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Fig 5.12

WHERE DO SEDIMENTS ORIGINATE?. Fig 5.12. WEATHERING OF PRE-EXISTING ROCKS. HOW ARE SEDIMENTS MOVED? (ERODED/TRANSPORTED). water wind ice gravity. WHERE DO SEDIMENTS ACCUMULATE?. 75% OF SURFACE ROCKS ARE SEDIMENTARY. JUST LIKE IGNEOUS ROCKS: TEXTURE MEANS SIZE OF GRAINS.

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Fig 5.12

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  1. WHERE DO SEDIMENTS ORIGINATE? Fig 5.12 WEATHERING OF PRE-EXISTING ROCKS

  2. HOW ARE SEDIMENTS MOVED? (ERODED/TRANSPORTED) • water • wind • ice • gravity

  3. WHERE DO SEDIMENTS ACCUMULATE?

  4. 75% OF SURFACE ROCKS ARE SEDIMENTARY.

  5. JUST LIKE IGNEOUS ROCKS: • TEXTURE MEANS SIZE OF GRAINS • Fine-grained Coarse- grained

  6. Sedimentary Rocks: • Form in surface environments (75% of earth’s surface) • Classified according to texture (in part) • Reflect conditions of environment of formation • Accumulate in layers over time (can be “read” like pages in a book)

  7. JUST LIKE IGNEOUS ROCKS: • TEXTURE IN SEDIMENTARY ROCKS • IS A MEANS TO CLASSIFY ROCKS • BUT ALSO TELLS US ABOUT FORMATION • OF ROCK … • TEXTURE RELATES TO ENERGY OF • ENVIRONMENT OF DEPOSITION

  8. WATER SORTS SEDIMENTS ACCORDNG TO SIZE, SO TEXTURE TELLS US ABOUT ENERGY OF E.O.D. Increasing energy = Increasing particle size

  9. Layered nature of sedimentary rocks reflects depositional processes

  10. What are SOURCES of sediments for sedimentary rocks?

  11. Mechanical Weathering

  12. Chemical Weathering KAlSi3O8 + H+ + HCO3- + H2O ►► Potassium feldspar Al2Si2O5(OH)4 + K+ + HCO3- + SiO2 Introduced in solution Clay mineral Carried away in solution

  13. Products from mechanical /chemical wxg Dissolved minerals From chem. wxg (in solution) Solids (residuals) secondary minerals from chemical wxg (clays, iron oxides) Primary minerals from mechanical wxg (quartz sand) CHEMICAL SED RX DETRITAL (CLASTIC) SED RX Minerals + organics = SOIL

  14. breccia conglomerate Conglomerate &breccia very coarse-grained detrital rocks formed in high-energy environments

  15. Sandstone* a coarse-grained detrital rocks formed in a medium to high-energy environment. * composition of grains is commonly quartz

  16. Shale* a fine-grained detrital rock formed in a low-energy environment (most common sedimentary rock). * Composition of grains is almost always clay

  17. Limestone* a chemical rock formed in a variety of environments, often with the assistance of organisms (most common chemical sedimentary rock). *composition is always calcite (CaCO3), grain size is variable

  18. solid solution solution solution Weathering Chemical Weathering Processes: • Solution of calcite • CO2 + H20 ► H2CO3 • CaCO3 + H2CO3► Ca 2+ + 2 (HCO3)-

  19. solid solution solution solution Formation of Limestone Precipitation of Calcite • CaCO3 + 2 H+ + (CO3)2- Ca 2+ + 2 (HCO3)-

  20. Rock Salt: a chemical rock formed from evaporation of water (evaporite)

  21. Sedimentary processes and life processes are intermingled Fossils are evidence of past life. They are concentrated in sedimentary rocks.

  22. What are fossil fuels? • Coal • Oil • Natural gas All are organic materials with C-H bonds Fossils fuels are concentrated in sedimentary rocks.

  23. Geologic requirements for oil production: • source rock • reservoir rock • trap

  24. What is proposed relationship between fossil fuels and global • warming?

  25. Global carbon cycle

  26. Non-metallic mineral • resources are concentrated • in sedimentary rocks. • Examples? • What processes concentrate • these materials?

  27. Limestone Quarry

  28. Crushed stone • Price: $6.80 per ton • Volume: 1.1 billion tons • Value? • Relative cost of development? • Copper • Price: $3,230 per ton • Volume: 2.2 million tons • Value? • Relative cost of development?

  29. Chemical Weathering KAlSi3O8 + H+ + HCO3- + H2O ►► Potassium feldspar Al2Si2O5(OH)4 + K+ + HCO3- + SiO2 Introduced in solution Clay mineral Carried away in solution

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