Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EOS > Sedimentary Geology > Flashcards

Sedimentary Geology Flashcards

1
Q

Sedimentology

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

sedimentary petrology

A

sedimentary products, characteristics and origins of sedimentary rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Facies

A

depositional environments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sedimentary processes

A

weathering, erosion/transportation, deposition, diagenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Produce all sediments

A

sedimentary processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Non-marine facies

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Marginal marine

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

marine

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Best facies for sedimentary preservation

A

anoxic basin, deep ocean basin

  • low energy
  • below sea level
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Anything above sea level

A

erosional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

stratigraphy

A

distribution of sedimentary rocks in space and time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

environmental geology

A

waste disposal, groundwater flow, sinkholes, slope stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

engineering geology

A

building site, offshore cable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

structural geology

A

most features are only observable in sed rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

resource geology

A

water, Pb-Zn deposits, drilling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

percent of rocks at earths surface that are sedimentary

A

75%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

structural geology rock features

A

folds, faults, bedding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

why do we study sedimentary rocks

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Principle of uniformitarianism

A

the present is the key to the past

understanding the past is key to understanding the future

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Paleogeography

A

geography at a time in the past

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How we interpret past environments and geography

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

sediments as hosts to economic minerals

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

construction materials (from sedimentary rocks)

A

limestone, sand, gravel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Distribution of water on earth

A

Oceans 97.2% / Freshwater 2.8%

Glaciers 2.15% / Groundwater 0.62%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Aluminum resources

A

Bauxites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The study of sedimentary rocks is based on

A

observation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Observations

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

colour tells

A

fresh or weathered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

composition is

A

lithology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

texture includes

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

fossil observations

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

outcrop observations

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

When was sedimentary rock deposited? Are nearby units contemporaneous?

A

-earth history

fossil content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

contemporaneous

A

existing or occurring at the same period of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

cement

A

chemically precipitated

clasts are “glued” together later

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

matrix

A

fine grained, deposited at same time as clasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

matrix, or cement, which tells about depositional environment

A

matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What and where was source of sediment (Provenance)

A

-Geological history, Mineral exploration

Composition, directional structures, regional variations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What were transport processes?

A

-Mineral exploration, paleoclimate

Directional structures, texture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what was depositional environment?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How have the properties changed? (diagenesis)

A

-Reservoir/aquifer potential

porosity permeability change, composition, texture, secondary structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Sedimentary rocks have unique features/minerals because

A

low T and P (compared to igneous and meta)

in contact with all spheres (hydro, bio, atmo)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Sedimentary rock components

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Minerals unique to sedimentary rocks

A

Clays, carbonates, evaporites, iron oxides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

sandstone composition

A

up to 99% quartz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

granite composition

A

30-50% plag, 5-35% k-spar, 5-10% quartz

where does all the feldspar go

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Physical weathering processes

A

freeze-thaw, insolation, stress release, organic activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

insolation

A

thermal expansion and contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

exfoliation

A

stress release- from erosion of overlying materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

organic activity

A

burrowing, root growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

effects of physical weathering

A

breaks rock, disaggregates grains, increases surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

products of physical weathering

A

Lithic fragments
K-spar
Quartz
Muscovite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Chemical weather processes

A

dissolution, oxidation, hydrolysis, hydration/dehydration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Dissolution

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Oxidation

A

olivine, pyroxene, amphibole, biotite, pyrite

Fe2SiO6 + O2 + H2O —– 4Fe(OH)3 + H4SiO4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Fe2SiO6

A

pyroxene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Fe(OH)3

A

limonite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

CaSO4•2H2O

A

gypsum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

CaSO4

A

anhydrite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Deydration

A

gypsum

CaSO4•2H2O —– CaSO4 + 2H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Hydrolysis

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Kaolinite

A

Al2Si2O5(OH)4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

k-spar

A

KAlSi3O8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Products of chemical weathering

A

Secondary minerals: Clays, Oxides
Carbonates
Dissolved materials/ ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Effects of chemical weathering

A

changing/decomposing

totally new products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

types of clays

A

illite
smectite
kaolinite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

dissolution products

A

ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

oxidation products

A

hydroxides— hematite, limonite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

hydrolysis products

A

clays, ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

what do you need in reactant in order to form clay

A

Al

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

breakdown of granite

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

what do products of weathering depend on

A

source rock composition and stability

intensity, duration of weathering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Goldich Stability series

A

silicates weather in same order as Bowens rxn

OPABKMQ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

source rock residues of chemically resistant minerals and fragments

A

residual minerals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

residual minerals indicate

A

source rock and duration/type of weathering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

secondary minerals

A

clays, iron oxides, hydroxides

products of hydrolysis and oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

secondary minerals indicate

A

nature of weathering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

dissolved ions indicate

A

solubility of source minerals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Arctic weathering

A

freeze/thaw–lithics

chemical dissolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Desert weathering

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Temperate weathering

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Tropical weathering

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

feldspars weather to

A

clays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

differences between clays

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

mafic clay

A

chlorite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

felsic clay

A

illite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

How sedimentary minerals are sorted

A

Origin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

origins

A

siliclastic/extrabasinal

intrabasinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

siliclastic

A

transported clasts; residual and secondary minerals

-extrabasinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

siliclastic subdivisions

A

conglomerate
sandstone
mudstone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

mudstone subdivisions

A

siltstone

claystone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

conglomerate clast size

A

> 2mm –gravel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

sandstone clast size

A

2-0.0625mm —sand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

mudstone clast size

A

< 0.0625mm (1/16 mm) —mud

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

silstone vs. claystone

A

siltstone–gritty

claystone— not gritty

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

extrabasinal materials

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

intrabasinal

A

originate with basin

deposition of dissolved constituents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

Intrabasinal subdivisions

A

chemical

biochemical/biogenic/organice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

intrabasinal chemical types

A

evaporites

iron formations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

intrabasinal biochemical/biogenic/organic types

A

carbonates, chert, phosphates, carbonaceous material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

fossil compositions

A 
silica = chert
carbon = limestone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

fossil

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

are fossils clasts

A

no- clasts come from pre-existing rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

conglomerate

A 
>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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

why conglomerates don’t contain fossils

A

they form in high energy environments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

provenance

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

conglomerate composition

A

clasts- lithics/fragments and quartz

matrix and clays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

conglomerate subdivisions

A

orthoconglomerate

paraconglomerate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

orthoconglomerate

A

<15% matrix

clast supported

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

paraconglomerate

A

> 15% matrix

matrix supported

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

conglomerate depositional environments

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

how to tell glacial rocks from debris flow rocks

A

striations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

conglomerate sorting types

A

bimodal - fine + course

polymodal - large range of sizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

bimodal sorting could be formed from what environment

A

fluvial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

polymodal could be formed from what environment

A

glacial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

Sandstone

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

sandstone depositional environments

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

where are sandstones NOT formed

A

deep ocean

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

what are sandstones economically important for

A

construction material
glass
reservoirs
chemical industry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

sandstone subdivisions

A

Arenites

Wackes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

Arenites

A

<15% matrix

usually bound with cement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
122
Q

Wackes

A

> 15% matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
123
Q

arenites subdivisions

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
124
Q

Most common type of sandstone

A

Lithic Arenite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
125
Q

where might arkose form

A

desert, immature rocks rapidly burried

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
126
Q

what is needed to form Quartz arenite

A

high weathering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
127
Q

Mudstone

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
128
Q

mudstone subdivisions

A

Claystones….clay

Siltstone……..quartz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
129
Q

mudstones are classified by

A

color, fossil content, structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
130
Q

Carbonates

A 
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
131
Q

types of carbonates

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
132
Q

Carbonate economic importances

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
133
Q

carbonates are especially prevalent in what times

A

greenhouse times
ordovician/devonian
jurassic/cretaceous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
134
Q

carbonate depositional environments

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
135
Q

limestone components

A

Allochems
Micrite
Sparite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
136
Q

Allochem

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
137
Q

types of allochems

A 
bioclastic debris (skeletal)
coated grains (ooids, pisoids)
Peloids (pellets..no internal structure)
grain aggregates
intraclasts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
138
Q

Micrite

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
139
Q

Sparite

A

equivalent of ‘Cement’

coarse calcite crystals that fill pore spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
140
Q

Intrabasinal phosphates

A

not common

3 types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
141
Q

phosphate subdivisions

A

Bone beds
Guano deposit
Phosphorite nodule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
142
Q

Organic rich sedimentary rocks

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
143
Q

organic rich carbon sources

A

Humic… plants

Sapropelic….animal..ie. algae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
144
Q

organic rich sedimentary rock subdivisions

A

coal
oil shale
petroleum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
145
Q

Coal

A

most abundant O rich sed rock
Humic matter
combustible
energy source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
146
Q

Coal subdivisions (rank)

A

Peat
Lignite
Bituminous coal
Anthracite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
147
Q

oil shale

A

kerogen bearing mudstones

~25% organic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
148
Q

kerogen

A

microbial altered plant and animal organic matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
149
Q

Petroleum

A

natural gas

mature kerogen–burial + heat = hydrocarbons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
150
Q

greatest problem with burning coal

A

it acts like a sponge, contains every element

low rank coal - ‘tainted’ - huge pollution factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
151
Q

Iron rich sedimentary rocks

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
152
Q

Iron rich subdivisions

A

Banded Iron Formations (Precambrian)

Ironstones (Phanerozoic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
153
Q

BIF

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
154
Q

Phanerozoic ironstone

A 
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
155
Q

Ironstones prevelant in

A

greenhouse conditions
deep weathering, high sea level
less siliclastic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
156
Q

How are sedimentary materials transported

A

in solution…fluids- substances that flow

as solids.. gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
157
Q

Fluid characteristics important for transport

A

Density
Viscosity
Velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
158
Q

Density

A 
mass/unit volume
water = 1g/cm3
air 0.1g/cm3
ice 0.9g/cm3
larger particles transported in denser fluids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
159
Q

viscosity

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
160
Q

velocity

A

coast size potential increases with velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
161
Q

Hjulstrom curve

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
162
Q

gravity effects on transport

A

Gravity– F_G
holds grains on bed
causes grains to settle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
163
Q

Forces involved in transport

A

F_D…. drag/shear force

F_L…lift force.. Bernoulli effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
164
Q

if F_G > F_D, F_L

A

sediment remains on bed or settles out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
165
Q

if F_G < F_D, F_L

A

sediment entrained or remains entrained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
166
Q

Fluid influences

A

Type of flow

Type of bedform

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
167
Q

type of flow dictated by

A

Reynold #

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
168
Q

Reynolds number =

A

2rV(rho) / µ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
169
Q

what is µ in reynolds number and what does it mean

A

µ = viscosity

if µ dominates - low Re – laminar flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
170
Q

Large Re

A

turbulent flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
171
Q

Laminar flow =

A

Re <500-2000

subparallel sheets flowing slowly, viscous fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
172
Q

Turbulent flow =

A

Re >500-2000

irregular flow with eddies, low viscosity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
173
Q

Types of bed forms dictated by

A

Frouds #

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
174
Q

Frouds number =

A

V / √(gD)

D= depth of flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
175
Q

Fr < 1

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
176
Q

Bedforms resulting from tranquil flow

A

ripples
sandwaves
dunes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
177
Q

Fr > 1

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
178
Q

Bedforms resulting from rapid flow

A

plane beds
antidunes
chutes
pools

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
179
Q

bedload

A

sediment that moves close to the bed surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
180
Q

types of bedload movement

A

Traction- rolling, sliding, creep

Saltation- intermittent contact with bed (eddies)- particles bounce along

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
181
Q

suspended load

A

grains ‘float’ continuously in fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
182
Q

Unidirectional flow bedforms

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
183
Q

creep

A

one particle hits another forcing it to move

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
184
Q

low flow regime bedform

A

plane bed–no velocity = no sed movement

ripples-waves-dunes = low velocity movement of sediment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
185
Q

upper flow regime bedform

A

plane bedding-sheets of sediment are moved

antidune- migrates upstream by high energy eddy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
186
Q

bedform most likely to be preserved

A

ripples, plane beds (then dunes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
187
Q

eroding side of a dune

A

Stoss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
188
Q

depositional side of a dune

A

Lee

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
189
Q

cross bedding in a dune as representation as flow direction

A
  • flow is perpendicular to cross beds (opposite of what imbrication would look like)
  • cross beds are concave TOWARD flow direction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
190
Q

climbing ripples

A

upward moving drifts

lots and lots of sediment moving in current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
191
Q

stable angle of rest

A

steeper in air
air ~30º
water ~18º

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
192
Q

how to tell cross beds are not upside down

A

look for tangential base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
193
Q

trough bedding

A

irregular fluid flow

sinuous in 3rd dimension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
194
Q

bidirectional flow

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
195
Q

Bidirectional bed forms

A 
symmetrical oscillation ripples
herringbone cross stratification
linsen/lenticular bedding
flaser bedding
wavy bedding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
196
Q

symmetrical ripples

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
197
Q

bidirectional dunes

A

form if bidirectional flows are equal ie.tides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
198
Q

linsen/lenticular, flaser, wavy bedding form from

A

asymmetry in tidal current strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
199
Q

hummocky bedding

A

on storm shelves

long and low profile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
200
Q

subaerial/subaqueous

A

taking place in air/water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
201
Q

Dry rockfalls

A

little internal deformation of material
slides
slumps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
202
Q

wet rockfalls

A

> fluid, grains separated and dispersed, cohesiveness reduced

sediment gravity flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
203
Q

subaerial sediment gravity flow

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
204
Q

subaqueous sediment gravity flow

A

grain flow, debris flow, turbidity current, fluidized flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
205
Q

Grain flow

A 
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
206
Q

Fluidized flow

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
207
Q

debris flow

A 
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
208
Q

bingham plastic

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
209
Q

turbidity current

A 
least dense, like fluid flow
sediment suspended in water
turbulence is grain support mechanism
Re high, low viscosity
very rapid flow
widespread dispursal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
210
Q

turbidity current deposit

A

turbidite

graded beds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
211
Q

bedding

A

> 1cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
212
Q

lamination

A

<1cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
213
Q

deformational structures

A 
load casts
flame structures
ball and pillow structure
slump structure
sandstone dyke/dish structure
convolute bedding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
214
Q

bedding plane structures

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
215
Q

ss plane

A

bedding plane (top of bed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
216
Q

bed

A

deposited in single event (same conditions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
217
Q

Bouma sequence

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
218
Q

tectonic vs. slump structure

A

tectonic-whole sequence folded same

slump- only an area folded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
219
Q

flute/scour marks

A

formed by eddies eroding bed plane

tell which way is upstream (shallower part of flute)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
220
Q

organism structures

A

tracks and trails, burrows, bioturbation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
221
Q

tracks and trails

A

fooprints

grooves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
222
Q

burrows

A

shafts (vertical)

tunnels (horizontal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
223
Q

bioturbation

A

extensive biological activity

mottled appearance - original structure destroyed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
224
Q

ichnofacies

A

biogenic structures characteristic of depths and bottom conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
225
Q

skolithos

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
226
Q

cruziana

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
227
Q

zoophycos

A

arcuate feeding traces
bathyal zone
low energy muds
low O2 level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
228
Q

nereites

A

meandering feeding traces

abyssal zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
229
Q

bilobate feature

A

trilobite feeding trail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
230
Q

sublittoral zone

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
231
Q

arcuate

A

shaped like a bow, curved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
232
Q

bathyal

A

between sublittoral and abyssal

beyond continental shelf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
233
Q

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

A

diagenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
234
Q

diagenetic conditions

A

<10kms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
235
Q

colour of fossils

A

varies with depth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
236
Q

types of diagenesis

A

biological
physical
chemical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
237
Q

biological diagenesis

A

bioturbation

microbial activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
238
Q

bioturbation diagenesis

A 
disrupts primary structure- burrowing, ingestion
changes chemistry of environment
produces structures (pellets)
reduces grain size
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
239
Q

microbial activity diagenesis

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
240
Q

physical diagenesis

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
241
Q

compaction, decreasing porosity and permeability

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
242
Q

Fabrics resulting from compaction

A 
grain/clast distortion, deformation, flattening
sutured grains (pressure solution)
stylolites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
243
Q

chemical diagenesis

A 
cementation
authigenesis
replacement
recrystallisation
dissolution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
244
Q

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

A

Mudstone- can thin by more than half

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
245
Q

sutured grains

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
246
Q

cementation

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
247
Q

effects of cementation

A

lithification of sediment

reduces porosity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
248
Q

sandstone cement

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
249
Q

carbonate cement

A

calcite, aragonite, dolomite

overgrowth, drusy, blocky, rim cement

250
Q

carbonate ‘grains’

A

allochems

251
Q

authigenisis diagenesis

A

new minerals from related, recycled elements or minerals

ex. glauconite (green) ONLY forms through authigenesis

252
Q

authigenesis common types

A

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

253
Q

alteration of clay minerals

A

kaolinite to illite
High T,P–chlorite, muscovite
low T,P—glauconite

254
Q

sericite

A

fine muscovite and clay formed from feldspar alteration

255
Q

Replacement diagenesis

A

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

256
Q

examples of replacement diagenesis

A

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

257
Q

recrystallization diagenesis

A

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

258
Q

recrystallization example

A

lime mud—-coarse sparite—-silicic ooze—-chert

all steps of recrystallization

259
Q

bivalve

A

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

260
Q

brachiopod

A

one shell is symmetric down middle

two shells are not symmetric

261
Q

dissolution diagenesis

A

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

262
Q

pressure solution in carbonates

A

may involve 25-90% of original rock

the dissolution provides Ca and CO3 for cements

263
Q

diagenetic structures

A 
obvious-tell nothing about original environment
liesegangen bands
concretion/nodules
sand crystals
geodes
264
Q

sand crystals

A

large calcite diagenetic crystals which have grown in sand

265
Q

geodes

A

diagenetic minerals that have grown into a void

266
Q

liesengangen bands

A

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

267
Q

concretions

A

regular rounded
forms about a nucleus
ex. a fossil

268
Q

nodules

A

irregular form
no nucleus
eg. flint

269
Q

how do we reconstruct sedimentary environments

A

uniformitarianism

facies models

270
Q

uniformitarianism principles

A

actualism- processes are the same in the past as now

gradualism- rates/intensities are the same as in the past

271
Q

largest amount of sediment accumulation

A

continental shelf

272
Q

relic sediments

A

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

273
Q

non-recurring changes in earth history

A

O2 levels

evolution

274
Q

how evolution has changed sedimentary record

A

before abundant life:

  • no carbonates, no bioturbation
  • SOME silicates
  • stromatolites more common
275
Q

Facies models

A

idealized sequence

may include; lithology, sed. structures, fossils, sequences, paleocurrents

276
Q

most likely to be preserved

A

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.

277
Q

alluvial deposition environments

A

alluvial fans
braided rivers
meandering rivers
deltas

278
Q

Alluvial fans

A

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

279
Q

Alluvial fan examples

A

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

280
Q

alluvial fan requirement

A

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

281
Q

Bajada

A

series of alluvial fans coalesce

282
Q

alluvial fan sediment transport mechanisms

A

stream flow: braided channel, sheet flood, sieve deposit

sediment gravity flow: debris flow, mudflow

283
Q

alluvial fan stream flow products

A

generally stratified, reasonably sorted, cross bedded, imbricated deposits

284
Q

alluvial fan braided channel product

A

lenticular

285
Q

alluvial fan sheet flood product

A

well sorted sheet, stratified

286
Q

alluvial fan sieve deposit product

A

no imbrication
no cross bedding
well sorted

287
Q

alluvial fan sediment gravity flow products

A

very poorly sorted
unstratified
lobe shaped
tabular deposits

288
Q

alluvial flow debris flow products

A

coarser

289
Q

alluvial fan mudflow products

A

finer

290
Q

alluvial fan sedimentology

A 
coarse grain- conglomerates, cross bedded sandstones
large range in grain size
size decreases distally
immature, angular sediment
red beds common
fossils rare
291
Q

fluvial environments

A

braided

meandering

292
Q

braided fluvial system

A

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

293
Q

meandering fluvial system

A

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

294
Q

longitudinal bar

A

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

295
Q

transverse bar

A

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

296
Q

braided river deposits

A

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

297
Q

meandering point bar

A

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

298
Q

how to recognize fluvial deposits

A 
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
299
Q

where aeolian deposits are formed

A 
deserts 
20-30ºN,S of equator
centre of large continent
rain shadows
area of persistent high pressure (dry defending air)
recently deglaciated areas
300
Q

wind weathering

A

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

301
Q

Loess

A

silt and clay suspended in wind

carried furthest

302
Q

silt and sand transported by wind

A

silt and sand- saltation

med and fine sand- rolling, carried

303
Q

deflation lag

A

coarse sediment left behind leaves desert pavement

left behind sed is sandblasted

304
Q

desert structures form

A

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)

305
Q

aeolian sediment characteristics

A 
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
306
Q

different types of dunes depend on

A

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

307
Q

types of dune

A 
barchan
transverse
draa 
sief
parabolic
308
Q

Barchan dune

A

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

309
Q

transverse dune

A 
lots of wind and sediment
accumulate at right angles 
constant wind direction
up to 200m high 
up to 3km wide
310
Q

sief dunes

A 
extremely long
lots of wind, high velocity
little sediment
not unidirectional--converging wind
3-100m high
up to 100km long (very long)
311
Q

Star/Draa dune

A

irregular shaped- multiple wind directions

highest- up to 450m high

312
Q

parabolic dune

A

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

313
Q

aeolian deposit characteristics

A

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

314
Q

aeolian environments

A

dunes
interdune areas
sheet sand environment

315
Q

interdune area

A

receive windblown sed and ephemeral stream sed

316
Q

sheet sand environment

A

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

317
Q

sand sheet deposits

A

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

318
Q

interdune deposits

A

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

319
Q

present glacial environments

A

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

320
Q

past glacial environments

A

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

321
Q

glacial depositional environments

A

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

322
Q

ice sediment transport

A 
high viscosity <ablation (@snout) = advance
flow is laminar
velocity greets near top and centre
VERY large range of grain size
abrasion at bottom and edges
poorly sorted
323
Q

glacial sediment comes from

A

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

324
Q

glacial sediment is deposited in

A

moraines

325
Q

Glacial deposits directly from ice

A

till/diamict

stratified diamict

326
Q

till/diamict

A

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

327
Q

stratified diamict

A

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

328
Q

consolidated glacial sediment

A

tillite/diamictite

329
Q

esker

A

subglacial meltwater stream (under glacier) deposit

better sorted, rounded, less fine, bedding

330
Q

proglacial environments

A

glaciofluvial (braided)
glaciolacustrine (lakes)
glaciomarine

331
Q

glaciofluvial deposit

A

stratified massive gravels - L bars

cross bedded sands - T bars

332
Q

glaciolacustrine deposit

A

varved deposit with dropstones

333
Q

varved deposit

A

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)

334
Q

varve anatomy

A

winter layers smaller and dark

summer layers thicker and lighter

335
Q

glaciomarine deposits

A

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

336
Q

diamict

A

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

337
Q

Heterolithic bedding

A

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

338
Q

Flaser bedding

A

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

339
Q

Wavy bedding

A

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

340
Q

Lenticular bedding

A

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

341
Q

convolute bedding

A

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

342
Q

slump structure

A

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

343
Q

dish structure

A

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

344
Q

ancient glacial deposit features

A 
very poor sorting
striated clasts
extreme variation in clast type/size
lack stratification
unfossiliferous
345
Q

ancient proglacial deposit features

A

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

346
Q

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

A

Delta

347
Q

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

A

Spits, beach, barrier island

348
Q

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

A

estuaries, tidal flats, tidal influenced lagoons

349
Q

major sediment transport processes on beaches

A

longshore drift, rip current

350
Q

Types of tides

A

microtidal
mesotidal
macrotidal

351
Q

microtidal

A

0-2m

352
Q

mesotidal

A

2-4m

353
Q

macrotidal

A

> 4m

354
Q

what influences the energy of tides

A

tidal current velocity

355
Q

longshore sediment transport is the results of

A

oblique breaking waves from longshore currents

356
Q

cause of rip current

A

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

357
Q

where is the highest energy between waves and beach

A

breaker zone

358
Q

swash backwash in the sediment record

A

very low angle (2º) seaward dipping laminations

359
Q

sediment sources to a beach

A

rivers, wind, coastal cliff slumping/erosions

360
Q

summer beach

A

low energy waves, beach builds up

361
Q

winter beach

A

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

362
Q

sedimentary structure you would expect from lower shoreface

A

hummocky/swaley cross stratification

363
Q

sedimentary structures you would expect from upper shoreface

A

small scale cross stratifications, truncated wave ripples

364
Q

if sea level is dropping what type of grading

A

reverse, CUS

365
Q

sedimentary structures in tidal channel

A

herringbone cross stratification, most likely sand

366
Q

sediment structures in tidal flats

A

flaser, linsen, wavy bedding, bioturbation, algal mats

most likely muds

367
Q

highest energy of tidal system

A

closest to the opening

368
Q

determining feature of tidal environments

A

reducing environments– anoxic (smells)

369
Q

much of the worlds coal, oil and gas reserves

A

Deltas

ex. Western Canada sedimentary basin

370
Q

factors influencing delta deposits

A

input

basin

371
Q

important factors of the basin in determining delta deposit

A

shape, salinity, tectonic regime, basinal processes

372
Q

important factors of the input in determining delta deposits

A

fluvial regime, sediment input

373
Q

Delta classifications

A

wave dominated
tide dominated
river dominated

374
Q

delta parts

A

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

375
Q

Upper delta plain

A

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

376
Q

lower delta plain

A

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

377
Q

delta front

A

high energy marine, extends up to 10m depth

378
Q

prodelta

A

finer sediments, sediment gravity flow, slumps

379
Q

delta extent

A

up to 10’s of km’s, 300m depth

380
Q

deltas are classified by

A

balance between river input and basin

381
Q

wave dominated deltas

A

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

382
Q

tide dominated deltas

A

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

383
Q

fluvial dominated

A

lobate or ‘birds foot’, sand mouth bars

384
Q

why a prodelta can be seen

A

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

385
Q

delta effects

A

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

386
Q

delta progradation sequence

A

coarsening upwards

laminated clay, laminated silt, x-bedded sands, sandstone

387
Q

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

A

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

388
Q

Diapir importance

A

form structures that can trap hydrocarbons

389
Q

upper delta plain deposits

A

meandering channel deposits

floodplain deposits

390
Q

lower delta plain deposits

A

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

391
Q

subaqueous delta sediments characterized by

A

soft sediment deformation, slumping, diapirs

392
Q

delta front deposits

A

well sorted

x bedded sands (distributary mouth bars)

393
Q

prodelta deposits

A

laminated silts/clays

394
Q

delta deposit cross section shape

A

wedge or lense

395
Q

delta sequence recognition

A

nomarine fluvial grading into shallow marine sands and muds

396
Q

continental margin

A

shelf, slope, and rise

397
Q

continental shelf

A

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

398
Q

continental slope

A

4º slope

399
Q

continental rise

A

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

400
Q

continental shelf environment

A

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

401
Q

continental shelf sedimentary regimes

A

siliciclastic

carbonate

402
Q

siliciclastic shelf features

A

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

403
Q

carbonate shelf features

A

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

404
Q

relic sediment

A

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

405
Q

normal shelf sediment

A

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

406
Q

types of siliciclastic continental shelves

A

tide dominant

wave dominant

407
Q

tide dominant siliciclastic continental shelf

A

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

408
Q

tide dominant siliciclastic shelf sedimentary structures

A 
sandwaves
sand ridges/ribbons
sand/gravel sheets
sand- herringbone
mud- mottled, small x-laminations, flaser and linsen
409
Q

sandwaves

A

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

410
Q

sand ridges/ribbons

A

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

411
Q

greater tidal ranges are due to

A

restricted flow

412
Q

Wave dominated shelves

A

predominate, low tide velocity <10m

413
Q

wave dominant shelf sediments

A

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

414
Q

windows

A

relict sand and gravel showing through modern

415
Q

recognition of shelf sediments

A

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

416
Q

tide dominated sequence may be indicative of

A

sea level rising- burrows on top of herringbone

417
Q

storm dominated sequence may be indicative of

A

falling sea level- hummocky on top of burrows

418
Q

ocean basins occupy how much of earth surface

A

~65%

419
Q

why is ocean basin poorly preserved

A

sea floor is recycled

420
Q

source of sediment in deep ocean

A

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

421
Q

deep sea sediment types

A

terrigenous/clastic, pelagic

422
Q

terrigenous sediments

A

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

423
Q

Hemipelagic muds

A

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

424
Q

pelagic deep sea sediments

A

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

425
Q

where do you diatom remains

A

near poles (silica)

426
Q

where do you get radiolaria remains

A

near equator (silica)

427
Q

can determine velocity of turbidity current from

A

bouma sequence- erosional powers

428
Q

Red clays

A

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

429
Q

Biogenic pelagic sediment

A

siliceous ooze

calcareous ooze

430
Q

siliceous ooze

A

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

431
Q

calcareous ooze

A

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

432
Q

Pelagic sediment controls

A

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

433
Q

CCD

A

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

434
Q

why CCD higher in some parts of the oceans

A

higher at equator to compensate for higher productivity

435
Q

why CCD different in time

A

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

436
Q

average depth of deep ocean

A

4-5km

437
Q

Carbonate shelf environment

A

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

438
Q

types of carbonates

A

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

439
Q

main site of carbonate production

A

middle-outer shelf “sub tidal carbonate factory”

440
Q

types of carbonate shelves

A

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

441
Q

Tufa

A

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

442
Q

Rimmed carbonate shelf

A

outer edge pronounced break in slope (lagoon-reef)

Great Barrier reef

443
Q

unrimmed carbonate shelf

A

open shelf, no pronounced marginal barrier

444
Q

Ramp carbonate shelf

A

gently sloping ~1º into deeper water

445
Q

Isolated platform carbonate shelf

A

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

446
Q

processes of carbonate sedimentations

A

chemical precipitation
biogenic precipitation
physical processes

447
Q

chemical precipitation carbonate sedimentation

A

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

448
Q

biogenic precipitation carbonate sedimentation

A

MOST important of carbonate processes, very high rates

ex. organisms and fine aragonite mud

449
Q

physical processes carbonate sedimentation

A

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

450
Q

what kinds of carbonate would you expect at inner shelf

A

Micrite- shoreline low energy

451
Q

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

A

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

452
Q

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

A

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

453
Q

laminations

A

<1cm

454
Q

what doesn’t tell you anything about deposition

A

diagenetic features

455
Q

outer carbonate shelf

A

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

456
Q

carbonate shelf rims

A

reefs, shoals

457
Q

folk classification

A

composition based

458
Q

dunham classification

A

texture based

459
Q

middle carbonate shelf

A

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)

460
Q

marine organisms normal to middle carbonate shelf

A

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

461
Q

inner carbonate shelf

A

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

462
Q

Humid environment carbonate shelf

A

algal mats, thin storm beds

463
Q

Arid environment (sabkhas) carbonate shelf

A

desiccation cracks, evaporite minerals

464
Q

inner carbonate shelf organisms/structures

A

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

465
Q

outer carbonate shelf rocks

A

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

466
Q

middle carbonate shelf rocks

A

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

467
Q

inner carbonate shelf rocks

A

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

468
Q

colour of micrite rich rock

A

dark

469
Q

colour of sparite rich rock

A

lighter

470
Q

geologic record carbonates

A

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

471
Q

order of evaporite precipitation

A

carbonates, sulfates, halides

472
Q

evaporites are

A

intrabasinal chemical sedimentary deposits

precipitate from solution, concentrated by evaporation

473
Q

evaporite environments

A

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

474
Q

main sulphate

A

gypsum (anhydrite in dryer settings)

475
Q

sabkha

A

supra tidal salt flat, forming along arid coastlines

fine grained material, tidal-dessication cracks

476
Q

shallow barred marine evaporite environment

A

none present day

repeatedly recharged to obtain thick sequences

477
Q

non-marine evaporite environment

A 
different salts than marine environments, depend on material deposited from weathering
desert associations (intermittent/playa lakes)
478
Q

stratigraphy involves

A

subdividing and managing sequences of strata
dating
correlation
interpreting

479
Q

dating of stratigraphy

A

placing sections in sequential order (relative dating)

480
Q

correlation of stratigraphy

A

determining which events happened at the same time

481
Q

breaks in stratigraphic record are due to

A 
base level changes (more/less erosion, lack of deposition)
tectonic activity (subduction, metamorphism)
482
Q

most of geologic scale is from

A

precambrian

483
Q

paleosols

A

‘fossil soils’ found within either sedimentary or volcanic deposits

484
Q

hardgrounds

A

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

485
Q

evidence that there are gaps in the record

A

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

486
Q

types of unconformities

A

Paraconformities
Disconformitites
Angular unconformities

487
Q

paraconformities

A

missing fossils, difficult to see, between horizontal beds

488
Q

disconformitites

A

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

489
Q

angular unconformity

A

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

490
Q

depositional events most likely to be preserved

A

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

491
Q

ways to divide sedimentary record

A

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

492
Q

lithostratigraphy fundamental unit

A

formation

493
Q

formations

A

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

494
Q

formations subdivided into

A

members

495
Q

formations are part of a

A

groups

496
Q

vertical contacts between facies

A

abrupt
gradational
intercalated (all conformable)

497
Q

a conformable contact indicated

A

that no significant break in deposition has occurred

498
Q

abrupt contact

A

sudden, distinct, changes in lithology

499
Q

gradational contact

A

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

500
Q

intercalated contact

A

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

501
Q

example of laterally very extensive lithology

A

high sea level carbonate shelf

502
Q

types of lateral changes in lithology

A

pinchouts
intertonguing
lateral gradation

503
Q

lateral facies changes represent

A

different parts of, or different depositional environments

504
Q

pinch-out

A

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

505
Q

intertonguing

A

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

506
Q

lateral gradation

A

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

507
Q

Walthers law of facies

A

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

508
Q

how do facies shift laterally

A

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

509
Q

shifts in environments shifting facies

A

delta distributary avulsion, glacial retreat, river channel migration

510
Q

avulsion

A

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

511
Q

changes in rate influx shifting facies

A

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

512
Q

eustatic sea level changes

A

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

513
Q

local sea level changes

A

local downwarping, subsidence, sediment aggradation, isostatic rebound

514
Q

aggradation

A

increase in land elevation due to the deposition of sediment

515
Q

isostatic rebound (isostasy)

A

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

516
Q

regression

A

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

517
Q

transgression

A

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

518
Q

diachronous

A

all parts of a formation are not the same age

519
Q

tsunamite

A

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

520
Q

stratigraphic cycles

A

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

521
Q

supercycles

A

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

522
Q

second order cycles

A

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

523
Q

third order cycles

A

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

524
Q

fourth order cycles

A

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

525
Q

icehouse times in supercycle

A

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

526
Q

greenhouse times in supercycle

A

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

527
Q

extracts CO2

A

weathering

528
Q

adds CO2

A

volcanism

529
Q

basis for the geological time scale

A

biostratigraphy

530
Q

law of faunal and floral succession

A

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

531
Q

biostratigraphic subdivisions

A

biozones

532
Q

biozone

A

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

533
Q

useful paleozoic fossils

A

trilobites, graptolites, ammonoids, conodonts, fusulinids

534
Q

useful mesozoic fossils

A

ammonites

535
Q

useful cenozoic fossils

A

planktonic foraminifera, radiolaria, coccolithophores, pollen

536
Q

Index fossils

A

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

537
Q

best index fossils

A

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

538
Q

types of biozones

A

interval zones
assemblage zones
abundance/acme zones

539
Q

interval zones

A

1-3 index fossils, different overlaps

540
Q

types of interval zones

A 
concurrent range zone
taxon range zone (total range)
lineage zone (consecutive range)
interval zone
541
Q

assemblage zone

A

biozone defined by >3 taxa

542
Q

acme zone

A

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

543
Q

concurrent range zone

A

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

544
Q

total range zone

A

biozone defined by total or local range of one taxon

545
Q

lineage zone

A

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

546
Q

LAD

A

last appearance datum, either local or global

547
Q

FAD

A

first appearance data, either local or global

548
Q

assemblage biozone

A

3 or more taxa in a natural assemblage or association

numerous FADs and LADs

549
Q

causes of missing fossil/species in sections

A

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

550
Q

minimum duration of a biozone depends on

A

rate of evolution

551
Q

average species duration

A

2my - 20-30my

552
Q

resolution of biostratigraphy

A

better than radiometric dating

errors: +/- 12my

553
Q

lateral distribution of fossils controlled by

A

migration times, barriers to migration

554
Q

barriers to migration

A

mountains, oceans, climate, salinity

555
Q

distribution of fossils within a biozone

A

faunal provinces

556
Q

biozone limitations

A

entire potential lateral space is rarely filled with the organism

557
Q

faunal provinces and realms

A

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

558
Q

what are the three groupings of sedimentary materials?

A

resistates, secondary minerals, dissolved ions

559
Q

biozone, formation difference

A

biozones determined by evolution

formations determined by changes in environment

560
Q

diachronous

A

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

561
Q

marker beds

A

Isochronous: ash beds, coals, chalk, distinctive patterns

562
Q

isochronous

A

occurring at the same time

563
Q

correlation with lithostratigraphy

A

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

564
Q

correlation with biostratigraphy

A

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

565
Q

other globally synchronous correlation options

A

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

566
Q

chronostratigraphy

A

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

567
Q

chronostratigraphy has two units

A

Period- time interval- geochronologic

Rocks formed in that period- chronostratigraphic

568
Q

Time units

A

eon, era, period, epoch, age, chron

569
Q

Time-rock units

A

eonothem, erathem, system, series, stage, chronozone

570
Q

calibrates geologic time sclae

A

radiometric age dating

571
Q

other methods of numerical dating

A

short periods of time, locally

tree rings, varies, shell growth increments

572
Q

radiometric dating issues

A 
decay constant imprecise 
only volcanogenic seeds can be dated
closure temperature uncertainty
sampling uncertainty
weathering- loss of parent/daughter
573
Q

C14 dating

A

only up 60-80,000yrs

half-life : 5730

574
Q

magnetostratigraphy

A

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

575
Q

types of magnetic signatures

A

TRM, DRM, CRM

576
Q

TRM

A

thermal remanent magnetisation

magma cools- hematite/magnetite minerals align- cool through curie pt. (500-600ºC)- orientation ‘frozen’

577
Q

DRM

A

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

578
Q

CRM

A

chemical remanent magnetization

orientation of chemically precipitated hematite cement, difficult to tell when it formed

579
Q

contemporaneous

A

existing or occurring in the same period of time

580
Q

reversals take place

A

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

581
Q

fundamental units of magnetostratigraphy

A

polarity zones

subzones

582
Q

polarity zones

A

longer than 10,000 yrs

single direction of polarization or distinct alternation

583
Q

subzones

A

10,000-100,000 years

named after important geographic locations

584
Q

magnetostratigraphy applications

A

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)

585
Q

Basins are controlled by

A

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

586
Q

plate tectonics in basin control

A

margin interaction- divergent, convergent, transform

flexural movement within plate

587
Q

geologic history of plate

A

plate may have several different basin types of different ages

588
Q

type of crust in basin control

A

ocean or continental, sediment type, different depositional environments

589
Q

Basin stress environments

A

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

590
Q

Extensional

A

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

591
Q

Compressional

A

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

592
Q

sedimentation on craton

A

platform sediments

basins

593
Q

platform sediments

A

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

594
Q

craton basins

A

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

595
Q

Divergent margin basins

A

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

596
Q

Development- Wilson Cycle

A

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

597
Q

Rift domal uplift

A

continent over deep mantle plume, heating causes expansion

598
Q

Rift stage

A

rift valleys from normal faulting, continental basement

coarse, immature sed., alluvial fan, fluvial, lacustrine, evaporite sed.

599
Q

graben

A

depressed block of land bordered by parallel faults

600
Q

Proto-ocean gulf stage

A

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

601
Q

normal ocean stage

A

ocean crust, fully developed MOR

few active faults, prograding wedge of sediment, pelagic oozes over most of sea floor

602
Q

Convergent margin basins

A

compressional stress, not extensively explored

603
Q

types of convergent margin basins

A

ocean-ocean / ocean-continent

continent-continent

604
Q

ocean- O/C convergence

A

subduction zones, magmatic arc basins

605
Q

continent-continent convergence

A

foredeeps, foreland basins

606
Q

o-o, o-c tectonic elements

A

Trench, Accretionary wedge, Forearc basin, Backarc basin

607
Q

Trench

A

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

608
Q

oldest trench sediment

A

pelagic muds/oozes

609
Q

trench pelagic muds overrlain by

A

turbidites and other sediment gravity flow deposits

610
Q

mass wasting and tectonic deformation develop

A

melanges and olistostromes on inner slope

611
Q

melange

A

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

612
Q

olistostrome

A

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

613
Q

Accretionary wedge/subduction complex

A

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

614
Q

in the depressions on top of the thrust slices you get

A

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

615
Q

forearc basins

A

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

616
Q

forearc basin sediment

A

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

617
Q

back arc basins

A

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

618
Q

back arc basin sediments

A

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)

619
Q

c-c Basins (orogenic belts)

A

foreland basins- loading of crust, adjacent crust subsides

620
Q

foreland basin sequence

A

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

621
Q

Flysch

A

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

622
Q

Molasse

A

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

EOS (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions