沉积岩石学(Sedimentary Rocks)英文课件
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• Facies: a distinct sediment or rock type
• Sorting: process by which particles are separated according to size (& density)
– Clay with clay – Sand with sand – Gravel with gravel Water & wind are excellent sorters, ice is poor
Sedimentary Rocks
• 95% of the Earth’s volume is igneous and metamorphic rocks bu 75% of the Earth’s surface is covered by sediments or sedimentary rocks.
• Clay 80% sand 20% mixture 5%
Well sorted
Porosity
• Compaction: weight of overlying sediment compresses sediments, forces water out and “glues”/lithifies mud siltstone & shale
• Rounded: angular fragments become rounded (& smaller) through abrasion as they are transported
Rounding
• Deposition: ice, wind, or water deposit/drop sediment in river bed, moraine, lake, beach, ocean, etc.
• Fissile: rock breaks easily along closely spaced parallel lines
– Like cleavage in rock
Fissile
Sedimentary Rocks
• 1. Detrital/Clastic • 2. Chemical • 3. Biochemical
gravel
angular breccia
gravel
• Sand 1/16 – 2mm (mostly Qtz) sandstone
• Mud <1/16 mm silt
siltstone
silt & clay mudstone
<1/256 mm clay
claystone shale
• Sandstone = Sst: sandy
ocean
• lithification
–
precipitation
• Rock
limestone
Terminology
• Precipitation: opposite of dissolve: aqueous to solid
• lithification: materials are compacted and/or cemented together to form rock.
– Red sandstone:
• with lots of K Fs (pink Fs) = arkose sst
• Siltstone: gritty with wet mud smell • Shale: greasy with wet mud smell
Siltstone
Sorting
high river
gravel
Energy
beach
delta
sand silt
low lake/ocean
clay
sorted
• Gravel facies
Sand facies
Silt facies
Clay facies
• Pore space = porosity = voids between particles
• Derived from pre-existing rocks:
– 1. detrital/clastic rocks: mineral grains or rock fragments (mechanical or biological weathering)
– 2. chemical: dissolved & precipitated minerals (chemical weathering).
• 1. Detrital/Clastic
– Detritus = solid particles or pre-existing rocks – Clastic = composed of rock fragments
Sediment size description rock name
• Gravel >2mm rounded conglomerate
• Cementation: weathered silica, calcite and iron oxides dissolved in water precipitate in pore spaces to cement/lithify particles together.
• Friable: rock is easily crumbled (like dry cake)
• Ex: granite: Quartz + Fs + Biotite
• Weathering: Mech/bio
quartz sand
clays
• Transport
–
wk.baidu.com
River, wind, ice
• Deposition
–
Beach delta ocean
• lithification
–
Cemented
• Rock
sandstone shale
Sedimentary Rocks
• Ex: granite: Qtz + Ca plag’ Fs + Biotite
• Weathering: Chem’
calcium
• Transport
–
solution in river
• Deposition
–
• Sorting: process by which particles are separated according to size (& density)
– Clay with clay – Sand with sand – Gravel with gravel Water & wind are excellent sorters, ice is poor
Sedimentary Rocks
• 95% of the Earth’s volume is igneous and metamorphic rocks bu 75% of the Earth’s surface is covered by sediments or sedimentary rocks.
• Clay 80% sand 20% mixture 5%
Well sorted
Porosity
• Compaction: weight of overlying sediment compresses sediments, forces water out and “glues”/lithifies mud siltstone & shale
• Rounded: angular fragments become rounded (& smaller) through abrasion as they are transported
Rounding
• Deposition: ice, wind, or water deposit/drop sediment in river bed, moraine, lake, beach, ocean, etc.
• Fissile: rock breaks easily along closely spaced parallel lines
– Like cleavage in rock
Fissile
Sedimentary Rocks
• 1. Detrital/Clastic • 2. Chemical • 3. Biochemical
gravel
angular breccia
gravel
• Sand 1/16 – 2mm (mostly Qtz) sandstone
• Mud <1/16 mm silt
siltstone
silt & clay mudstone
<1/256 mm clay
claystone shale
• Sandstone = Sst: sandy
ocean
• lithification
–
precipitation
• Rock
limestone
Terminology
• Precipitation: opposite of dissolve: aqueous to solid
• lithification: materials are compacted and/or cemented together to form rock.
– Red sandstone:
• with lots of K Fs (pink Fs) = arkose sst
• Siltstone: gritty with wet mud smell • Shale: greasy with wet mud smell
Siltstone
Sorting
high river
gravel
Energy
beach
delta
sand silt
low lake/ocean
clay
sorted
• Gravel facies
Sand facies
Silt facies
Clay facies
• Pore space = porosity = voids between particles
• Derived from pre-existing rocks:
– 1. detrital/clastic rocks: mineral grains or rock fragments (mechanical or biological weathering)
– 2. chemical: dissolved & precipitated minerals (chemical weathering).
• 1. Detrital/Clastic
– Detritus = solid particles or pre-existing rocks – Clastic = composed of rock fragments
Sediment size description rock name
• Gravel >2mm rounded conglomerate
• Cementation: weathered silica, calcite and iron oxides dissolved in water precipitate in pore spaces to cement/lithify particles together.
• Friable: rock is easily crumbled (like dry cake)
• Ex: granite: Quartz + Fs + Biotite
• Weathering: Mech/bio
quartz sand
clays
• Transport
–
wk.baidu.com
River, wind, ice
• Deposition
–
Beach delta ocean
• lithification
–
Cemented
• Rock
sandstone shale
Sedimentary Rocks
• Ex: granite: Qtz + Ca plag’ Fs + Biotite
• Weathering: Chem’
calcium
• Transport
–
solution in river
• Deposition
–