I present physical shear-box experiments investigating the relationship between
geometrical properties of shear zones and mechanical properties of deformed
rocks. Experimental methodology is also examined critically and new materials
for analogue modelling of shear localization are presented.
First, I tested experimentally whether meaningful rheological information
can be deduced from finite geometrical shear zone data. The results predict
characteristic geometrical responses for certain end-member materials.
However, it will be difficult to constrain such responses in the field. In the second
part physical controls on deformation in the shear box are analysed for
Newtonian and power-law fluids and an elastoviscoplastic strain-softening
material. Since models always represent simplifications of the natural problem, it
is essential to understand fully the physics of a given simulation. I show that
displacement boundary conditions, model geometry, and rheology control shear zone geometry. Practical applications of the shear box for modelling natural
shear localization and limitations of isothermal physical models with
displacement boundary conditions in general are discussed. In the third part,
new data on the rheology of highly-filled silicone polymers are introduced. Since
dynamic similarity must be satisfied in analogue models to permit scaled,
quantitative simulations of deformation processes, the choice of suitable rock
analogues is critical for physical experiments. In particular, we address the
problem of designing power-law fluids to model rocks deforming by dislocation
creep. We found that highly-filled polymers have complex rheologies. Hence,
such materials must be used with care in analogue modelling and only for
certain experimental stress-strain rate conditions. Finally, I investigated whether
fault network geometry and topography of brittle strike-slip faults are influenced
by the degree of compaction of the host rock. Analogue shear experiments with
loose and dense sand imply that the degree of sediment compaction may be a
governing factor in the evolution of fault network structure and topography along
strike-slip faults in sedimentary basins. Therefore, models of strike-slip faults
should consider potential volume changes of deformed rocks.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/19088 |
| Date | 23 February 2010 |
| Creators | Schrank, Christoph Eckart |
| Contributors | Cruden, Alexander R. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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