Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geology (MINE 7041) > Week 4 Lecture: Structure > Flashcards

Week 4 Lecture: Structure Flashcards

1
Q

What are the three processes of deformation?

A
  • Compression
  • Extension (tension)
  • Shear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What process of deformation causes the Crust to fold and thicken?

A

Compression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does tension do to the Crust and what formation is associated with it?

A
  • Thins and stretches it
  • Is associated with rifting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the 2 names for the direction of shear faults

A
  • Sinistral: To your left
  • Dextral: To your right
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the difference between Hydrostatic and Lithostatic pressure?

A

Hydrostatic: weight of overlying column of water

Lithostatic: weight of overlying column of rock (density x gravity x depth)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Lithostatic and Hydrostatic stress is equal in all _______, and produces a change in ________.

A

Lithostatic/hydrostatic stress is equal in all directions and produces a change in size (volume).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Differential Stress?

A

The difference between the greatest and least compressive stress experienced by an object. (sigma 1, 2, and 3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

If Differential stresses are not equal, what occurs?

A

A change in shape (Strain / Deformation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is strain / deformation?

A
  • Change in shape
  • Change in position
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 styles of strain (rock behaviour)?

A
  • Elastic
  • Brittle
  • Ductile
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define Elastic Strain

A

Proportional to stress and reversible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define Ductile strain

A

continuous, irreversible, dispersed strain, no breakage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are two types of ductility?

A

Plastic behaviour - can retain shape
Viscous behaviour - cannot retain shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define Brittle strain

A

Irreversible strains that include discontinuities (breakage)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the primary control on the style of deformation?

A

The material or rock type (more specifically, mineral composition and texture)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is stronger, basalt or schist?

A

basalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is more ductile, quartzite or marble?

A

marble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is confining pressure?

A

The stress or pressure forced on a layer of soil or rock by the heaviness of the overlying substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does the amount of confining pressure do to the type of deformation of a rock?

A

High stresses - brittle

Higher stresses - ductile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does temperature affect ductile deformation?

A

Low Temperature - fracturing

High Temperature - folding ductile shearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does history of a material affect it?

A

Pre-existing cracks, crystal defects, etc can affect its deformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Do crustal rocks deform in a brittle or ductile manner?

A

Brittle. At higher depths, rocks begin to become more brittle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does deformation affect the rock Mylonite?

A

It is strongly deformed and has undergone grain size reduction due to plastic deformation

24
Q

TEST QUESTION (ACCORDING TO ELSBETH)

What are the two types of Fractures? Describe them.

A

Joints and Faults.

Joint: no measurable displacement
Fault: measurable displacement

25
Q

When do Joints form?

A

When the elastic limit of the rock is exceeded and there is failure

26
Q

Name and describe the 2 subcategories of Joint Arrays:

A

Joint Groups: repeated regularly across rock (parallel)

Joint Sets: two or more groups of joints (with different orientation)

27
Q

Name and describe the 2 subcategories of Joint Sets:

A

Orthogonal sets: 90 deg to each other

Conjugate sets: between 30 and 60 deg to each other

28
Q

List some natural processes that cause Joints

A
  • Uplift and Erosion
  • Cooling
  • Hydraulic Fracturing
  • Folding
29
Q

What kind of joints are caused by uplift and erosion?

A

Exfoliation joints

30
Q

What is hydrofracturing?

A

Where the pore pressure exceeds the lithostatic pressure causing brittle rupture

31
Q

Describe what Folding does

A

Folding produces a region of tensile stress in the outer arc of the fold and forms joints.

32
Q

List the key terminology of Fault geometry

A
  • Footwall
  • Hanging wall
  • Strike Line
  • Fault Plane
  • Angle of dip
33
Q

What is the Strike Line?

A

The horizontal line (with respect to Earth’s surface) of a rock layer that gives the angle from North. (It’s the compass direction on a horizontal line)
The Strike always is perpendicular to the direction of dip.

34
Q

What is the Angle of dip?

A

The angle between a horizontal plane (the Earth’s surface) and the tilted rock layer.

35
Q

What is Plunge?

A

Plunge is used to describe the tilt of any line on the dipping plane. (Can include the strike line and angle of dip line)

36
Q

Name and describe two components of Plunge

A
  • the angle of plunge: vertical angle
  • the plunge direction (trend): the compass direction
37
Q

List the following faults in order of how common they are (common to rare):

  • Thrust
  • Strike-slip
  • Normal
  • Oblique slip
  • Reverse
A
  • Normal
  • Thrust
  • Reverse
  • Strike-slip
  • Oblique slip
38
Q

Describe a Reverse Fault

A

A fault that is undergoing horizontal compression with a dip from 45 to 60 deg. Hanging wall travels upwards

39
Q

Describe a Thrust Fault

A

Similar to a Reverse Fault except that the angle of dip is only between 15 to 45 deg.

40
Q

What kind of fault is tension responsible for?

A

Normal Fault

41
Q

Describe what a horst and a graben is

A

When tension creates a normal fault, the block of land that drops down is the graben and the uplifted block is the horst

42
Q

Name and describe the two types of strike-slip faults

A

If you’re standing on one side of a strike-slip fault, and look across at the block/plate on the other side:

  • A Left-lateral strike-slip fault is where the block on the other side moves to the left
  • A Right-lateral strike-slip fault is where the block on the other side moves to the right
43
Q

What are folds?

A

Wave-like structures that result from the deformation of planar surfaces in a rock. Directly related to compression

44
Q

What is the Axis of a fold?

A

The line that traces the crest or trough of a fold

45
Q

What is an Axial plane?

A

Imaginary plane that includes the axis and divides the fold as symmetrically as possible

46
Q

What is the hinge of a fold?

A

Tightest part of a fold

47
Q

What is the limb of a fold?

A

Arm of the fold, intersects at the hinge

48
Q

Differentiate an anticline from a syncline

A

An anticline has the shape of an upward arching fold with older rocks in the center/core of the arch and younger rocks along the perimeter

A syncline has the shape of a downward arching fold with older rock away from the core of the arch and younger rocks towards the core

49
Q

What is an overturned fold?

A

A fold with an axial plane inclined so much that one limb is essentially leaning over another

50
Q

What is a recumbent fold?

A

A fold with an essentially horizontal axial plane

51
Q

What is one thing to remember when studying Folds?

A

They are 3d

52
Q

What are Penetrative Fabrics and how are they caused?

A

The regularly spaced alignment of minerals. They are caused due to the stresses associated with plate tectonics.

53
Q

What is structure when discussing rock bodies

A

Any definable shape or fabric in 3d

54
Q

What are Planar fabrics?

A
  • Cleavage
  • Schistosity
  • Gneissosity
55
Q

Describe Linear fabrics?

A

Developed by stretching of pre-existing minerals, growth of new minerals, or by intersection of two planar fabrics

Geology (MINE 7041) (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions