EOSC 114 Study Guide - Continental Crust, Volcanic Gas, Volcanic Explosivity Index
22 Oct 2013
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Explain what magma density and magma viscosity are: magma: mixture of molten rock, crystals and gas below the earth"s surface, created by the melting of pre-existing rock in earth"s interior (mantle + crust). Reaches the surface through fractures, erupts as lava or pyroclastic material (tephra) In order for magma to rise, it must be. List the different categories of volcanic rocks and less dense than crust. Hot enough to stay liquid: main gases: h2o< co2, so2, cl2. As pressure decreases, the gases become less soluble and bubbles form: viscosity = runninses, resistance to flow. Explain the differences between the magmas they came from. Rich in low density minerals (quartz, pyroxene), darker in colour feldspar) ls, light colour. Big crystals = intrusive aka plutonic (granite, gabbro). Explain why some magmas erupt explosively (as pyroclastic material) and some magmas erupt effusively (as lava) Viscosity and gas content are related to explosively: as pressure decreases, bubbles grow.
