Exam 3: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks

Basaltic magmas crystallize at higher temperatures than granitic magmas.

Although batholiths may contain mafic and intermediate rocks, they almost never composed of granite.

Granite and ______ are composed predominantly of feldspar and quartz.

Ultramafic igneous rocks are composed almost entirely of __.

Fine-grained igneous rocks (grains < 1.0 mm) that have small grains cooled rapidly and are likely to be _______.

A useful tool illustrating the relationships among igneous, sedimentary, and metamorphic rocks is called the ___.

Extrusive igneous rocks are typically fine grained because they crystallized slowly, deep below the Earth's surface.

______ are extremely coarse-grained with crystal up to 10 meters across.

Pegmatites are extremely coarse-grained igneous rocks.

Geologists regard basaltic magma (Hawaiian lava, for example) as the result of the partial melting of ultramafic rock in the ____.

The continuous branch in Bowen's Reaction Series contains the ferromagnesian minerals.

To explain the great volumes of granite plutonic rocks, most geologists think that partial melting of the _______ must take place.

Both andesite and ___ are composed of feldspars and 30% to 50% ferromagnesian minerals.

Mafic magma generated in the _______ rises to the base of the crust.

______ is the predominant igneous rock of the continents.

Diorite and andesite are composed of similar amounts of feldspars and ferromagnesian minerals.

The melting point of a rock decreases with increasing pressure.

What is the process through which magma differentiation takes place?

The huge volume of mafic magma that erupted to form the Columbia plateau basalts of Washington and Oregon are attributed to ___.

A dike is a discordant intrusive igneous structure.