SEDIMENTARY ROCKS

1
Introduction to
SEDIMENTARY ROCKS
2
Introduction to
SEDIMENTARY ROCKS
3
Introduction to
SEDIMENTARY ROCKS
Weathering of an Igneous Rock
clasts clay minerals insoluble Fe oxides ions in
solution
4
Introduction to
SEDIMENTARY ROCKS
Resulting in

• 65 mudrocks
• 20-25 sandstones
• 10-15 carbonates

2/3 of the continental surface
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SEDIMENTARY ROCKS
Texture, structure and composition
Form sheet for clastic sedimentary rocks
I Color II Texture gr. size, sorting,
roundness III Structure IV Allogenic
constituents A. Grains B. Matrix V
Authigenic constituents A. Cement B.
Secondary minerals VI Name
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SEDIMENTARY ROCKS
Classifications
The Udden-Wentworth Scale
boulder gt256 mm cobble 64-256 mm pebble 4-64
mm granule 2-4 mm coarse sand ½-2 mm medium
sand ¼- ½ mm fine sand 1/16 ¼ mm silt
1/256-1/16 mm clay lt 1/256 mm
gravel
sand
mud
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SEDIMENTARY ROCKS
Classifications
Gravel
Sand
Mud
Complete continuum between sizes!!
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SEDIMENTARY ROCKS
Classifications
The Sandstones

• Conglomerates breccias
• Arenites
• Wackes

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Introduction to
SEDIMENTARY ROCKS
The Sandstones
Conglomerates breccias
Lithic cobble breccia
Chert pebble conglomerate
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SEDIMENTARY ROCKS
Classifications
Folks Arenite Classification
Q
Q quartz, metaquartzite, not
chert F feldspars, granite granite gneiss
fragments R all other rock fragments
quartz arenite
95
subarkose
sublitharenite
75
feldspathic litharenite
lithic arkose
arkose
litharenite
F
R
31
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13
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SEDIMENTARY ROCKS
Classifications
Folks Wacke Classification
mudrocks
Q
quartz wacke

arenites
75
feldspathic wacke
lithic wacke
15
percent matrix
0
R
F
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SEDIMENTARY ROCKS
Classifications
Mudrocks
Field criteria Composition Fissile Nonfissile
abundant visible silt gt2/3 silt shaley
siltstone siltsone feels gritty to teeth
gt1/3 lt2/3 silt silty shale mudstone feels
smooth to teeth gt2/3 clay shale
claystone