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# Strike-slip fault and its related structure PowerPoint PPT Presentation

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

Strike-slip fault and its related structure

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## 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

dextral(right lateral)-----the opposite block moves to the right.

### Mechanism of strike-slip fault

Fault is the result of force and stress.

Different force situations would generate

different faults.

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)

σ3

σ1

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

###  Fault plane  Fault zone

• Fault plane usually is a plane and the

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

form a zone(C).

A

B

C

### Flower structure

• If the fault plane curves,under the effect of greatest stress,it would bear movement along two direction.

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

flower structure.

A

B

C

Strike-slip faultsystem

A- Local compressional

and extensional struc-

tures produced by fault terminations and fault

overlaps.

B-Formation of raised

and depressed wedge-

shaped blocks by local

transpression and

transtension.

C- Positive and negative

flower structures produ-

ced by convergence and

divergence respectively

in strike-slip motion

D-Strike-slip duplex

FLOWER STRUCTURE IN STRIKE-SLIP FAULTS

Positive flower structure

for uplift blocks

Negative flower structure

for depressed blocks

### Analysis of flower structure

• We observe the structure carefully,it can be inferred that

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

 displacement

 joint

 attitude of fault plane

 breccia

 slikenline

### Kink band&Fault zone

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

（据Johnson，1977）

A.对称共轭膝折带；B.非对称共轭膝折带；C.单斜膝折带；σ1.最大主应力； σ3.最小主应力

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

Kink band

### Analysis

• In fact,the mechanism of en-echelon formed by strike-slip

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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