EVSC 1010 Lecture Notes - Lecture 8: Stratovolcano, Wrinkle, Shield Volcano
24 Oct 2016
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Document Summary
Three processes function to melt the asthenosphere to form magma: Increasing temperature, decreasing pressure, and addition of water. Produces magma beneath a spreading center, where hot asthenosphere rises to fill the gap left by the two separating tectonic plates (divergent boundary) Produces magma in a rising mantle plume (small rising column of hot, plastic mantle rock: the magma rises to form a volcanic hot spot. 3 processes melt the asthenosphere to form magma at a subduction zone. Steam rises from wet oceanic crust on top of the subducting plate. Circulation in the asthenosphere decreases pressure on hot mantle rock. Friction heats rocks in the subduction zone. In most cases, magma solidifies within the earth"s crust forming a pluton. A large mass of granite: any intrusive igneous rock. Batholith more than 100 square km exposed at earth"s surface. Stock similar to batholith, but smaller surface area. In some cases, the magma intrudes on country rock, forming dikes.
