Brainscape's Knowledge GenomeTM

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


See full index

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
Q

Landslides move

A

occurs/recurs on failure surface
debris slides ride on trapped air
reduces friction
increases velocity – can be up to 300 km/hr

26
Q

Water rich flow: Debris . flow

A

mudflow with many large rocks

unsorted, matrix-rich sediment: diamicton/diamictite

27
Q

Water rich: Mud flow

A

slurry of water and fine-grained sediment

28
Q

Lahar

A

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
Q

Biggest influence on large . scale

A

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
Q

Vibration through Liquefication

A

quick clay water-saturated sediment
electrostatic forces broken
particles suspended in a slurry, bridges, buildings

31
Q

Saturated Sand

A

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
Q

clastic sedimentary rocks production . cycle

A

Deposition of clast → affected (time scakes and ways vary) → diagenesis → lithification of rock → held together by cement (often clacite)

33
Q

water . during sediment compaction

A

Whatever the transporting medium, sediments become compacted by the overburden, water/air is squeezed out and pore space decreases

34
Q

4 important . parts of sediment rock

A

Grains
Porosity
Cement
Matrix

35
Q

Grains

A

Sand grains, fosils, acids, clasts

36
Q

Porosity

A

space with no mineral matter, mostly filled with waer taht . carries ions

37
Q

Intergranular Porosity

A

occurs between the grains of soil, sediment, or incompletely cemented sedimentary rock

38
Q

intragranular porosity

A

The porosity due to voids within the rock grains. (ix) Dissolution porosity The porosity resulting from dissolution of rock grains

39
Q

Cement

A

chemically precipitated mineral material (more effective than matrix)

40
Q

Matrix

A

fine grained, clay size sediment

41
Q

Diagenis

A

steps from sediment to sedimentary rock

42
Q

Diagenesis bioturbation

A

sediment modified by biological activity (food and oxygen)

43
Q

Burial

A

new sediment on old sediment

44
Q

dissolution : pressure solution

A

minerals begin to deform, flow & segregate in response to pressure = stylolite - most common in limestones

45
Q

dissolution: mineral precipitation

A

common in lime stones

46
Q

dissolution

A

cementation

47
Q

Cementation

A

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
Q

friable

A

weakly cemented, clay matrix

49
Q

indurated

A

strongly cemented

50
Q

Common cements, easily dissolve

A

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
Q

most effective change on sedimentary rocks made structures

A

sea level,

everything would move if sea level rises or lowered ( expansion of collapse) , rebuilt somewhere else

52
Q

Siliciclastic Sediments and rocjks originate

A

Originate from exposed, weathered and eroded continental rocks

53
Q

Siliciclastic Sediments and rock examples

A

stable end-products of weathering & transport
quartz & clay
iron oxides commonly present

54
Q

Siliciclastic abundant

A

feldspar, mica and lithic fragments

indicative of less transport and weathering

55
Q

less common siliciclastic mineras

A

mafic minerals

because they break down on the surface, less stable, chemically and mechanically attacked

56
Q

Quartz

A

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
Q

Clay Minerals

A

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
Q

Pyrite

A

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
Q

Iron Oxides, Haematite and Limonite

A

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
Q

Feldspar

A

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
Q

Mica

A 
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.
© 2024 Bold Learning Solutions. Terms and Conditions