbation model of the upper mantle down to 300 km retrieved by teleseismic tomography beneath the southern part of the Bohemian Massif (BM) and its surroundings. Though the upper mantle beneath the BM appears as extensive low-velocity heterogeneity in large-scale tomography studies of Europe, our regional study based on data from passive experiment BOHEMA III and the northern part of the ALPASS array reveals also velocity features at scales of ~40 km. The most distinct low-velocity perturbations concentrate along the Eger Rift down to ~200 km, while velocities at greater depths beneath this rift show high-velocity perturbations relative to the overall low-velocity character of the BM mantle. Two significant high-velocity heterogeneities dominate the tomography images. The most distinct and extensive one, located south of the BM, we associate with the eastern Alpine root. The second high-velocity heterogeneity can be traced in horizontal slices down to 215 km beneath the central part of the BM. These positive perturbations seem to shift from the southwestern part of the massif at shallower depths to the northeastern part of the BM at greater depths. The heterogeneity can reflect the lithosphere thickening resulting from the collision of the BM with the Brunovistulian (BV) microplate from the east and the following underthrusting of the BV beneath the Moldanubian part of the BM.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 8
    Publication Date: 2010-10-01
    Description: The Cheb Basin (CHB), located in the western part of the Eger Rift (ER) and the western Bohemian Massif, is characterized by earthquake swarms, neotectonic crust movements and emanations of CO2 dominated gases of mantle origin. Deep structure of the region can be characterized as junction of three domains of mantle lithosphere with different olivine fabrics revealed by consistent orientations of seismic anisotropy. The domains represent mantle components of the major tectonic units (micro-plates): Saxothuringian (ST), Teplá-Barrandian (TB) and Moldanubian (MD), which were assembled during the Variscan orogeny. The ST-TB boundary, reactivated during the Cenozoic extension, controlled the position and development of the ER and the CHB. We show that the CHB originated above the rejuvenated mantle suture between the ST and TB. Though the basin is located within the ST crust domain, which is thrust over the mantle junction, it is the mantle suture that controls the CHB shape and its development through the allochthonous ST crust. The seismically active Mariánské Lázně Fault limits the basin against the uplifted block of the Erzgebirge Crystalline Complex. The most subsided parts of the ER and CHB developed above the centre of the mantle transition, whereas a well expressed morphology developed above its flanks. Our study documents a long memory of the mantle lithosphere assembly inherited from the Variscan orogeny. It is possible that other continental regions also contain some of intra-plate basins that originated above healed palaeo-plate mantle boundaries. ©2010 Springer-Verlag
    Print ISSN: 1437-3254
    Electronic ISSN: 1437-3262
    Topics: Geosciences
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  • 9
    Publication Date: 2010-03-30
    Print ISSN: 1437-3254
    Electronic ISSN: 1437-3262
    Topics: Geosciences
    Published by Springer
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  • 10
    Publication Date: 2014-01-17
    Description: We analyse splitting of teleseismic shear-wave recorded during the PASSEQ passive experiment (2006–2008) focussed on the upper mantle structure across the Trans-European Suture Zone (TESZ). 1009 pairs of the delay times of the slow split-shear waves and orientations of the polarized fast-shear waves exhibit lateral variations across the array, as well as backazimuth dependences of measurements at individual stations. While a distinct regionalization of the splitting parameters exists in the Phanerozoic part of Europe, a correlation with the large-scale tectonics around the TESZ and in the East European Craton (EEC) is less evident. No general and abrupt change in the splitting parameters (anisotropic structure) can be related to the Teisseyre–Tornquist Zone (TTZ), marking the edge of the Precambrian province on the surface. Instead, regional variations of anisotropic structure were found along the TESZ/TTZ. We suggest a south-westward continuation of the Precambrian mantle lithosphere beneath the TESZ and the adjacent Phanerozoic part of Europe, probably as far as towards the Bohemian Massif.
    Electronic ISSN: 1869-9537
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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