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19 terms

Chapter 4

Igneous Rocks
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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.
15
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.
batholith
Stratovolcanoes form by alternating __ of pyroclastic material (ash) and thick __ flows.
eruptions, lava
Caldera formation from collapsed craters are like?
cracks
What is divergent?
plates moving away from eachother
what is convergent?
plates moving toward one another
Mafic rocks are generated at __ (divergent plate boundaries).
ridges
Mafic rocks are also generated within the __ crust.
oceanic
Shield volcanoes due to extensive outpouring of __/basaltic lava with little pyroclastic material.
mafic
What is intrusive?
magma
What is extrusive?
lava