Exam 4: Igneous Rocks and Intrusive Igneous Activity

Large crystals found in a fine-grained groundmass can indicate

Magma composition may change by crystal settling.

Most batholiths are of what rock composition?

The discontinuous branch of Bowmen's reaction series contains only ___________minerals.

What is the evidence of forceful injection of magma as batholiths intrude into the country rock?

Felsic lavas would tend to be slow moving, thick, and move only short distances.

A basalt would form under conditions that included

According to Bowen's reaction series, you would not find a mineral assemblage containing

List several uses for granitic rocks.

Briefly explain the differences between granitization, assimilation, and forceful injection as processes of batholith emplacement.

What is the rock name for a volcanic glass that is so porous it can float in water?

When magma cools slowly, crystal growth (slows/speeds)___________ the rate of nucleation, and the resultant rock is___________ -grained.

What are the two main categories of igneous rocks?

Phaneritic textures indicate that the rock formed under extrusive conditions as the lava cooled and crystallized on Earth's surface.

Mafic magma is silica poor and may be derived from melting of Earth's upper mantle.

Aphanitic, phaneritic and porphyritic are textural terms which

Why can pegmatite mineral crystals reach such a large size?

Pegmatites are composed of very large crystals that formed from water-rich magma.

Viscosity of a magma provides an indication of the temperature and pressure under which it crystallizes.

Magma chambers generally exist at depths of 100's of km beneath spreading ridges.