Date of Award
Master of Science (MS)
This work has involved an experimental approach and a study of naturally produced slickensides.
The experiments, carried out on a pyrophyllitic rock, have been performed in order to define some extrinsic parameters that control surface and microstructural features. Normal stress, speed (i.e. strain rate), and amount of slip and total displacement were related to measureable surface features, such as length, and spacing between the developing ridges and grooves. Special attention was paid to a newly recognized type of slickenside lineation (Means, 1986). This lineation produced experimentally cannot be explained in terms of the traditional asperity ploughing or dissolution/precipitation models. It has the following distinctive features: (1) ridges and grooves are present, and occupy about the same amount of area of both hangingwall and footwall blocks, (2) ridges and grooves show a shallow U-shaped profile with planar bottom and top segments, (3) hangingwall and footwall blocks show complementary morphologies and fit perfectly into each other, (4) ridge and groove length can exceed the length of the slip displacement. A model is proposed to explain these features.
It could be demonstrated that slickensides are penetrative features. In both, the deformed samples and the naturally produced slickensides, a strain-modified sub-surface zone of variable thickness is present. The microstructural features observed indicate a wide span of deformation processes ranging from brittle (intergranular cracks, open and refilled tension gashes, faulting) to ductile behaviour (undulose extinction, recrystallization).
A new slickenside definition is proposed.
Will, Thomas Michael, "Structural investigations on experimentally and naturally produced slickensides" (1987). Geology Theses and Dissertations. 98.