|
|
Reconstruction of the geological evolution of the Southern Main Ethiopian Rift
Dvořák, Štěpán ; Verner, Kryštof (advisor) ; Tomek, Filip (referee)
The Main Ethiopian Rift represents a unique insight into process of continental rifting and its comprehensive research can provide partial clarification of open questions such are the causes, mechanisms, and timing of overall tectonic and magmatic evolution. The Main Ethiopian Rift is an intermediary between the Afar triple junction to the north and Kenyan Rift to the south, representing incipient plate boundary between Nubian and Somalian plates. Based on comprehensive geological research of the northern flank of the Southern Main Ethiopian Rift including field geological and structural mapping, petrological and geochemical description of individual lithologies, morphotectonic analysis of Digital Elevation Model, paleostress analysis and gravity pattern assessment including calculation of Linsser indices, some aspects in geodynamic evolution of northern flank of the Southern Main Ethiopian Rift is interpreted. The area recorded typical continental rift-related tectonic and magmatic evolution including "pre-rift" (Eocene to Oligocene) volcanic activity initiated by extensive flood (plateau) alkaline basalt to trachybasalt basalt eruptions due to crustal thinning and mantle plume(s) ascent, followed by fault-dominated "early-rift" (Miocene) bimodal volcanism associated with origin of the rift...
|
|
|
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....
|
|
|
Silurian and Devonian volcanism of the Prague Basin
Tasáryová, Zuzana
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....
|
|
|
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....
|
|
|
Silurian and Devonian volcanism of the Prague Basin
Tasáryová, Zuzana
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....
|
guest ::
