National Repository of Grey Literature 7 records found  Search took 0.00 seconds. 
Contribution to geodynamic evolution and post-collisional magmatic activity in the Arabian-Nubian Shield (East African Orogeny) and southwestern Moldanubian Zone (Central European Variscides)
Megerssa, Leta Alemayehu ; Verner, Kryštof (advisor) ; Závada, Prokop (referee) ; Johnson, Kenneth (referee)
The Variscan orogenic belt along the exhumed root domain, known as the Moldanubian Zone as well as the Arabian-Nubian Shield (ANS) in the East African Orogeny (EAO) of Ethiopia, are considered as typical areas for studying late-orogenic (post-collisional) processes and magmatism. Based on a wider range of field and analytical methods: field structural mapping, anisotropy of magnetic susceptibility (AMS) analysis, thermobarometric calculation and P-T evolution, conventional U/Pb dating, a reconstruction of geodynamic evolution and magmatism in the southwestern part of Moldanubian Zone (Bohemian Massif) and Tokar-Barka Terrain (southern part of Arabian-Nubian Shield is undertaken. The Variscan case portrays the peculiar overprint by the Late Orogenic tectonothermal event which is absent in the case of the Arabian-Nubian Shield (ANS) hence offering a compelling contrast to investigate the possible underlying mechanism involved for the different processes in the post-orogenic phase. In the southern ANS a post-collisional intrusive Chewo pluton composed of monzodiorite and quartz monzonite marks the late tectonic overprint which intruded into a low-grade Neoproterozoic juvenile crustal Tokar-Barka terrane. Thermobarometric estimations indicate its emplacement to be c. 10-13 Km depth, idealized from AMS...
Magnetic fabrics and emplacement of the Eisgarn granitoids (Moldanubian Plutonic Complex)
Paclíková, Jana ; Verner, Kryštof (advisor) ; Buriánek, David (referee)
English abstract We consider our preliminary results of structural and AMS analyses of granitoids of the Mrákotín and Klenov Plutons located in the northeastern part of the Moldanubian Plutonic Complex. Both plutons have a peraluminous, high-K character formed by partial melting of a crustal metasedimentary (metapelite) source at relatively lower temperatures. The Mrákotín pluton (eastern part of the plutonic complex) was emplaced posttectonically at around 327 Ma and records a crucial role of magmatic stoping during magma ascent and emplacement. In contrast, the Klenov pluton (western part of the plutonic complex) was emplaced syntectonically with regional HT-LP tectonometamorphic event (formation of gently to moderately NNE dipping metamorphic schistosity).
Magnetic fabric of loess and paleosols on selected localities in South Moravia
Obersteinová, Tereza ; Kadlec, Jaroslav (advisor) ; Chadima, Martin (referee)
Pleistocene loess-palaeosol sequences provide a unique proxy-record enabling detailed reconstruction of Quaternary palaeoenvironments. Environmental magnetic methods are often used to read the natural archives. The loess-palaeosol sequences exposed in two sections located in southern Moravia and a sequence from central Bohemia were studied in a frame of this Diploma Thesis. Variations of bulk magnetic susceptibility, measured in the sediments, show similar pattern as in the Chinese loess-palaeosol bodies - i.e. palaeosols reveal higher magnetic susceptibility in comparison with loess due to magnetic enhancement. The magnetic enhancement is driven by weathering during pedogenic processes related to the formation of ultra-fine magnetite particles. The magnetite content is controlling the sediment magnetic behavior. The magnetic enhancement rate indicates more intense pedogenic processes in the Moravia in comparison with Bohemia. Magnetic fabric in studied loess, represented by space orientation of anisotropy of magnetic susceptibility ellipsoid, indicates dominating glacial wind palaeocurrents across the southern Moravia blowing from W or SW, respectively. The magnetic fabric in the central Bohemian sequence has revealed a dominant control of running water and re-deposition of the loess material...
Magnetic fabric of loess and paleosols on selected localities in South Moravia
Obersteinová, Tereza ; Kadlec, Jaroslav (advisor) ; Chadima, Martin (referee)
Pleistocene loess-palaeosol sequences provide a unique proxy-record enabling detailed reconstruction of Quaternary palaeoenvironments. Environmental magnetic methods are often used to read the natural archives. The loess-palaeosol sequences exposed in two sections located in southern Moravia and a sequence from central Bohemia were studied in a frame of this Diploma Thesis. Variations of bulk magnetic susceptibility, measured in the sediments, show similar pattern as in the Chinese loess-palaeosol bodies - i.e. palaeosols reveal higher magnetic susceptibility in comparison with loess due to magnetic enhancement. The magnetic enhancement is driven by weathering during pedogenic processes related to the formation of ultra-fine magnetite particles. The magnetite content is controlling the sediment magnetic behavior. The magnetic enhancement rate indicates more intense pedogenic processes in the Moravia in comparison with Bohemia. Magnetic fabric in studied loess, represented by space orientation of anisotropy of magnetic susceptibility ellipsoid, indicates dominating glacial wind palaeocurrents across the southern Moravia blowing from W or SW, respectively. The magnetic fabric in the central Bohemian sequence has revealed a dominant control of running water and re-deposition of the loess material...
Magnetic fabrics and emplacement of the Eisgarn granitoids (Moldanubian Plutonic Complex)
Paclíková, Jana ; Verner, Kryštof (advisor) ; Buriánek, David (referee)
English abstract We consider our preliminary results of structural and AMS analyses of granitoids of the Mrákotín and Klenov Plutons located in the northeastern part of the Moldanubian Plutonic Complex. Both plutons have a peraluminous, high-K character formed by partial melting of a crustal metasedimentary (metapelite) source at relatively lower temperatures. The Mrákotín pluton (eastern part of the plutonic complex) was emplaced posttectonically at around 327 Ma and records a crucial role of magmatic stoping during magma ascent and emplacement. In contrast, the Klenov pluton (western part of the plutonic complex) was emplaced syntectonically with regional HT-LP tectonometamorphic event (formation of gently to moderately NNE dipping metamorphic schistosity).
Reconstruction of the Kozákov lava flow based on magnetic- and mineral-fabric study
Černá, Aneta ; Rapprich, Vladislav (advisor) ; Hradecký, Petr (referee)
Combined anisotropy of magnetic susceptibility (AMS) and crystallographic studies were applied on a neogenne lava flow, for which we know the supposed flow path. Samples were studied under microscope, the minerals were analysed on microprobe, the orientation of olivine crystals was determined via EBSD and magnetic properties were studied. AMS data acquired from samples collected from representative outcrops of lava flow show weak preferred orientation of magnetite-ulvöspinel. EBSD analysis suggests only slight orientation of plagioclase in one sample. Analysed composition of olivine corresponds with mathematical model for eruption temperature and crystallization succession. Rootless cone (disorderly breccia cone) in lava body was found and desribed in the abandoned Machův lom quarry.
Komplexní geologická charakterizace prostorů PVP Bukov
Verner, K. ; Bukovská, Z. ; Souček, Kamil ; Vavro, Martin ; Staš, Lubomír ; Kaláb, Zdeněk ; Havlová, V. ; Kučera, P.
This report summarizes results of ongoing basic and applied research related to the project "Comprehensive geological characterization of underground research facility (PVP) Bukov" (PB-2014-ZL-U2301-004-BUKOV). In the wider area of the PVP Bukov a steep NW-SE trending metamorphic foliation was identified which is partly refolded into sub-horizontal direction. Faults and extensional joints with variable mineralization are mostly steep, trending mostly NW - SE or NNE - SSW. In addition, geological map at the scale of 1 : 4 500 of this area has been processed based on new field geological mapping and archival data. Moreover, a detailed petrographic and structural analysis of boreholes S-1 to S-4 (a total length of 470 meters) has been made. On the basis of U/Pb dating the age of the protolith of prevailing migmatized amphibolic gneisses was determined at 500-600 Ma as well as the subsequent regional metamorphism associated with partial melting and deformation at around 338 Ma. Results of thermodynamic modeling revealed the P-T conditions of regional metamorphism at T: 692–727 °C and P: 5 kbar.

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