Strike-slip fault and its related structure. 01003117 LuoMao. Strike-slip fault. Definition : a kind of fault that the two blocks move along the strike direction of fault plane. It can be subdivided into two kinds. sinistral(left lateral)-----the opposite block moves to the left
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Strike-slip fault and its related structure
sinistral(left lateral)-----the opposite block moves to the left
dextral(right lateral)-----the opposite block moves to the right.
Fault is the result of force and stress.
Different force situations would generate
The force system of strike-slip fault
is plotted as follows
The greatest stress is horizontal,
the smallest stress is horizontal,
two sets of strike-slip fault inter-
sect along the intermediate Picture in two dimension
stress,each dipping vertically. (Down plunge view)
Fault orientation in relation to principal stress axes
(After E.M.Anderson, 1951)
A Normal fault sets. B Thrust fault sets. C Strike-slip fault sets
dip angle is approximate 90 degree.
The strike line on the ground extends
straightly in a region(picture A).But
there are some exceptions.
Sometimes the strike line curves(B).
because of the characteristics
of adjacent blocks and even
form a zone(C).
Part A combines both strike-slip movements and
compression.It would move upwards to form
positive flower structure,as to
part B,the extension and the
gravity prompt block to fall
downwards,thus form negative
A- Local compressional
and extensional struc-
tures produced by fault terminations and fault
B-Formation of raised
and depressed wedge-
shaped blocks by local
C- Positive and negative
flower structures produ-
ced by convergence and
in strike-slip motion
FLOWER STRUCTURE IN STRIKE-SLIP FAULTS
Positive flower structure
for uplift blocks
Negative flower structure
for depressed blocks
positive flower structure is a combination of reverse fault,
whereas the negative consists of a group of normal fault.
Several methods can be used to identify the structure
attitude of fault plane
It is a kind of chevron fold which possesses planar limbs
and sharp angular hinges.If it is symmetrical,we call it
conjugate kink ,and if not,we call it monoclinal Kink band.
Fault zone developed in strike-slip fault is between two
boundings,As slip occurs along the fault bounding the
rock between them develops parallel en-echelon tension
cracks that give the zone an oblique foliation.
Conjugate folds(A,B) with opposite sense of
asymmetry and polyclinal folds(C) with
variable axial surfaces
The band is the zone in which the common short straight
limb bounded by the two adjacent fold surfaces
Markedly asymmetric chevron with a very long
limb and a very short limb
fault and the kink band is the same,though result is
different.The key to this problem I think is the rock character.
One situation is that the block is a whole that every parts is
the same,when undergoing the slides,en-echelon is formed.
Another situation is that the block has planar features.
Slides would occur between two strata,thus make the stress
outlet,and prevent it from cracking.
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