Microstructural evolution of single, small-displacement faults in sandstone
Supervisor: Steven Smith
Small faults in sandstone – commonly called “deformation bands” (e.g. Fossen et
al. 2007) – are extremely important in determining the fluid flow properties of
petroleum reservoirs and aquifers. To understand how such faults initiate and
evolve, the aim of this project is to sample single deformation bands along a
displacement gradient from band tip (i.e. zero displacement) to band centre (i.e.
maximum displacement). Displacement will then be correlated to the evolution
of fault rock microstructure (e.g. grain size, grain shape, microfracture density
and orientation, degree of strain localization) and petrophysical properties
(porosity, permeability). This project will involve fieldwork, imaging and data
collection on the SEM, possibly micro-CT, and both qualitative and quantitative
analysis of fault rock microstructure. This project is suitable for students with
good quantitative skills who did well in 275/375.
Key reference: H. Fossen, R.A. Schultz, Z.K. Shipton & K. Mair (2007) Deformation
bands in sandstone: a review. Journal of the Geological Society of London, 164,
755-769
Level: BSc(Hons)
A single deformation band
cuts layered volcaniclastic
sandstones at Oamaru.
Displacement, no greater
than c. 5 cm in this case,
can be measured from the
offset of layers. Samples
collected along the length
of the deformation band,
from zero displacement at
the band tips to maximum
displacement in the band
centre, can be used to
determine the evolution of
microstructure during
band initiation and growth.