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Igneous Rocks and Volcanoes

Igneous Rocks and Volcanoes. View From Space - Klyuchevskaya, Russia. Magma – molten rock beneath the surface Lava – molten rock on the surface. Igneous Rocks Cool from the Molten State. Volcanic -- Erupted on Surface Plutonic -- Solidify Within Earth Large Grain Size ---> Slow Cooling

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Igneous Rocks and Volcanoes

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  1. Igneous Rocks and Volcanoes

  2. View From Space - Klyuchevskaya, Russia

  3. Magma – molten rock beneath the surfaceLava – molten rock on the surface

  4. Igneous Rocks Cool from the Molten State • Volcanic -- Erupted on Surface • Plutonic -- Solidify Within Earth Large Grain Size ---> Slow Cooling • Volcanic Rocks -- Fine Grained • Plutonic Rocks -- Coarse Grained Porphyritic Texture:Large Crystals in Fine-grained Setting

  5. Igneous Rock Classification How Much Silica? (account for Si) • Excess - Rock Has Quartz • Just Enough to Form Other Silicates • Deficient - Silica-Poor Minerals (Like Olivine) What Feldspars? (Account for Al, Ca, K, Na ) • Potash Feldspar KAlSi3O8 • Plagioclase SeriesNaAlSi3O8......CaAl2Si2O8 What Other Minerals Are Present? (Account for Fe, Mg)

  6. Feldspars K - Feldspar: KAlSi3O8 • Several Slightly Different Forms: • Microcline • Orthoclase Plagioclase (Solid Solution) • Albite: NaAlSi3O8 • Anorthite: CaAl2Si2O8 • Any Mixture of the Two Is Possible

  7. Bowen's Reaction Series • The geologist N.L. Bowen found that minerals tend to form in specific sequences in igneous rocks • These sequences could be assembled into a composite sequence.

  8. Bowen's Reaction Series No igneous rock ever displays the whole sequence, just a slice across the sequence.

  9. Bowen's Series and Igneous Rocks

  10. Bowen's Series and Igneous Rocks Volcanic Rocks (Rare)  Basalt   Andesite                 Rhyolite Plutonic Rocks Dunite  Gabbro   Diorite                   Granite 1200 C            Melting Point              700 C Mg, Fe              Rich In...             Si, Na, K Rapid              Weathering                   Slow Usually Dark       Color              Often Light

  11. Bowen's Series and Volcanoes Volcanic Rocks (Rare)  Basalt   Andesite                 Rhyolite Plutonic Rocks Dunite  Gabbro   Diorite                   Granite Fluid               Lava Is...                 Viscous Mild                Eruptions                 Violent Type of Volcano Shield Volcano     Stratovolcano    Plug Dome

  12. Some Igneous Rocks Are Named on Textural Criteria • Pumice - Porous • Obsidian - Glass • Tuff - Cemented Ash • Breccia - Cemented Fragments • Porphyry - Fine Matrix, Large Crystals

  13. Types of Volcanoes

  14. A Cinder Cone:Wizard Island, Crater Lake, Oregon

  15. Anatomy of a Cinder Cone, Hawaii

  16. Tuff Ring: Diamond Head, Hawaii

  17. Tuff Ring: Diamond Head, Hawaii

  18. Shield Volcano: Haleakala, Hawaii

  19. Stratovolcano: Mount Shasta, California

  20. Shastina and Landslide Deposit

  21. Lava Dome, California

  22. Lava Flows Pyroclastic Debris Bombs Lapilli Ash Mudflows Landslides Gases Steam Carbon Dioxide H2S SO2 HCl HF Products of Eruptions

  23. Pollution SO2, HCl in Water Lava Flows Falling Ejecta Ash Falls Building Collapse Crop Destruction Mudflows Direct Damage (Colombia, 1985) Floods (Several Types) Blast (Mt. St. Helens, 1980) Pyroclastic Flow (St. Pierre, 1902) Gas (Lake Nyos, Cameroon, 1986) Environmental Hazards of Volcanoes

  24. Pyroclastic Flow or Nuee Ardente (French: Fiery Cloud)

  25. How Calderas Form

  26. Crater Lake, Oregon

  27. Jemez Caldera, New Mexico

  28. Collapsing Volcanoes – Mount Rainier

  29. Collapsing Volcanoes - Hawaii

  30. Evolution of Volcanoes An active volcanic landscape

  31. Evolution of Volcanoes A volcanic landscape after a million years or so

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