Sedimentary Geology

Question 1

Sedimentology

Answer 1

sedimentary processes; processes that erode, transport, and deposit sediments

Question 2

sedimentary petrology

Answer 2

sedimentary products, characteristics and origins of sedimentary rocks

Question 3

Facies

Answer 3

depositional environments

Question 4

Sedimentary processes

Answer 4

weathering, erosion/transportation, deposition, diagenesis

Question 5

Produce all sediments

Answer 5

sedimentary processes

Question 6

Non-marine facies

Answer 6

esker, alluvial fan, mass wasting, floodplains, desert, rivers, glacial system, lake/playa, slope

Question 7

Marginal marine

Answer 7

Estuaries, deltas, beaches, lagoons, tidal flats/swamps

Question 8

marine

Answer 8

deep ocean basin, continental shelf/slope/rise, abyssal plain

Question 9

Best facies for sedimentary preservation

Answer 9

anoxic basin, deep ocean basin

• low energy
• below sea level

Question 10

Anything above sea level

Answer 10

erosional

Question 11

stratigraphy

Answer 11

distribution of sedimentary rocks in space and time

Question 12

environmental geology

Answer 12

waste disposal, groundwater flow, sinkholes, slope stability

Question 13

engineering geology

Answer 13

building site, offshore cable

Question 14

structural geology

Answer 14

most features are only observable in sed rocks

Question 15

resource geology

Answer 15

water, Pb-Zn deposits, drilling

Question 16

percent of rocks at earths surface that are sedimentary

Answer 16

75%

Question 17

structural geology rock features

Answer 17

folds, faults, bedding

Question 18

why do we study sedimentary rocks

Answer 18

surface of planet is dominated by sediment and sed rocks
provide a record of changing conditions at earths surface
earth history
sedimentary rocks preserve the record of life
hosts to economic minerals

Question 19

Principle of uniformitarianism

Answer 19

the present is the key to the past

understanding the past is key to understanding the future

Question 20

Paleogeography

Answer 20

geography at a time in the past

Question 21

How we interpret past environments and geography

Answer 21

matching rocks and fossils
magnetic record
what kinds of rocks are found and what they represent

Question 22

sediments as hosts to economic minerals

Answer 22

entire store of oil gas and coal
construction material
fertilizer
reservoirs and aquifers

Question 23

construction materials (from sedimentary rocks)

Answer 23

limestone, sand, gravel

Question 24

Distribution of water on earth

Answer 24

Oceans 97.2% / Freshwater 2.8%

Glaciers 2.15% / Groundwater 0.62%

Question 25

Aluminum resources

Answer 25

Bauxites

Question 26

The study of sedimentary rocks is based on

Answer 26

observation

Question 27

Observations

Answer 27

Colour, composition, texture, sed structures, fossils, porosity, sphericity, patterns in arrangement

Question 28

colour tells

Answer 28

fresh or weathered

Question 29

composition is

Answer 29

lithology

Question 30

texture includes

Answer 30

grain size, sorting, shape, rounding, sphericity, clastic or crystalline, preferred grain orientation

Question 31

fossil observations

Answer 31

type, diversity, quantity, preservation, borken/intact, orientation

Question 32

outcrop observations

Answer 32

rock body geometry- ribbons, lens, sheet associated sed rocks- inter bedding structural info- dip and strike, tectonic structure

Question 33

When was sedimentary rock deposited? Are nearby units contemporaneous?

Answer 33

-earth history | fossil content

Question 34

contemporaneous

Answer 34

existing or occurring at the same period of time

Question 35

cement

Answer 35

chemically precipitated | clasts are "glued" together later

Question 36

matrix

Answer 36

fine grained, deposited at same time as clasts

Question 37

matrix, or cement, which tells about depositional environment

Answer 37

matrix

Question 38

What and where was source of sediment (Provenance)

Answer 38

-Geological history, Mineral exploration | Composition, directional structures, regional variations

Question 39

What were transport processes?

Answer 39

-Mineral exploration, paleoclimate | Directional structures, texture

Question 40

what was depositional environment?

Answer 40

-Paleogeography, paleoclimate, earth history, resource exploration Textures, structures, geometry of deposit, fossils

Question 41

How have the properties changed? (diagenesis)

Answer 41

-Reservoir/aquifer potential | porosity permeability change, composition, texture, secondary structure

Question 42

Sedimentary rocks have unique features/minerals because

Answer 42

low T and P (compared to igneous and meta) | in contact with all spheres (hydro, bio, atmo)

Question 43

Sedimentary rock components

Answer 43

Quartz, feldspar, clay, k-spar, muscovite, carbonate, evaporites, organic C, rock fragments/clasts/lithics, cement, iron oxides

Question 44

Minerals unique to sedimentary rocks

Answer 44

Clays, carbonates, evaporites, iron oxides

Question 45

sandstone composition

Answer 45

up to 99% quartz

Question 46

granite composition

Answer 46

30-50% plag, 5-35% k-spar, 5-10% quartz | where does all the feldspar go

Question 47

Physical weathering processes

Answer 47

freeze-thaw, insolation, stress release, organic activity

Question 48

insolation

Answer 48

thermal expansion and contraction

Question 49

exfoliation

Answer 49

stress release- from erosion of overlying materials

Question 50

organic activity

Answer 50

burrowing, root growth

Question 51

effects of physical weathering

Answer 51

breaks rock, disaggregates grains, increases surface area

Question 52

products of physical weathering

Answer 52

Lithic fragments K-spar Quartz Muscovite

Question 53

Chemical weather processes

Answer 53

dissolution, oxidation, hydrolysis, hydration/dehydration

Question 54

Dissolution

Answer 54

calcite, halite CaCO3 + H2CO3 -----Ca2+ + 2HCO3- NaCl + H2O ----Na+ + Cl-

Question 55

Oxidation

Answer 55

olivine, pyroxene, amphibole, biotite, pyrite | Fe2SiO6 + O2 + H2O ----- 4Fe(OH)3 + H4SiO4

Question 56

Fe2SiO6

Answer 56

pyroxene

Question 57

Fe(OH)3

Answer 57

limonite

Question 58

CaSO4•2H2O

Answer 58

gypsum

Question 59

CaSO4

Answer 59

anhydrite

Question 60

Deydration

Answer 60

gypsum | CaSO4•2H2O ----- CaSO4 + 2H2O

Question 61

Hydrolysis

Answer 61

silicates KAlSi3O8 # H+ ------ Al2Si2O5(OH)4 # K+ # H4SiO4 Mg2SiO4 # 4H+ ----2Mg2+ # 4H4SiO4

Question 62

Kaolinite

Answer 62

Al2Si2O5(OH)4

Question 63

k-spar

Answer 63

KAlSi3O8

Question 64

Products of chemical weathering

Answer 64

Secondary minerals: Clays, Oxides Carbonates Dissolved materials/ ions

Question 65

Effects of chemical weathering

Answer 65

changing/decomposing | totally new products

Question 66

types of clays

Answer 66

illite smectite kaolinite

Question 67

dissolution products

Answer 67

ions

Question 68

oxidation products

Answer 68

hydroxides--- hematite, limonite

Question 69

hydrolysis products

Answer 69

clays, ions

Question 70

what do you need in reactant in order to form clay

Answer 70

Al

Question 71

breakdown of granite

Answer 71

feldspar--hydrolysis--clay--Na, K ions--eroded,wash away--deposit in quiet water biotite,amphibole--hydrolysis--clay biotite, amphibole--oxidation--iron oxide quartz--residual minerals--eroded--q.sand--transported to sea--beaches ions--dissolved load--transport to sea

Question 72

what do products of weathering depend on

Answer 72

source rock composition and stability | intensity, duration of weathering

Question 73

Goldich Stability series

Answer 73

silicates weather in same order as Bowens rxn | OPABKMQ

Question 74

source rock residues of chemically resistant minerals and fragments

Answer 74

residual minerals

Question 75

residual minerals indicate

Answer 75

source rock and duration/type of weathering

Question 76

secondary minerals

Answer 76

clays, iron oxides, hydroxides | products of hydrolysis and oxidation

Question 77

secondary minerals indicate

Answer 77

nature of weathering

Question 78

dissolved ions indicate

Answer 78

solubility of source minerals

Question 79

Arctic weathering

Answer 79

freeze/thaw--lithics | chemical dissolution

Question 80

Desert weathering

Answer 80

insolation/heat expansion--lithics--Feldspar, Quartz Oxidation-- iron oxide feldspar unique to location--dissolves in other areas

Question 81

Temperate weathering

Answer 81

insolation, freeze/that--lithics, quartz Hydrolysis, dissolution, rain, biological--clay--illite, ions immature soil--large grains, lack of lithic breakdown, possible loss of feldspar

Question 82

Tropical weathering

Answer 82

dissolution---ions hematite, clay: kaolinite, oxides: aluminum, quartz thick soils, higher weathering rates

Question 83

feldspars weather to

Answer 83

clays

Question 84

differences between clays

Answer 84

elemental make-up (source material), temperature, pH, precipitation

Question 85

mafic clay

Answer 85

chlorite

Question 86

felsic clay

Answer 86

illite

Question 87

How sedimentary minerals are sorted

Answer 87

Origin

Question 88

origins

Answer 88

siliclastic/extrabasinal | intrabasinal

Question 89

siliclastic

Answer 89

transported clasts; residual and secondary minerals | -extrabasinal

Question 90

siliclastic subdivisions

Answer 90

conglomerate sandstone mudstone

Question 91

mudstone subdivisions

Answer 91

siltstone | claystone

Question 92

conglomerate clast size

Answer 92

>2mm --gravel

Question 93

sandstone clast size

Answer 93

2-0.0625mm ---sand

Question 94

mudstone clast size

Answer 94

< 0.0625mm (1/16 mm) ---mud

Question 95

silstone vs. claystone

Answer 95

siltstone--gritty | claystone--- not gritty

Question 96

extrabasinal materials

Answer 96

solids from physical weathering: iron oxides, muscovite, clay, residuals, quartz, feldspar, lithic fragments

Question 97

intrabasinal

Answer 97

originate with basin | deposition of dissolved constituents

Question 98

Intrabasinal subdivisions

Answer 98

chemical | biochemical/biogenic/organice

Question 99

intrabasinal chemical types

Answer 99

evaporites | iron formations

Question 100

intrabasinal biochemical/biogenic/organic types

Answer 100

carbonates, chert, phosphates, carbonaceous material

Question 101

fossil compositions

Answer 101

``` silica = chert carbon = limestone ```

Question 102

fossil

Answer 102

previously living, preserved in sediment or sed rock, >10,000 years old

Question 103

are fossils clasts

Answer 103

no- clasts come from pre-existing rocks

Question 104

conglomerate

Answer 104

``` >30% large grained siliclastic 1-2% of sed rocks don't weather easy don't form over large areas lack fossils useful info--depositional enviro., provenance, paleogoegraphy, tectonic setting ```

Question 105

why conglomerates don't contain fossils

Answer 105

they form in high energy environments

Question 106

provenance

Answer 106

place of origin or earliest known history of something (source)

Question 107

conglomerate composition

Answer 107

clasts- lithics/fragments and quartz | matrix and clays

Question 108

conglomerate subdivisions

Answer 108

orthoconglomerate | paraconglomerate

Question 109

orthoconglomerate

Answer 109

<15% matrix | clast supported

Question 110

paraconglomerate

Answer 110

>15% matrix | matrix supported

Question 111

conglomerate depositional environments

Answer 111

upstream high energy river, glacial till, shoreline, mass wasting/debris flow

Question 112

how to tell glacial rocks from debris flow rocks

Answer 112

striations

Question 113

conglomerate sorting types

Answer 113

bimodal - fine + course | polymodal - large range of sizes

Question 114

bimodal sorting could be formed from what environment

Answer 114

fluvial

Question 115

polymodal could be formed from what environment

Answer 115

glacial

Question 116

Sandstone

Answer 116

10-20% sed rocks clast fmwk, pore spaces, fluid/matrix/cement important for earth history

Question 117

sandstone depositional environments

Answer 117

Aeolian, beaches (passive margins), estuaries, deltas, floodplains, sandbar, dunes, continental shelf

Question 118

where are sandstones NOT formed

Answer 118

deep ocean

Question 119

what are sandstones economically important for

Answer 119

construction material glass reservoirs chemical industry

Question 120

sandstone subdivisions

Answer 120

Arenites | Wackes

Question 121

Arenites

Answer 121

<15% matrix | usually bound with cement

Question 122

Wackes

Answer 122

>15% matrix

Question 123

arenites subdivisions

Answer 123

Quartz arenite... qtz Arkose..............feldspar Lithic Arenite.....fragments/lithics (divided by composition)

Question 124

Most common type of sandstone

Answer 124

Lithic Arenite

Question 125

where might arkose form

Answer 125

desert, immature rocks rapidly burried

Question 126

what is needed to form Quartz arenite

Answer 126

high weathering

Question 127

Mudstone

Answer 127

50-80% of all sed rocks clay minerals, qtz, feldspar weather easily economically unimporant

Question 128

mudstone subdivisions

Answer 128

Claystones....clay | Siltstone........quartz

Question 129

mudstones are classified by

Answer 129

color, fossil content, structure

Question 130

Carbonates

Answer 130

``` most abundance intrabasinal type 10% of sed rocks variable origin--biochemical or chemical paleogeology, paleoecology, evolution >50% carbonate minerals very susceptible to diagenetic change high porosity ```

Question 131

types of carbonates

Answer 131

Limestone...calcite, aragonite Dolomite.....dolostone Tyndall stone...limestone with burrows

Question 132

Carbonate economic importances

Answer 132

agriculture... lime, fertilizer, animal feed filler industrial.. cement, concrete, paper filler reservoirs.. oil, gas, water minerals... host for Pb-Zn deposits building stone.. tyndall stone, marble

Question 133

carbonates are especially prevalent in what times

Answer 133

greenhouse times ordovician/devonian jurassic/cretaceous

Question 134

carbonate depositional environments

Answer 134

marine: reefs, deep ocean, continental shelf Playa lakes Sabkhas

Question 135

limestone components

Answer 135

Allochems Micrite Sparite

Question 136

Allochem

Answer 136

equivalent of 'clast' intrabasinal formed carbonate grains may be transported WITHIN basin

Question 137

types of allochems

Answer 137

``` bioclastic debris (skeletal) coated grains (ooids, pisoids) Peloids (pellets..no internal structure) grain aggregates intraclasts ```

Question 138

Micrite

Answer 138

equivalent of 'matrix' carbonate mud <5µm inorganic prepcipitaion, breakdown of algal tissue

Question 139

Sparite

Answer 139

equivalent of 'Cement' | coarse calcite crystals that fill pore spaces

Question 140

Intrabasinal phosphates

Answer 140

not common | 3 types

Question 141

phosphate subdivisions

Answer 141

Bone beds Guano deposit Phosphorite nodule

Question 142

Organic rich sedimentary rocks

Answer 142

undecayed carbon rich matter correspond with greenhouse periods in earth history distinguished by Carbon source

Question 143

organic rich carbon sources

Answer 143

Humic... plants | Sapropelic....animal..ie. algae

Question 144

organic rich sedimentary rock subdivisions

Answer 144

coal oil shale petroleum

Question 145

Coal

Answer 145

most abundant O rich sed rock Humic matter combustible energy source

Question 146

Coal subdivisions (rank)

Answer 146

Peat Lignite Bituminous coal Anthracite

Question 147

oil shale

Answer 147

kerogen bearing mudstones | ~25% organic

Question 148

kerogen

Answer 148

microbial altered plant and animal organic matter

Question 149

Petroleum

Answer 149

natural gas | mature kerogen--burial + heat = hydrocarbons

Question 150

greatest problem with burning coal

Answer 150

it acts like a sponge, contains every element | low rank coal - 'tainted' - huge pollution factor

Question 151

Iron rich sedimentary rocks

Answer 151

>15% iron <1% of all sed rocks very economically important

Question 152

Iron rich subdivisions

Answer 152

Banded Iron Formations (Precambrian) | Ironstones (Phanerozoic)

Question 153

BIF

Answer 153

1900-2400mya Marine (reduced iron) / Anaerobic (low O atm.) 50-600m thick bands w/ cm thick Fe rich mudstone or chert layers laterally extensive

Question 154

Phanerozoic ironstone

Answer 154

``` Ordovician, Silurian, Jurassic metres to 10s of metres thick (thinner) Fe oxides and Fe silicates interbedded with shallow marine sediment replace shallow marine sediment (ooids) erosion of lateritic soils ```

Question 155

Ironstones prevelant in

Answer 155

greenhouse conditions deep weathering, high sea level less siliclastic

Question 156

How are sedimentary materials transported

Answer 156

in solution...fluids- substances that flow | as solids.. gravity

Question 157

Fluid characteristics important for transport

Answer 157

Density Viscosity Velocity

Question 158

Density

Answer 158

``` mass/unit volume water = 1g/cm3 air 0.1g/cm3 ice 0.9g/cm3 larger particles transported in denser fluids ```

Question 159

viscosity

Answer 159

ability to flow/resistance to shearing air - low viscosity ability to transport large particles increases with viscosity

Question 160

velocity

Answer 160

coast size potential increases with velocity

Question 161

Hjulstrom curve

Answer 161

need higher velocity at lower grain size to entrain particles- critical entrainment velocity

Question 162

gravity effects on transport

Answer 162

Gravity-- F_G holds grains on bed causes grains to settle

Question 163

Forces involved in transport

Answer 163

F_D.... drag/shear force | F_L...lift force.. Bernoulli effect

Question 164

if F_G > F_D, F_L

Answer 164

sediment remains on bed or settles out

Question 165

if F_G < F_D, F_L

Answer 165

sediment entrained or remains entrained

Question 166

Fluid influences

Answer 166

Type of flow | Type of bedform

Question 167

type of flow dictated by

Answer 167

Reynold #

Question 168

Reynolds number =

Answer 168

2rV(rho) / µ

Question 169

what is µ in reynolds number and what does it mean

Answer 169

µ = viscosity | if µ dominates - low Re -- laminar flow

Question 170

Large Re

Answer 170

turbulent flow

Question 171

Laminar flow =

Answer 171

Re <500-2000 | subparallel sheets flowing slowly, viscous fluids

Question 172

Turbulent flow =

Answer 172

Re >500-2000 | irregular flow with eddies, low viscosity

Question 173

Types of bed forms dictated by

Answer 173

Frouds #

Question 174

Frouds number =

Answer 174

V / √(gD) | D= depth of flow

Question 175

Fr < 1

Answer 175

low velocity-- tranquil flow irregular water surface small amount of sed transport

Question 176

Bedforms resulting from tranquil flow

Answer 176

ripples sandwaves dunes

Question 177

Fr > 1

Answer 177

high velocity--- rapid flow glassy, streaked out water surface large amount of sed transport

Question 178

Bedforms resulting from rapid flow

Answer 178

plane beds antidunes chutes pools

Question 179

bedload

Answer 179

sediment that moves close to the bed surface

Question 180

types of bedload movement

Answer 180

Traction- rolling, sliding, creep | Saltation- intermittent contact with bed (eddies)- particles bounce along

Question 181

suspended load

Answer 181

grains 'float' continuously in fluid

Question 182

Unidirectional flow bedforms

Answer 182

ripples, sandwaves, dunes, plane beds, anti dunes, chutes, pools

Question 183

creep

Answer 183

one particle hits another forcing it to move

Question 184

low flow regime bedform

Answer 184

plane bed--no velocity = no sed movement | ripples-waves-dunes = low velocity movement of sediment

Question 185

upper flow regime bedform

Answer 185

plane bedding-sheets of sediment are moved | antidune- migrates upstream by high energy eddy

Question 186

bedform most likely to be preserved

Answer 186

ripples, plane beds (then dunes)

Question 187

eroding side of a dune

Answer 187

Stoss

Question 188

depositional side of a dune

Answer 188

Lee

Question 189

cross bedding in a dune as representation as flow direction

Answer 189

- flow is perpendicular to cross beds (opposite of what imbrication would look like) - cross beds are concave TOWARD flow direction

Question 190

climbing ripples

Answer 190

upward moving drifts | lots and lots of sediment moving in current

Question 191

stable angle of rest

Answer 191

steeper in air air ~30º water ~18º

Question 192

how to tell cross beds are not upside down

Answer 192

look for tangential base

Question 193

trough bedding

Answer 193

irregular fluid flow | sinuous in 3rd dimension

Question 194

bidirectional flow

Answer 194

Waves: when wave orbits interact with bed surface they become elliptical and cause back and forth sediment motion Tides: bidirectional every ~6hours

Question 195

Bidirectional bed forms

Answer 195

``` symmetrical oscillation ripples herringbone cross stratification linsen/lenticular bedding flaser bedding wavy bedding ```

Question 196

symmetrical ripples

Answer 196

form from waves no stoss or lee side internal structure looks like a bunch of stacked tents

Question 197

bidirectional dunes

Answer 197

form if bidirectional flows are equal ie.tides

Question 198

linsen/lenticular, flaser, wavy bedding form from

Answer 198

asymmetry in tidal current strength

Question 199

hummocky bedding

Answer 199

on storm shelves | long and low profile

Question 200

subaerial/subaqueous

Answer 200

taking place in air/water

Question 201

Dry rockfalls

Answer 201

little internal deformation of material slides slumps

Question 202

wet rockfalls

Answer 202

>fluid, grains separated and dispersed, cohesiveness reduced | sediment gravity flow

Question 203

subaerial sediment gravity flow

Answer 203

avalanche, pyroclastic flow, grain flow, debris flow, mud flow

Question 204

subaqueous sediment gravity flow

Answer 204

grain flow, debris flow, turbidity current, fluidized flow

Question 205

Grain flow

Answer 205

``` sediment beyond critical angle of repose- steep slopes >30º, or trigger event deposit rapidly form massive structures entrained by grain to grain interaction ex. sand dune, submarine canyon ```

Question 206

Fluidized flow

Answer 206

upward motion of escaping pore fluid- separates grains, weakens sediment 'liquifies' behaves like viscous liquid flows on low angle slope stabilizes when grain to grain contact is restored

Question 207

debris flow

Answer 207

``` supported by cohesive mud matrix large amount of matrix provides strength need trigger event slurrylike flow-like wet cement very poorly sorted carry very large sed move fast -alluvial fan, lahar ```

Question 208

bingham plastic

Answer 208

behaves as rigid material until disturbed to loose cohesion then behaves as viscous fluid

Question 209

turbidity current

Answer 209

``` least dense, like fluid flow sediment suspended in water turbulence is grain support mechanism Re high, low viscosity very rapid flow widespread dispursal ```

Question 210

turbidity current deposit

Answer 210

turbidite | graded beds

Question 211

bedding

Answer 211

>1cm

Question 212

lamination

Answer 212

<1cm

Question 213

deformational structures

Answer 213

``` load casts flame structures ball and pillow structure slump structure sandstone dyke/dish structure convolute bedding ```

Question 214

bedding plane structures

Answer 214

sole marks: tool marks- grooves, prods, flutes/scoures surface marks: desiccation cracks, rain pits sand volcanoes

Question 215

ss plane

Answer 215

bedding plane (top of bed)

Question 216

bed

Answer 216

deposited in single event (same conditions)

Question 217

Bouma sequence

Answer 217

The Bouma Sequence (after Arnold H. Bouma, 1932-2011) describes a classic set of sedimentary structures in turbidite beds deposited by turbidity currents at the bottoms of lakes, oceans and rivers

Question 218

tectonic vs. slump structure

Answer 218

tectonic-whole sequence folded same | slump- only an area folded

Question 219

flute/scour marks

Answer 219

formed by eddies eroding bed plane | tell which way is upstream (shallower part of flute)

Question 220

organism structures

Answer 220

tracks and trails, burrows, bioturbation

Question 221

tracks and trails

Answer 221

fooprints | grooves

Question 222

burrows

Answer 222

shafts (vertical) | tunnels (horizontal)

Question 223

bioturbation

Answer 223

extensive biological activity | mottled appearance - original structure destroyed

Question 224

ichnofacies

Answer 224

biogenic structures characteristic of depths and bottom conditions

Question 225

skolithos

Answer 225

lots of vertical, tube-like burrows shallow sandy shoreline higher energy

Question 226

cruziana

Answer 226

horizontal U shaped troughs, bilobate features sublittoral low energy sands/silts/muds

Question 227

zoophycos

Answer 227

arcuate feeding traces bathyal zone low energy muds low O2 level

Question 228

nereites

Answer 228

meandering feeding traces | abyssal zone

Question 229

bilobate feature

Answer 229

trilobite feeding trail

Question 230

sublittoral zone

Answer 230

areas where sunlight reaches the ocean floor water is never so deep as to take it out of the photic zone. high primary production location of the majority of sea life

Question 231

arcuate

Answer 231

shaped like a bow, curved

Question 232

bathyal

Answer 232

between sublittoral and abyssal | beyond continental shelf

Question 233

all the changes that occur in sediment once it has been deposited that turn it in to a sedimentary rock

Answer 233

diagenesis

Question 234

diagenetic conditions

Answer 234

<10kms

Question 235

colour of fossils

Answer 235

varies with depth

Question 236

types of diagenesis

Answer 236

biological physical chemical

Question 237

biological diagenesis

Answer 237

bioturbation | microbial activity

Question 238

bioturbation diagenesis

Answer 238

``` disrupts primary structure- burrowing, ingestion changes chemistry of environment produces structures (pellets) reduces grain size ```

Question 239

microbial activity diagenesis

Answer 239

decomposition of organics influences pH, eH, chemistry of pore fluids

Question 240

physical diagenesis

Answer 240

compaction- compression and squeezing from weight of overlying grains increase density, thinning, reduce porosity/permeability, distortion, bending, pressure solution

Question 241

compaction, decreasing porosity and permeability

Answer 241

sands: from 25-35% down to 20% muds: from 60-80% down to 10-20% carbonate muds: 50-70% down to 35-45%

Question 242

Fabrics resulting from compaction

Answer 242

``` grain/clast distortion, deformation, flattening sutured grains (pressure solution) stylolites ```

Question 243

chemical diagenesis

Answer 243

``` cementation authigenesis replacement recrystallisation dissolution ```

Question 244

biggest difference in porosity from compaction is seen in what sed.

Answer 244

Mudstone- can thin by more than half

Question 245

sutured grains

Answer 245

pressure solution occurs at the boundary btw grains-- where most pressure is applied-- dissolves in carbonates a whole layer may dissolve

Question 246

cementation

Answer 246

growth of new minerals btw grains in pore spaces new minerals precipitate from pore fluids onto grain surface cement material may be same as clasts or different

Question 247

effects of cementation

Answer 247

lithification of sediment | reduces porosity

Question 248

sandstone cement

Answer 248

high pH, T..... calcite low pH, T....quartz minimally Iron oxide overgrowth, mosaic

Question 249

carbonate cement

Answer 249

calcite, aragonite, dolomite | overgrowth, drusy, blocky, rim cement

Question 250

carbonate 'grains'

Answer 250

allochems

Question 251

authigenisis diagenesis

Answer 251

new minerals from related, recycled elements or minerals | ex. glauconite (green) ONLY forms through authigenesis

Question 252

authigenesis common types

Answer 252

alteration of clay minerals formation of sericite formation of hematite/pyrite

Question 253

alteration of clay minerals

Answer 253

kaolinite to illite High T,P--chlorite, muscovite low T,P---glauconite

Question 254

sericite

Answer 254

fine muscovite and clay formed from feldspar alteration

Question 255

Replacement diagenesis

Answer 255

different mineral precipitates in the space occupied once by another mineral or material common in sed rocks original texture may be preserved

Question 256

examples of replacement diagenesis

Answer 256

petrified wood- C replaced by chert sand grains replaced by calcite carbonate fossils replaced by silica or pyrite

Question 257

recrystallization diagenesis

Answer 257

existing clasts/minerals retain their chemistry but grain size gets larger original texture lost

Question 258

recrystallization example

Answer 258

lime mud----coarse sparite----silicic ooze----chert | all steps of recrystallization

Question 259

bivalve

Answer 259

two shells are symmetric one is not symmetric down the middle oyster

Question 260

brachiopod

Answer 260

one shell is symmetric down middle | two shells are not symmetric

Question 261

dissolution diagenesis

Answer 261

associated with compaction increases porosity--generates 2º porosity thins beds

Question 262

pressure solution in carbonates

Answer 262

may involve 25-90% of original rock | the dissolution provides Ca and CO3 for cements

Question 263

diagenetic structures

Answer 263

``` obvious-tell nothing about original environment liesegangen bands concretion/nodules sand crystals geodes ```

Question 264

sand crystals

Answer 264

large calcite diagenetic crystals which have grown in sand

Question 265

geodes

Answer 265

diagenetic minerals that have grown into a void

Question 266

liesengangen bands

Answer 266

groundwater flow and mineral precipitation result in diagenetic colour bands especially in sandstones may follow bedding- usually not

Question 267

concretions

Answer 267

regular rounded forms about a nucleus ex. a fossil

Question 268

nodules

Answer 268

irregular form no nucleus eg. flint

Question 269

how do we reconstruct sedimentary environments

Answer 269

uniformitarianism | facies models

Question 270

uniformitarianism principles

Answer 270

actualism- processes are the same in the past as now | gradualism- rates/intensities are the same as in the past

Question 271

largest amount of sediment accumulation

Answer 271

continental shelf

Question 272

relic sediments

Answer 272

large grains on shelf from past glaciation when sea level was lower

Question 273

non-recurring changes in earth history

Answer 273

O2 levels | evolution

Question 274

how evolution has changed sedimentary record

Answer 274

before abundant life: - no carbonates, no bioturbation - SOME silicates - stromatolites more common

Question 275

Facies models

Answer 275

idealized sequence | may include; lithology, sed. structures, fossils, sequences, paleocurrents

Question 276

most likely to be preserved

Answer 276

marine env. - below base level continental shelf better than deep ocean (sub ducted) local base levels: tectonic basin, rift valley times of high sea level- more marine environment.

Question 277

alluvial deposition environments

Answer 277

alluvial fans braided rivers meandering rivers deltas

Question 278

Alluvial fans

Answer 278

closest and coarsest to source of sediment map view- triangular x-section- wedge shaped slopes 1-25º, lateral extent ms to ams from source merge downstream into meandering fluvial valley or playa coarsest at Apex

Question 279

Alluvial fan examples

Answer 279

Arid- death valley Wet fans- SE Alaska, mt. mckinley wet much larger than arid

Question 280

alluvial fan requirement

Answer 280

major change in slope drop in hydraulic power typical of rift valleys- tectonic activity moves fan forward

Question 281

Bajada

Answer 281

series of alluvial fans coalesce

Question 282

alluvial fan sediment transport mechanisms

Answer 282

stream flow: braided channel, sheet flood, sieve deposit | sediment gravity flow: debris flow, mudflow

Question 283

alluvial fan stream flow products

Answer 283

generally stratified, reasonably sorted, cross bedded, imbricated deposits

Question 284

alluvial fan braided channel product

Answer 284

lenticular

Question 285

alluvial fan sheet flood product

Answer 285

well sorted sheet, stratified

Question 286

alluvial fan sieve deposit product

Answer 286

no imbrication no cross bedding well sorted

Question 287

alluvial fan sediment gravity flow products

Answer 287

very poorly sorted unstratified lobe shaped tabular deposits

Question 288

alluvial flow debris flow products

Answer 288

coarser

Question 289

alluvial fan mudflow products

Answer 289

finer

Question 290

alluvial fan sedimentology

Answer 290

``` coarse grain- conglomerates, cross bedded sandstones large range in grain size size decreases distally immature, angular sediment red beds common fossils rare ```

Question 291

fluvial environments

Answer 291

braided | meandering

Question 292

braided fluvial system

Answer 292

upper part of river coarse sediment, high sed supply, steep gradient, rapid variation in discharge, channels shift rapidly, several channels, wide and shallow, low sinuosity, bars between channels, no floodplain, channels move with every season

Question 293

meandering fluvial system

Answer 293

lower part of river finer sed., less sed., lower gradient, steady flow, stable channels and banks, one channel, narrow and deep, high sinuosity, bars occur at edges of channels, substantial floodplain max. velocity is on outside of bend

Question 294

longitudinal bar

Answer 294

sandbar in a braided stream that is parallel to direction of flow mostly in upper reaches- plane bedding, massive downstream- may develop cross bedding,

Question 295

transverse bar

Answer 295

downstream braided river perpendicular to flow sandier, cross bedded, broader

Question 296

braided river deposits

Answer 296

unfossiliferous, too high energy some root casts, burrows--if vegetated coarse sediment--fines at top

Question 297

meandering point bar

Answer 297

deposited on inside of bend finer sand, cross laminated, point bar/levee muds, mudcracks, floodplains fossiliferous fining upward sequence, epsilon cross beds

Question 298

how to recognize fluvial deposits

Answer 298

``` absence of marine fossils poor sorting (compared to aeolian) red colours common (oxidation) unidirectional paleocurrent patttern downstream decrease in grain size distinct fining upward cycles; alluvial fan, meandering common in records but not abundant ```

Question 299

where aeolian deposits are formed

Answer 299

``` deserts 20-30ºN,S of equator centre of large continent rain shadows area of persistent high pressure (dry defending air) recently deglaciated areas ```

Question 300

wind weathering

Answer 300

1000th density of water less effective at eroding most effective with no vegetation only transports coarse sand

Question 301

Loess

Answer 301

silt and clay suspended in wind | carried furthest

Question 302

silt and sand transported by wind

Answer 302

silt and sand- saltation | med and fine sand- rolling, carried

Question 303

deflation lag

Answer 303

coarse sediment left behind leaves desert pavement | left behind sed is sandblasted

Question 304

desert structures form

Answer 304

disruption of wind flow by obstacle---wind shadow in which grains are deposited-- accumulate self generating increase in size dunes migrate in direction of wind (except draas)

Question 305

aeolian sediment characteristics

Answer 305

``` very well sorted texturally mature relatively fine grained very well rounded grains often pitted and frosted/sandblasted sand typically quartz rich loess deposits silt sized ```

Question 306

different types of dunes depend on

Answer 306

wind direction/consistancy/speed obstacles type/amount of sediment

Question 307

types of dune

Answer 307

``` barchan transverse draa sief parabolic ```

Question 308

Barchan dune

Answer 308

little sediment constant wind direction up to 30m tall (small) crescent shaped

Question 309

transverse dune

Answer 309

``` lots of wind and sediment accumulate at right angles constant wind direction up to 200m high up to 3km wide ```

Question 310

sief dunes

Answer 310

``` extremely long lots of wind, high velocity little sediment not unidirectional--converging wind 3-100m high up to 100km long (very long) ```

Question 311

Star/Draa dune

Answer 311

irregular shaped- multiple wind directions | highest- up to 450m high

Question 312

parabolic dune

Answer 312

coastal dunes blown out vegetation-strong winds erode a section of the vegetated sand sand from the blowout is deposited on the opposite slope Vegetation holds the "arms" in place as the leeward "nose" migrates forward

Question 313

aeolian deposit characteristics

Answer 313

medium-large scale high angle 30-35º planar tabular cross bedding up to 35m thick SS planes mainly horizontal thicks sets x-beds, thin upwards fossils rare less of tangential base than alluvial systems extent dependent on amount of sed. and wind

Question 314

aeolian environments

Answer 314

dunes interdune areas sheet sand environment

Question 315

interdune area

Answer 315

receive windblown sed and ephemeral stream sed

Question 316

sheet sand environment

Answer 316

around margins of dune field no active sand movement opportunity for vegetation/ bioturbation ephemeral rivers present

Question 317

sand sheet deposits

Answer 317

flat sand bodies low-mod. dipping 0-20º cross bedding interbedded with ephemeral stream deposit bioturbation common

Question 318

interdune deposits

Answer 318

erosion>deposition---deflation,desert pavement deposition>erosion: dry- ripples, grain flows, more poorly sorted, gently dipping, extensive bioturbation wet- lakes, ponds, silts, clays, bioturbation, evaporitic-dessication cracks

Question 319

present glacial environments

Answer 319

10% earths surface high latitudes Antractica- 86% earths glaciated area greenland- 11%

Question 320

past glacial environments

Answer 320

larger parts of globe during icehouse times snowball earth- 3 separate major advances pleistocene- 30% earth covered

Question 321

glacial depositional environments

Answer 321

complex, involve fluvial, lacustrine, shallow marine Glacial- in contact proglacial- influenced, not in contact

Question 322

ice sediment transport

Answer 322

``` high viscosity

Question 323

glacial sediment comes from

Answer 323

abrasion, quarrying, plucking as glacier erodes, falling and sliding from valley sides

Question 324

glacial sediment is deposited in

Answer 324

moraines

Question 325

Glacial deposits directly from ice

Answer 325

till/diamict | stratified diamict

Question 326

till/diamict

Answer 326

unstratified very poorly sorted pebbles/cobbles/boulders in matrix of sand/silt/cly pebbles striated/polished angular/subangular

Question 327

stratified diamict

Answer 327

till reworked by meltwater in/on/around glacier some stratification better sorted often associated with slump structure

Question 328

consolidated glacial sediment

Answer 328

tillite/diamictite

Question 329

esker

Answer 329

subglacial meltwater stream (under glacier) deposit | better sorted, rounded, less fine, bedding

Question 330

proglacial environments

Answer 330

glaciofluvial (braided) glaciolacustrine (lakes) glaciomarine

Question 331

glaciofluvial deposit

Answer 331

stratified massive gravels - L bars | cross bedded sands - T bars

Question 332

glaciolacustrine deposit

Answer 332

varved deposit with dropstones

Question 333

varved deposit

Answer 333

repetitive sedimentary rock stratification either bed or lamination, deposited within a one-year time period may comprise paired contrasting laminations of alternately finer and coarser silt or clay, reflecting seasonal sedimentation (summer and winter)

Question 334

varve anatomy

Answer 334

winter layers smaller and dark | summer layers thicker and lighter

Question 335

glaciomarine deposits

Answer 335

coarse fans, poorly sorted, poorly stratified, diamict marine fossils

Question 336

diamict

Answer 336

sediment that consists of a wide range of nonsorted to poorly sorted terrigenous sediment

Question 337

Heterolithic bedding

Answer 337

interbedded deposits of sand and mud tidal flats, glacial environments alternations in sediment supply and tidal velocity flaser, wavy, and lenticular

Question 338

Flaser bedding

Answer 338

sand deposit > mud deposit ripples with isolated mud drapes in ripple troughs and crests concave when the bed is upright

Question 339

Wavy bedding

Answer 339

mud deposit = sand deposit mud is deposited over the whole area of a bed of rippled and/or cross stratified sand concave-convex nature of the ripples creating a wavy appearance Wavy bedding marks the boundary between flaser and lenticular bedding

Question 340

Lenticular bedding

Answer 340

sand ripples are deposited in mud in an isolated distribution pattern ripples laterally and horizontally discontinuous

Question 341

convolute bedding

Answer 341

complex folding and crumpling of beds or laminations found in fine or silty sands usually confined to one rock layer

Question 342

slump structure

Answer 342

usually in sandy shales and mudstones displacement and movement of unconsolidated sediments areas with steep slopes and fast sedimentation rates often faulted

Question 343

dish structure

Answer 343

thin, dish-shaped formations normally occur in siltstones and sandstones 1 cm - 50 cm in size result of dewatering

Question 344

ancient glacial deposit features

Answer 344

``` very poor sorting striated clasts extreme variation in clast type/size lack stratification unfossiliferous ```

Question 345

ancient proglacial deposit features

Answer 345

somewhat better sorted than glacial deposit some stratification associated with outwash braided deposits, varied lacustrine clays, dropstones

Question 346

Environment you'd expect from a major river with large sediment load

Answer 346

Delta

Question 347

environment you'd expect from abundant sediment with a small tidal range and large wave induced currents

Answer 347

Spits, beach, barrier island

Question 348

environment you'd expect to find in a coastal area with little sediment and dominant tidal influences

Answer 348

estuaries, tidal flats, tidal influenced lagoons

Question 349

major sediment transport processes on beaches

Answer 349

longshore drift, rip current

Question 350

Types of tides

Answer 350

microtidal mesotidal macrotidal

Question 351

microtidal

Answer 351

0-2m

Question 352

mesotidal

Answer 352

2-4m

Question 353

macrotidal

Answer 353

>4m

Question 354

what influences the energy of tides

Answer 354

tidal current velocity

Question 355

longshore sediment transport is the results of

Answer 355

oblique breaking waves from longshore currents

Question 356

cause of rip current

Answer 356

as water hits the beach it can't all go back the same way- forms a narrow concentrated channel and increases velocity to allow large amount of water to flow back

Question 357

where is the highest energy between waves and beach

Answer 357

breaker zone

Question 358

swash backwash in the sediment record

Answer 358

very low angle (2º) seaward dipping laminations

Question 359

sediment sources to a beach

Answer 359

rivers, wind, coastal cliff slumping/erosions

Question 360

summer beach

Answer 360

low energy waves, beach builds up

Question 361

winter beach

Answer 361

high energy storm waves, beach eroded away + hummocky sequences off shore

Question 362

sedimentary structure you would expect from lower shoreface

Answer 362

hummocky/swaley cross stratification

Question 363

sedimentary structures you would expect from upper shoreface

Answer 363

small scale cross stratifications, truncated wave ripples

Question 364

if sea level is dropping what type of grading

Answer 364

reverse, CUS

Question 365

sedimentary structures in tidal channel

Answer 365

herringbone cross stratification, most likely sand

Question 366

sediment structures in tidal flats

Answer 366

flaser, linsen, wavy bedding, bioturbation, algal mats | most likely muds

Question 367

highest energy of tidal system

Answer 367

closest to the opening

Question 368

determining feature of tidal environments

Answer 368

reducing environments-- anoxic (smells)

Question 369

much of the worlds coal, oil and gas reserves

Answer 369

Deltas | ex. Western Canada sedimentary basin

Question 370

factors influencing delta deposits

Answer 370

input | basin

Question 371

important factors of the basin in determining delta deposit

Answer 371

shape, salinity, tectonic regime, basinal processes

Question 372

important factors of the input in determining delta deposits

Answer 372

fluvial regime, sediment input

Question 373

Delta classifications

Answer 373

wave dominated tide dominated river dominated

Question 374

delta parts

Answer 374

Subaerial: upper delta plain, lower delta plain Subaqueous: delta front, prodelta

Question 375

Upper delta plain

Answer 375

above high tide, dominated by meandering/braided channel deposits, floodplain swamps, lakes

Question 376

lower delta plain

Answer 376

between high and low tide levels, active distributary system, interdistributary bays

Question 377

delta front

Answer 377

high energy marine, extends up to 10m depth

Question 378

prodelta

Answer 378

finer sediments, sediment gravity flow, slumps

Question 379

delta extent

Answer 379

up to 10's of km's, 300m depth

Question 380

deltas are classified by

Answer 380

balance between river input and basin

Question 381

wave dominated deltas

Answer 381

have parallel beaches (perpendicular to river flow)- sed is rapidly reorganized and moved down coast distributary channel progradation is restricted high sorting- high reservoir potential not much mud ripples, low angle from swash and backwash

Question 382

tide dominated deltas

Answer 382

channel becomes aligned with tidal current tides go up distributaries ~equal mud and sand some mouth bars herringbone x-strati in sandstones (channels) flaser, wavy, linsen in finer materials

Question 383

fluvial dominated

Answer 383

lobate or 'birds foot', sand mouth bars

Question 384

why a prodelta can be seen

Answer 384

less dense than marine water, floats overtop (including the brown silt)

Question 385

delta effects

Answer 385

increased nutrients for organisms some organisms can't tolerate fresh water a boat going from dense salty water to fresh can sink

Question 386

delta progradation sequence

Answer 386

coarsening upwards | laminated clay, laminated silt, x-bedded sands, sandstone

Question 387

when coarser sediments are deposited on top of wet muds this can form

Answer 387

Diapir - may be a dome, mushroom, dyke, wave, teardrop

Question 388

Diapir importance

Answer 388

form structures that can trap hydrocarbons

Question 389

upper delta plain deposits

Answer 389

meandering channel deposits | floodplain deposits

Question 390

lower delta plain deposits

Answer 390

distributary channel sands interdistributary muds/peat thin sand wedges (crevasse splays)

Question 391

subaqueous delta sediments characterized by

Answer 391

soft sediment deformation, slumping, diapirs

Question 392

delta front deposits

Answer 392

well sorted | x bedded sands (distributary mouth bars)

Question 393

prodelta deposits

Answer 393

laminated silts/clays

Question 394

delta deposit cross section shape

Answer 394

wedge or lense

Question 395

delta sequence recognition

Answer 395

nomarine fluvial grading into shallow marine sands and muds

Question 396

continental margin

Answer 396

shelf, slope, and rise

Question 397

continental shelf

Answer 397

shoreline - shelf break ~0.1º slope average width (today) - 75km average water depth ~130m

Question 398

continental slope

Answer 398

4º slope

Question 399

continental rise

Answer 399

gentler slope, from sub fans at base of slope 3000-4500m

Question 400

continental shelf environment

Answer 400

low energy, little/no slope, relatively shallow pericontinental or epicontinental sea level change has large effect

Question 401

continental shelf sedimentary regimes

Answer 401

siliciclastic | carbonate

Question 402

siliciclastic shelf features

Answer 402

most common today, dominated by tides/storms, narrow, cool, relic and normal sediment, not good model for ancient shelves

Question 403

carbonate shelf features

Answer 403

most common during greenhouse, dominated by chemical/biochemical processes, wide, warm shallow, less river input, small proportion today

Question 404

relic sediment

Answer 404

coarse gravel and sand, from lower sea level glaciations, doesn't match current water depth and energy

Question 405

normal shelf sediment

Answer 405

sand and mud, from river inflow, wind, erasing, cross bedding, bioturbation

Question 406

types of siliciclastic continental shelves

Answer 406

tide dominant | wave dominant

Question 407

tide dominant siliciclastic continental shelf

Answer 407

tidal velocity: 0.5-1.0 m/s meso tidal and macro tidal alternating sand and bioturbated muds over relict seds

Question 408

tide dominant siliciclastic shelf sedimentary structures

Answer 408

``` sandwaves sand ridges/ribbons sand/gravel sheets sand- herringbone mud- mottled, small x-laminations, flaser and linsen ```

Question 409

sandwaves

Answer 409

few ms high, transverse, right angle to current, symmetric or asymmetric, x-bedded, >15,000km^2 areas, 100m wavelength

Question 410

sand ridges/ribbons

Answer 410

up to 40m high, 5km wide, 60km long, 5000km^2 area, parallel to flow, steep sided

Question 411

greater tidal ranges are due to

Answer 411

restricted flow

Question 412

Wave dominated shelves

Answer 412

predominate, low tide velocity <10m

Question 413

wave dominant shelf sediments

Answer 413

seaward fining, sed types depend on relict:modern, muds thoroughly bioturbated, hummocky intersect at low angles with 1-5m wave length and 25cm high, thin storm layers of coarser sed in finer muds possibly graded

Question 414

windows

Answer 414

relict sand and gravel showing through modern

Question 415

recognition of shelf sediments

Answer 415

tabular geometry, extensive laterally, 100s of ms thick, hummocky, tidal features, storm layers, most preserved in geologic record, diverse fossils, influenced by sea level changes

Question 416

tide dominated sequence may be indicative of

Answer 416

sea level rising- burrows on top of herringbone

Question 417

storm dominated sequence may be indicative of

Answer 417

falling sea level- hummocky on top of burrows

Question 418

ocean basins occupy how much of earth surface

Answer 418

~65%

Question 419

why is ocean basin poorly preserved

Answer 419

sea floor is recycled

Question 420

source of sediment in deep ocean

Answer 420

suspension settling (pelagic), from rivers, storms, ice debris, sub canyons, biogenies, MORs, wind, volcanogenic, meteoritic

Question 421

deep sea sediment types

Answer 421

terrigenous/clastic, pelagic

Question 422

terrigenous sediments

Answer 422

deposit close to continent margin, mostly derived from shelf, accumulate at base of slope (form rise), turbidity currents very important, hemipelagic muds, sed gravity flows, slumps, slides

Question 423

Hemipelagic muds

Answer 423

sediments deposited on shelves and rises, accumulate too rapidly to react chemically with seawater, individual grains retain characteristics imparted to them in the area where they formed

Question 424

pelagic deep sea sediments

Answer 424

mainly clay sized, slow settling of suspended particles, planktonic remains (siliceous and calcareous), terrigenous (wind born, ice rafted), volcanogenic, meteorite dust, terrigenous red clays

Question 425

where do you diatom remains

Answer 425

near poles (silica)

Question 426

where do you get radiolaria remains

Answer 426

near equator (silica)

Question 427

can determine velocity of turbidity current from

Answer 427

bouma sequence- erosional powers

Question 428

Red clays

Answer 428

background sediment, siliciclastic muds, red/brown (oxidized), slow sedimentation, 34% of deep seafloor, volcanic/windblown/meteorite/sharks teeth/ice debris lots of Fe

Question 429

Biogenic pelagic sediment

Answer 429

siliceous ooze | calcareous ooze

Question 430

siliceous ooze

Answer 430

>30% biogenic ----chert Diatoms, Radiolaria, sponge spicule water depths >4500m

Question 431

calcareous ooze

Answer 431

>30% biogenic----chalk foaminifera, pteropods, coccolithophores warm surface water <4500m

Question 432

Pelagic sediment controls

Answer 432

primary productivity- availability of nitrate, P, Fe, O, C, Si -upwelling -solar radiation (euphotic zone) -CCD

Question 433

CCD

Answer 433

calcite compensation depth <4500m level which rate solution of calcite is balanced by rate of supply above CCD calcareous ooze accumulate, below dissolution varies with space and time

Question 434

why CCD higher in some parts of the oceans

Answer 434

higher at equator to compensate for higher productivity

Question 435

why CCD different in time

Answer 435

compensate for heightened removal/addition of calcite and dissolve Ca CO3 Greenhouse periods-- CCD moves up (compensate for high productivity)

Question 436

average depth of deep ocean

Answer 436

4-5km

Question 437

Carbonate shelf environment

Answer 437

low latitude ~30º N and S (equatorial belt) shallow 10m depth clear water - low terrigenous input

Question 438

types of carbonates

Answer 438

shallow water marine: tropical/subtropical, temperate (largest carbonate contribution) Deep water pelagic: oozes (very slow sedimentation) Freshwater carbonates: Tufa

Question 439

main site of carbonate production

Answer 439

middle-outer shelf "sub tidal carbonate factory"

Question 440

types of carbonate shelves

Answer 440

rimmed, unrimmed, ramp, isolated platform, epicontinental seas, epeiric platform

Question 441

Tufa

Answer 441

a variety of limestone, formed by the precipitation of carbonate minerals from ambient temperature water bodies

Question 442

Rimmed carbonate shelf

Answer 442

outer edge pronounced break in slope (lagoon-reef) | Great Barrier reef

Question 443

unrimmed carbonate shelf

Answer 443

open shelf, no pronounced marginal barrier

Question 444

Ramp carbonate shelf

Answer 444

gently sloping ~1º into deeper water

Question 445

Isolated platform carbonate shelf

Answer 445

10s-100s ams wide, offshore platform surrounded by deep water Bahamas

Question 446

processes of carbonate sedimentations

Answer 446

chemical precipitation biogenic precipitation physical processes

Question 447

chemical precipitation carbonate sedimentation

Answer 447

from supersaturated waters, increases with T, pH, water agitation increase ex. whiting in persian gulf, oolite formation

Question 448

biogenic precipitation carbonate sedimentation

Answer 448

MOST important of carbonate processes, very high rates | ex. organisms and fine aragonite mud

Question 449

physical processes carbonate sedimentation

Answer 449

waves (storms, hurricanes), tidal currents, gravity moving allochems/matrix, forming sed. structures

Question 450

what kinds of carbonate would you expect at inner shelf

Answer 450

Micrite- shoreline low energy

Question 451

what kinds of carbonate would expect at middle shelf of rimmed platform

Answer 451

Micrite- most extensive, low energy, no spa rite, no pore spaces

Question 452

what kinds of carbonate would you expect at outer shelf of rimmed platform (rim)

Answer 452

reef with reef breaks for tidal channels sparite on middle shelf side of reefs ooids/shell frags/sparite/biosparite in middle of reefs rouger shell frags and bioclastic sand bars on outer reefs

Question 453

laminations

Answer 453

<1cm

Question 454

what doesn't tell you anything about deposition

Answer 454

diagenetic features

Question 455

outer carbonate shelf

Answer 455

highest energy, productive, precipitation from wave action reefs, sand shoals, shelf break lime sand, gravel shoal, lag deposit of ooids, skeletal material, broken bits of reef well sorted, cross bedded very low angle (swash/backw) bioclastic/oolitic grainstone, bio/oosparites, reef limestones in tidal channel- herringbone

Question 456

carbonate shelf rims

Answer 456

reefs, shoals

Question 457

folk classification

Answer 457

composition based

Question 458

dunham classification

Answer 458

texture based

Question 459

middle carbonate shelf

Answer 459

low energy, below wave base, often restricted circulation, high carbonate production, mostly mud (lime mud, skeletal sands, peloids, gravestones), marine organisms, extensive bioturbation, extensive (common in geological record)

Question 460

marine organisms normal to middle carbonate shelf

Answer 460

brachiopods, pelycopods, gastropods, crionids, echinoids, algae, bryozoa

Question 461

inner carbonate shelf

Answer 461

low energy, tidal flat environment (peritidal), fine grained sediment, type of shelf depends on climate, restricted fossils, tide more important than wave, micrite rich

Question 462

Humid environment carbonate shelf

Answer 462

algal mats, thin storm beds

Question 463

Arid environment (sabkhas) carbonate shelf

Answer 463

desiccation cracks, evaporite minerals

Question 464

inner carbonate shelf organisms/structures

Answer 464

stromatolites, pelleted mudstones, nodular anhydrite/gypsum, genestral laminated mudstones

Question 465

outer carbonate shelf rocks

Answer 465

well sorted, cross bedded, bioclastic oolitic grainstones, bio/oosparites and reef limestones

Question 466

middle carbonate shelf rocks

Answer 466

not so well sorted, abundant micrite, wackestones (biomicrites)

Question 467

inner carbonate shelf rocks

Answer 467

stromatolites, pelleted mudstones, nodular anhydrite/gypsum, fenestral laminated mudstones

Question 468

colour of micrite rich rock

Answer 468

dark

Question 469

colour of sparite rich rock

Answer 469

lighter

Question 470

geologic record carbonates

Answer 470

epieiric or epicontinental shelves mostly generally micritic carbonates normal organisms, influenced by storms and tides dominated by shallowing upward cycles reflect evolution of invertebrate organisms

Question 471

order of evaporite precipitation

Answer 471

carbonates, sulfates, halides

Question 472

evaporites are

Answer 472

intrabasinal chemical sedimentary deposits | precipitate from solution, concentrated by evaporation

Question 473

evaporite environments

Answer 473

marine sabkhas, marine shallow barred basins/seas, non-marine semiarid playas

Question 474

main sulphate

Answer 474

gypsum (anhydrite in dryer settings)

Question 475

sabkha

Answer 475

supra tidal salt flat, forming along arid coastlines | fine grained material, tidal-dessication cracks

Question 476

shallow barred marine evaporite environment

Answer 476

none present day | repeatedly recharged to obtain thick sequences

Question 477

non-marine evaporite environment

Answer 477

``` different salts than marine environments, depend on material deposited from weathering desert associations (intermittent/playa lakes) ```

Question 478

stratigraphy involves

Answer 478

subdividing and managing sequences of strata dating correlation interpreting

Question 479

dating of stratigraphy

Answer 479

placing sections in sequential order (relative dating)

Question 480

correlation of stratigraphy

Answer 480

determining which events happened at the same time

Question 481

breaks in stratigraphic record are due to

Answer 481

``` base level changes (more/less erosion, lack of deposition) tectonic activity (subduction, metamorphism) ```

Question 482

most of geologic scale is from

Answer 482

precambrian

Question 483

paleosols

Answer 483

'fossil soils' found within either sedimentary or volcanic deposits

Question 484

hardgrounds

Answer 484

is material (mostly those that trickle down onto the ocean floor) that has been compacted, de-watered, and cemented into rock and can usually be found at the bottom of a column of water where the water has been above the sediment for a while

Question 485

evidence that there are gaps in the record

Answer 485

bedding planes, hardgrounds, paleosols, major environment changes, unconformities

Question 486

types of unconformities

Answer 486

Paraconformities Disconformitites Angular unconformities

Question 487

paraconformities

Answer 487

missing fossils, difficult to see, between horizontal beds

Question 488

disconformitites

Answer 488

erosional surfaces and features, between horizontal bed but can see erosional surface

Question 489

angular unconformity

Answer 489

tectonism, horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers

Question 490

depositional events most likely to be preserved

Answer 490

big events, large changes, below base level, high magnitude: volcanic eruption, turbidity current, earthquake, tsunami, glacial changes, flooding

Question 491

ways to divide sedimentary record

Answer 491

biostratigraphy (evolution), lithostratigraphy (rock types), chronostratigraphy (age), magnetostratigraphy (paleomagnetic reversals), sequence stratigraphy (sea level changes), seismic stratigraphy

Question 492

lithostratigraphy fundamental unit

Answer 492

formation

Question 493

formations

Answer 493

consist dominantly of a certain lithology or combination thicknesses 1-1000s ms tabular may not be same age everywhere recognized named for geographic location

Question 494

formations subdivided into

Answer 494

members

Question 495

formations are part of a

Answer 495

groups

Question 496

vertical contacts between facies

Answer 496

abrupt gradational intercalated (all conformable)

Question 497

a conformable contact indicated

Answer 497

that no significant break in deposition has occurred

Question 498

abrupt contact

Answer 498

sudden, distinct, changes in lithology

Question 499

gradational contact

Answer 499

one lithology grades into another by progressive, uniform changes in grain size, composition, or other physical characteristic. ex. sandstone that gets progressively finer up until mudstone

Question 500

intercalated contact

Answer 500

increasing number of inter bedding that appears later in the section ex. sandstone--sandstone/mudstone interbedded---mudstone

Question 501

example of laterally very extensive lithology

Answer 501

high sea level carbonate shelf

Question 502

types of lateral changes in lithology

Answer 502

pinchouts intertonguing lateral gradation

Question 503

lateral facies changes represent

Answer 503

different parts of, or different depositional environments

Question 504

pinch-out

Answer 504

a lateral change in lithology accompanied by progressive thinning of units to extinction

Question 505

intertonguing

Answer 505

lateral splitting of a lithologic unit into many thin units that pinch-out independently

Question 506

lateral gradation

Answer 506

where one lithology grades onto another laterally by more or less uniform changes in grain size, mineral composition, or other physical characteristics

Question 507

Walthers law of facies

Answer 507

facies that occur in conformable vertical successions of strata occupy laterally adjacent environments

Question 508

how do facies shift laterally

Answer 508

shifts in environments locally, changes in rate of influx, sea level changes

Question 509

shifts in environments shifting facies

Answer 509

delta distributary avulsion, glacial retreat, river channel migration

Question 510

avulsion

Answer 510

rapid abandonment of a channel and formation new channel, occur as a result of differing channel slopes due to high sediment input

Question 511

changes in rate influx shifting facies

Answer 511

tectonism, changing climatic conditions (changes in erosion/weathering), system progradation

Question 512

eustatic sea level changes

Answer 512

glacial formation/melting, changes in water temperature, rate of seafloor spreading

Question 513

local sea level changes

Answer 513

local downwarping, subsidence, sediment aggradation, isostatic rebound

Question 514

aggradation

Answer 514

increase in land elevation due to the deposition of sediment

Question 515

isostatic rebound (isostasy)

Answer 515

the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period

Question 516

regression

Answer 516

relative lowering in sea level shoreline 'moves out' coarsening upward sequence produce thick sequences, not as likely to be reworked

Question 517

transgression

Answer 517

relative rise in sea level shoreline 'moves landward' fining up sequence more erosive, seeds reworked before burial, lower preservation

Question 518

diachronous

Answer 518

all parts of a formation are not the same age

Question 519

tsunamite

Answer 519

tsunami sequence, angular rip up clasts ~20inch, between layered shelf sediments

Question 520

stratigraphic cycles

Answer 520

first order (super cycles) second order third order fourth order

Question 521

supercycles

Answer 521

100's of my, major plate movements, formation/break up of supercontinents, icehouse/greenhouse periods

Question 522

second order cycles

Answer 522

10's of my, changes in MOR volume/sea floor spreading rates (SLOSS CYCLES), eustatic fast sea floor spreading- high sea level, mantle convects rapidly, core cool and quiet slow spreading- low sea level, strong stable mag. field, core hot and turbulent

Question 523

third order cycles

Answer 523

1-10 my, not eustatic, shorter cycles superimposed on 1st and 2nd order cycles, may be from local tectonic subsidence

Question 524

fourth order cycles

Answer 524

100's of 1000's of years, changes in global ice volume and climate, milankovitch cycles, earth orbital geometry

Question 525

icehouse times in supercycle

Answer 525

extensive polar ice caps, steep T gradients from pole to equator, low sea level, mean ocean T ~3º, mantle activity slow, little volcanism, supercontinents

Question 526

greenhouse times in supercycle

Answer 526

no polar ice cap, T gradient less steep, high sea level, average ocean T ~15º, major plate motion, increase in volcanism, large volume of greenhouse gases, traps solar radiation, warms earth, breakup supercontinents

Question 527

extracts CO2

Answer 527

weathering

Question 528

adds CO2

Answer 528

volcanism

Question 529

basis for the geological time scale

Answer 529

biostratigraphy

Question 530

law of faunal and floral succession

Answer 530

rocks formed during any particular interval of geological time can be recognized and distinguished by their fossil content because identical assemblages do not recur

Question 531

biostratigraphic subdivisions

Answer 531

biozones

Question 532

biozone

Answer 532

characterized by fossil content ranges- FAD LAD index fossils independent of thickness, lithology, or geographic extent

Question 533

useful paleozoic fossils

Answer 533

trilobites, graptolites, ammonoids, conodonts, fusulinids

Question 534

useful mesozoic fossils

Answer 534

ammonites

Question 535

useful cenozoic fossils

Answer 535

planktonic foraminifera, radiolaria, coccolithophores, pollen

Question 536

Index fossils

Answer 536

abundant, preserved hard parts, morphologically distinct/easily identifiable, wide geographic distribution, short stratigraphic range (rapid evolutionary turnover), swift migration, relatively in depended of environment and lithology

Question 537

best index fossils

Answer 537

pelagic, plaktic, free swimming nekto-benthic, unaffected by bottom facies conodonts, graptolites, ammonoids, foramanifera

Question 538

types of biozones

Answer 538

interval zones assemblage zones abundance/acme zones

Question 539

interval zones

Answer 539

1-3 index fossils, different overlaps

Question 540

types of interval zones

Answer 540

``` concurrent range zone taxon range zone (total range) lineage zone (consecutive range) interval zone ```

Question 541

assemblage zone

Answer 541

biozone defined by >3 taxa

Question 542

acme zone

Answer 542

characterized by exceptional abundance of certain taxa- not having to do with evolution or age more having to do with environmental

Question 543

concurrent range zone

Answer 543

defined by overlap of multiple taxa ex. A FAD before strata, LAD at end of strata B FAD start of strata, LAD after strata C FAD and LAD outside of strata in question

Question 544

total range zone

Answer 544

biozone defined by total or local range of one taxon

Question 545

lineage zone

Answer 545

biozone defined by the range of one taxon B, of lineage A--B--C defined by the evolution of B

Question 546

LAD

Answer 546

last appearance datum, either local or global

Question 547

FAD

Answer 547

first appearance data, either local or global

Question 548

assemblage biozone

Answer 548

3 or more taxa in a natural assemblage or association | numerous FADs and LADs

Question 549

causes of missing fossil/species in sections

Answer 549

environmental changes, slow rate of dispersal from origin, barriers to dispersal, local extinction, locally incomplete successions, locally incomplete sampling, preservation biases, evolution into new unrecognized form

Question 550

minimum duration of a biozone depends on

Answer 550

rate of evolution

Question 551

average species duration

Answer 551

2my - 20-30my

Question 552

resolution of biostratigraphy

Answer 552

better than radiometric dating | errors: +/- 12my

Question 553

lateral distribution of fossils controlled by

Answer 553

migration times, barriers to migration

Question 554

barriers to migration

Answer 554

mountains, oceans, climate, salinity

Question 555

distribution of fossils within a biozone

Answer 555

faunal provinces

Question 556

biozone limitations

Answer 556

entire potential lateral space is rarely filled with the organism

Question 557

faunal provinces and realms

Answer 557

areas within which a group of distinctive animals or plants are uniformly distributed

Question 558

what are the three groupings of sedimentary materials?

Answer 558

resistates, secondary minerals, dissolved ions

Question 559

biozone, formation difference

Answer 559

biozones determined by evolution | formations determined by changes in environment

Question 560

diachronous

Answer 560

a sedimentary rock formation in which apparently similar material varies in age from place to place ex. quaternary glacial seds not yet deposited in greenland

Question 561

marker beds

Answer 561

Isochronous: ash beds, coals, chalk, distinctive patterns

Question 562

isochronous

Answer 562

occurring at the same time

Question 563

correlation with lithostratigraphy

Answer 563

diachronous, more useful locally, doesn't require specialized knowledge, regionally need to use marker beds

Question 564

correlation with biostratigraphy

Answer 564

isochronous, fossil assemblages are unique, independent of rock type, good regionally, require specialized knowledge, harder to do in field (microfossils), migration barriers may lead to faunal provinces, need fossils that carry over between diff. environments

Question 565

other globally synchronous correlation options

Answer 565

cretaceous iridium layer, magnetostratigraphy, eustatic sea level curves (sequence stratigraphy)

Question 566

chronostratigraphy

Answer 566

age of strata, geologic time scale, numerical ages applied to relative time scale based on fossil content in composite standard reference section

Question 567

chronostratigraphy has two units

Answer 567

Period- time interval- geochronologic | Rocks formed in that period- chronostratigraphic

Question 568

Time units

Answer 568

eon, era, period, epoch, age, chron

Question 569

Time-rock units

Answer 569

eonothem, erathem, system, series, stage, chronozone

Question 570

calibrates geologic time sclae

Answer 570

radiometric age dating

Question 571

other methods of numerical dating

Answer 571

short periods of time, locally | tree rings, varies, shell growth increments

Question 572

radiometric dating issues

Answer 572

``` decay constant imprecise only volcanogenic seeds can be dated closure temperature uncertainty sampling uncertainty weathering- loss of parent/daughter ```

Question 573

C14 dating

Answer 573

only up 60-80,000yrs | half-life : 5730

Question 574

magnetostratigraphy

Answer 574

reversals due to instabilities in outer core, synchronous agin, primarily igneous rocks

Question 575

types of magnetic signatures

Answer 575

TRM, DRM, CRM

Question 576

TRM

Answer 576

thermal remanent magnetisation | magma cools- hematite/magnetite minerals align- cool through curie pt. (500-600ºC)- orientation 'frozen'

Question 577

DRM

Answer 577

detrital remanent magnetisation magnetic minerals rotate in unconsolidated sediment to align to earth field, frozen upon lithification, 2-3 orders weaker, less stable

Question 578

CRM

Answer 578

chemical remanent magnetization | orientation of chemically precipitated hematite cement, difficult to tell when it formed

Question 579

contemporaneous

Answer 579

existing or occurring in the same period of time

Question 580

reversals take place

Answer 580

over 1000-2000 years, decrease in intensity in ~10,000 years before, followed by buildup over the next 10,000 years

Question 581

fundamental units of magnetostratigraphy

Answer 581

polarity zones | subzones

Question 582

polarity zones

Answer 582

longer than 10,000 yrs | single direction of polarization or distinct alternation

Question 583

subzones

Answer 583

10,000-100,000 years | named after important geographic locations

Question 584

magnetostratigraphy applications

Answer 584

Geochronology- date fossil zones and stratigraphic boundaries- high resolution -most useful in last 5-7my -worldwide correlation of lithos. units and biostrat units (across faunal provinces)

Question 585

Basins are controlled by

Answer 585

plate tectonics geological history of plate type of crust latitude of basin

Question 586

plate tectonics in basin control

Answer 586

margin interaction- divergent, convergent, transform | flexural movement within plate

Question 587

geologic history of plate

Answer 587

plate may have several different basin types of different ages

Question 588

type of crust in basin control

Answer 588

ocean or continental, sediment type, different depositional environments

Question 589

Basin stress environments

Answer 589

extensional- divergent margin compressional- convergent margin shear- transform margin

Question 590

Extensional

Answer 590

symmetrical basins, concave up, normal faulted, associated with crustal stretching and thinning ex. rift valley basins

Question 591

Compressional

Answer 591

Assymetric basins, wedge-shaped, thrust faulted, associated with crustal thickening, stacking of thrust slices, loading, subsidence ex. foreland basins

Question 592

sedimentation on craton

Answer 592

platform sediments | basins

Question 593

platform sediments

Answer 593

~1km thick, lots of unconformities, very mature sed, marine-non-marine, mostly shallow water carbonate, sandstones, evaporites

Question 594

craton basins

Answer 594

broad shallow bowl shaped system, affected by global cyclicity pattern, on continental crust, up to 4.5km thick, interiors of continents, marine-non-marine, more complete sequence than platform

Question 595

Divergent margin basins

Answer 595

very extensive and thick, excellent record of plate margin interactions and timing, major hydrocarbon reserves

Question 596

Development- Wilson Cycle

Answer 596

~80my, rift domal uplift--rift stage--proto-ocean gulf stage--normal ocean stage

Question 597

Rift domal uplift

Answer 597

continent over deep mantle plume, heating causes expansion

Question 598

Rift stage

Answer 598

rift valleys from normal faulting, continental basement | coarse, immature sed., alluvial fan, fluvial, lacustrine, evaporite sed.

Question 599

graben

Answer 599

depressed block of land bordered by parallel faults

Question 600

Proto-ocean gulf stage

Answer 600

ocean crust starts to form, new ocean-restricted seaways fluvial and lacustrine at margins, deltas, marine basins containing thick evaporites, black organic shales/carbonates, deep pelagic sediment

Question 601

normal ocean stage

Answer 601

ocean crust, fully developed MOR | few active faults, prograding wedge of sediment, pelagic oozes over most of sea floor

Question 602

Convergent margin basins

Answer 602

compressional stress, not extensively explored

Question 603

types of convergent margin basins

Answer 603

ocean-ocean / ocean-continent | continent-continent

Question 604

ocean- O/C convergence

Answer 604

subduction zones, magmatic arc basins

Question 605

continent-continent convergence

Answer 605

foredeeps, foreland basins

Question 606

o-o, o-c tectonic elements

Answer 606

Trench, Accretionary wedge, Forearc basin, Backarc basin

Question 607

Trench

Answer 607

trough, narrow, steep sided, up to 11km deep, sediment deformed and overridden by subduction, some trenches empty others full

Question 608

oldest trench sediment

Answer 608

pelagic muds/oozes

Question 609

trench pelagic muds overrlain by

Answer 609

turbidites and other sediment gravity flow deposits

Question 610

mass wasting and tectonic deformation develop

Answer 610

melanges and olistostromes on inner slope

Question 611

melange

Answer 611

large-scale breccia, body of rock characterized by a lack of continuous bedding and inclusion of fragments of rock of all sizes, consist of altered oceanic crustal material and blocks of continental slope sediments

Question 612

olistostrome

Answer 612

chaotic mass of heterogeneous material, such as blocks and mud, known as olistoliths, that accumulates as a semifluid body by submarine gravity sliding or slumping of the unconsolidated sediments

Question 613

Accretionary wedge/subduction complex

Answer 613

dominated by imbricate thrusts developed in a melange of pervasively sheared sediment debris. main constituents; ophiolites, melange

Question 614

in the depressions on top of the thrust slices you get

Answer 614

CU cycles, siltstone, claystone, distal turbidites, shelf sediments, calcareous/terrigenous sandstone, conlglomerate

Question 615

forearc basins

Answer 615

where subduction complex forms a ridge or terrace, may get depression in front of arc may get substantial thicknesses of sediment basins may be 100km wide, several 100km long

Question 616

forearc basin sediment

Answer 616

basal sediments deep marine shallows upward to shallow marine/delta overlain by fluvial sediment sediments derived from arc- lithic rich

Question 617

back arc basins

Answer 617

marginal seas often get extensional basins associated with volcanic arc sediment thickness may be 2-3km in basin centre deep marine environments except at margins

Question 618

back arc basin sediments

Answer 618

pelagic clays, oozes, volcaniclastic turbidite fans, wedge progades into basin (inter fingering with pelagics) as basin fills sediments coarsen and shallow up (pelagic mud--shelf sediments--marginal marine)

Question 619

c-c Basins (orogenic belts)

Answer 619

foreland basins- loading of crust, adjacent crust subsides

Question 620

foreland basin sequence

Answer 620

continental basement, passive margin platform sequence (ex. carbonates), major unconformity related to compression, deep water sediment, tubidites (flysch), sediments prograde into basin (shallow marine, marginal marine, alluvial), molasse

Question 621

Flysch

Answer 621

high sedimentation rate, mostly turbidity current, laterally continuous, thick sequences, unfossiliferous

Question 622

Molasse

Answer 622

prograding phase, shallower water and deltaic compexes filling the basin, sandstone and mudstone coarsening/shallowing up into alluvial fans, deltaic, and fluvial floodplains associated with coal deposits