Exam 4: Igneous Rocks and Plutons

____________________ are concordant,mushroom-shaped plutons.

A dark colored igneous rock with no visible crystals cooled ____.

Briefly explain how pegmatites form.

Natural glass such as obsidian forms when magma does what?

Most plutons form ____.

Most igneous rocks are classified by what?

Where are mantle plumes primarily found?

Rapid cooling of magma results in a(n)____________________ grained texture called ____________________.

Is the process of partial melting more likely to produce magmas which are more mafic or more felsic? Why?

The process of assimilation includes the incorporation of felsic country rock.

Briefly explain batholith formation.

What role does stoping play in the emplacement of batholiths?

Explain how a laccolith is similar to a sill.

Laccoliths are sills that inflate,causing the overlying rock to bow upward.

The ultramafic rock composed predominantly of ____________________ is known as peridotite and is likely the rock that makes up the part of Earth known as the ____________________.

What does a glassy texture tell us about the history of an igneous rock?

What two types of volcanic features result from volcanism above a mantle plume? How are hot spots related to plate boundaries?

Igneous rocks with a two-stage intrusive-extrusive origin are recognized by a texture which is ____.

The most widely accepted explanation for chains of volcanoes in the oceans and lines of volcanoes on land is that they formed at ____.

Granite and rhyolite are extrusive and intrusive igneous rocks of the same composition.