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Magmatic and Volcanic Evolution of the Doupovské hory Volcanic Complex
Rapprich, Vladislav ; Holub, František (advisor) ; van Wyk de Vries, Benjamin (referee) ; Renno, Axel D. (referee)
The Doupovské hory Volcanic Complex (DHVC) occupies the western part of the northeast- southwest trending Eger Graben in northwestern part of the Bohemian Massif. The Graben follows the older Variscan suture between the Saxothuringian and Teplá-Barrandian Domains. The rocks of the DHVC are alkaline with setting and composition similar to other Cenozoic intraplate volcanic complexes of the Central and Western Europe (CIMACi). The Doupovské hory Volcanic Complex started the activity in the Lowermost Oligocene and lasted until Lower Miocene. The volcanic activity resulting in accumulation of the Doupovské hory Volcanic Complex was several times interrupted by periods of volcanic edifice decay and sector collapses. The magmatic activity lasted for ca. 14 M.y. and built a volcanic complex of total thickness 600-1000 m. The earliest volcanic activity was explosive in style and the eruptions could be classified as Strombolian to Sub-plinian and phreatomagmatic. The eruptions deposited about 80 m of volcaniclastics. This initial activity was dated by paleontology to the Lowermost Oligocene. The volcanic activity subsequently became calmer and lava flows dominated over explosive events. The growth of the early DHVC edifice culminated with intrusions of the Flurbühl intrusive complex by about 30-29 Ma. The...
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Silurian and Devonian volcanism of the Prague Basin
Tasáryová, Zuzana ; Frýda, Jiří (advisor) ; Renno, Axel D. (referee) ; Awdankiewicz, Marek (referee)
The principal goal of the thesis is to constrain nature of magmatic and alteration processes, character of mantle source(s), geotectonic setting and palaeogeographic implications of the Silurian and Devonian volcanism in Prague Basin (Teplá-Barrandian Unit, Bohemian Massif). The thesis is based on extensive geochemical study covering major- and trace-element geochemistry, neodymium isotope geochemistry and mineral chemistry supported by petrographic and field observations. The most important conclusions of the thesis are as follows: 1. The Silurian volcanic rocks of the Prague Basin represent within-plate, transitional alkali to tholeiitic basalts, which erupted in continental rift setting through thick Cadomian crust. The basalts originated by low degrees of partial melting of garnet peridotite mantle source. Older Wenlock basalts are similar to alkaline ocean island basalts (OIB) derived from subcontinental lithospheric mantle (SCLM), enriched most probably by frozen pods of Ordovician magmas. Younger Ludlow basalts resemble tholeiitic enriched mid-oceanic ridge basalts (EMORB) derived from subduction-modified SCLM depleted by Late Cambrian melting. The Wenlock-Ludlow melting is characterized by contemporaneous mixing of melts derived from both enriched and depleted SCLM mantle domains. 2....
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Magmatic and Volcanic Evolution of the Doupovské hory Volcanic Complex
Rapprich, Vladislav ; Holub, František (advisor) ; van Wyk de Vries, Benjamin (referee) ; Renno, Axel D. (referee)
The Doupovské hory Volcanic Complex (DHVC) occupies the western part of the northeast- southwest trending Eger Graben in northwestern part of the Bohemian Massif. The Graben follows the older Variscan suture between the Saxothuringian and Teplá-Barrandian Domains. The rocks of the DHVC are alkaline with setting and composition similar to other Cenozoic intraplate volcanic complexes of the Central and Western Europe (CIMACi). The Doupovské hory Volcanic Complex started the activity in the Lowermost Oligocene and lasted until Lower Miocene. The volcanic activity resulting in accumulation of the Doupovské hory Volcanic Complex was several times interrupted by periods of volcanic edifice decay and sector collapses. The magmatic activity lasted for ca. 14 M.y. and built a volcanic complex of total thickness 600-1000 m. The earliest volcanic activity was explosive in style and the eruptions could be classified as Strombolian to Sub-plinian and phreatomagmatic. The eruptions deposited about 80 m of volcaniclastics. This initial activity was dated by paleontology to the Lowermost Oligocene. The volcanic activity subsequently became calmer and lava flows dominated over explosive events. The growth of the early DHVC edifice culminated with intrusions of the Flurbühl intrusive complex by about 30-29 Ma. The...
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Silurian and Devonian volcanism of the Prague Basin
Tasáryová, Zuzana ; Frýda, Jiří (advisor) ; Renno, Axel D. (referee) ; Awdankiewicz, Marek (referee)
The principal goal of the thesis is to constrain nature of magmatic and alteration processes, character of mantle source(s), geotectonic setting and palaeogeographic implications of the Silurian and Devonian volcanism in Prague Basin (Teplá-Barrandian Unit, Bohemian Massif). The thesis is based on extensive geochemical study covering major- and trace-element geochemistry, neodymium isotope geochemistry and mineral chemistry supported by petrographic and field observations. The most important conclusions of the thesis are as follows: 1. The Silurian volcanic rocks of the Prague Basin represent within-plate, transitional alkali to tholeiitic basalts, which erupted in continental rift setting through thick Cadomian crust. The basalts originated by low degrees of partial melting of garnet peridotite mantle source. Older Wenlock basalts are similar to alkaline ocean island basalts (OIB) derived from subcontinental lithospheric mantle (SCLM), enriched most probably by frozen pods of Ordovician magmas. Younger Ludlow basalts resemble tholeiitic enriched mid-oceanic ridge basalts (EMORB) derived from subduction-modified SCLM depleted by Late Cambrian melting. The Wenlock-Ludlow melting is characterized by contemporaneous mixing of melts derived from both enriched and depleted SCLM mantle domains. 2....
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