GEOL 1001 Chapter : Chapter 5 Notes Exam 2
Document Summary
Chapter 5: basaltic lava flow, andesite flow, rhyolite flow. Has a low viscosity (travel very fast up to 30 km/h) Can have a a"a" texture (jumble of sharp fragments) Columnar jointing texture (contracts as it cools) Not going to flow very far from volcano. Lava is in a rhyolite dome : lava flow, pyroclastic flow, volcanic gas, volcanic eruptions, products of eruption, different volcanoes, shield volcano. Once contents are released from the pressure, the contents explode and reduce pressure: basaltic pyroclastic, andesite pyroclastic/ rhyolite pyroclastic. Silica-rich rocks are more likely to be gaseous. Ignimbrite => explosive eruption that creates a large layer of ash flow. Up to 9% of lava = gas. H2o, co2, so2 (sulfur dioxide), h2s (hydrogen sulfate) common. Leads to vesicles => holes in rocks. Made up of many eruptions: cinder cones (scoria cones) Made of one or a few eruptions: strato-volcano (composite volcano) Alternating pyroclastic/lava: lava flow, pyroclastic, volcanic monitoring.
