EXTRUSIVE IGNEOUS What’s your favorite volcano? ROCKS Volcanoes and Volcanic Rocks Famous Volcanoes Do you clean your volcanoes regularly? • Basalts • Andesites • Rhyolites • Dotsero, CO • Fuji • Yellowstone • Kilauea • St. Helens • Valles • Mauna Loa • Ranier • Long Valley • Haleakala • Shasta • Crater Lake • Hekla • Stromboli • Pinatubo • Vesuvius • Krakatao • Popocatepetl • Santorini • Orizaba • Campi Phlegri • Pelée (Naples) Where do volcanoes occur? Where do volcanoes occur? • Plate Boundaries (98%) – Divergent – Ocean-ocean convergent – Ocean-continent Convergent • Hot (wet) Spots 1 Most Volcanoes are at Plate Boundaries Where do volcanoes not occur? • Cratons • Passive continental margins • Oceanic abyssal plains • Continent – continent convergent boundaries Igneous Rock Names Magma and Lava and Compositions • Magma is the term for any molten • Composition • Intrusive • Volcanic silicate material, whether below the surface or on top. Name Rock Name Rock Name • Volcanic rocks are erupted on the • Ultramafic • Peridotite • (Komatiite) surface. • Mafic • Gabbro • Basalt – Volcanic rocks are fine-grained (<1 • Diorite • Andesite • Intermediate mm) • Silicic (felsic) • Granite • Rhyolite • Lava is the term for a magma on the surface. Most Volcanoes are at Plate Boundaries Geologic Settings 2 Basaltic Eruptions Pahoehoe, Hawaii (Basalt) • Low Viscosity • High Temperature (1000 - 1200ºC) • Normally Quiescent Lava Flows – Aa - early, low temperature, blocky flow – Pahoehoe - later high temperature ropy flow – Pillow Lavas - underwater flow • Edifice – Shields – Cinder cones Aa, Hawaii (Basalt) Pillow Lava, Kauai (Basalt) Most Volcanoes are at Plate Boundaries Cinder Cone, Pu’uo’o, Hawaii (Basalt) 3 Cinder Cone + Caldera, (Basalt) Skjaldbreidur Shield, (Basalt) Caldera, (Basalt) Halemaumau Basalt Flow Grand Canyon < 1My old Columnar Basalt Basaltic Eruptions • Low Viscosity • High Temperature (1000 - 1200ºC) • Normally Quiescent Lava Flows – Aa - early, low temperature, blocky flow – Pahoehoe - later high temperature ropy flow – Pillow Lavas - underwater flow • Edifice – Shields – Cinder cones 4 Famous Volcanoes Most Volcanoes are at Plate Boundaries • Basalts • Andesites • Rhyolites • Dotsero, CO • Fuji • Yellowstone • Kilauea • St. Helens • Valles/Jemez • Mauna Loa • Ranier • Long Valley • Haleakala • Shasta • Crater Lake • Hekla • Stromboli • Pinatubo • Vulcan’s • Vesuvius • Krakatao Throne • Popocatepetl • Santorini • Orizaba • Campi Phlegri • Pelée (Naples) • Etna Andesite Eruptions Geologic Settings • Higher viscosity (higher polymerization) • Lower temperature • More water, more explosive • Subduction zone volcanism • Flows – Viscous lava flows – Pyroclastic flows • Edifice – Composite Cones Clicker Question Clicker Question Plate tectonics explains the Plate tectonics explains the global pattern of volcanism. global pattern of volcanism. Which volcanic environment will, on average, produce Which volcanic environment will, on average, produce the most felsic (silicic) lavas? the most felsic (silicic) lavas? A. Mid-ocean ridge A. Mid-ocean ridge B. Island arc B. Island arc C. Continental arc C. Continental arc D. Oceanic hotspot D. Oceanic hotspot 5 Clicker Question Clicker Question Plate tectonics explains the Plate tectonics explains the global pattern of volcanism. global pattern of volcanism. What composition volcanic rocks characterize What composition volcanic rocks characterize magmatism at mid-ocean ridges? magmatism at mid-ocean ridges? A. Carbonatite A. Carbonatite B. Basalt B. Basalt C. Andesite C. Andesite D. Rhyolite D. Rhyolite Andesite Flow, Mt Shasta Composite Cone, Mt. Fuji, Japan Composite Cone, Mt. Daisen Composite Cone, Llaima Volcano, Chile 6 Ash Flow Eruption, Composite Cone, Mt. St Helens Llaima Volcano, Chile 7 Andesite Eruptions • Higher viscosity (higher polymerization) • Lower temperature • More water, more explosive • Subduction zone volcanism • Flows – Viscous lava flows – Pyroclastic flows (Nuée Ardente) • Edifice – Composite Cones Famous Volcanoes Clicker Question • Basalts • Andesites • Rhyolites • Which of the following is an • Dotsero, CO • Fuji • Yellowstone example of a basalt volcano? • Kilauea • St. Helens • Valles/Jemez • Mauna Loa • Ranier • Long Valley – A. Mt St. Helens • Haleakala • Shasta • Crater Lake – B. Yellowstone • Hekla • Stromboli • Pinatubo – C. Mauna Loa • Vulcan’s • Vesuvius • Krakatao – D. Mt Pinatubo Throne • Popocatepetl • Santorini – E. Mt. Fuji • Orizaba • Campi Phlegri • Pelée (Naples) • Etna Clicker Question Clicker Question • Which of the following is an • Which of the following is an example of a basalt volcano? example of an andesite volcano? – A. Mt St. Helens – A. Kilauea – B. Yellowstone – B. Yellowstone –C. Mauna Loa – C. Mauna Loa – D. Mt Pinatubo – D. Mt Pinatubo – E. Mt. Fuji – E. Mt. Fuji 8 Clicker Question Rhyolite Eruptions • Which of the following is an • Very high viscosity example of an andesite volcano? • Low temperature (600 - 800ºC) • Massive Pyroclastic eruptions – A. Kilauea – Air fall (pumice) – B. Yellowstone – Ash Flow (Nuée Ardente) Tuff – C. Mauna Loa – Obsidian Flows – D. Mt Pinatubo • Edifice –E. Mt. Fuji – Caldera (5 - 25 km) – Resurgent dome Rhyolite Eruptions Geologic Settings • Associated Phenomena – Hot Springs – Geysers – Fumaroles • Geologic Setting – Continental Margins and Interiors – Subduction Zones Ash-Flow Pumice = Glass foam Tuff with Air-Fall Units (pumice) 9 Ash-Flow Tuff Unit Ash-Flow Tuff Unit Non-Welded Top Welded Core Vitrophyre Non-welded base Silicic Tuff Units (Jemez, NM) Sulfur Fumarole, Nysseros Obsidian Flow Non-welded Air-Fall Units Caldera with Cinder Cone Crater Lake, OR 10 Rhyolite Eruptions Geyser • Very high viscosity Old Faithful • Low temperature (600 - 800ºC) (Yellowstone) • Massive Pyroclastic eruptions – Air fall (pumice) – Ash Flow (Nuée Ardente) Tuff – Obsidian Flows • Edifice – Caldera (5 - 25 km) – Resurgent dome Andesite Eruptions Basaltic Eruptions • Higher viscosity (higher polymerization) • Low Viscosity • Lower temperature • High Temperature (1000 - 1200ºC) • More water, more explosive • Normally Quiescent Lava Flows • Subduction zone volcanism – Aa - early, low temperature, blocky flow • Flows – Pahoehoe - later high temperature – Viscous lava flows ropy flow – Pyroclastic flows – Pillow Lavas - underwater flow • Edifice • Edifice – Composite Cones – Shields – Cinder cones Crater Lake, OR Crater Lake, OR A.Basalt A.Basalt B.Andesite B.Andesite C.Rhyolite C.Rhyolite 11 Mt. St. Helens Mt. St. Helens A.Basalt A.Basalt B.Andesite B.Andesite C.Rhyolite C.Rhyolite Kilauea Kilauea A.Basalt A.Basalt B.Andesite B.Andesite C.Rhyolite C.Rhyolite Geologic Settings Most Volcanoes are at Plate Boundaries 12 Famous Volcanoes Volcanic Terms • Ultramafic • Pillow Lava • Basalts • Andesites • Rhyolites • Tuff • Mafic • Shield • Dotsero, CO • Fuji • Yellowstone • Obsidian • Intermediate • Composite • Kilauea • St. Helens • Valles/Jemez • Vitrophyre • Silicic Cone • Mauna Loa • Ranier • Long Valley • Pumice • Basalt • Cinder Cone • Haleakala • Shasta • Crater Lake • Resurgent • Andesite • Caldera • Hekla • Stromboli • Pinatubo dome • Magma • Pyroclastic • Vesuvius • Krakatao • Hot Spring • Lava • Nuée Ardente • Popocatepetl • Santorini • Geyser • Aa • Air Fall • Orizaba • Campi Phlegri • Rhyolite • Pahoehoe • Ash Flow • Pelée (Naples) EXTRUSIVE IGNEOUS Igneous Rock Names ROCKS and Compositions • Composition • Intrusive • Volcanic Name Rock Name Rock Name • Ultramafic • Peridotite • (Komatiite) • Mafic • Gabbro • Basalt • Diorite • Andesite Volcanoes and Volcanic Rocks • Intermediate • Silicic (felsic) • Granite • Rhyolite Most Volcanoes are at Plate Boundaries Famous Volcanoes • Basalts • Andesites • Rhyolites • Dotsero, CO • Fuji • Yellowstone • Kilauea • St. Helens • Valles • Mauna Loa • Ranier • Long Valley • Haleakala • Shasta • Crater Lake • Hekla • Stromboli • Pinatubo • Vulcan’s • Vesuvius • Krakatao Throne • Popocatepetl • Santorini • Orizaba • Campi Phlegri • Pelée (Naples) 13 Volcanic Terms Clicker Not Registered • Ultramafic • Pillow Lava • Tuff • Mafic • Shield • Obsidian • Intermediate • Composite • Vitrophyre • Silicic Cone • Pumice • Basalt • Cinder Cone • Resurgent • Caldera • Andesite dome • Pyroclastic • Magma • Hot Spring • Nuée Ardente • Lava • Geyser • Air Fall • Aa • Rhyolite • Pahoehoe • Ash Flow Clicker Not Registered Clicker Not Registered • McClelland, A • Keegan, R. • McClelland, A • Keegan, R. • Moten, J. • Moten, J. • Runyon, K. • Runyon, K. • Scott, G. • Scott, G. • Shepley, J. • Shepley, J. • Wheeler, S. • Wheeler, S. 14.