Structural Test 2

Front 1

annealing

Back 1

recovery/recrystallization after deformation

Front 2

Coble (grain-boundary) diffusion

Back 2

diffusion of material along grain boundaries from areas of high compressive stress to areas of lower stress. Relatively fast, occurring at low temps.

Front 3

chemical concentration gradients

Back 3

change in chemical concentration of certain materials along surface due to dissolution creep

Front 4

dislocation climb

Back 4

propagation of a dislocation through a crystal lattice

Front 5

dissolution creep

Back 5

Same as pressure solution. Minerals dissolve into pore fluid at areas of high stress and are transported to areas of low stress and reprecipitated.

Front 6

high-angle boundary

Back 6

grain boundary with dislocation greater then 11% from grain to grain

Front 7

brittle-ductile transition

Back 7

Depth Where deformation of material begins to behave ductile instead of brittle due to increased temperature and pressure. (i.e. for quartz this is about 12 km)

Front 8

crustal strength envelope

Back 8

composite of Byerlee's law for upper crust and quartz flow law for lower crust

Front 9

deformation map

Back 9

show the active deformation mechanisms as function of temperature and differential stress (and strain rate) for a specific mineral or mineral. Maps broken in dominant deformation mechanisms.

Front 10

dislocation creep

Back 10

shearing of the crystal lattice along crystallographic planes

Front 11

dynamic recrystallization

Back 11

recovery/recrystallization during deformation counteracts hardening and determines rate of dislocation creep

Front 12

intergranular microcrack

Back 12

microcrack around grains or along grain boundaries

Front 13

cataclasis

Back 13

brittle granulation of rock, angular fragments, progressive decrease in grain size with deformation, occurs at low temperatures and pressures.

Front 14

diffusion creep

Back 14

distortion and dilation of crystals by dissolution under stress and precipitation of material in the presence of water

Front 15

dilatency

Back 15

increase of volume. For us it is the reference to cataclasis that causes a increase in rock volume.

Front 16

vacancies

Back 16

unoccupied sites within a given crystal

Front 17

edge dislocation

Back 17

Occurs when stress causes an edge of a crystal lattice to move laterally relative to the lattice below. This edge then moves across the mineral until it is terminated at the grain boundary.

Front 18

interstitial atoms

Back 18

ions in between normal sites in the crystal lattice.

Front 19

cataclastic flow

Back 19

slip on discrete surfaces that separate undeformed areas

Front 20

deformation mechanisms

Back 20

brittle mechanisms, diffustion creep, dislocation creep, dissolution creep, and mechanical twinning.

Front 21

dislocation

Back 21

line that bound a planar defect in the crystal lattice

Front 22

transgranular microcrack

Back 22

microcrack that cuts across adjacent grains

Front 23

grain boundary sliding

Back 23

grain-scale sliding between grains in a rock

Front 24

intragranular

Back 24

sliding around grains and or along grain boundaries,

Front 25

ionic bonds

Back 25

when one atom loses/borrows an electron from another atom

Front 26

mechanical twinning

Back 26

shearing parallel to a crystallographic plane e.g. calcite, plagioclase feldspar

Front 27

planar defects

Back 27

grain boundaries, or crystallographic twin planes, or extra planes of atoms within a lattice.

Front 28

recovery

Back 28

"heals" lattice by rearranging or destroying dislocations

Front 29

strain hardening

Back 29

hardening of a rock as a result of strain

Front 30

Theoretical strength

Back 30

Based on calculations. Basically what the strength of a rock should be.

Front 31

microcracks

Back 31

small cracks within a rock. That can be intergranular, intragranular, or transgranular

Front 32

point defects

Back 32

The crystal lattice has an equilibrium distribution of point defects created during lattice formation, ductile deformation, or rapid cooling from high temperatures.

Front 33

recrystallization

Back 33

converts old grains with defects into "new" grains. Favored by high temperature.

Front 34

stylolites

Back 34

Planar occurrences of pressure solution where minerals are dissolved out and usually replaced by less soluble minerals such as mica or clay.

Front 35

kinks

Back 35

non-uniform bends within a structure

Front 36

Nabarro-Herring creep

Back 36

volume-diffusion creep. diffusion within grains, effective at high temperatures & low-moderate differential stress. vacancies migrate to max stress. crystals grow parallel to minimum

Front 37

pressure shadows

Back 37

precipitation on other minerals of low stress

Front 38

grain boundary slip

Back 38

coble-creep. diffusion of material along grain boundaries from areas of high compressive stress to areas of lower stress

Front 39

line defects

Back 39

A line defect is made up of a line of atoms that moves through the crystal lattice as a single unit

Front 40

overgrowths

Back 40

precipitation on the same mineral in area of low stress

Front 41

pressure solution

Back 41

solution caused by pressure conditions in which minerals are reconfigured to create rock structure

Front 42

solid state diffusion

Back 42

point defects migrate through the crystal lattice from areas of high stress to areas of low stress.

Front 43

abnormal fluid pressure

Back 43

abnormal fluid pressure based on fluid pressure ratio = fluid pressure/lithostatic (normal) pressure fpr = Pf/PL

Front 44

asperities

Back 44

irregularities on the sliding surface.

Front 45

Coulomb law of failure

Back 45

critical shear stress = cohesive strength + coefficient of internal friction (normal stress) find ratio of shear stress to normal for failure.

Front 46

effective stress

Back 46

the difference between normal stress and fluid pressure. On-Pf

Front 47

hydraulic fracture

Back 47

fracture due to fluid

Front 48

joint fringe

Back 48

joint termination

Front 49

ribs

Back 49

curved steps in joint face, oriented perpendicular to hackles, old joint terminations

Front 50

tensile strength

Back 50

the strength a rock has available relative to tensile motion

Front 51

slickenlines

Back 51

Occur at fault boundaries when protuberances scratch the surface opposite block and or when minerals are reprecipitated along a straight line parallel to fault movement.

Front 52

angle of internal friction

Back 52

slope of the failure envelope φ

Front 53

Byerlee's law

Back 53

Failure criterion for pre-fractured rocks. critical shear stress = a (normal stress)

Front 54

crack-seal vein

Back 54

preserve inclusions indicating repeated fracturing

Front 55

fluid pressure ratio

Back 55

fluid pressure ratio = fluid pressure/lithostatic (normal) pressure fpr = Pf/PL

Front 56

hydrostatic pressure

Back 56

pressure within a rock due to fluid inclusion

Front 57

joint intersections

Back 57

intersections of different types of joints. X-int due to cooling, Y-int systematic joints, T-int younger joint terminate at older ones.

Front 58

plume axis

Back 58

axis relative to volcanic plume

Front 59

ridge-in-groove lineations

Back 59

lineations produced by sinistral movement along a fault

Front 60

angle of sliding friction

Back 60

the angle in which fracture occurs due to sliding

Front 61

cohesive strength

Back 61

cohesive strength of rock = point where failure envelope intersects τ-axis

Front 62

crystal fibers

Back 62

They fill openings in joints, preserve record of the opening.

Front 63

Griffith Cracks

Back 63

cracks due to failure of a brittle material

Front 64

joint

Back 64

cracks along the axis of a rock/mineral

Front 65

Systematic Joints

Back 65

Most obvious joint sets along a rock. Non Systematic joints are usually perpendicular and less apparent.

Front 66

plumose structure

Back 66

hackles. linear or curved markings on joint face

Front 67

scissor fractures

Back 67

shear parallel to the fracture surface and parallel to the fracture front (faults)

Front 68

opening fractures

Back 68

fractures that cause a opening due to joints and can be refilled

Front 69

Mode I

Back 69

(opening, dilation) fractures: extension perpendicular to fracture surface (joints)

Front 70

Coulumb envelope

Back 70

envelope is parabolic in tensile field of Mohr diagram and linear in compressive field. In particular the failure envelope.

Front 71

en echelon joints

Back 71

Three or more faults oriented laterally and slightly offset forming a stair-like pattern

Front 72

hackles

Back 72

feather-like striations on a rock face due to tensile fracturing. They begin at an origin and radiate outward.

Front 73

Mode III

Back 73

scissor fractures

Front 74

shear fractures

Back 74

AKA mode II. shear parallel to the fracture surface and perpendicular to the fracture front (faults)

Front 75

process zone

Back 75

zone of processing

Front 76

vein

Back 76

a area that can be filled with secondary minerals or precipitation. Crystals grow here.

Front 77

syntaxial vein

Back 77

add material along the center of the vein

Front 78

aspirates

Back 78

unevenness of a surface

Front 79

thrust-slip

Back 79

shorten and thicken layering

Front 80

fault-line scarp

Back 80

steps in earth formed by active faults that represent accurate faulting planes

Front 81

fault zone

Back 81

Countless sub parallel connections of fault surfaces

Front 82

slip-fiber lineations

Back 82

crystals grow in pressure shadow of small steps on fault surface

Front 83

microfaults

Back 83

faults on a microscopic scale with rocks

Front 84

Offset

Back 84

the distance between two faulted bodies

Front 85

stratigraphic throw

Back 85

The distance separating one bedding layer from another one on the fault.

Front 86

slickensided surfaces

Back 86

striations or lineations on fault surfaces that record the direction of slip

Front 87

Breccia

Back 87

angular rock fragments in finer matrix, fragments more abundant than matrix, various sizes, from microbreccia (>0.1 mm - <1 mm) to megabreccia (>0.5 m fragments)

Front 88

dip-slip fault

Back 88

defined by relative movement of hanging wall (above fault surface, or block that fault dips towards) and footwall (below fault surface). slip parallel to dip

Front 89

footwall

Back 89

rock face below faulting surface

Front 90

strike-slip fault

Back 90

(horizontal) slip parallel to strike of fault

Front 91

Normal fault

Back 91

hanging wall moves down relative to footwall but we only know the offset and no slip

Front 92

Overlap

Back 92

overlapping areas of fault movement

Front 93

repetition/omission of strata

Back 93

allow us to observe faults that are typically not observable

Front 94

right-lateral fault

Back 94

strike fault in which the main block uses right hand rule

Front 95

slickensides

Back 95

striations or lineations on fault surfaces that record the direction of slip

Front 96

cataclasite

Back 96

very fine grained, strongly indurated rock made up of rock fragments and matrix, typically formed under higher temperatures and pressures than breccias

Front 97

drag

Back 97

when a rock body drags and causes local folding

Front 98

fault scarp

Back 98

steps in earth surface formed by recent active faults

Front 99

gouge

Back 99

fine clay like powder generated at fault boundaries. It is composed of finely, grounded pieces of fault blocks.

Front 100

normal-slip fault

Back 100

same as normal fault but we know the slip

Front 101

paleoseismic

Back 101

study of timing, location, and size of prehistoric earthquakes using the rock record

Front 102

reverse fault

Back 102

hanging wall moves up relative to footwall

Front 103

rollover anticline

Back 103

anticline that has rolled over

Front 104

conjugate set fault

Back 104

intersection that cross cuts a fault plane that is parallel to principal stress

Front 105

fault surface

Back 105

a surface along which fault slip occurred

Front 106

hanging wall

Back 106

rock face above faulted surface

Front 107

listric fault

Back 107

a normal fault where the fault plane is curved

Front 108

oblique-slip fault

Back 108

slip fault that occurs at an oblique angle

Front 109

pseudotachylite

Back 109

Glass like formation found along fault boundaries. They are formed from frictional heating of fault edges, typically characteristic in deep faults.

Front 110

reverse-slip fault

Back 110

slip fault where the motion is towards us using the right hang rule

Front 111

separation slip

Back 111

strike slip fault where separation of the body occurs

Front 112

decollement

Back 112

gliding surface between two masses in a thrust fault system

Front 113

ramp

Back 113

angled body due to faulting

Front 114

allocthonous

Back 114

place other then its origin

Front 115

balanced cross section

Back 115

cross-section that is balanced in terms of displaying equal bodies separated by a fault

Front 116

fault reactivation

Back 116

reactivation of a fault due to change in stress

Front 117

hanging wall ramp

Back 117

ramp due to relative hanging wall

Front 118

tectonic transport direction

Back 118

direction of transport based on tectonic activity

Front 119

coefficient of sliding friction

Back 119

static friction that is overcame between two bodies to allow sliding

Front 120

blind thrust

Back 120

fault-propagation folds - flat-ramp fault geometry

Front 121

lateral ramp

Back 121

ramp that is lateral to fault movement

Front 122

autochthanous

Back 122

placed at the point of the bodies origin

Front 123

bed-length balancing

Back 123

balancing beds using length

Front 124

footwall flat

Back 124

geometrically flat of footwall

Front 125

Hubbert & Rubey

Back 125

thrust sheets are too big to be moved by simply pushing from the back of the sheet. normal stress must be offset by elevated pore pressure Otherwise there would just be fracturing.

Front 126

Anderson's theory of faulting

Back 126

shear stress must be zero at the surface

Front 127

foreland-dipping duplex

Back 127

largely displaced dipping anticlinal structures

Front 128

thin-skinned

Back 128

thin-skinned does not involve basement rocks, thick skinned does involve basement

Front 129

transfer zones

Back 129

zones of displacement due to fault transfer of displacement

Front 130

duplex

Back 130

multiple faults controlled by presence of an upper detachment horizon

Front 131

tear fault

Back 131

A very steep to vertical fault associated with and perpendicular to the strike of an overthrust.

Front 132

klippe

Back 132

an erosional remnant of thrust sheet (hanging wall) surrounded by footwall rocks

Front 133

window(fenester)

Back 133

an exposure of the footwall of a thrust viewed through the hanging wall

Front 134

footwall ramp

Back 134

ramp geometry of footwall

Front 135

horse

Back 135

fault block surrounded by fault surfaces

Front 136

syntectonic basin

Back 136

basin that was deposited at the same time as formation

Front 137

overthrusting

Back 137

low angle and large displacement of fault characterized as overthrusting

Front 138

Why are actual yield strengths of minerals much lower than theoretical yield strengths?

Back 138

This is due to griffiths theory. There are small fractures and discontinuities within a rock. Nothing is perfect unless it is synthetically made, and therefor the strength is always less then what the calculation says.

Front 139

Contrast deformation features resulting from pressure solution(dissolution creep) and cataclasis?

Back 139

Pressure disolution involved fluid moving through a material. Stylolites are observed in pressure disolution. Dislocation occurs due to defects in crystal structure of a rock. Cataclasis are due to mechanical discontinuities and subsequent fracture movement. Pressure disolution occurs at lower pressures and temperatures.

Front 140

Describe the ornamentation associated with the surfaces of tensile fractures in rocks and outline their genetic meaning:

Back 140

Tensile fractures show three ornamentations: ribs,origins, and hackles. Ribs are circular and radiate out from origin of fracture. They give us a history of deformation. Origins are simply the point of origin. Hackles are feather like features that radiate out from origin. Most common ornamentatins in faults are slicklines. They are caused by recystallization of minerals and or scratches made by proturbences. They show direction of fault movement.

Front 141

What is the physical basis for griffith theory and what does the theory predict?

Back 141

Theoretical strength = actual strength. Griffith suggested that the low fracture strength observed in experiments, as well as the size-dependence of strength, was due to the presence of microscopic flaws in the bulk material. We can see this in the way synthetics tend to not break as easy.

Front 142

Describe how faults can be recognized in the field?

Back 142

Faults are recognized by displacement of rock bodies and related strike and dip. Faults can then be categorized by the direction of movement and the displacement of the surrounding rock bodies.