EVSC 2800 Study Guide - Midterm Guide: Lava Dome, Volcanic Gas, Pumice
12 May 2016
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Contributing processes that cause crust to evolve toward granitic composition: Partial melting mobilizes felsic components for upward migration. Mixtures of sedimentary, metamorphic, and igneous rocks can be incorporated in the magma: magma invades cracks and melts walls of country rock causing magma to break off the rock- most slowly melt but a few are preserved. The type of tectonic setting determines the composition of the magma which in turn establishes the type of volcano eruption and the type of extrusive igneous rock formed. Some extrusive rock types: basalt (mafic, low viscosity lava), rhyolite (felsic, highly viscous lava), andesite (intermediate, viscous lava) Volcanosssssssssssss: occur at two types of plate boundaries (convergent and divergent) and at intraplate hot spots, in the pacific northwest, the juan de fuca plate is subducting beneath the north. Pyroclasts are fragments of volcanic material ejected during an eruption (ash, cinder, pumice, rocks, bombs) Large pyroclasts don"t travel far from the central vent]
