EPSC 201 Lecture Notes - Lecture 13: Mount Vesuvius, Cano, Brown Sugar
11 Mar 2013
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Volcanoes are also associated wit hot spots, such as hawaii. Volcanoes are forming from magma that is subjected from decompression melting. Upwelling of mantle (plume) causes melting, which in turn causes a volcano. The magma has a very low viscosity, meaning it flows easily. These volcanoes are termed shield volcanoes, which have very subtle hills because the lava flows far out from the crater. The lava is made of basalt in these types of volcanoes. At low silica content, the lava is made of isolated tetrahedrons. This flows easier then lavas made of complex silicate mixtures. Some magmas, in a rift environment, have high al- kali content (sodium and potassium). There is also carbonate lava in the rift environment. Intrusions is magma that did not make it to the surface, while extru- sions are lava that did make it through to the sur- face. Africa contains rift volcanoes, so one would expect to see alkalia and carbonate content.
