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Unpublished MSc.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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