Exam 11: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks

Mineralogically and chemically equivalent rocks are ___ and __.

Pegmatites are extremely coarse-grained igneous rocks.

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

Under ideal conditions rock can melt and yield a granite composition at temperatures as low as ___.

The most common minerals in a granite are the ______.

Crystal settling accounts for important deposits of ______.

The geothermal gradient is the rate at which pressure increases with increasing depth beneath the surface.

An ultramafic rock is composed almost entirely of quartz.

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

The first plagioclase crystals to form as a hot melt cools are high in ______.

A pluton is an igneous structure that crystallized at very shallow depths.

A _______ is a tabular (thin but large area)intrusive body that is concordant (parallel to the host rock structure).

Partial melting of the lower continental crust produces a silicic magma that eventually solidifies into granite or rhyolite.

______ igneous rocks,like gabbro and basalt,are silica-deficient with high magnesium and iron.

What type of melting takes place when a body of hot mantle rock moves upward and the pressure is reducted to the extent that the melting point drops to the temperature of the body?

The term mafic comes from the terms magnesium and ferric.

______ are fragments of country rock that are distinct from the body of igneous rocks in which they are enclosed.

The crust beneath the world's oceans is mafic ________.

Viscosity is a property of a fluid that relates to how easily the fluid flows.A material that is viscous __.

The geothermal gradient for a volcanic region is greater than that for the continental interior.