Structure Quiz 2

Front 1

Formula for extension?

Back 1

Lf-Lo/Lo

Front 2

Formula for stretch?

Back 2

Lf/Lo

Front 3

Formula for quadratic elongation?

Back 3

(Lf/Lo)^2

Front 4

Homogenous strain

Back 4

Lines that were straight before must be straight after, rotation can occur.

Front 5

Coaxial strain

Back 5

Pure shear. Finite stretching directions are the same before and after deformation.

Front 6

Displacement field

Back 6

Shows the start and finish points of the particles.

Front 7

Particle path

Back 7

Gives you the whole path of the particles.

Front 8

Non-coaxial strain

Back 8

Simple shear. Finite stretching axis are not the same after deformation.

Front 9

Angular shear

Back 9

Change in angle between two angles that were perpendicular.

Front 10

Shear strain

Back 10

The tangent of the angular shear angle.

Front 11

Rf method

Back 11

Set up internal coordinate system, get a 3d ellipsoid.

Front 12

The fry method

Back 12

Good for fine-grained rocks

Front 13

Flynn diagram

Back 13

y axis is x/y

x axis is y/z

Front 14

Flynn Diagram: Field of Flattening

Back 14

X, y, z shorten

Front 15

Flynn Diagram: Field of constriction

Back 15

Z, y shorten. X gets bigger

Front 16

Flynn Diagram: Plane strain

Back 16

X grows, y stays the same, z shortens

Front 17

Flynn Diagram: 6:2:1

Back 17

X:Y = 6/2 = 3

Y:Z = 2/1 = 2

Front 18

Most important process is shaping shear zones

Back 18

Simple Shear

Front 19

Strain Rate

Back 19

(Lf-Lo/Lo)/seconds

Contraction -

Extension +

Front 20

Volume increase? Decrease?

Back 20

- Veins

-Stylolites, pressure solution

Front 21

Continuous strain

Back 21

Ex: Folding

Front 22

Discontinuous strain

Back 22

Broken up

Front 23

Four mechanisms of Rheology

Back 23

1) Elastic: Recoverable, instantaneous

2) Plastic: Non-recoverable, breaks bonds

3) Viscous: Non-recoverable, accumulates w/ time

4) Nonlinear viscosity: Non-recoverable

Front 24

Viscoelastic behavior

Back 24

Strain is recoverable but its accumulation and recovery is delayed.

Front 25

Elastico-viscous behavior

Back 25

Material behaves elastically but then behaves viscously. When stress is removed only the elastic component is recovered.

Front 26

Tensile strength

Back 26

Stress required to rupture bonds in tension

Front 27

What is a preferred orientation for slip?

Back 27

Cleavage, or a slip plane.

Front 28

Three types of crystal defects

Back 28

Point defects

Front 29

Brittle Deformation

Back 29

The permanent change that occurs in a solid material due to the growth of fractures and/or due to sliding on fractures.

Front 30

Why do cracks propogate?

Back 30

Huge stresses at crack tips

Front 31

Griffith Cracks

Back 31

Preexisting microcracks and flaws in a rock that when stresses are applied, grow and intersect other cracks.

Front 32

Crack Mode 1

Back 32

Tensile-mode cracks

Front 33

Crack Mode 2

Back 33

Sliding

Front 34

Crack Mode 3

Back 34

Tearing

Front 35

Shear Fracture

Back 35

A fracture that grows in association with a component of shear

Front 36

Cataclastite

Back 36

Fault rock comprised of rock fragments of various sizes set within a fine matrix.

Front 37

Joint

Back 37

A fracture that forms by tensile-loading. Planar and often smooth.

Front 38

Plumose structure

Back 38

On joints, resembles an imprint of a feather, due to inhomogeneity of rock.

Front 39

Why are plumose structures more prominent away from the origin?

Back 39

This is due to stress concentration at crack tips.

Front 40

Types of plumes

Back 40

Straight, curvy, cyclical plume (lots of start-stop)

Front 41

Twist Hackle

Back 41

A twisted joint. Occurs when a fracture tip grows and must rotate with changing stress. Often occurs in the "Hackle Fringe".

Front 42

Systematic Joints

Back 42

Planar joints that comprise a family of joints that are all parallel and maintain the rough spacing.

Front 43

Nonsystematic Joints

Back 43

Joints that aren't parallel or evenly spaced.

Front 44

Joint Set

Back 44

A group of systematic joints.

Front 45

Conjugate joints

Back 45

60 degree, 120 degree angles

Front 46

Sigmoidal

Back 46

Front 47

Three mechanisms that contribute to joint formation during uplift & erosion:

Back 47

1) Contraction during cooling

2) Poisson effect: rock expands vertically and contracts horizontally during unloading

3) Membrane effect: expansion due to increase in curvature of layer

Front 48

Cooling joints

Back 48

Form by thermal contraction

Front 49

Exfoliation joints

Back 49

Form by unloading of bedrock through erosion, form parallel to topography

Front 50

Tectonic joints

Back 50

Form by tectonic stresses

Front 51

En echelon tension gashes

Back 51

Form 45 degrees from plane of max shear stress

Tails are parallel to the direction of principal stress