Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Sedimentary Petrology > Lesson 8: Mudrocks > Flashcards

Lesson 8: Mudrocks Flashcards

1
Q

define mudrocks in terms of composition

A

they have to be at least 50% silt or finer particles

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

describe mudrocks in terms of abundance

A
  • most abundant among sedimentary rocks
  • compromise 50% of stratigraphic record
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

mudstones vs siltstones vs shales

A

mudstones are massive, siltstones are more silt than clay, shales have fissility (they can easily split along planes)

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

what is the difference between conglomerates and mudstones in terms of erosional process, what is the implication?

A

unlike conglomerates with various agents for reworking, mudstone particles actually have little to no modification/reworking during erosion and transportation.
reason: they are mostly transported as suspended particles
effect: cannot be rounded by collision = they are mostly angular; maintained their crystal shape

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

3 main processes that affect the microfabric of mudrocks

A
  1. physiochemical processes
  2. burial diagenesis
  3. bioorganic processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

3 specific processes under physiochemical processes

A
  1. electrochemical
  2. thermochemical
  3. interface dynamics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

2 specific processes under burial diagenesis

A
  1. mass gravity mechanisms
  2. cementation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

3 specific processes under bioorganic processes

A
  1. biomechanical
  2. biophysical
  3. biochemical
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

refers to the bonding among minerals, the electromagnetic bonds

A

electrochemical processes

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

refers to how temperature affects the interaction between minerals and their ions

A

thermochemical processes

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

refers to how the overall environment affects mudstone formation

A

interface dynamics

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

refers to how overburden affects the formation of mudstones (compresses them)

A

mass gravity mechanisms

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

process mainly involving cementing minerals

A

cementation

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

differentiate burial diagenesis vs bioorganic proesses

A

burial diagenesis is more on lithification while bioorganic processes are more on biological aspects

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

an example of this process would be bioturbation (burrowing animals)

A

biomechanical processes

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

refers to when organic particles create new minerals

A

biochemical processes

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

specific example of biochemical processes affecting microfabric

A

when organic matter produces methane gas/natural gas which affects the overall make up of mudstones

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

property where splitting between roughly planar and parallel surfaces can occur (has parting)

A

fissility

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

what does fissility among shales favor?

A

favors the abundance of peptizing agents

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

explain peptizing agents

A

agents that orient mineral assemblages of rock

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

example of peptizing agent

A

organic matter (needs anoxic environment)

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

2 requirements for peptizing agents in the fissility of shales (high chance for shales to form)

A
  • organic matter are the main peptizing agents
  • anoxic environments favor the preservation of organic matter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

why is it that organic matter needs to be preserved in anoxic environments?

A

because aerobic environments oxidizes the organic matter which will cause it to decay.

thus, no oxygen = no decay = preserved organic matter = fissility

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

enumerate entire mineralogy of lutites

A

silicate minerals:
- quartz
- feldspar
- zeolite

clay minerals:
- kaolinite
- smectite-illite-muscovite
- chlorite, corrensite, vermiculite
- sepiolite and attapulgite

oxides/hydroxides
- Fe-O
- gibbsite

carbonates:
- calcite
- dolomite
- siderite and ankerite

sulfites and sulfates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
mineral composition of most coarse grained lutites (silty/siltstones)
silicate minerals: - quartz - feldspar - zeolite
26
pyroclastic materials that have undergone low temperature alteration under seawater
zeolite
27
mineral composition of most fine grained lutites
clay minerals: - kaolinite - smectite-illite-muscovite - chlorite, corrensite, vermiculite - sepiolite and attapulgite oxides/hydroxides - gibbsite
28
mineralogy of coatings
Fe-O
29
example of coatings
Hematite -most common in shales goethite or limonite -may be more common in modern muds
30
weathering and oxidation products of iron minerals and gives color/pigmentation to the lutites
coatings
31
mineral composition of concretions/cement in lutites
carbonates: - calcite - dolomite - siderite and ankerite
32
what is gibbsite
an aluminum hydroxide clay
33
what do sulfides indicate
- reducing environment - post-deposition
34
what do sulfates indicate
hypersaline environment
35
example of sulfate in lutites
gypsum
36
example of evaporites in lutites
halite, gypsum, potassium salts or sulfosalts
37
other constituents found in lutites
apatite, volcanic glass, heavy minerals
38
accumulated organic matter (phosphate oxide mineral)
apatite, ex. guano
39
occurs along zeolite
volcanic glass
40
rare occurrence in lutites
heavy minerals
41
describe organic substances in lutites
discrete and structured
42
examples of organic substances in lutites
vitrine and kerogen in oil shales
43
particles from wood/plant materials
vitrine
44
altered remains of microorganisms
kerogen
45
how to classify lutites (bases)
there is no formal classification because there are a lot of ways to classify it: - color - abundance of minerals/organics - particle size (mostly used) - fabric/microstructures
46
how to classify lutites based on color
red shale -associated with iron oxidation black shale -a lot of organic matter within shale green shale -anoxic environment with iron minerals white siltstone -eroded away pyroclastic materials
47
example of how the abundance of minerals/organics can be used to classify lutites
- oil shale: bc a lot of oil, petroleum products preserved within shale) - argillaceous shale: because it is mainly composed of clay minerals (mud-sized doesn't mean composed of clay/muddy minerals)
48
example of how fabric/microstructures can be used to classify lutites
- fossiliferous: if there are fossils - on the basis of fissility (see chart) - bedded siltstone: if the siltstone is bedded:")
49
why is it that lutites are the most common sedimentary rocks?
- most are of marine origin - occurs in all ages: meaning at all times, there is always going to be a deep, basin-like area with gentle currents to make it possible for lutites to form, regardless if they would be preserved or not
50
what is reflected in sedimentary records about lutites
- high abundance of fine-grained material - erosional and efficiency of transport agents
51
4 transport agents of lutites
- wind - bottom currents - suspension transport mechanisms - turbidity currents
52
expound about the transportation agents for lutites
if transportation agent is sufficient, it can carry sediments to portions where it can be preserved (deposited then eventually lithified)
53
example of wind as a transport agent
sand from the sahara desert gets carried by wind to the amazon rain forest. thus the desert is feeding the forest
54
discuss how bottom currents can be transport agents
if there are fine particles with bottom currents, it can carry the particles away from deposition area
55
discuss how suspension transport mechanisms can be transport agents
finer sediments are usually transported through suspension because of their size
56
discuss how turbidity currents can be transport agents
good transportation mechanism for silt and finer particles - bouma sequence, fining up
57
3 different environments of lutites
fluvial, coastal and marine, eolian
58
3 specific depositional areas under fluvial for lutites
1. meandering rivers and anastomosing streams 2. deltas 3. estuary
59
4 specific depositional areas under coastal and marine for lutites
1. lagoons 2. deep waters 3. shelf and slope 4. tidal flats
60
example of sediments that make up lutites from eolian environments
loess deposits
61
describe setting in meandering rivers and anastomosing streams
- near final base level - water velocity becomes slow - calm river causes deposition in floodplain
62
describe deltas and estuary
- transition between rivers and seas - low energy environment - if silt/mud is still suspended by flowing water, coming to contact with standing water will suddenly decrease velocity and cause desposition
63
describe setting in lagoons
- enclosed areas from the sea - no deposition for a time in a year, but sediments from the sea eventually get deposited here
64
T or F: lagoons are good hosts of mudstones (sulfate rich shales)
true
65
Lutites found in deep waters and shelf slope
turbidites and deep marine shales
66
describe tidal flat settings
- platform areas that reveal if high or low tide - gentle environment - enough to form shales, thin layers or intercalation because of episodic high and low tides
67
describe loess deposits
structureless (no internal structure within it)

Sedimentary Petrology (11 decks)

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