Open Positions

We are looking for M.S. students! See below for open research topics:


Masters Thesis linking Geochemistry and Structure on Syros Island, Greece

Structural Geology and Tectonics Group @ ETH Zurich                      

Primary supervisor: Dr. Jesús Muñoz-Montecinos

Co-supervisor: Prof. Dr. Whitney Behr

Project Motivation

Subduction zones are regions where chemical changes due to fluid-rock interaction (i.e., metasomatism) affect the rheological properties of the shear zone. This process results in a variety of deformation patterns that could be associated with the weakening of the subduction megathrust and a variety of fault slip styles. Nowadays, indirect evidence of deformation and fluid-rock interaction processes is obtained through seismological and experimental investigations, but key insights into that deep environment are obtained by studying now-exhumed high-pressure metamorphic rocks. This Master’s thesis aims to characterize the products of fluid rock interaction in exhumed high-pressure metamorphic rocks and to document how metasomatic processes affected the distribution of strain within the metamorphic pile. In this case, the study locality corresponds to the Syros Island. There, lithological layers, apparently formed due to fluid-rock interactions, occur parallel to the host mafic lithologies. Interestingly, these layers show reaction haloes towards the host-rock lithologies and a distinctive structural fabric. However, the mechanisms of fluid rock-interactions that could have produced these metasomatic layers, as well as their distinctive structural fabric are not yet understood.

Research Objectives

  • Characterize the fluid-rock interaction processes in order to understand the metamorphic reactions that would have formed the metasomatic mineral association and determine what would have been its protolith. In addition, the possible fluid sources and fluid circulation pathways would also be studied.
  • Quantify the fluid-rock interaction processes using thermodynamic modelling approaches.
  • Study the deformation mechanisms and their micro- and meso-scale implications on the deformation of the entire metamorphic stack and possible implications on subduction zone processes.

Prerequisites

  • Skills to work with the petrographic microscope
  • Motivation for field work (this project involves a field trip to the Syros Island, Greece)
  • Experience in structural geology and petrology as well as motivation to learn new technique

Figure 1. Field photographs showing a diversity of structures and lithologies at the study locality. A. Overview of metamorphic vein systems, greenschist and chloritite rocks. B. Detail view of a metasomatic chloritite layer within a greenschist. Note that the deformation patterns are distinct relative to the adjacent lithology.


Masters Theses in the Rock Deformation Laboratory

Structural Geology and Tectonics Group @ ETH Zurich

Primary Supervisor: Dr. Leif Tokle

Co-supervisor: Prof. Dr. Whitney Behr

The goal of the rock deformation lab is to understand and constrain micromechanical processes and their application to large-scale tectonic processes such as plate boundary shear zones and planetary dynamics. To do this we conduct high pressure and temperature deformation experiments, together with a variety of microstructural analyses. Masters projects can involve characterizing mechanical relationships (flow laws), understanding the effect of secondary phases on the rheology of a polyphase rock, or understanding the influence of extrinsic and intrinsic variables (Temperature, pressure, stress, strain rate, fluid content, grain size) affect a minerals mechanical properties.

Potential M.S. Projects*

  • Developing a diffusion creep flow law for either muscovite or biotite
  • Effect of muscovite on the brittle-ductile transition in a micaceous quartzite
  • Effect of fluid chemistry on quartz-muscovite aggregates
  • Quantifying the viscous anisotropy of a foliated blueschist
  • Characterizing the effect of stress pulses (simulated earthquakes) on quartz microstructures

*For more detailed information on these projects, contact Leif Tokle.

General Tasks

-Conduct rock deformation experiments (trained by Leif Tokle)

-Microstructural analysis (petrographic and electron microscopy)

-Processing and integrating mechanical data


Masters Theses on Fluid-flow in Flowing Rocks

Structural Geology and Tectonics Group @ ETH Zurich

Primary Supervisor: Dr. Alberto Ceccato

Co-supervisor: Prof. Dr. Whitney Behr

Understanding how fluids are transported within and interact with crustal rocks has relevant implications for our understanding of the mechanics and rheology of deforming continental plates, as well as of how (ore) mineral or waste (CO2) deposits have formed or might have been modified by deformation processes. Through the characterization of natural shear zones developed at mid crustal conditions in granitoid rocks, it is possible to gain fundamental insights on the micro-/meso-structural processes controlling fluid flow in the ductile mid-lower continental crust, and on how the transported fluid affect the strength of the rock through the interaction/reaction with mineral phases. Within this broad spectrum of subjects, we will work together on the analysis of samples from mid- to upper-crustal ductile and brittle-ductile shear zones from the Rotondo granite (Gotthard massif), with the final aim of characterizing and quantifying the feedback processes between deformation and fluid flow at different scales.

Tasks

  • Optical (reflected/transmitted) & electron microscopy (EDS, BSE, EBSD, CL)
  • Modelling of rheological properties (dedicated Matlab script) and phase diagram sections (Perple_X)
  • [Fieldwork: only possible after mid-June/July 2023 – high altitude Alpine environment]

Proposed topics for Master thesis

-Fe-oxide sheared breccias and Y-REE ores in the Rotondo granite

-Microstructural processes controlling CO2 transport in mid-crustal shear zones

-Effects of pre-/syn-kinematic fluid-rock interactions on the rheology of granitoid mylonites