Usu Geol 1110 Test 2

Front 1

Types of Sedimentary Rocks

Back 1

- Clastic

- Chemical

- Biogenic

Hint 1

3 Types

Front 2

Particle sizes of Clastic Sedimentary rocks

Back 2

- Gravel (>2 mm)

- Sand (1/16 - 2 mm)

- Silt (1/256 - 1/16 mm)

- Clay (<1/256 mm)

Front 3

Rhythmic Layering

Back 3

Paired light and dark colored lake sediments. (From frozen lakes)

Hint 3

Varves

Front 4

Cross Bedding

Back 4

Beds inclined with respect to thicker stratum in which they occur.

Hint 4

Sand dunes

Front 5

Methods of Diagenesis

Back 5

- Compaction

- Cementation

- Recrystallization

- Chemical Alteration

Front 6

Compaction

Back 6

Weight of sediment reduces pore space, forces water out.

Front 7

Cementation

Back 7

Dissolved substances precipitate from water in pores. (Calcite)

Front 8

Recrystallization

Back 8

Less stable minerals may recrystallize to more stable forms. (Oragonite => Calcite)

Front 9

Chemical Alteration

Back 9

If O2 present, organic remains converted to CO2 and H20.

If O2 absent, organic matter transforms into solid carbon. (Coal)

Front 10

Graded Bedding

Back 10

Particles grade upward from coarser to finer.

Front 11

Facies

Back 11

Sediment that can be distinguished from a contemporary sediment that formed in different depositional environments.

Hint 11

- Nonmarine- Stream, lake, glacial, eolian

- Shoreline and Continental shelf- Estuarine, deltaic, beach, offshore, etc.

Front 12

Chemical Rocks

Back 12

Formed by precipitation of minerals from solution in water.

Front 13

Biogenic Rocks

Back 13

Formed from fossils. (Oyster shells are common)

Front 14

Conglomerate

Back 14

Rounded clasts, lithified gravel.

Hint 14

Clastic

Front 15

Breccia

Back 15

Angular clasts, lithified gravel.

Hint 15

Clastic

Front 16

Sandstone

Back 16

- Quartz _____ - Quartz is predominant

- Arkosic _____ - Feldspar is major component

- Greywacke - Dark with lots of rock fragments

Hint 16

Clastic

Front 17

Evaporite Deposits

Back 17

Most salt formed from marine evaporite deposits

Hint 17

Chemical

Front 18

Mudstone

Back 18

Very fine-grained; breaks down into block fragments.

Hint 18

Clastic

Front 19

*Shale (On Test)

Back 19

Very fine-grained; cleaves into sheet-like fragments.

Hint 19

Clastic

50% of all sedimentary rocks

Front 20

Banded Iron Deposits

Back 20

Ancient; probably formed when less O2 in atmosphere.

Hint 20

Chemical

Front 21

Chert

Back 21

Composed very fine-grained, interlocking quartz crystals.

Hint 21

Chemical

Does not effervesce with HCl

Front 22

Limestone

Back 22

- Can be either chemical or biogenic

- Coquina- Lithified shell fragments

- Chalk- Compacted shells of microscopic marine organisms

- Oolitic _____- Consists of tiny, round accretionary bodies (ooliths)

Front 23

Dolostone

Back 23

Forms when calcite in limestone is replaced by dolomite.

Front 24

Coal

Back 24

Usually black, combustible rock with >50% plant matter.

Front 25

Sole Marks

Back 25

Collective term for features preserved on bedding surfaces.

Front 26

Ripple Marks

Back 26

Preserved in sand that was moved by wind, streams, or waves.

Hint 26

Bedding Plane Feature

Front 27

Mud Cracks

Back 27

Polygonal markings caused by shrinking and cracking of drying mud.

Hint 27

Bedding Plane Feature

Front 28

Trace Fossils

Back 28

Footprints and trails of animals.

Hint 28

Bedding Plane Feature

Front 29

Fossils

Back 29

Provide significant clues about former environments.

Hint 29

Environmental Clue

Front 30

Color

Back 30

May indicate if sediment was deposited in reducing or oxidizing environment.

Hint 30

Environmental Clue

Front 31

Metamorphism

Back 31

- Changes in mineral assemblage/texture in rocks

- Due to changes in Temp. and Pressure

- Changes happen in solid state (no melting occurs)

Front 32

Deformation

Back 32

- Low grade vs. High grade (T/P)

- Stress- directed pressure

Front 33

Stress

Back 33

- Uniform Stress- Equal in all directions; igneous; random alignment

- Differential Stress- Not equal in all directions; metamorphic; parallel alignment

Hint 33

Directed pressure

Front 34

Intergranular Fluid

Back 34

Acts as transporting medium; speeds up chemical reactions

Front 35

Vein

Back 35

Formed by precipitation of minerals from intergranular fluid into fractures

Front 36

Prograde vs. Retrograde

Back 36

Rising T/P w/ H2O

vs.

Falling T/P w/o H20

Hint 36

NOT ON TEST

Front 37

Time

Back 37

Coarse grained- High T/P over long periods

Fine grained- Low T/P and/or short reaction times

Front 38

Migmatite

Back 38

Hybrid rock of metamorphic and igneous components.

Hint 38

On Test

Front 39

Textural Change

Back 39

- Foliation

- Slaty Cleavage

- Schistosity

Front 40

Foliation

Back 40

Planar texture; parallel mineral alignment due to differential stress.

Front 41

Slaty Cleavage

Back 41

Fine-grained rock splits into plate-like fragments along planes; low grade; new mineral grains only seen with microscope.

Front 42

Schistosity

Back 42

Parallel, but not necessarily planar, arrangement of minerals; high grade; grains seen with unaided eye

Front 43

Metamorphic Rocks from Shale and Mudstone

Back 43

- Slate

- Phyllite

- Schist

- Gneiss

Front 44

Slate

Back 44

Quartz, clays, calcite metamorphose into muscovite and/or cholrite; slaty cleave proves rock is metamorphic.

Hint 44

Low grade Metamorphic from shale/mudstone

Front 45

Phyllite

Back 45

Larger grains and new mineral assemblage (biotite, garnet, kyanite); micas barely seen with unaided eye.

Hint 45

Intermediate grade Metamorphic from shale/mudstone

Front 46

Schist

Back 46

Coarse grained; pronounced schistosity; new mineral assemblage.

Hint 46

High grade Metamorphic from shale/mudstone

Front 47

Gneiss

Back 47

Coarse grained; pronounced foliation; micaceous layers segregated from layers of minerals such as quartz and feldspar.

Hint 47

High grade Metamorphic from shale/mudstone

Front 48

Metamorphic Rocks from Basalt

Back 48

- Greenschist

- Amphibolite

- Granulite

Front 49

Greenschist

Back 49

Pronounced foliation; green color from cholorite.

Hint 49

Low grade Metamorphic from Basalt

Front 50

Amphibolite

Back 50

Amphibole replaces chlorite; foliation less distinct.

Hint 50

Intermediate grade Metamorphic from Basalt

Front 51

Granulite

Back 51

Amphibole replaced by pyroxene; foliation indistinct.

Hint 51

High grade Metamorphic from Basalt

Front 52

Metamorphic Rocks from Limestone and Sandstone

Back 52

- Marble

- Quartzite

Front 53

Marble

Back 53

Coarse interlocking calcite crystals; froms from limestone; sedimentary features largely obliterated; usually white, may be colored.

Hint 53

Metamorphic from limestone

Front 54

Quartzite

Back 54

Forms from quartz sandstone; pores filled with SiO2; entirely recrystallized

Hint 54

Metamorphic from Sandstone

Front 55

Types of Metamorphism

Back 55

- Mechanical deformation

- Chemical recrystallization

Front 56

Cataclastic Metamorphism

Back 56

Mechanical deformation with minor chemical recrystallization; elongated grains/rock fragments; foliated.

Hint 56

Mechanical def.- Yes

Chemical Rec.- No

(High P, Low T)

Front 57

Contact Metamorphism

Back 57

Occurs adjacent to hot magma bodies; involves chemical recrystallization; mechanical deformation minor or absent.

Hint 57

Mechanical def.- No

Chemical Rec.- Yes

(Low P, High T)

Front 58

Metamorphic Aureole

Back 58

Well-defined shell of altered rock adjacent to intrusion.

Front 59

Hornfels (Maybe on Test)

Back 59

Hard, fine-grained rock; formed by contact with small intrusion without fluid.

Comes from contact metamorphism of shale.

Front 60

Regional Metamorphism

Back 60

Most common/widespread; differential stress/mechanical deformation and chemical recrystallization; distinctly foliated.

Hint 60

Mechanical def.- Yes

Chemical Re .- Yes

(High P, High T)

Front 61

Metamorphic zones (On Exam)

Back 61

Regions between isograds (lines connecting points of first occurrence of index minerals)

Hint 61

Fig. 8-15

Front 62

Metasomatism (On Exam)

Back 62

Process whereby rock compositions are altered by ions from large volumes of fluids; associated with contact metamorphism, especially of limestones; fluids may also deposit metals.

Hint 62

Only case by which metamorphic rocks don't depend solely on protolith's composition.

Front 63

Confining Stress

Back 63

Same as uniform stress.

Front 64

Tensional Stress

Back 64

Stress that "pulls" the rock.

Hint 64

Type of differential stress.

Front 65

Compressional Stress

Back 65

Stress that "pushes" the rock.

Hint 65

Type of differential stress.

Front 66

Shear Stress

Back 66

Stress that acts in different directions across different faces of rocks.

Hint 66

Type of differential stress.

Front 67

Strain

Back 67

Change in size, shape or both in a solid as a result of stress (response to stress).

Front 68

Elastic Deformation

Back 68

Reversible/non-permanent change in volume/shape; rock returns to original size and shape when stress is removed.

Front 69

Elastic Limit

Back 69

Limiting stress, beyond which a solid is permanently deformed.

Front 70

Ductile Deformation

Back 70

Irreversible change in shape/volume of rock stressed beyond elastic limit

Front 71

Brittle Deformation/Fracture

Back 71

Occurs when limits of both elastic and ductile deformation are exceeded.

Front 72

Ductile Deformation Vs. Fracture

Back 72

- Temperature- High T, more ductile

- Confining stress- High C.S., less brittle

- Time and Strain Rate- Low S.R., more ductile

- Composition- Mineral dependent; High water content, low brittleness

Front 73

Brittle - Ductile Transition

Back 73

About 15 km in crust; 40 km in mantle.

Front 74

Abrupt Movement

Back 74

Fracture of brittle rocks and movement along faults (causes earthquakes).

Hint 74

Deformation in Progress

Front 75

Gradual Movement

Back 75

Fault movement may be gradual or below brittle-ductile transition.

Hint 75

Deformation in Progress

Front 76

Test Question (Q. 1 on Exam)

Back 76

Lithification of loose fragmental detritous (sediment) produces a _________ sedimentary rock.

Hint 76

Answer: Clastic

Front 77

Structural Geology

Back 77

Branch of geology that studies rock deformation.

Front 78

Flow of Original Horizontality

Back 78

Sedimentary strata and lava flows were initially horizontal; where tilted, deformation has occurred.

Front 79

* Strike

Back 79

Compass direction of line of intersection of horizontal and inclined planes.

Front 80

* Dip

Back 80

Angle between horizontal and inclined planes, measured down from horizontal.

Front 81

Geologic Maps

Back 81

Observations made at outcrops plotted on maps, and geology in between is inferred.

Front 82

Deformation by Fracture

Back 82

Only determined by relative displacement along faults.

Front 83

Hanging Wall

Back 83

Block of rock above inclined fault.

Front 84

Footwall

Back 84

Block of rock below inclined fault.

Front 85

Normal Fault

Back 85

Hanging wall moves down relative to footwall.

Hint 85

Caused by tensional stress

Fig. 9-14

Front 86

Reverse Fault

Back 86

Hanging wall moves up relative to footwall.

Hint 86

Caused by compressional stress

Front 87

Graben

Back 87

Down-dropped block between two normal faults; also half-graben.

Hint 87

Type of normal fault

Front 88

Horst

Back 88

Up-thrust block between two normal faults.

Hint 88

Type of normal fault

Front 89

Thrust Fault

Back 89

Reverse faults with dips <15 degrees.

Hint 89

Type of reverse fault

Front 90

Strike-Slip Faults

Back 90

Principal movement is horizontal, parallel to strike of fault.

Hint 90

Caused by shear stress

Front 91

Left and Right Lateral

Back 91

Displace features to left or right, respectively. Doesn't matter which side you observe.

Hint 91

Type of strike-slip fault

Front 92

Test Question (Q. 5 on exam)

Back 92

Lithification of silt and clay sized sediment produces:

A. Conglomerate

B. Breccia

C. Sandstone

D. Shale

Hint 92

Answer: D. Shale

Front 93

Evidence of Movement Along Faults

Back 93

Includes:

- Slickensides:

- Fault Breccia:

Front 94

Folding

Back 94

Bending of rocks; easiest to see in layered rocks; individual bend is a fold.

Hint 94

Deformation by bending

Front 95

Monocline

Back 95

Local steepening in otherwise uniformly dipping strata.

Hint 95

Deformation by bending

Front 96

Anticline

Back 96

Up-fold in form of an arch.

Hint 96

Deformation by bending

Front 97

Syncline

Back 97

Down-fold with a trough-like form.

Hint 97

Deformation by bending

Front 98

Limbs

Back 98

Sides of a fold.

Front 99

Axis

Back 99

Median line between limbs; along crest of anticline or trough of syncline.

Front 100

Plunging Fold

Back 100

Has inclined axis; angle between axis and horizontal line is plunge.

Front 101

Axial Plane

Back 101

Imaginary plane symettrically dividing fold; passes through axis.

Front 102

Open Fold

Back 102

Limbs dip gently and equally away from the axis.

Front 103

Isoclinal Fold

Back 103

Compressional stress so intense that limbs become parallel.

Front 104

Asymmetric Fold

Back 104

Limbs have unequal dips.

Front 105

Overturned Fold

Back 105

Limbs dip in the same direction.

Front 106

Recumbent Fold

Back 106

Limbs are horizontal or nearly so.

Front 107

Relationship Between Folds and Faults

Back 107

Faults die out as folds; folds die out becoming smaller; some monoclines result from fault movement that causes ductile strata to bend; some thrust faults probably started as recumbent folds.

Front 108

Folds and Topography

Back 108

Anticlines/synclines not necessarily ridges/valleys; easily eroded strata underlie valleys, resistant strata form ridges.

Front 109

Test Question (Q. 10 on exam)

Back 109

The type of foliation developed during low-grade metamorphism of a shale is called:

A. Facility

B. Slatey Cleavage

C. Schistosity

D. Gneissosity

Hint 109

Answer: B. Slatey Cleavage

Front 110

Test Question (Q. 25 on exam)

Back 110

(T/F) A group of assymetric folds has parallel limbs and axial planes.

Hint 110

Answer: False (Isoclinal have parallel limbs and axial planes)

Front 111

Test Question (Q. 14 on exam)

Back 111

(T/F) Metamorphic Aureoles contain Gneiss

Hint 111

Answer: False *(high grade/low grade metamorphism question)

Front 112

Test Question (Q. 20 on exam)

Back 112

Fractures along which movement has occurred are known as ___________.

Hint 112

Answer: Faults