Sedimentary Rock Types

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Sedimentary Rock Types
Sedimentary Rock Types
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Three Types based on origin
Sedimentary Rock Types
Clastic fragments of pre-existing
rocks
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Three Types based on origin
Sedimentary Rock Types
Clastic fragments of pre-existing
rocks Chemical precipitated from
compounds dissolved in solution
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Three Types based on origin
Sedimentary Rock Types
Clastic fragments of pre-existing
rocks Chemical precipitated from
compounds dissolved in solution Organic
skeleton precipitated by an animal or plant.
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Three Types based on origin
Sedimentary Rock Types
Clastic Rock classification based on Size
Composition of clasts
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Characteristics of clastic rocks
Sedimentary Rock Types

• 1. Grain Size
• clast name rock name
• boulders
• cobbles conglomerate
• pebbles or breccia
• granules
• ---------- 2 mm ----------------------
• sand sandstone
• ---------- gritty ----------------------
• silt siltstone
• ---------- smooth ----------------------
• clay claystone or shale

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Sedimentary Rock Types

• ---------- 2 mm ----------------------
• very coarse
• sand coarse
• medium
• fine
• very fine
• ---------- gritty ----------------------
• silt
• ---------- smooth ----------------------

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Characteristics of clastic rocks
Sedimentary Rock Types

• Grain Size provides information about
• its transportation history
• Coarse high energy
• Fine low energy (calm)

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Characteristics of clastic rocks
Sedimentary Rock Types
High Energy required to move big (coarse) clasts
glacier
steep gradient river
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Characteristics of clastic rocks
Sedimentary Rock Types
What rocks form from these sediments?
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Characteristics of clastic rocks
Sedimentary Rock Types
Low Energy can only move small clasts
lakes
low gradient river
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Characteristics of clastic rocks
Sedimentary Rock Types
What rocks form from these sediments?
lakes
low gradient river
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Characteristics of clastic rocks
Sedimentary Rock Types

• 2. Composition of grains commonly
• quartz
• feldspar
• clay minerals
• Fe Mg silicates
• micas
• calcite
• rock fragments

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Characteristics of clastic rocks
Sedimentary Rock Types
quartz
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Characteristics of clastic rocks
Sedimentary Rock Types
rock fragments
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Characteristics of clastic rocks
Sedimentary Rock Types
Fe Mg minerals
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Characteristics of clastic rocks
Sedimentary Rock Types
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Characteristics of clastic rocks
Sedimentary Rock Types
calcite (biogenic)
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Characteristics of clastic rocks
Sedimentary Rock Types

• 2. Composition of grains reflects
• Kind of rock eroded (original source)
• Weathering conditions (climate)
• Distance from source (transportation)

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Characteristics of clastic rocks
Sedimentary Rock Types

• 3. Sorting of grains
• range of particle sizes
• present in sediment

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Characteristics of clastic rocks
Sedimentary Rock Types

• Sorting of grains reflects
• the style of
• transportation (how far or long?)
• deposition (gradual/sudden?)
• (original range available)

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Sedimentary Rock Types

• Well sorted
• sustained velocity
• gradual deflation

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Sedimentary Rock Types

• Poorly sorted
• abrupt velocity
• change
• multiple events
• with different
• velocity

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Sedimentary Rock Types

• Poorly sorted
• abrupt velocity
• change
• multiple events
• with different
• velocity

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Sedimentary Rock Types

• Poorly sorted - - - - Well Sorted
• glacier -- stream -- wave -- wind

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Characteristics of clastic rocks
Sedimentary Rock Types

• 4. Shape of the grains
• rounding (angular vs. smooth)
• sphericity (spherical vs. elongate)

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Sedimentary Rock Types
rounding sphericity
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Sedimentary Rock Types
Rounded Spherical
Angular Elongate
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Characteristics of clastic rocks
Sedimentary Rock Types

• Shape of the grains reflects
• the transportation history
• Short (time - distance)
• angular not spherical
• Long (time - distance)
• well rounded spherical

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rock fragment conglomerates?
well sorted quartz sand?
silt and shale?
poorly sorted quartz sand?