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Structural Geology Exam > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Which of the ff. type of fault has a curve fault plane (concave up) with decreasing dip with depth or flattens downward?

A. Thrust fault
B. Listric Fault
C. Low-angle fault
D. Synthetic fault
E. Shallowly dipping fault

A

B. Listric Fault

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2
Q

A displaced fault block, either downthrown or upthrown, and is above the fault plane.

A. Horst
B. Footwall
C. Graben
D. Hanging Wall

A

D. Hanging Wall

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3
Q

Which of the ff. pertains to a strongly ground down version of the original rock (>30% matrix), and is sometimes also used for strongly reworked clay or shale in the core of faults in sedimentary sequences?

A. Fault gouge
B. Pseudotachylyte
C. Cataclasite
D. Fault breccia

A

A. Fault gouge

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4
Q

A manifestation of deformation in the brittle regime by which a rock body or mineral loses coherency by simultaneously breaking many atomic bonds.

A. particulate flow
B. cataclastic flow
C. fracturing
D. all of the above

A

C. fracturing

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5
Q

Most rocks have an angle of internal friction where normal faults, theoretically, should form at?

A. ~15°
B. ~30°
C. ~45°
D. ~60°

A

D. ~60°

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6
Q

Rock materials have been divided into classes depending on their relative behavior under stress with respect to temperature, confining pressure, strain rate, and composition. This material has a low temperature condition, low confining pressure and high strain rate. Also, it has a small to large region of elastic behavior, but only a small region of ductile behavior before they fracture.

A. elastic material
B. plastic material
C. brittle material
D. ductile material

A

C. brittle material

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7
Q

It is a cohesive and fine-grained fault rock brought by brittle crushing of grains (grain size reduction). accompanied by frictional sliding and rotation.

A. breccia
B. mylonite
C. fault gouge
D. cataclasite
E. pseudotachylyte

A

D. cataclasite

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8
Q

What type of fault brings older rocks on top of younger rocks, and rocks of higher metamorphic grade on top of rocks of lower metamorphic grade?

A. reverse fault
B. thrust fault
C. wrench fault
D. horst and graben
E. normal fault

A

B. thrust fault

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9
Q

What is the term that describes the horizontal component or amount of dip separation, perpendicular to the strike of the fault?

A. pitch
B. dip separation
C. heave
D. throw

A

C. heave

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10
Q

A rock with a high E-value (GPa) is mechanically weak, as its resistance to deformation is small.

A

False

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11
Q

Elasticity is about how a rock responds to stress above the limit where strain becomes permanent.

A

False

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12
Q

Faults tend to reduce permeability in non-porous rocks, while they commonly increase permeability in porous rocks.

A

False

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13
Q

Increasing the temperature, increasing the amount of fluid, lowering the strain rate and, in plastically deforming rocks, reducing the grain size all tend to cause strain weakening.

A

True

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14
Q

An increase in temperature lowers the yield stress or weakens the rock.

A

True

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15
Q

In general, great differential stress promotes rock fracturing.

A

True

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16
Q

Extension fractures are more likely to develop in rock layers with the highest Young’s modulus and the lowest Poisson’s ratio, which in simple terms means that stiff and competent layers (e.g. sandstones and limestones) build up more differential stress than surrounding layers.

A

False

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17
Q

Disaggregation deformation bands show the most significant permeability reductions.

A

False

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18
Q

A stress vector oriented perpendicular to a surface is called the normal stress on that surface.

A

True

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19
Q

Joints are more likely to initiate in shale than in sandstones during uplift of clastic sedimentary rocks.

A

False

20
Q

Pore fluid pressure reduces the normal stress, which is the stress at grain contacts in porous rocks.

A

False

21
Q

Fractures and deformation bands involve permeability reduction

A

False

22
Q

Plastic strain is recoverable because it involves stretching rather than breaking of atomic bonds.

A

False

23
Q

Stress is concentrated at the tips of open microfractures in a rock, and the concentration increases with increasing thickness/length ratio of the microfracture.

A

False

24
Q

1-4. The variation of the following factors, determines whether a rock will fault or fold ______________,____________,____________ and ______________

A

TEMPERATURE, PRESSURE, STRAIN RATE, ROCK TYPE/COMPOSITION

25
Q

_______________are general type of faults with motion of the fault blocks parallel to the dip direction

A

DIP-SLIP FAULT

26
Q

______________ is a well-foliated (and commonly also lineated) tectonic rock formed by intense plastic deformation, usually at middle crustal levels and deeper. Normally characterized by grain size reduction

A

MYLONITE

27
Q

Listric faulting is an example of tensile fault with depth in such a way that the fault surface is ________________

A

CONCAVE UPWARD

28
Q

_____________is a low-angle fault or shear zone where the hanging wall has been transported over the footwall. The movement should be predominantly__________________

A

THRUST FAULT

DIP SLIP

29
Q

__________________are fractures that show extension perpendicular to the walls, such as joints, that can expand to become extensive structures.

A

EXTENSION FRACTURES

30
Q

This process occurs predominantly by means of plastic deformation mechanisms, commonly with subordinate brittle microfracturing. _______________

A

MYLONITIZATION

31
Q

______________________-means increasing the fluid pressure until the rock fractures

A

HYDROFRACTURING

32
Q

The fault segment run parallel to bedding, called__________________

A

FLATS

33
Q

_____________________is a cohesive brittle fault rock that differs from gouge or breccia in that the fragments interlock, allowing the fragmented rock to remain coherent even without cementation

A

CATACLASITE

34
Q

Minor, typically tensile fractures occur in the tip zone that are asymmetrically arranged with respect to the main fracture are referred to as____________________

A

HORSETAIL FRACTURES

35
Q

______________–pertains to air or fluid-filled extension fractures.

A

FISSURES

36
Q

________________is the plastic deformation (no strain hardening) of a material that is subjected to a persistent and constant stress when that material is at a high homologous temperature

A

CREEP

37
Q

_____________is a tabular volume of rock (or a structure) consisting of a central slip surface or core, formed by intense shearing, and a surrounding volume of rock that has been affected by more gentle brittle deformation formation spatially and genetically related to the structure.

A

FAULT

38
Q

_________are mm-thick zones of localized compaction, shear and/or dilation in deformed porous rocks

A

DEFORMATION BANDS

39
Q

What do you call objects revealing the state of strain in a deformed rock?_____________

A

STRAIN MARKERS

40
Q

What type of deformation is involved to translated or rotated rock masses without having any internal change in shape and volume?

A

RIGID BODY DEFORMATION

41
Q

_________________describes how hard it is to deform a certain elastic material or rock

A

YOUNG’S MODULUS

42
Q

________________are very narrow zones, often thought of as surfaces, associated with discontinuities in displacement and mechanical properties (strength or stiffness).

A

FRACTURES

43
Q

A normal fault that has a curved fault plane with the dip decreasing with depth can cause the down-dropped block to rotate is called______________

A

HALF-GRABEN

44
Q

In the field of rheology and rock mechanics, a _________________ is one that accumulates permanent strain (flows) without macroscopically visible fracturing, at least until a certain point where its ultimate strength is exceeded.

A

DUCTILE MATERIAL

45
Q

____________ are fault segments that cut across bedding.

A

RAMPS

46
Q

Once the density of microfractures reaches a critical level, the main fracture expands by linkage of favorably oriented microfractures. The zone of microfractures (and mesofractures) ahead of the fracture tip zone is called the ________________

A

FRICTIONAL BREAKDOWN ZONE

47
Q

Secondary fractures in the tip zone represent a fan shaped splaying of the main fracture and are synthetic with respect to the main fault.___________

A

SPLAY FAULTS

Structural Geology Exam (3 decks)

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