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Sedimentary Rock
Geology Lecture Series,
From various sources
By M. Nukman
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Three Components
Transportation
Deposition
Diagenesis
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Transportation
Sedimentary particle can be transported by sliding (longsoran)
from a slope (energi gravitasi),
It can be transported by the wind,
It can be transported by water (river, ocean current)
Gravitational within water (turbidite)
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By water (transportation contd)
Traction (touch the bottom, saltation)
Density current (no traction, but more dense suspension, form a
chaotic texture)
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Deposition
Sediment particle is deposited when the transportation energy is
too low to bring those particles
Type
Suspension (flying out in water)
Gravitational process (a denser particle will be faster to reach
the bottom)
Implication to sedimentary structure
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Diagenetic
Compaction due to overburden,which will reduce the pores
A water filled the pores will precipitate,could form a new
mineral within the pore
Those new minerals joined the grains together cemented
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Sedimentary Texture
1. Grain Size
= energi transportasi,
see Wentworth scale
2. Sortasi
= keseragaman ukuran butir
v.w. sorted-w.sorted-m.sorted-p.sorted
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Wentworth ScaleName of
ParticleSize Range Loose
SedimentConsolidated
Rock
Boulder >256 mm Gravel Conglomerate or Breccia (depends on
rounding)
Cobble 64 - 256 mm Gravel
Pebble 2 - 64 mm Gravel
Sand 1/16 - 2mm Sand Sandstone
Silt 1/256 - 1/16 mm
Silt Siltstone
Clay
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Sedimentary Texture
1. Grain Size
= energi transportasi,
see Wentworth scale
2. Sortasi
= keseragaman ukuran butir
v.w. sorted-w.sorted-m.sorted-p.sorted
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Coarser-grained,
Very poorly sorted
Finer-grained,
moderately sorted
Lower
K
Higher
K
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Yellow = grains The two areas are equal
Purple = pores
Thicker bedded, less grain contact
Higher permeability
Thinner bedded, more grain contact,
Lower permebility
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3. Bentuk Butir
Tingkat Pembolaan (sphericity)
high sphericity low sphericity
Tingkat Kebundaran (roundness)
v.angular well rounded
Surface Texture
(permukaan halus permukaan kasar)
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4. Kemas (Fabric)
= Orientasi dan hubungan antar butir (packing)
Orientasi Flow Direction
Packing Grain supported Matrix supported
