Volcanoes are associated with plate boundaries and hot spots
What do you remember about oceanic and continental crust? Oceanic crust: – Composition? Continental crust: – Composition?
Oceanic crust: – Lower in silicon and oxygen – Higher in magnesium and iron Continental crust: – Higher in Si and O – Lower in Mg and Fe What do you remember about oceanic and continental crust?
Who cares about the composition? Composition determines the explosivity of a volcano
Volcanic rock names are based on the composition BasaltAndesiteRhyolite Lowest % of silicon and oxygen Intermediate % of silicon and oxygen Highest % of silicon and oxygen Oceanic crustMixture of oceanic and continental crust Continental crust Divergent plate boundaries and hot spots under oceanic crust (Hawaii) Subduction zones: Ring of Fire (Cascadia subduction zone) Hot spot under continental crust (Yellowstone)
Magma or lava? Within the crustOn the Earth’s surface
The more silicate tetrahedrons in a lava, the more explosive the volcano. Which lava contains the higher percentage silicon and oxygen? Rhyolitic or andesitic lavas