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Sedimentary Geology > Chapter 5 > Flashcards

Chapter 5 Flashcards

1
Q

What are framework grains?

A

The sediment size of silicate minerals and rock fragments

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2
Q

How much does quartz make up of the framework?

A

50 to 60%

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3
Q

How do you distinguish feldspars from quartz under the microscope?

A

Quartz has undulatory extinction.

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4
Q

How do you distinguish between alkali and plagioclase feldspars?

A

Chemical composition

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5
Q

How much do feldspars make up of the framework?

A

10 to 20%

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6
Q

How much do sandstones make up of all sedimentary rocks?

A

20 to 25%

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7
Q

What is the size range for grains in sandstones?

A

(1/16th-2mm)

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8
Q

How much do rock fragments make up of the framework?

A

15-20%

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9
Q

What are the kinds of cement?

A

Can be of silicate or carbonate origin

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10
Q

What is syntaxial overgrowth?

A

Quartz cement that retains the crystallography of the actual grain

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11
Q

How are carbonate cements formed?

A

precipitated through pore space in framework grains

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12
Q

What is a matrix mineral?

A

Grains in sandstones that are less than 0.03mm that fill space

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13
Q

What are the clay mineral groups?

A

Illite, smectite, kaolinite, chloride

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14
Q

What are sandstones that are free of matrix (less than 5%) known as?

A

Quartzarenites, feldspathic arenites, litic arenites

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15
Q

When is the term arkose used?

A

Arkose is used in feldspathic arenites that is less greater than 25% feldspars

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16
Q

When is the term greywacke used?

A

a matrix rich sandstone that is dark green/gray and very hard

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17
Q

What is compositional maturity?

A

The relative abundance of stable and unstable grains in a sandstone

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18
Q

What is a mature sandstone?

A

A sandstone of mostly quartz

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19
Q

What is an immature sandstone?

A

Sandstone of mostly unstable (feldspars)

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20
Q

What is textural maturity?

A

The relative abundance of matrix and the degree of roundness and sorting of framework grains

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21
Q

What is texturally mature?

A

No clay, well sorted grains that are well rounded

22
Q

What is texturally immature?

A

Much clay, poorly sorted and angular framework grains

23
Q

What does textural maturity represent?

A

the degree of sediment transport and reworking

24
Q

What are quartz arenites composed of?

A

greater than 90% silica grains

25
Q

What are the common colors?

A

Light gray, can be stained red, pink, yellow, or brown

26
Q

what is the textural maturity of quartz arenites

A

Mature to super mature

27
Q

What is the percentage of quartz arenites in all sandstones?

A

!/3rd of all sandstones

28
Q

What is the composition of feldspathic arenites?

A

less than 90% quartz

29
Q

What are the common colors of feldspathic arenites?

A

Pink/red
light gray to white

30
Q

What is the grain size/ shape of feldspathic arenites?

A

medium to coarse
angular to subangular

31
Q

What is the amount of matrix in f-arenites?

A

trace amounts to 15%

32
Q

What is the textural maturity of f-arenites?

A

Immature to sub-mature (wacke)

33
Q

What is the composition of lithic arenites?

A

More unstable rock fragments than feldspars

34
Q

What is the composition of l-arenites?

A

immature sandstones

35
Q

What is the grain size in conglomerates?

A

at least 30% grains bigger than 2mm

36
Q

What is a monomict conglomerate?

A

stable conglomerates composed of a single clast type

37
Q

What is a polymict conglomerate?

A

a conglomerate that contains an assortment of many clasts types

38
Q

What is a petromict conglomerate?

A

Polymicts that are composed of unstable or metastable clasts

39
Q

What is monomict derived from?

A

Sedimentary rocks containing quartzite beds

40
Q

What is petromict derived from?

A

volcanic, metamorphic, or sedimentary rocks
one type is dominant clast

41
Q

What is intraformational derived from?

A

clast sediments formed within a depositional basin
flat pebble conglomerates

42
Q

What is the grain size in shales?

A

Fine sized grains between 1/16th-1/256mm that make up more than 50% of the rock?

43
Q

What is a shale?

A

A rock with silt size grains that has laminations?

44
Q

What is a mudrock?

A

a rock with silt size grains without laminations

45
Q

What is the composition of shales/mudrocks?

A

Clay minerals, free of quartz and feldspars

46
Q

what is a mudstone?

A

33-65% clay size constituents

47
Q

What is a mud shale?

A

33-65% with laminations

48
Q

What is a claystone?

A

66-100% clay grains

49
Q

What is a clay shale?

A

66-100% with laminations

50
Q

What is the diagenetic process of clastic rocks?

A

Uplict to burial and sedimentation

Sedimentary Geology (6 decks)

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