EARTHSC 1G03 Chapter Notes - Chapter 4: Mantle Convection, Jigsaw Puzzle, Hornblende
5 Apr 2017
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Document Summary
Touter core= the outermost zone of the earth"s core at 2900-5140km depth. Abrupt changes in seismic velocities- density changes indicate that outer core is molten. Composed mostly out of iron and silicon. Mantle plumes are exceptions to general picture of mantle convection. Plume of hot mantle which rises and forms volcanoes on the surface. Guyots: flat eroded top, was/is above sea level. Hotspot: area of volcanic activity produced by a plume of magma rising from the mantle. Subduction zones can spontaneously occur when the rocks get too old (more dense) and sink. Reducing pressure lowers melting temperature of solid rocks. Deep mantle rocks brought to surface experience a drop in pressure. Rifts pulling apart thin the crust and underlying rocks experience a drop in pressure. Texture: fine or coarse depending on how quickly magma cooled. Igneous rocks formed by 6 types of minerals usually. Intrustive: individual minerals can be seen, looks smooth, cooled very slowly, non-volcanic rock.
