Reza Syahputra: Mechanisms and time scales of formation of ribbon continents
The Ph.D. project elaborates on the concept of ribbon terranes, narrow linear belts composed of juvenile or recycled crust that form by lithospheric extension of continental margins. The ribbon continents are of prime paleogeographic and plate-tectonic importance, now being increasingly recognized to play a crucial role in closure of oceanic domains, continental assemblies, growth of continental crust, large-magnitude strike-slip terrane displacements, and the development of oroclines. In its present stage, the Ph.D. research concentrates on formation and rift–drift transition of ribbon microplates using Cambrian sedimentary basins in the Bohemian Massif as a case example.
Funded by the Charles University Grant Agency project No. 952220 to Reza Syahputra.
Irena Olšanská: Late Variscan volcano-plutonic complexes as markers of evolution of post-orogenic tectonic processes
This Ph.D. project is focused on the volcanic and igneous processes associated with the late Variscan post-orogenic tectonomagmatism. The content of the work includes field mapping, structural, and geochronological research, along with the analysis of rock-magnetism and paleomagnetism of Tharandt Wald and Altenberg–Teplice calderas in the NW Bohemian Massif. The scientific outputs aim to create modern interpretations and a general geological model for the magmatism and tectonic processes closely related to and following the collapse of the Variscan orogen during the Upper Carboniferous.
Funded by the Charles University Grant Agency project No. 124320 to Irena Olšanská.
Petr Vitouš: Influence of regional tectonics on dike swarms evolution beneath volcanics complexes
The research includes the structural study of rhyolite ignimbrites and associated subvolcanic igneous systems. A The research includes a structural study of rhyolite ignimbrites and associated subvolcanic igneous systems, in particular at the Altenberg–Teplice Caldera and Broumov ignimbrites (Bohemian Massif) and Gréixer rhyolite complex (Pyrenees). A combination of several methods will be used on these complexes: detailed field and structural mapping, rock magnetism, anisotropy of magnetic susceptibility (AMS), and paleomagnetism. This doctoral project aims to introduce modern interpretations and a general geological model of the influence of extensional regional tectonics on the geometry of feeding structures of volcanic complexes, and dynamics of emplacement of pyroclastic density currents. Last but not least, a comparative study of structure of basaltic to intermediate alkaline complexes of rift regions and felsic caldera volcanoes in collapsing orogens will be compiled.
Funded by the Charles University Grant Agency project No. 354821 to Petr Vitouš.
Jonah Jonathan: Thermal and mechanical interactions of dikes and hydrothermal fluids during collisional orogeny
Magma and and hydrothermal fluids percolate through the upper crust during all stages of collisional orogeny, from early closure of oceanic basins to late stage orogenic collapse, and are often closely spatially and temporally related, though occurring on different length scales. Except the well-known close genetic relationship between voluminous granitoid plutons and associated hydrothermal systems, the role of small-volume dikes, and especially of regional dike swarms, in facilitating hydrothermal fluid flow remains poorly known. The main issue is how and to what extent dikes and hydrothermal fluid pathways interact during the various phases of orogeny: (1) Do they represent completely separate events that just coincide in time and space? (2) Do they interact thermally, i.e., is magma transported through dikes able to trigger significant hydrothermal activity in the host rock? (3) Are the magma and fluid flows separate processes at deeper mantle/crustal levels to become coupled in the upper crust, driven by a single tectonic stress field and inherited basement structures? (4) Or are these processes entirely linked from their origin up to the final emplacement level? The project will address these and other related issues through analysis of several case examples in the Bohemian Massif, with a possible extension to other orogenic belt(s). The key initial example to be examined will be the Central Bohemian Plutonic Complex, where a prominent, regional dike swarms composed of numerous NW–SE and E–W dikes intrude into granitic plutons and their host rock, which, in turn, are cross-cut by abundant hydrothermal veins, in places making up large ore deposits.
Funded by the Charles University Grant Agency project No. 304721 to Jonah Jonathan
Tatiana Tkáčiková: Analog modeling of subduction zone processes
Magma and and hydrothermal fluids percolate through the upper crust during all stages of collisional orogeny, from A wide range of complex depositional, deformational, and metamorphic processes that operate along subduction zones may be experimentally reproduced under laboratory conditions. The Bachelor research is focused on a critical evaluation of the existing experimental approaches and material parameters used to model subduction zone processes and evolution of accretionary wedges. Several pilot experiments will also be designed and interpreted in terms of geological processes during the second part of the project.