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Igneous Rocks

Igneous rocks form by the?

solidification of magma or lava

Importance of igneous rocks?

building materials, ores

Igneous rocks distribution?

Canadian Shield, Rocky Mtns, Appalachian Mtns, Central TX

Igneous rocks compose __% of basement rock. 85% is metamorphic.


What are the two types of magma/lava?

silicic and mafic

What is silicic magma/lava?

>50% SiO2, gooey, highly viscous, becomes explosive, convergent system associated with continental crust formation.

What is mafic lava/magma?

<50% SiO2, very fluid, non-explosive, quiet, low viscosity, divergent associated with oceanic crust.

Silicic rocks are generated with __ zones at __ plate boundaries as magma chambers.

subduction, convergent

Silicic rocks process via __.

magnetic differentiation

When solidified, magma chamber becomes a __ composed of granite and/or diorite.


Stratovolcanoes form by alternating __ of pyroclastic material (ash) and thick __ flows.

eruptions, lava

Caldera formation from collapsed craters are like?


What is divergent?

plates moving away from eachother

what is convergent?

plates moving toward one another

Mafic rocks are generated at __ (divergent plate boundaries).


Mafic rocks are also generated within the __ crust.


Shield volcanoes due to extensive outpouring of __/basaltic lava with little pyroclastic material.


What is intrusive?


What is extrusive?


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