lecs_20&21_Volcanism

lecs_20&21_Volcanism - IGNEOUS ROCKS EXTRUSIVE...

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Unformatted text preview: IGNEOUS ROCKS EXTRUSIVE (Volcanic) Fine-grained INTRUSIVE (Plutonic) Coarse-grained MAGMA Molten Rock Usually with dissolved gases Generated at depth Eruptions if magma (lava) reaches surface If doesnt reach surface, solidifies underground Intrudes country rock Intrusive contact Chill zone Xenolith VOLCANISM Lava = magma at Earths surface Usually with dissolved gases Silica content controls viscosity, explosivity Pyroclasts fragments of rock created by explosion Lava flows hot, low viscosity liquid Pyroclastic rocks & lavas = Extrusive rocks Extrusive rocks commonly form Volcanoes VOLCANISM Lava = Magma at Earths surface Usually with dissolved gases Silica content controls viscosity, explosivity Pyroclasts fragments of rock created by explosion Lava flows hot, low viscosity liquid Pyroclastic rocks & lavas = Extrusive rocks Extrusive rocks commonly form Volcanoes VOLCANISM Lava = Magma at Earths surface Usually with dissolved gases Silica content controls viscosity, explosivity Pyroclasts fragments of rock created by explosion Lava flows hot, low viscosity liquid Pyroclastic rocks & lavas = Extrusive rocks Extrusive rocks commonly form Volcanoes VOLCANISM...
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lecs_20&21_Volcanism - IGNEOUS ROCKS EXTRUSIVE...

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