Transversely isotropic lower crust of Variscan central Europe imaged by ambient noise tomography of the Bohemian Massif.

Kvapil, J., Plomerova, J., Kampfova Exnerova, H., Babuska, V., Hetenyi, G., Abreu , Rafael, Allegretti, Ivo, Apoloner, Maria-Theresia, Aubert, Coralie, Besançon, Simon, Bés de Berc, Maxime, Bokelmann, Götz, Brunel, Didier, Capello, Marco, Čarman, Martina, Cavaliere, Adriano, Chéze, Jérôme, Chiarabba, Claudio, Clinton, John, Cougoulat, Glenn, C. Crawford, Wayne, Cristiano, Luigia, Czifra, Tibor, D’Alema, Ezio, Danesi, Stefania, Daniel, Romuald, Dannowski, Anke , Dasović, Iva, Deschamps, Anne, Dessa, Jean-Xavier, Doubre, Cécile, Egdorf, Sven, Fiket, Tomislav, Fischer, Kasper, Friederich, Wolfgang, Fuchs, Florian, Funke, Sigward, Giardini, Domenico, Govoni, Aladino, Gráczer, Zoltán, Gröschl, Gidera, Heimers, Stefan, Heit, Ben, Herak, Davorka, Herak, Marijan, Huber, Johann, Jarić, Dejan, Jedlička, Petr, Jia, Yan, Jund, Hélène, Kissling, Edi, Klingen, Stefan, Klotz, Bernhard, Kolínský, Petr, Kopp, Heidrun , Korn, Michael, Kotek, Josef, Kühne, Lothar, Kuk, Krešo, Lange, Dietrich , Loos, Jürgen, Lovati, Sara, Malengros, Deny, Margheriti, Lucia, Maron, Christophe, Martin, Xavier, Massa, Marco, Mazzarini, Francesco, Meier, Thomas, Métral, Laurent, Molinari, Irene, Moretti, Milena, Nardi, Anna, Pahor, Jurij, Paul, Anne, Péquegnat, Catherine, Petersen, Daniel, Pesaresi, Damiano, Piccinini, Davide, Piromallo, Claudia, Plenefisch, Thomas, Pondrelli, Silvia, Prevolnik, Snježan, Racine, Roman, Régnier, Marc, Reiss, Miriam, Ritter, Joachim, Rümpker, Georg, Salimbeni, Simone, Santulin, Marco, Scherer, Werner, Schippkus, Sven, Schulte-Kortnack, Detlef, Šipka, Vesna, Solarino, Stefano, Spallarossa, Daniele, Spieker, Kathrin, Stipčević, Josip, Strollo, Angelo, Süle, Bálint, Szanyi, Gyöngyvér, Szűcs, Eszter, Thomas, Christine, Thorwart, Martin, Tilmann, Frederik, Ueding, Stefan, Vallocchia, Massimiliano, Vecsey, Luděk, Voigt, René, Wassermann, Joachim, Wéber, Zoltán, Weidle, Christian, Wesztergom, Viktor, Weyland, Gauthier, Wiemer, Stefan, Wolf, Felix Noah , Wolyniec, David, Zieke, Thomas, Živčić, Mladen and Žlebčíková, Helena (2021) Transversely isotropic lower crust of Variscan central Europe imaged by ambient noise tomography of the Bohemian Massif. Open Access Solid Earth, 12 . pp. 1051-1074. DOI 10.5194/se-12-1051-2021.

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The recent development of ambient noise tomography, in combination with the increasing number of permanent seismic stations and dense networks of temporary stations operated during passive seismic experiments, provides a unique opportunity to build the first high-resolution 3-D shear wave velocity (vS) model of the entire crust of the Bohemian Massif (BM). This paper provides a regional-scale model of velocity distribution in the BM crust. The velocity model with a cell size of 22 km is built using a conventional two-step inversion approach from Rayleigh wave group velocity dispersion curves measured at more than 400 stations. The shear velocities within the upper crust of the BM are ∼0.2 km s−1 higher than those in its surroundings. The highest crustal velocities appear in its southern part, the Moldanubian unit. The Cadomian part of the region has a thinner crust, whereas the crust assembled, or tectonically transformed in the Variscan period, is thicker. The sharp Moho discontinuity preserves traces of its dynamic development expressed in remnants of Variscan subductions imprinted in bands of crustal thickening. A significant feature of the presented model is the velocity-drop interface (VDI) modelled in the lower part of the crust. We explain this feature by the anisotropic fabric of the lower crust, which is characterised as vertical transverse isotropy with the low velocity being the symmetry axis. The VDI is often interrupted around the boundaries of the crustal units, usually above locally increased velocities in the lowermost crust. Due to the north-west–south-east shortening of the crust and the late-Variscan strike-slip movements along the north-east–south-west oriented sutures preserved in the BM lithosphere, the anisotropic fabric of the lower crust was partly or fully erased along the boundaries of original microplates. These weakened zones accompanied by a velocity increase above the Moho (which indicate an emplacement of mantle rocks into the lower crust) can represent channels through which portions of subducted and later molten rocks have percolated upwards providing magma to subsequently form granitoid plutons.

Document Type: Article
Keywords: isotropic lower crust, Variscan central Europe, ambient noise tomography, Bohemian Massif
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Main POF Topic: PT3: Restless Earth
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Related URLs:
Projects: AlpArray
Date Deposited: 30 Nov 2021 12:43
Last Modified: 07 Feb 2024 15:34

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