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Relative susceptibility To weathering

Relative susceptibility To weathering. Products of Weathering. Factors influencing Weathering Rates. Rock structures – chemical/mineral composition, physical features Topography Climate Vegetation Time. Sediments and Sedimentary Rocks. Sediments - unconsolidated particles created by.

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Relative susceptibility To weathering

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  1. Relative susceptibilityTo weathering

  2. Products of Weathering

  3. Factors influencing Weathering Rates • Rock structures – chemical/mineral composition, physical features • Topography • Climate • Vegetation • Time

  4. Sediments and Sedimentary Rocks

  5. Sediments - unconsolidated particles created by 1. The weathering of rock 2. The secretions of organisms or decomposition of organic matter 3. Chemical precipitation

  6. Sedimentary Rock Formation • Weathering – breakdown both physically (clasts) or chemically • Erosion – loosening of weathered products (clasts) and initial transport • Transportation – movement of materials via wind, water, or ice; sorting and rounding can occur • Deposition – material settles out of the transporting medium • Lithification – process of either cementation or compaction of the material

  7. W. W. Norton

  8. Sedimentary Rocks Composed of lithified sediments • by compaction – weight of overlying sediment compresses sediment, important in fine-grained sediments • by cementation – materials carried in solution precipitates minerals - iron oxides, carbonates, silica Two Classifications - clastic -nonclastic

  9. Fig. 7.16 W. W. Norton

  10. Sedimentary Rocks Clastic Rock – composed of fragments of preexisting rocks. Nonclastic Rock – composed of chemical precipitates or biochemical matter.

  11. Daily Question Use a Venn diagram to compare and contrast clastic, chemical nonclastic, and biochemical nonclastic sedimentary rocks. Identify at least five characteristics. Clastic Chemical Biochemical

  12. Types of Sediments - Clastic • Broken fragments of rock produced by weathering. • Classified according to size. • Range in size from largest boulder to smallest clay particle.

  13. Clastic Texture Increasing distance from source The size, shape, and distribution of particles that collectively make up a rock Increasing distance from source

  14. Which sample is closer to the source of sediment?

  15. Sorting - a function of transport mechanism 1. Water 2. Wind 3. Glaciers

  16. Sorting by Wind

  17. Fig. 7.26a Stephen Marshak

  18. Graded Beds Fining up

  19. Texture and Transport Distance In general, as transport distance increases, rounding and sorting increase. Examples: Breccia – cemented close to source Conglomerate – transported then cemented

  20. Types of Sediments - Biogenic Terrestrial sediments - mainly plant matter ex. Coal Marine sediments - mainly carbonates Corals - large components of reefs. Bivalves, gastropods, foraminifers - whole or partial skeletons form sand and gravels. Algae, crinoids, echinoderms, bryozoans - disintegrate to form some sand particles and lime mud. Diatoms, Radiolaria – bedded chert sio2

  21. Coral (carbonate)

  22. Foramanifera

  23. Diatoms

  24. Types of Sediments - Chemical Inorganic process, no biological activity involved. Formed by minerals precipitating from solution. i.e. – Ca2+ + CO32- = CaCO3 Na+ + Cl- = NaCl

  25. Chemical Sediments • Terrestrial - Evaporites: Gypsum - CaSO4 . H2O Anhydrite -CaSO4 Halite - NaCl

  26. Chemical Sediments 2. Marine Carbonates - CaCO3 (limestone) Chert (Quartz) – SiO2

  27. Bedding – Layering or stratification in sedimentary rock

  28. Fig. 7.25abc W. W. Norton

  29. Cross Bedding – water or wind

  30. Ripple Marks

  31. Sedimentary Environments

  32. Sedimentary Systems and Plate Tectonics

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