2015: Year in review

The Group's research centres on high-pressure, high-temperature laboratory studies of (1) seismic properties of crustal and mantle lithosphere materials, and (2) deformation processes associated with fault slip in seismogenic and aseismic slip regimes, especially in the presence of reactive pore fluids.

Laboratory measurements of macroscopic physical properties such as seismic wave speeds and attenuation, strength, deformation rates and permeability are interpreted through microstructural studies using optical and electron microscopy. Often it is necessary to prepare, from either natural or synthetic precursors, simpler synthetic materials whose properties are amenable to more detailed interpretation than those of complex natural rocks. Our interest in Earth materials is shared by members of the School's Petrochemistry and Experimental Petrology Group, whose research focuses primarily upon the chemical aspects of their behaviour.

The experimental studies on fault mechanics are complemented by field-based studies, along with microstructural and isotopic studies and numerical modeling aimed at exploring coupling between deformation and fluid flow in exhumed faults, shear zones and hydrothermal ore deposits.

Our research has application to:

  • geodynamics and seismology
  • understanding controls on earthquake nucleation and rupture propagation
  • understanding links between deformation, fluid flow and ore deposit formation.

Microstructure of quartz melt layer formed by fast (seismogenic) slip of 400 µm on a bare quartz interface at 40 MPa confining pressure and at room temperature. High resolution FE-SEM image. Image is dominated by glass filaments that have been stretched parallel to the fault slip direction during a slip event lasting only a few milliseconds. Fragments of broken glass and quartz gouge are also present.

A highlight this year was Kathryn Hayward's completion of her M.Phil. thesis which was an experimental study of fault slip processes on bare quartz interfaces. The study is the first demonstration of frictional melting of quartz during slip at seismogenic slip rates.  A significant result was the demonstration that frictional melting can occur over slip distances of less than 100 µm at realistic crustal normal stresses.  Kathryn received the "best student oral presentation award" at the recent conference of the Specialist Group in Tectonics and Structural Geology in Queensland.

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