Brainscape's Knowledge GenomeTM

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


See full index

GEOL 365 > Clastic Sedimentary Rocks > Flashcards

Clastic Sedimentary Rocks Flashcards

1
Q

What is sedimentation?

A

Is the separation of particles from a parent rock to the consolidation of the particles into another rock.

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

What is stratigraphy?

A

Branch of geology which deals with the formation, composition, sequence and correlation of the stratified rocks within the Earth’s crust.

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

What are the processes involved in forming clastic sedimentary rocks?

A

Weathering and erosion, transportation and deposition, and burial and lithification.

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

What are the 2 categories of weathering?

A
  1. Mechanical

2. Chemical

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

What is lithification?

A

Compaction and cementation into a sedimentary rock.

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

What type of rock is formed near the beach via weathering?

A

Sandstone, mechanical weathering.

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

What type of rock is formed in the near shelf via weathering?

A

Shale, mechanical weathering.

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

What type of rock is formed in the far shelf via weathering?

A

Limestone, chemical weathering.

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

What is weathering?

A

It is the mechanical and chemical alteration of Earth materials at or near the surface.

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

What is erosion?

A

Involves removing weathered materials from their place of origin by water or wind.

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

What are some examples of physical weathering?

A

Freeze-thaw
Salt growth
Temperature changes

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

What are 3 processes of chemical weathering?

A

Solution
Hydrolysis
Oxidation

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

What are the processes involved in mechanical weathering?

A

Pressure release on unloading
Thermal expansion/contraction
Growth of foreign crystals within a rock
Plant growth

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

What is chemical weathering?

A

The process by which rocks and minerals are decomposed by chemical alteration of the parent material.

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

Agents of chemical weathering are?

A

Atmospheric gases, especially O2
Water
Acids

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

What are the processes involved in chemical weathering?

A

Oxidation
Carbonation
Hydrolysis
Hydration

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

What is Bowen’s reaction series?

A

hi

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

What are siliclastic sedimentary rocks primarily classified by?

A

Their grain size.

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

What are the grain size classes?

A

Gravel>2mm
Sand 2mm - 1/16mm
Silt 1/16mm - 1/256mm
Clay <1/256mm

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

What is the definition of “matrix”?

A

It is all the fine grained “stuff” between the larger grains.

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

What are the transport agents of sediments?

A 
Gravity
Organisms
Wind
Ice
Water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which gravity mechanisms do not necessarily include water?

A

Rock falls and slides.

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

Which gravity mechanisms do include water?

A

Slumps
Debris flows
Turbidity currents
(all to increasing degrees)

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

What is bed loading?

A

It’s a transport mechanism of fine to coarse sand particles. Includes saltation (bouncing) and creeping (rolling and sliding).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is suspended load?

A

Transport mechanisms that affect very fine sand and silt particles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is graded bedding?

A

Depsoition of a graded bed takes place as the flow slows and deposes progressively smaller particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is turbidity current?

A

Flows downslope along the seafloor (or lake bottom) because it is denser than sediment-free water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What do clay-rich sediments that dry and shrink form?

A

Mud cracks.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is bioturbation?

A

Process where sediment is mixed by the movement of living organisms (worms moving in clay)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the 8 depositional environments?

A 
Glaciers
Alluvial
Fluvial
Marine
Eolian
Deltaic
Lacustrine
Estuarine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the 3 types of rivers associated with the fluvial system?

A

Braided
Anastomosing
Meandering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are the 3 environments in marine deposition?

A

Near-shore
Shelf
Deep-water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is an estuarine environment?

A

An estuary is a semi-enclosed coastal body of water along a coastline and is influenced by the tidal and wave action of the open sea.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are some examples of deltaic environments?

A

Nile ‘original’ delta
Mississippi, a river dominated delta
Rhode, a wave-dominated delta
Ganges, a tide-dominated delta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

In near-shore environments…

A

…sediments become increasingly fine with distance from the coast. Sand is limited to shallow waters and are affected by wave, tides and storms. silt and clays are deposited in quieter, deep water. These sediments have a large volume of organic material.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

In continental shelf environments….

A

Turbidity currents are common in deep-water environment’s downslopes. These flows move towards the deeper parts of the seafloor due to density difference.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Deep-water deposits….

A

hi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are some examples of primary sedimentary structures?

A 
Planar bedding
Ripple marks
Cross-bedding
Graded bedding
Mud cracks
Trace fossils
39
Q

What is planar bedding?

A

Laminations separated by variations in color, composition, grain size with bedding plane surfaces parallel to bedding.

40
Q

What type of environment does planar bedding occur?

A

Deposition from high flow velocity, e.g. swash zone of a beach. Also, settling from standing body of water with very low flow velocity, e.g. lake deposits (varves).

41
Q

What is hummocky cross-bedding?

A

Distinctive sign of storms, like hurricanes. The structure is formed when piles of sand (at least 1m high) are built up at the bottom of the seafloor near the beach. The pile is continuously eroded off the upstream and dumped on the leading downstream side. Resulting in a permanent new coat of sand covering the seafloor.

42
Q

What are glacial varves?

A

They are annual glacial lake laminations (<1cm thick layers) consisting of 1 dark clay layer (winter) and 1 light silt layer (summer).

43
Q

How are asymmetrical ripple marks formed?

A

By unidirectional currents.

44
Q

How are symmetrical ripple marks formed?

A

Generated by multidirectional flows (currents, waves)
Graded & imbricate bedding
Bedding plane structures

45
Q

What is imbrication?

A

It is a stacking patter of sediment that points to ancient currents. Formed by transportation (rolling) of disk-shaped gravel clasts.

46
Q

How are wave ripples generated?

A

The orbital movement of water flattens close to sediment surface and well developed symmetrical shapes for at this surface (see diagram in ppt2)

47
Q

How is cross-bedding occur?

A

Results in a change in current direction.

48
Q

In what environments does cross-bedding occur?

A

Common in eolian (wind-blown), fluvial (river) and marine sand bar deposits.

49
Q

Graded bedding (fining upwards sequence) is a primary clue in…

A

The identification of deep water turbidites, which are prolific HC reservoirs in the Gulf of Mexico

50
Q

Bouma Sequence

A

See diagram

51
Q

A coarsening upwards sequence indicates what?

A

A delta.

52
Q

How much is the estimated recoverable oil in the Niger Delta?

A

More than 30 billion barrels.

53
Q

What are Barchan Dunes?

A

An arc-shaped sand ridge, comprising of well sorted sand.

54
Q

What are secondary bedding plane markings?

A

Related to alteration of depositional fabric e.g. mud volcanoes and load casts, biogenic - trace fossils of ichnofossils, diagenetic - nodules, concretions, stylolites

55
Q

Define secondary bedding plane markings.

A

Signs of vigorous activity in sediments before they turn to rock. Caused due to the alteration of primary depositional structures.

56
Q

Where are mud volcanoes prominent?

A

Azerbaijan

57
Q

What are mud volcanoes?

A

Cones of mud and clay (usually <1-2m tall) built by a mixture of hot water, mud & clay that either pours gently from a vent in the ground like a lava flow. Can be ejected into air like a lava fountain of escaping volcanic gas & boiling water.

58
Q

How are flame structures generated?

A

Load cast is pushed down into mud, the flame structure is then injected up into weakness in the sand. See diagram.

59
Q

How are ball and pillow structures formed?

A

Formed when a sudden load of sand deposits is laid down on a soft mud bed. The result is the partial sinking of the heavy material into the soft underlying deposits.

60
Q

How are pillar structures formed?

A

Formed as fluid escapes from under pressure sediments.

61
Q

What are flute casts in turbidites?

A

They are irregular and asymmetrical ridges showing the flow was originated from the direction of the steeper side of the flute. See diagram in ppt 2.

62
Q

What is a rill?

A

It’s a narrow and shallow incision into the underlying structure.

63
Q

What is a gully?

A

They are small valleys formed by the development of rills.

64
Q

How are mud cracks formed?

A

They are a product of desiccation and contraction of deposited muddy sediments.

65
Q

What areas are some mud cracks found?

A

Death Valley (modern)
Montana (PreCambrian)
Texas (Edwards limestone)

66
Q

What are ichnofossils or trace fossils?

A

Biogenic sedimentary structures, where preserved intact, are closely related to the depositional setting. Trace fossils may be common in otherwise un-fossiliferous rocks.

67
Q

What are stromatolites?

A

They are layered bio-chemical structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially blue-green algae.

68
Q

Where are there examples of stromatolites?

A

Great Slave Group Canada (PreCambrian)
Bahamas
Shark Bay Australia

69
Q

Sedimentary structures provide…

A

…clues as to the depositional setting of the sedimentary rocks.

70
Q

What are the 5 principles of stratigraphy?

A 
Principle of Uniformitarianism
Principle of Original Horizontality
Walther's Law
Law of Superposition
Law of Faunal Succession
71
Q

What is the principle of Uniformitarianism?

A

Processes that alter the Earth are uniform through time.

72
Q

What is the principle of Original Horizontality?

A

When sedimentary particles settled from fluids under influence of gravity, they form horizontal beds.

73
Q

What is Walther’s Law?

A

The vertical succession of facies reflects lateral changes in environment.

74
Q

What is the Law of Superposition?

A

In a succession of undisturbed strata, oldest stratum are at its base, with successive younger ones above.

75
Q

What is the Law of Faunal Succession?

A

Sedimentary rock units containing fossils succeed each other vertically in a specific, time-related order that can be identified over wide horizontal distances.

76
Q

Why is sedimentation and stratigraphy important for petroleum geology?

A

The world runs on fossil fuels found in sedimentary rocks: coal, oil and natural gas. Unravelling Earth’s processes and history to illustrate sequences that are favourable for petroleum accumulation.

77
Q

Define Walther’s Law

A

Facies adjacent to one another in a continuous vertical sequence also accumulated adjacent to one another laterally.

78
Q

What are facies?

A

A mappable body of rock characterized by a particular type of lithology, texture, mineralogy, fossil content, physical and biological structures that bestow and aspect (facies) different from the bodies of rock above, below and laterally adjacent.

79
Q

What distinguishes one facies from another?

A

Mineralogy and sedimentary source, fossil content, sedimentary structures and texture.

80
Q

What are some examples of facies?

A

Sandstone facies
Turbidite facies
Ammonite facies

81
Q

Why are sedimentary facies important?

A

It is important to establish a framework of genetically related stratigraphic facies geometries and their bounding surfaces to determine depositional settings.

82
Q

When studying the correlation of separated strata what 3 things are considered?

A

Lithology (lithostratigraphy)
Fossil content (biostratigraphy)
Relative or absolute age (chronostratigraphy)

83
Q

What are the units in lithostratigraphy?

A

Supergroup (# of groups e.g. Purcell)
Group (# of formations e.g. Mannville)
Formation (fundamental unit, e.g. Watt Mountain)
Member (subdivision of formation, e.g. Gilwood)
Bed (subdivision of member)

84
Q

What are the units in chronostratigraphy?

A 
Eon (half a billion years or more)
Era (several hundred million years)
Period
Epoch (tens of millions of years)
Age (millions of years)
85
Q

What are the units in biostratigraphy?

A

System (a group of series)
Series (a group of stages)
Stage (a group of zones)
Zone (fundamental unit-a small scale time unit characterized by the 1st appearance of distinctive new fossils at its base and the disappearance of other species at its top)

86
Q

Where is there an example of a marie-transgressive sequence?

A

Grand Canyon AZ

87
Q

What types of deposits are included in terrestrial systems?

A 
Rivers
Deserts
Lakes
Downslope basins in mountains
Ice sheets/glaciers
88
Q

What are the 3 subdivisions of terrestrial basins?

A
  1. Basins with thorough drainage are dominated by well-established river systems.
  2. Basins with internal drainage characterized by seasonal (ephemeral) river systems, generally shallow and short-lived lakes, as well as continental sabkhas and deserts.
  3. Basins with well developed lake environments.
89
Q

Meandering rivers

A
  • sand deposition is normally restricted to the main channel.
  • channel floor commonly has a coarse layer of pebbles moved only at max flood velocities.
  • sand is moved thru the system in dunes on the chanel floor and in ripples higher on the point bar.
  • fining upward of particles is typical.
  • during floods, the adjacent flood plains receive fine grade sediments.
90
Q

Sandy braided rivers

A
  • have complex internal structures dominated by bars, channels, and sinuous crested dunes.
  • extensive sand flats may grow when low water flows are dominant.
91
Q

Anastomosing rivers

A
  • occur when a river has a multiple number of relatively stable channels exists.
  • form by high rates of vertical sediment accumulation/aggradation.
  • as a result, the available channels of the basin get stabilized in the course of time.
92
Q

Eolian depositional environments include what types of deserts?

A
  • deserts include a variety of enviros, the giant sand seas, stony wastelands, interdune sabkhas with temporary lakes, dried up rivers.
  • arctic deserts, form where sediments are derived from wasting glaciers.
  • tropical deserts, form due to extensive physical weathering of mountains in arid areas.
93
Q

What do eolian deposits indicate in a stratigraphic record?

A

An ancient climatic zone.

94
Q

Eolian sequences are…

A

…dominated by cross-stratified sandstones reflecting migrating eolian bedforms developing during the lateral movement of sand dunes.
Where the water table is elevated, sabkhas with evaporites may form.

GEOL 365 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions