Basalt, the dominant volcanic rock along the Pacific Ocean's "Ring of Fire," is considered a melting product of the Earth's mantle. On the left is vesicular basalt, in which dissolved gases formed bubbles as the magma decompressed. On the right is a magnesium-rich olivine crystal that formed inside the volcano, embedded in a fine-grained solid. Detailed chemical analyses found that magnesium in arc volcano basalt shows surprising traces of the descending ocean crust.
Para saber mais: Misturas em Arcos vulcânicos
