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Weathering and Erosion Formation of Sedimentary Rocks

Weathering and Erosion Formation of Sedimentary Rocks. Weathering – the physical breakdown ( disintegration ) and chemical alteration ( decomposition ) of rock at or near Earth’s surface Erosion – the physical removal of material by agents such as water, wind, ice, or gravity. insoluable.

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Weathering and Erosion Formation of Sedimentary Rocks

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  1. Weathering and ErosionFormation of Sedimentary Rocks • Weathering – the physical breakdown (disintegration) and chemical alteration (decomposition) of rock at or near Earth’s surface • Erosion – the physical removal of material by agents such as water, wind, ice, or gravity

  2. insoluable

  3. basalt (Mg,Fe)2SiO4 (Mg,Fe)SiO3 pyroxine H4SiO4 in solution Mg2+ in solution Fe (III) hydroxide (insoluble, rust) CaAl2Si2O8 Ca-feldspar and NaAlSi3O8 Na-Feldspar Ca+2 in solution Na+1 in solution Al2Si2O5(OH)4 (insoluble, “clay”)

  4. granite SiO2 quartz SiO2 (insoluble, “sand”) CaAl2Si2O8 Ca-feldspar; NaAlSi3O8 Na-Feldspar KAlSi3O8 K-Feldspar Ca+2 , Na+1, K+1 in solution Al2Si2O5(OH)4 (insoluble, “clay”) (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22(OH)2 amphibole (and also mica) Mg+2, Ca+2 , Na+1 in solution Al2Si2O5(OH)4 (insoluble, “clay”) Fe (III) hydroxide (insoluble, rust)

  5. Climateand Weathering

  6. Hot and wet favors chemical weathering

  7. Cold and snowy favors mechanial weathering

  8. Differential Weathering and Erosioncreates topography Slowly weathered and eroded - high (Morningside Heights, Palisades, Ramapo Mountains) Quickly weathered and eroded - low (sediments beneath Hudson River and west of Palisades)

  9. erosion uplift Hill formed by differential erosion Residual topography

  10. Clastic Sediments and Clastic Sedimentary Rocks A. Sediments B. Sedimentary Rocks

  11. Energy and Depositional Environment

  12. Worldwide sediment yield of major drainage basins

  13. Migrationof meandersleads tocross-bedding crossbed from fieldtrip

  14. Cross-section of Deltanote that delta grows (progrades) towards sea

  15. Hjulstrom Curve

  16. Hjulstrom Curve Pebbles and cobbles Pebbles and cobbles: hard to get moving, an hard to keep moving

  17. Hjulstrom Curve Sand: easy to get moving, a fairly easy to keep moving Sand

  18. Hjulstrom Curve Silt and Clay Silt and Clay: hard to get moving, but very easy to keep moving

  19. Ocean Sediments Part 1

  20. Evapotite: common during with continental rifting

  21. Fossil Fuels Solid Earth System

  22. petroleum Organic-rich source rock, e.g. shale Maturation through burial at the right temperature Collection in a porous reservoir rock Concentration in trap through buoyancy

  23. Formation of Ores

  24. Some unusual process must: 1) remove specific elements, compounds or minerals from ordinary rock,2) transport these elements, compounds, or minerals3) concentrate the elements, compounds, or minerals preferentially at one spot or zone where the transport stops.

  25. the primary mechanisms for concentrating minerals into ores involves either:sorting by densitysorting by solubility.

  26. Concentration through liquid immiscibility High T Low T Desirable element preferentially concentrated into low-volume melt

  27. Aqueous fluids in magma As magma cools, the volatiles (mostly water and carbon dioxide) that they contain can form super-critical fluids. supercritical fluids are on the verge of making the phase transition from liquid to gas. because of their extremely high temperature, many elements are soluble. These fluids can concentrate copper, molybdenum, gold, tin, tungsten and lead. The fluids from a large pluton can invade surrounding rocks, along cracks called hydrothermal veins).

  28. Aqueous fluids from granitic magma have invaded surrounding rock porphery copper ore

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