7.1. Igneous Rocks – Learning Outcomes

After reading this chapter of the textbook, learning the vocabulary, and working through the review questions, students should be able to:

• Explain the properties we use to categorize igneous rocks.
• Describe the four igneous rock textures.
• Discuss the information an igneous rock’s texture gives you about the environment where the rock formed.
• Describe how igneous rock composition and mineralogy vary along the spectrum from felsic to ultramafic rocks.
• What are names of intrusive and extrusive rocks that are found in each igneous rock type? Describe each of these types of rock in terms of their composition, mineralogy, and texture.
• How does magma viscosity vary with igneous magma composition? Temperature? Density?
• Describe how the temperature of the lithosphere changes with depth in the following environments: ocean crust, continental crust, mid-ocean ridges, hotspots, and in island arcs
• Explain the concept of partial melting.
• Explain how the composition of magma and the minerals that form can change in a magma chamber as the magma cools.
• Describe how the composition of magma varies by tectonic environment.
• Define plutonic rock.
• Describe the types of igneous intrusions and their features (e.g. dykes).
• Describe features associated with contact metamorphism of country rock by intrusions.
• Classify each type of igneous intrusion as discordant or concordant.
• Describe the process of magmatic stoping.
• Describe the relationship of contact metamorphism to igneous intrusions.

Learning outcomes not covered in the textbook chapter in detail, but we may discuss them in class (depending on your professor):

• Explain the process of magma differentiation: what factors can affect magma composition?
• Describe how the process of igneous evolution happens.