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Structural evolution of infra- and superstructure boundary in orogens
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Franěk, Jan (referee)
ENGLISH ABSTRACT This work focuses on structural and deformational aspects of the crust development during orogeny, based on historical suprastructure/infrastructure concept. The uppermost suprastructure is dominated by steep fabrics, which evolved in a brittle regime within early stages of orogeny, and which sustain almost unchanged for the whole period of orogenic evolution. On the other hand, the infrastructure is located in the lower crust, where ductile processes dominate. Because the ductility is a thermally activated process, sufficiently long time is needed to heat the lower crust, and therefore the infrastructure is younger than suprastructure. Gently to shallowly dipping structures develop as a consequence of ductile flow. The aim of this study is to describe processes on the suprastructure/infrastructure boundary. Position of this boundary is closely related to brittle/ductile transition, and so that a brief introduction to rheology is included. Rheological boundaries are often places of high strain and high displacement gradients, which must be somehow accomodated. One possibility is to lose communication between adjacent levels and create a detachment plane, which is commonly supposed in the conventional thrust tectonics model. The other possibility is, that layers are at least partially...
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The role of deformation partitioning on the tectonic evolution of the superstructure-infrastructure transition in the Teplá-Barrandian domain
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Konopásek, Jiří (referee) ; Grasemann, Bernhard (referee)
Upper part of the orogenic crust (superstructure) significantly differs from the lower part of the crust (infrastructure) by structural and metamorphic record. This fundamental observation is explained by interruption of the mutual evolution due to mechanical decoupling of the hot and ductile infrastructure from the cold and brittle superstructure at certain stages of the orogenic evolution. The superstructure-infrastructure transition zone is a rheologically predisposed domain of sharp deformation and metamorphic gradients with polyphase structural record. Understanding of the deformation partitioning in such a rheologically complex setting is a key aspect in linking of the individual deformation stages between upper and lower crust. The transition zone between unmetamorphosed early-Variscan superstructure (Teplá-Barrandian Domain) and late Variscan high- grade infrastructure (Saxothuringian Domain) crops out at the western margin of the Teplá- Barrandian Domain in the Bohemian Massif. This area is a continuous mid- to lower-crustal section with early-Variscan structural and metamorphic record, which is superposed onto pre-Variscan episode. This thesis aims to decipher individual deformation events, to evaluate their manifes- tations at different crustal levels and to bring new and unifying...
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The role of deformation partitioning on the tectonic evolution of the superstructure-infrastructure transition in the Teplá-Barrandian domain
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Konopásek, Jiří (referee) ; Grasemann, Bernhard (referee)
Upper part of the orogenic crust (superstructure) significantly differs from the lower part of the crust (infrastructure) by structural and metamorphic record. This fundamental observation is explained by interruption of the mutual evolution due to mechanical decoupling of the hot and ductile infrastructure from the cold and brittle superstructure at certain stages of the orogenic evolution. The superstructure-infrastructure transition zone is a rheologically predisposed domain of sharp deformation and metamorphic gradients with polyphase structural record. Understanding of the deformation partitioning in such a rheologically complex setting is a key aspect in linking of the individual deformation stages between upper and lower crust. The transition zone between unmetamorphosed early-Variscan superstructure (Teplá-Barrandian Domain) and late Variscan high- grade infrastructure (Saxothuringian Domain) crops out at the western margin of the Teplá- Barrandian Domain in the Bohemian Massif. This area is a continuous mid- to lower-crustal section with early-Variscan structural and metamorphic record, which is superposed onto pre-Variscan episode. This thesis aims to decipher individual deformation events, to evaluate their manifes- tations at different crustal levels and to bring new and unifying...
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Polyphase structural evolution of superstructure and infrastructure in orogenic zones
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Pitra, Pavel (referee)
Polyphase structural evolution of superstructure and infrastructure in orogenic zones Proterozoic basement rocks of the Teplá-Barrandian Unit (TBU) are affected by two main tectono-metamorphic events. The central and SW part of the TBU is a well-preserved relict of Cadomian episode. On the other hand, the western margin of the TBU shows superposition of polyphase early-varicsan deformation and metamorphism onto the pre- variscan fabric. The Střela river profile in the northern part of Teplá Crystalline Complex (TCC) exposes a continuous crustal section through western margin of the TBU from the low-grade phyllites (near biotite izograd) in the east to the high-grade rocks of kyanite zone at the contact with high-pressure Mariánské-Lázně Complex (MLC). Three main deformation events were distinguished in the studied area and the cross-section is interpreted as a fossil (devonian) suprastructure-infrastructure transition zone preserved in the carboniferous TBU superstructure. The oldest pre-variscan D1 phase produced flat-lying metamorphic foliation showing normal metamorphic zonation from the very low-grade in the upper part to at least garnet zone in the structurally lower part. Large scale upright folding of prevariscan foliation S1 occurred during early-variscan D2 event. Tight F2 folds were...
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Structural evolution of infra- and superstructure boundary in orogens
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Franěk, Jan (referee)
ENGLISH ABSTRACT This work focuses on structural and deformational aspects of the crust development during orogeny, based on historical suprastructure/infrastructure concept. The uppermost suprastructure is dominated by steep fabrics, which evolved in a brittle regime within early stages of orogeny, and which sustain almost unchanged for the whole period of orogenic evolution. On the other hand, the infrastructure is located in the lower crust, where ductile processes dominate. Because the ductility is a thermally activated process, sufficiently long time is needed to heat the lower crust, and therefore the infrastructure is younger than suprastructure. Gently to shallowly dipping structures develop as a consequence of ductile flow. The aim of this study is to describe processes on the suprastructure/infrastructure boundary. Position of this boundary is closely related to brittle/ductile transition, and so that a brief introduction to rheology is included. Rheological boundaries are often places of high strain and high displacement gradients, which must be somehow accomodated. One possibility is to lose communication between adjacent levels and create a detachment plane, which is commonly supposed in the conventional thrust tectonics model. The other possibility is, that layers are at least partially...
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