Chapter 2

Question 1

It is the transformation from an initial to
a final geometry by means of rigid body translation, rigid body rotation, strain (distortion) and/or volume change

Answer 1

Deformation

Question 2

This do not tell us how the
particles moved during the deformation history – they merely link the undeformed and deformed states.

the positions of points before and after deformation (can be connected with vectors.)

Answer 2

Displacement Vectors

Question 3

moves every particle in the rock in the same direction and the same distance, and its displacement
field consists of parallel vectors of equal length.

Answer 3

Translation

Question 4

The term refers to the distortion (strain) that is expressed in a (deformed) rock.
A change in form or shape.

Answer 4

Deformation

Question 5

Rigid body deformation

Answer 5

Rotation and Translation

Question 6

Non-rigid body deformation

Answer 6

Strain or Distortion

Question 7

are the field of displacement vectors.

Answer 7

Displacements field

Question 8

________trace the actual motion of individual particles in the deforming rock. while __________ simply connect the initial and final positions.

Answer 8

Particle path, Displacement Vector

Question 9

The actual path that each particle follows during the deformation history.

Answer 9

Particle Path

Question 10

referring to the progressive changes that take place during deformation

Answer 10

deformation History

Question 11

is here taken to mean rigid rotation of the entire deformed rock volume that is being studied. It should not be confused with the rotation of the (imaginary) axes of the strain ellipse during progressive deformation.

Answer 11

Rotation

Question 12

is non-rigid deformation and relatively simple to define:

Answer 12

Strain

Question 13

also referred to as dilation, is commonly considered to be a special type of strain, called volumetric strain.

Answer 13

Volume Change

Question 14

Where the deformation applied to a rock volume is identical throughout that volume, the deformation is

Answer 14

homogeneous.

Question 15

Homogeneous: Rigid rotation and translation
Heterogeneous: Strain and volume or area change

Question 16

originally straight and parallel lines will be straight and parallel also after the deformation. Further, the strain and volume/area change will be constant throughout the volume of rock under consideration.

Answer 16

homogenous deformation

Question 17

ratio between the long and short axes of the ellipse.

Answer 17

Ellipticity

Question 18

Homogeneous deformation can therefore be described by a set of first-order equations (three in three dimensions) or, more simply, by a transformation matrix referred to as the

Answer 18

deformation matrix

Question 19

called the deformation matrix or the position gradient tensor, and the equation describes a linear transformation or a homogeneous deformation.

Answer 19

Matrix D

Question 20

takes the deformed rock back to its undeformed state.

Answer 20

reciprocal or inverse deformation

Question 21

(a single direction), strain is about stretching and shortening (negative stretching) of lines or approximately linear (straight) objects.

Answer 21

one-dimension

Question 22

of a line is defined as e= (l-l0)/l0 where l0 and l are the lengths of the line before and after deformation.

Answer 22

Elongation

Question 23

a line is identical to elongation (e) and is used in the analysis of extensional basins where the elongation of a horizontal line

Answer 23

Extension

Question 24

Negative extension is called

Answer 24

Contraction

Question 25

which describes the change in angle between two originally perpendicular lines in a deformed medium.

Answer 25

Angular shear

Question 26

can be found where objects of known initial angular relations occur. Where a number of such objects occur within a homogeneously strained area, the strain ellipse can be found

Answer 26

Shear strain

Question 27

the ellipse that describes the amount of elongation in any direction in a plane of homogeneous deformation.

Answer 27

strain ellipse

Question 28

Having constant volume or area.

Answer 28

Isochoric

Question 29

An arbitrary section through a deformed rock contains a strain ellipse that is called

Answer 29

sectional strain ellipse.

Question 30

is a state of strain were stretching in X is compensated for by equal shortening in the plane orthogonal

Answer 30

Uniform Extension

Question 31

is the opposite, with shortening in a direction Z compensated for by identical stretching in all directions perpendicular to Z.

Answer 31

Uniform flattening

Question 32

where stretching in one direction is perfectly compensated by shortening in a single perpendicular direction.

Answer 32

plane strain

Question 33

- is the deformed shape of an imaginary sphere with unit radius that is deformed along with the rock volume under consideration.

Answer 33

strain ellipsoid

Question 34

The strain ellipsoid has three mutually orthogonal planes of symmetry, the principal planes of strain, which intersect along three orthogonal axes that are referred to as the principal strain axes. Their lengths (values) are called the principal stretches.

Answer 34

important

Question 35

the eigenvectors and eigenvalues will always be identical for any given state of strain. Another way of saying the same thing is that they are

Answer 35

strain invariants

Question 36

example of strain invariants.

Answer 36

Shear strain, volumetric strain, and kinematic vorticity number (Wk)

Question 37

Any strain ellipsoid contains

Answer 37

two surfaces of no finite strain.

Question 38

For constant volume deformations

Answer 38

isochoric deformations

Question 39

The radial lines in this diagram indicate equal amounts of strain, based on the natural octahedral unit shear.

Answer 39

Hsu Diagram

Question 40

Volume and area changes do not involve any internal rotation, meaning that lines parallel to the principal strain axes have the same orientations that they had in the undeformed state. Such deformation is called

Answer 40

coaxial

Question 41

is real volume change where the object is equally shortened or extended in all directions.

Answer 41

Isotropic Volume Change

Question 42

involves not only a volume (area) change but also a change in shape because its effect on the rock is different in different directions

Answer 42

Anisotropic volume change

Question 43

implies expansion in one direction. This may occur by the formation of tensile fractures or veins or during metamorphic reactions.

Answer 43

Uniaxial extension

Question 44

where the rock shortens or extends in one direction, is another example of coaxial deformation.

Answer 44

Uniaxial strain

Question 45

implies that lines along the principal strain axes have the same orientation as they had in the undeformed state.

Answer 45

Coaxial deformation

Question 46

is a special type of constant volume plane strain deformation. There is no stretching or shortening of lines or movement of particles in the third direction.

Answer 46

Simple shear

Question 47

Between pure shear and simple shear is a spectrum of planar deformations

Answer 47

subsimple shear

Question 48

is the sum of particle paths in a deforming medium.

Answer 48

flow pattern

Question 49

Parameters that act instantaneously during the deformation history

Answer 49

flow parameters

Question 50

are the three perpendicular axes (two for plane deformations) that describe the directions of maximum and minimum stretching at any time during deformation.

Answer 50

Instantaneous Stretching Axes (ISA)

Question 51

separate different domains of particle paths.

Answer 51

flow apophyses

Question 52

describes how fast a particle rotates in a soft medium during the deformation.

Answer 52

Vorticity

Question 53

describes the velocity of the particles at any instance during the deformation history.

Answer 53

velocity field

Question 54

is a measure of the internal rotation during the deformation. The term comes from the field of fluid dynamics.

Answer 54

Vorticity

Question 55

If the flow pattern and the flow parameters remain constant throughout the deformation history, then we have

Answer 55

steady state flow

Question 56

If, on the other hand, the ISA rotates, Wk changes value or the particle paths change during the course of deformation, then we have

Answer 56

non-steady-state flow.

Question 57

which is the result of the entire deformation history.

Answer 57

Finite deformation

Question 58

which concerns only a portion of the deformation history

Answer 58

Incremental deformation

Question 59

progressive volume change

Answer 59

dilating