GEO 103 Lecture Notes - Lecture 4: Volcanic Arc, Himalayas, Juan De Fuca Ridge
31 Jan 2017
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Document Summary
Plate movements can accurately be measured by satellites. Lithospheric plates overlie hotter and weaker semiplastic asthenosphere. Results from some type of heat-transfer system within the asthenosphere. Collide (converge) in areas such as oceanic trenches where they may subduct into mantle. Slide past each other along transform faults. (san andreas) Divergent plate boundaries occur where plates separate and new oceanic lithosphere forms. Basaltic magma originates from partial melting of mantle. Some rises to the surface and extruded as lava flows. Certain material are subjected to this melting which is at a 20% rate. When layers are weakened, they are more susceptible to melting. Successive injections of magma cool and solidify to from new oceanic crust. Divergent boundaries most commonly occur along crests of the oceanic ridges (like the mid- These are zones of a lot of earthquakes, but they are usually small and never large enough to cause tsunamis. Ridges have high heat flow, basalt flows, or pillow lavas.
