GEOL107 Lecture Notes - Lecture 22: Convergent Boundary, Continental Crust, Oceanic Crust
27 Nov 2018
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Subduction - oceanic lithosphere beneath oceanic lithosphere (one oceanic plate denser (older, colder) than other) Volcanoes on non-subducted oceanic lithosphere (create volcanic chains called island arcs) Earthquakes - small to large magnitude, shallow to deep (600-700 km) focal depths. Earthquakes - small to large in magnitude, shallow to intermediate depths (to 150 km) Note no subduction, no volcanoes, no deep earthquakes. As plates try to slide past one another, frictional forces prevent them from doing so. Earthquakes - small to intermediate in magnitude, shallow to intermediate depth (to 150 km) Motion of lithospheric plates with respect to deep interior (e. g. lower mantle) of earth. Direction and rate - can be determined by studying volcanoes produced by hot spots. Areas within lower mantle where melting occurs - these melting zones are fixed in their positions. Magma from hot spots rises up through mantle, asthenosphere and lithosphere and forms volcanoes on lithospheric plates (these plates are in motion)
