Sedimentary Rocks and Processes Flashcards

1
Q

What is sediment?

A

Particles transported by water, ice, wind, and gravity.

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

What is stratification/bedding?

A

The arrangement of sedimentary particles in layers

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

What is a stratum?

A

A distinct layer of sediment

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

What do you call the top and bottom surfaces of a bed?

A

The bedding plane

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

What are the 2 main types of sediment/

A

Clastic (‘rock’) and non-clastic

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

What are the 2 main types of non-clastic sediment?

A
  • Chemical precipitates
  • Biogenic sediment (made from plants or animals)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 4 sub-categories of clastic sediment in size order?

A

Gravel
Sand
Silt
Clay

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

How is sediment sorting described?

A

Poorly sorted (large range) or well sorted (similarly sized particles)

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

What is till?

A

Glacial sediment

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

How does water speed differentiate sediment?

A

Faster flowing water can transport larger/heavier particles
- As water slows, heavier particles are deposited first and lighter ones carried further

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

What is roundness?

A

A measure of the sharpness of the edges of a particle

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

What is sphericity?

A

A measure of how similar a particle’s shape is to that of a sphere

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

Used together, what can sorting, roundness and sphericity tell us?

A

About the environment sediment was transported and deposited in

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

What is graded bedding? What does it show?

A

A bedding in which particles are deposited mostly by size with the coarsest at the bottom
- Shows a change in energy of the depositional system over time

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

What is cross bedding? What does it show?

A

Inclined beds of sediment.
- Shows dominant wind directions

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

What is diagenesis?

A

Sediment becoming rock ( a collective term for all processes including compaction and chemical processes )

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

What is lithification?

A

The overall process for creating sedimentary rock

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

What is the difference between lithification and diagenesis?

A

Lithification is the overall process of creating sedimentary rock.
Diagenesis is the collective term for all chemical, physical, and biological processes that cause lithification.

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

What is compaction as a diagenesis process?

A

The weight of an accumulating sediment forces the grains together and the pore space is reduced.

20
Q

What is cementation?

A

Substances dissolved in water precipitate to form a cement that binds sediment grains together

21
Q

How do cementation and compaction work together?

A

Water being squeezed out by compaction allows chemicals to precipitate and cement.

22
Q

What is recrystallisation?

A

Less stable minerals recrystalise into more stable forms

23
Q

What is dissolution?

A

When some minerals are dissolved during burial

24
Q

Name 4 common clastic sedimentary rocks.

A

Conglomerate, Breccia, Sandstone, Mudstone/Shale

25
What are the 4 vague categories of sedimentary structures?
- erosional - depositional - biogenic - post depositional
26
What type of rock is coal?
A biogenic sedimentary rock
27
How is coal formed/
Plant remains accumulate and form peat which is compressed to become coal
28
How are erosional structures formed?
Aqueous flows run over recently deposited sediment and gouge out depressions which are usually then infilled by sediment from the flow
29
What are the two most notable erosional structures?
Flute marks (asymmetric dips, wider upstream), Groove marks (ridges)
30
What do depositional structures depend on?
Flow velocity, flow depth, grain size
31
What are some examples of depositional structures?
Ripples, dunes, cross stratification
32
What are biogenic structures?
Structures left by animals such as burrows
33
Name two types of biogenic structures.
Ichnofacies, Bioturbation
34
What is an ichnofacie?
Trace fossil left by something like a burrow or feeding structure
35
What are bioturbations?
Shapes/erosions in sediment caused by things like footprints
36
Name two post-depositional structures?
Mud cracks, raindrop depressions
37
What is an evaporite?
A rock formed from salts produced by evaporation
38
What makes biogenic sediment bioclastic sediment?
When the remains of plants/animals are then broken and scattered
39
What is deep sea ooze?
Fine deep sea mud formed of skeletal material
40
What are the two types of deep sea ooze?
Calcareous ooze is made from material with more than 30% calcium carbonate Siliceous ooze is made from material that's mostly silica
41
What are stromatolites? How are they formed?
Algae reef systems, formed incrementally as algae deposit calcium in laminations
42
What are BIFs?
Banded iron formations, iron concentrations in layers
43
What is limestone?
Rocks formed from the deposition of calcium carbonate
44
What is oolitic limestone?
Limestone containing 0.5-2mm spherical grains of carbonate, shaped when these particles roll around in tidal environments
45
What is chalk formed from?
Compacted carbonate shells of coccolithophores