中国地质大学：《构造地质学》课程PPT教学课件（英文版）Lecture 12 Fold geometry（1）

Review of faults and fractures (Read the summary of faulting in the copy papers after class)

Review of Faults and Fractures (Read the summary of faulting in the copy papers after class)

2 cm Fault breccia

Fault breccia

Protomylonite Grain> 2mm, Matrix 0-50

Protomylonite Grain ＞ 2mm, Matrix 0～50

a graben B horst Graben and horst structures

Graben and Horst Structures

moving slab stationary slab Transfer fault Transference of displacement from thrust to strike-slip fault

Transference of displacement from thrust to strike-slip fault Transfer fault Transfer fault

hangingwall ramp A-Ramps and flats hangingwall B- Hangingwall ramp and footwall footwall ramp footwall ramp C-? thrust sequence New thrusts develop in the footwall D-? thrust sequence New thrusts develop in the Hangingwall E- Thrust duplex roof thrust imbricate thrust slices are contained between a floor imbricate zone floor thrust thrust and a roof thrust F-Pop-up structure frontal ramp back thrust G- Triangle zone

A - Ramps and flats B – Hangingwall ramp and footwall ramp C – ? thrust sequence New thrusts develop in the footwall D – ? thrust sequence New thrusts develop in the Hangingwall E – Thrust duplex: imbricate thrust slices are contained between a floor thrust and a roof thrust F - Pop -up structure G – Triangle zone ? ? ?

Extensional Fault Systems Mylonites forming in delamination z A- Evolutionary model illustrating Progressive extension accommodated by blockrotation above a lowangle Rumple detachment taunts matay extensional fault Kinematic aotive meloni B- Listric fault with hangingwall rollover Youngest detachment faull A Hall-graben anticline. Area A and b are equal wogo C-Flat/ramp geometry of fault produces geometrically necessary folding in Hollow hangingwall hangingwall bloc Ramp 需吧D- Antithetic faults in hangingwall E-Synthetic faults in footwall forming Litre fan listric fan hangingwall Hangingwall F- Extensional duplex with listric fan and Listne tan Counter fan antithetic counter fan G- Two listric faults linked by a transfer fault all three detach on the same sole fault

Extensional Fault Systems A- Evolutionary model illustrating Progressive extension accommodated By blockrotation above a lowangle extensional fault. B- Listric fault with hangingwall rollover anticline. Area A and B are equal. C – Flat/ramp geometry of fault produces geometrically necessary folding in hangingwall. D- Antithetic faults in hangingwall. E – Synthetic faults in footwall forming listric fan. F- Extensional duplex with listric fan and antithetic counter fan. G- Two listric faults linked by a transfer fault;all three detach on the same sole fault

Strike-slip fault system A- Local compressional and extensional struc tures produced by fault terminations and fault overlaps Fault overlap B-Formation of raised And depressed wedge Shaped blocks by local Transpression and Transtension Positive and negative flower structures Produ- ced by convergence and Positive flower structure iII TTTT divergence respectively strike-slip motion Out of page into page fufi TIIifTfiT D-Strike-slip duplex Negative flower structure

Strike-slip fault system 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

A B Inversion: extensional half-graben reactivated in compression. Note that compressional folds coexisit with net normal displacement

Inversion: extensional half-graben reactivated in compression. Note that compressional folds coexisit with net normal displacement

a Fold axis Relationship of joint sets to a major fold alongitudinal joints, b. diagonaljoints c transverse joints, d sheet joints

Relationship of joint sets to a major fold a.longitudinal joints, b.diagonal joints, c.transverse joints, d.sheet joints Fold axis d