Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying...
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Transcript of Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying...
![Page 1: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/1.jpg)
Chapter 8 – FROM SEDIMENT INTO
SEDIMENTARY ROCK
![Page 2: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/2.jpg)
Sediments and Sedimentation• Deposition
– Laying down of sediment• Separated into 3 broad
categories– Clastic (Detrital)– Chemical– Biogenic (Biochemical)
![Page 3: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/3.jpg)
• Clastic sediment– Fragmented rock &
mineral debris from weathering & erosion
– Described by particle shape, angularity, & size
– Volcani-clastic sediments• Pyroclasts
– Distinguished by size (bombs, lapilli, ash)
Sediments and Sedimentation
![Page 4: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/4.jpg)
• Chemical sediment– Precipitation of minerals dissolved in lake, river, or sea
water• Limestone
– Shallow sea water evaporation causes dissolved salts to precipitate
Sediments and Sedimentation
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• Biogenic sediment– Primarily composed of plant or
animal remains• Shells, bones, teeth• Wood, roots, leaves
Sediments and Sedimentation
![Page 6: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/6.jpg)
Sedimentary Rocks• Lithification
– Processes where loose sediment transforms into sedimentary rock• Bedding
– Layers of strata in sediment/sedimentary rock
• Bedding surface– Top or bottom of rock
bed• Graded bed
– Bed with large clasts at bottom, fining toward top
• Cross bedding– Beds are inclined
relative to layer they occur in
![Page 7: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/7.jpg)
Lithification Processes• Compaction
– Reduced pore space due to weight of sediments above
• Cementation– Dissolved substances
precipitate out & act as glue
• Recrystallization– Form new crystalline
mineral grains from old ones
• Diagenesis– Low
temperature/pressure changes
![Page 8: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/8.jpg)
Types of Sedimentary Rocks• Clastic sedimentary
rock– Conglomerate or breccia
• Large fragments in fine grained matrix
– Sandstones• Medium grained (sand
sized)• Arkose or Quartz
Sandstone– Mudstones
• Very fine grained rock• Same composition as
shale but lacks fissility– Shale
• Very fine grained fissile rock
• Fissile = breaks into layers
Particle Sizes in Clastic Sedimentary Rocks
Diameter (mm)
Particle Type
Sediment Name
Sedimentary Rock
More than 256
Boulder
GravelConglomerate
or Breccia64 to 256 Cobble
4 to 64 Pebble
2 to 4 Granule
1/16 to 2 Sand Sand Sandstone
1/256 to 1/16
Silt
MudSiltstone, Shale
or MudstoneLess than 1/256
Clay
![Page 9: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/9.jpg)
Types of Sedimentary Rocks• Chemical sedimentary rocks
– Classified mainly by composition– Evaporite
• Formed by lake or sea water evaporation
• Rock salt; rock gypsum
– Limestone & related• Oolitic• Dolostone
– Chert
![Page 10: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/10.jpg)
• Biogenic sedimentary rocks– Limestone
• Mostly made of calcite• Coquina• Chalk
– Peat• Formed by
accumulation & compaction of plant remains
– Coal• Formed by lithification
of plant-rich sediment• Bituminous coal
Types of Sedimentary Rocks
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Depositional Environments• Interpreting
environmental clues– Patterns made by air
& water that moved over sediments
– Ripple marks– Fossils– Mud cracks
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Depositional Environments on Land• Streams
– Alluvial fan• Forms where stream is not
constrained by valley walls• Fan-shaped
• Lakes– Delta
• Forms where stream enters standing body of water
• Usually triangle-shaped– Playa
• Seasonal lake
![Page 13: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/13.jpg)
Depositional Environments on Land
• Glacier– Till
• Mixed particles sizes & shapes
• Wind– Eolian sediment
• Sediments carried & deposited by wind
– Loess• Wind-blown silt & clay sediment
![Page 14: Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK. Sediments and Sedimentation Deposition –Laying down of sediment Separated into 3 broad categories –Clastic.](https://reader035.fdocuments.us/reader035/viewer/2022062313/56649cbb5503460f94983579/html5/thumbnails/14.jpg)
Depositional environments in & near the ocean• Delta• Estutary
– Semi-enclosed body of coastal water
– Fresh water mixes with sea water• Beaches
– Mixed material; quartz common• Shelves
– Silt or sand sediment; numerous fossils
• Carbonate platforms and reefs– Reef: wave-resistant structure built
of marine invertebrate skeletons
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Depositional environments in & near the ocean• Turbidites & turbidity currents
– Turbulent, gravity driven flow of sediment & water
– Moves sediment from continental shelf to deep sea
• Seafloor– Nutrient-rich
• Calcareous ooze• Siliceous ooze
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Depositional environments in and near the ocean• Sedimentary facies
– Changes in the character of sediment from one environment to another
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How Plate Tectonics Affect Sedimentation• Divergent plate
boundaries– Rift valleys
• Convergent plate boundaries– Collisional type – Subduction type
• Back-arc basin• Accretionary wedges