Abstract
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, T.M., 1987. Structural investigations on experimentally and
naturally produced slickensides.
Unpublished MSc. thesis, State University of New York at Albany.
156 pp., +x
University at Albany Science Library call number: SCIENCE
Oversize (*) QE 40 Z899 1987 W54
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