How would you classify a coarse-grained igneous rock that contains about 50 percent pyroxene and 50 percent olivine?
What kind of rock would contain some plagioclase feldspar crystals about 5 mm long “floating” in a dark gray matrix of crystals of less than 1 mm?
What observations might you make to show that a pluton solidified during fractional crystallization?
Why are plutons more likely than dikes to show the effects of fractional crystallization?
What might be the origin of a rock composed almost entirely of olivine?
What processes create the unequal sizes of crystals in porphyries?
Water is abundant in the sedimentary rock and oceanic crust at subduction zones. How would that water affect melting in these zones?