Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Surface Processes > W3 Sediment types > Flashcards

W3 Sediment types Flashcards

1
Q

Grain Flows

A

Sediment moves downward under the pull of gravity

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

Thixotropy

A

describes the property of a concentrated dispersion of grains supported by pore water to be a relatively stable solid at low pressure and a liquefied body of sediment at high pressure

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

example thixotropy

A

quicksand

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

Liquefaction

A

occurs in shockwaves sent through saturated sediment by an earthquake
liquefication of clay by breaking electrostatic bonds

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

mudflow

A

are a slurry-like mass of liquefied mud that moves downhill under the force of gravity

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

Increase of pressure

A

decreases frictional contacts in sand

apply pressure by adding more grains

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

Debris Flow

A

Debris flow consist of matrix-supported large to very large clasts
move extreme masses

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

Debris Flow occur

A

common in steep mountain canyons during heavy rainstorms but also occur as submarine flows when masses of unconsolidated sediment flow off the shelf edge and down the continental shelf

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

debris flow flows if

A

as long as there is a gradient and more matrix than what it carries debris flow flows

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

debris flow consistency

A

Debris flows have the consistency of wet cement but move as fast as water in a flash flood

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

Clasts in debris flow

A

clasts as large as cars
Clasts are weathered in the flow and in turn weather and erode the bedrock along the path of the flow
erosional feature

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

Largest erosional land force

A

Water in Rivers, canyons not created by water but by what it carries

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

Largest erosional force in ocean

A

submarine canyons created by transport of material that erodes the bed

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

Turbidity Currents, gravity flows

A

sediment is supported by upward turbulence of fluid within the flow.

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

turbidity currents triggered by

A

gravity and/or submarine earthquakes

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

Turbidity currents transports

A

sediment from the shelf down submarine canyons to the deep ocean

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

turbidity flow mass of sediment

A

mass of suspended sediment is denser than water

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

flows effect on canyons

A

canyons are eroded and deepened by the turbulence of the flows
deposition occurs when the current exits the canyon and flow slows

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

turbidity flow produces

A

produces normal graded bedding due to deposition from a decelerating flow.

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

turbidity current deposits

A

are known as a Bouma Sequence

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

Slumps are

A

slippage along a spoon-shaped failure surface

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

slump movement

A

wide range of scales – metres to kilometres, smallscale on land
continuous – mm/day
catastrophic – 10s of m/minute

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

slump characteristic feature

A

steep head scarp

bulging toe

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

Landslides, Avalances

A

udden movement down non-vertical slope

rock/debris/snow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Landslides move
occurs/recurs on failure surface debris slides ride on trapped air reduces friction increases velocity – can be up to 300 km/hr
26
Water rich flow: Debris . flow
mudflow with many large rocks | unsorted, matrix-rich sediment: diamicton/diamictite
27
Water rich: Mud flow
slurry of water and fine-grained sediment
28
Lahar
a slurry of volcanic ash and mud breaching of volcanic crater during eruption and/or violent thunderstorm accompanying an eruption and/or melting of glacier during eruption
29
Biggest influence on large . scale
Tectonics movement of the earth crust creating movement on earths surface greatly influence mass movements create uplift and promote weathering and erosion fragment the crust – joints and fractures promote disintegration generate seismicity – earthquakes trigger motion
30
Vibration through Liquefication
quick clay water-saturated sediment electrostatic forces broken particles suspended in a slurry, bridges, buildings
31
Saturated Sand
saturated sand – sand with water-filled pores grains in frictional contact shaking increases pore pressure, sand fluidised caused most of the earthquake-triggered destruction at San Francisco
32
clastic sedimentary rocks production . cycle
Deposition of clast → affected (time scakes and ways vary) → diagenesis → lithification of rock → held together by cement (often clacite)
33
water . during sediment compaction
Whatever the transporting medium, sediments become compacted by the overburden, water/air is squeezed out and pore space decreases
34
4 important . parts of sediment rock
Grains Porosity Cement Matrix
35
Grains
Sand grains, fosils, acids, clasts
36
Porosity
space with no mineral matter, mostly filled with waer taht . carries ions
37
Intergranular Porosity
occurs between the grains of soil, sediment, or incompletely cemented sedimentary rock
38
intragranular porosity
The porosity due to voids within the rock grains. (ix) Dissolution porosity The porosity resulting from dissolution of rock grains
39
Cement
chemically precipitated mineral material (more effective than matrix)
40
Matrix
fine grained, clay size sediment
41
Diagenis
steps from sediment to sedimentary rock
42
Diagenesis bioturbation
sediment modified by biological activity (food and oxygen)
43
Burial
new sediment on old sediment
44
dissolution : pressure solution
minerals begin to deform, flow & segregate in response to pressure = stylolite - most common in limestones
45
dissolution: mineral precipitation
common in lime stones
46
dissolution
cementation
47
Cementation
material dissolves at grain contacts, new material forms around grain crystallises from solution in pore spaces (cement) the easier soluble the rock is the more affected it is rock becomes more compact and harder
48
friable
weakly cemented, clay matrix
49
indurated
strongly cemented
50
Common cements, easily dissolve
materials that easily dissolve in water and/or under pressure or are very fine-grained - biogenic quartz (early stage quartz such as opal stil leasy to dissolve) calcite haematite clay minerals
51
most effective change on sedimentary rocks made structures
sea level, | everything would move if sea level rises or lowered ( expansion of collapse) , rebuilt somewhere else
52
Siliciclastic Sediments and rocjks originate
Originate from exposed, weathered and eroded continental rocks
53
Siliciclastic Sediments and rock examples
stable end-products of weathering & transport quartz & clay iron oxides commonly present
54
Siliciclastic abundant
feldspar, mica and lithic fragments | indicative of less transport and weathering
55
less common siliciclastic mineras
mafic minerals | because they break down on the surface, less stable, chemically and mechanically attacked
56
Quartz
Second most abundant mineral of the Earth’s crust – essential constituent of granite & felsic igneous rocks and a common constituent of schist & gneiss therefore, very common in clastic sedimentary rocks also (in variable amounts) in most carbonate rocks silica (SiO2), nothing else, that is why so stable glassy lustre no cleavage conchoidal fracture hard - will scratch a steel blade stable and resistant to physical weathering very slow chemical weathering precipitated quartz - any colour (impurities) igneous quartz – colourless metamorphic quartz - white
57
Clay Minerals
Very common in clastic sediments and sedimentary rocks the end-product of feldspar weathering hydrous aluminium phyllosilicates - iron – magnesium - alkali metals - alkaline earths flat hexagonal sheets with weak electrostatic bonds common as matrix between larger clasts also occurs as pure claystones
58
Pyrite
FeS2 Unstable mafic minerals easily weather to clays and iron - transported in solution & very commonly deposited with sediments metallic lustre brass-yellow (aka fool's gold) black streak can be scratched by a steel blade common component of organic-rich, oxygen-poor sediments (reducing environment of deposition) during consumption of organic matter, sulphate-reducing bacteria produce hydrogen sulphide (H2S) → reacts with iron → pyrite sedimentary pyrite indicative of high productivity of organic material
59
Iron Oxides, Haematite and Limonite
Weathering: reduced iron can be dissolved, transported, oxidised Haematite = iron(III) oxide (Fe2O3) one of several iron oxides black to steel or silver-grey brown to reddish brown red streak diagnostic of long exposure to an oxygen-rich environment commonly seen as staining on quartz grains terrestrial/continental rocks deep-sea clays Limonite = hydrated iron(III) oxyhydroxide yellowish-brown streak is brownish not a true mineral – aka lemon rock forms mostly in or near oxidized iron and other metal ore deposits and as sedimentary beds may occur as cement in iron-rich sandstones sometimes forms pseudomorphs after pyrite indicates arid environments
60
Feldspar
Feldspar constitutes 60% of the Earth’s crust, but is not truly abundant in sedimentary rocks because of its instability at surface conditions - easily weathers( compared to quartz) to clay minerals & irons ions glassy lustre can be almost any colour can be scratched by a steel blade platey cleavage (ie flat surfaces, angular corners) sometimes twinned in clastic rocks = diagnostic of short transport
61
Mica
``` platey cleavage sparkly lustre easily scratched with a fingernail. not easily dissolved persists as small flakes – easily transported by wind and light currents common in sedimentary rocks especially quartz sandstones Phyllosilicates consist of - potassium magnesium iron aluminium silicon water ```

Surface Processes (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions