GEOLOGY 103 Lecture Notes - Lecture 2: Seafloor Spreading, Subduction, Plat
25 Aug 2016
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Document Summary
The lithosphere is in isotactic equilibrium with the underlying asthenosphere. Continental drift and seafloor spreading create new ocean basins and passive continental margins. Notice how the pacific ocean basins has been shrinking in size over the past 300 million years. Theory that the earth is made up of a fixed number of plates and they move in relations to each other. Passive continual margin is when there is no activity. Divergent- plates moving apart: upwelling at divergent boundaries this is where youngest crust is formed (volcanos raising magma makes new crust) Strike/ slip margin- moving side by side. More earthquakes at convergent boundaries than at divergent plate boundaries: island arcs (convergent plat boundaries: ocean-ocean collisions, volcanic mountain ranges (convergent plate boundaries: ocean-continent collisions, high mountain range (convergent plate boundary; continent- continent collisions) Trenches (subduction zones: deep long, narrow, steep-sided trough seismically active, associated with volcanism landward of the trenches.
