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Igneous Rocks and Volcanoes

Igneous Rocks and Volcanoes. View From Space - Klyuchevskaya, Russia. Cleveland Volcano, Alaska. Mount Etna From Space. Mount Etna From Space. Mount Etna From Space. Mount Etna. Shiveluch, Russia. Magma – molten rock beneath the surface Lava – molten rock on the surface.

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Igneous Rocks and Volcanoes

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  1. Igneous Rocks and Volcanoes

  2. View From Space - Klyuchevskaya, Russia

  3. Cleveland Volcano, Alaska

  4. Mount Etna From Space

  5. Mount Etna From Space

  6. Mount Etna From Space

  7. Mount Etna

  8. Shiveluch, Russia

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

  10. 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

  11. 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)

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

  13. 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.

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

  15. Bowen's Series and Igneous Rocks

  16. 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

  17. 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

  18. Basalt and Andesite • Hard to tell apart by eye • Distinction is mostly chemical • Why it Matters: • Basalt = Planetary Raw Material • Andesite = Basalt reacting with silica rich crust

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

  20. Types of Volcanoes

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

  22. Anatomy of a Cinder Cone, Hawaii

  23. Tuff Ring: Diamond Head, Hawaii

  24. Tuff Ring: Diamond Head, Hawaii

  25. Shield Volcano: Haleakala, Hawaii

  26. Stratovolcano: Mount Shasta, California

  27. Shastina and Landslide Deposit

  28. Lava Dome, California

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

  30. 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

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

  32. How Calderas Form

  33. Crater Lake, Oregon

  34. Jemez Caldera, New Mexico

  35. Collapsing Volcanoes – Mount Rainier

  36. Collapsing Volcanoes - Hawaii

  37. Evolution of Volcanoes An active volcanic landscape

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

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