Two PhD positions in Deformation experiments and Tectonics in Prague

Dear CETEG members,
please pass the information about two available PhD positions to your talented students.

The Faculty of Science, Charles University in Prague invites talented students to apply for a special PhD scholarship program STARS.

Within the scope of this program, the Institute of Petrology and Structural Geology invites applications for two PhD projects in geology:

  1. Physics of the water weakening effect in deformation of quartz
  2. Restoration of pre-collisional crustal architecture of the Northern Gondwana thinned continental margin

The deadline for online application is 28.2. 2017 with the start of the PhD project from 1.10.2017
For further inquiries please contact jerabek.petr@natur.cuni.cz
With very best regards
Petr

PhD 1 - Physics of the water weakening effect in deformation of quartz

Supervised by: Petr Jeřábek and Holger Stünitz

Plate Tectonics processes are controlled by the mechanical properties of the Earth´s mantle and crust. While the mechanical properties of the mantle are commonly monitored using olivine, those of the crust can be monitored using quartz, which is one of the most ubiquitous minerals in crustal rocks, and there already exists abundant data for quartz. The mechanical properties of quartz depend critically on the presence of water, although the physics of the H2O-weakening on quartz are poorly understood. In particular two parameters will be studied: the pressure dependence and the effects of different amounts of H2O involved in weakening. This project intends to acquire new data to quantify these aspects of quartz deformation in order to incorporate them into constitutive equations, which will be fundamental for successful modeling of geodynamic processes. The research will start with a series of deformation experiments in the deformation laboratories at the University of Tromsø (cooperation with H. Stunitz) and University of Orléans (cooperation with H. Raimbourg, H. Stünitz, and J. Precigout). The resulting samples will be studied using the analytical facilities of the Institute of Petrology and Structural Geology at Charles University, Prague. This topic addresses first order geological and geophysical problems, related to understanding earthquakes and mountain building.

PhD 2 - Restoration of pre-collisional crustal architecture of the Northern Gondwana thinned continental margin

Supervised by: Ondrej Lexa and Petr Jeřábek

Recent studies of structure and evolution of continental margins have led to significant reconsideration of conceptual models of their evolution and their involvement in subsequent collision. It is generally accepted that the tectonic history and resulting geometries of “cold” Atlantic type passive margins control the early stages of subduction and subsequent collisional processes. The tectonic evolution is mostly explained in terms of the “crocodile mouth” model, where mechanical behaviour of the converging lithosphere reflects inherited passive margin architecture and its thermal structure. In contrast, the tectonic evolution of extended “hot” Pacific type margins during convergence is less well understood. This is probably due to a limited preservation within orogens and/or due effect of subduction erosion. Another reason for poor documentation of these types of continental margins stems from an important syn-extensional metamorphic reworking of thinned lithosphere, which may be confused with a syn-collisional metamorphic overprint. Consequently, geological record of convergence in former “highly metamorphosed” and magma-rich extended margins may be more commonly preserved than currently assumed. In this project we will focus on large-scale restoration of Ordovician crustal architecture involved in the polyphase Variscan deformation, which resulted in formation of crustal stack recently preserved across the contact of the Teplá-Barrandian and Saxothuringian domain. Candidate will study in detail the individual metamorphic and deformation fabrics and will define still unclear structural position of several key complexes involved in the subduction-collision process. The obtained results should significantly improve our understanding of rheology and mechanical behaviour of hot extended crust involved in collisional processes.