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Lecture 13 - Large Large volume flows flows Small volume...

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Unformatted text preview: Large Large volume flows flows Small volume Small flows flows Flood Basalts 06.05.a Columbia Plateau Thick dike Thin dike Columbia Plateau Origin of Flood Basalts Continenta l c ru s t Lithosphere Plume rises through mantle Plume partially melts Plume rises to base liithosphere lt Melting of liithosphere lt Rising Rising mantle plume plume Asthenosphere Flood Flood basalt basalt Plume spreads with Plume additional melting additional 06.05.c1-3 Observe the location of flood basalts of the world Columbia Plateau North Atlantic India Siberia South America 06.05.c4 Afar Kerguelen Ontong Java divergent margin settings What regions have a high risk for volcanic activity? 06.12.c Composite Composite volcanoes volcanoes Calderas Shield Shield volcanoes volcanoes Observe some Observe characteristics of a volcano volcano Vent where Vent magma erupted erupted Crater Crater 05.09.a Commonly a hill or mountain Can erupt Can lava or ash lava Can be erupted from fissure Can or depression, so not a hill or Observe how a hill capped by volcanic rocks can form. Observe Is it a volcano? Is Fissure feeds a lava flow Erosion of flow Hill was not over Hill a vent vent Example of such a hill Example that is not a volcano that 06.01.b2-4 Types of Volcanoes: Part 1 Scoria Cone Shield Volcano 06.01.c Types of Volcanoes: Part 2 Composite Volcano Volcanic Dome 06.01.c Types of Volcanoes: Part 3 Fissure Caldera 06.01.c Observe these types of eruptions 06.02.a Lava flow Lava fountain Dome Eruption column How Do Gases Affect Magma? What happens when What you open a soda? you Propels eruption Propels and forms ash and Under less Under pressure, gas forms bubbles forms Dissolved gas held in Dissolved magma by pressure magma 06.02.b How Does Viscosity Affect Eruptions? More viscous: More difficult to flow and traps gas and 06.02.c1-2 Less viscous: Less flows easier and gas can escape gas Scoria Cones and Basalt Flows: Rock Types Vesicular Vesicular basalt basalt Nonvesicular Nonvesicular basalt basalt Scoria 06.03.a Features of Lava Flows 06.03.a Lava tubes AA lava Pahoehoe lava Scoria Cones and Basalt Flows Early formation of a Early scoria cone scoria Switch to lava Switch flows flows 06.03.b Scoria cones Lava flow Shield Volcanoes Mauna Kea Can have craters and Can small calderas small Mauna Loa Kilauea 06.04.a Fluid magma from Fluid fissures and scoria cones fissures Fissures fed Fissures by dikes by Observe these eruptions from shield volcanoes Fissure eruption Eruption into water Lava flow Pillow basalt 06.04.b Observe hazards associated with basaltic eruptions, Observe noting if a hazard only affects areas near the vent Lava fountain Lava Lava-caused fire Volcanic ash Lava flow 06.06.b1 ...
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