Test 2 (Lectures 4-8) Pt. 1 Flashcards
Where is lava found?
Above/on the Earth’s surface
Where is magma found?
Beneath the Earth’s surface
What do extrusive magma create?
Lava flows and pyroclastic deposits
Where do intrusive rocks form?
They form below the ground
The extrusive realm is __ the ground
Above
The intrusive realm is ___ the ground
Below
Many volcanoes are part of the ___ zone volcanism
Subduction
Where do igneous rocks come from?
They come from lava or magma
Where do most igneous activities occur in?
They occur along the mid-ocean ridge. And most occur below the sea level.
Magma is a mixture of…?
Melts
How is magma formed?
When water melts the mantle it forms magma
What does rift-related lithospheric thinning cause?
It causes decompressional melting of the asthenosphere
When heat transfer melts the crust what does the process create?
It creates felsic magmas
What kind of activity does mantle plume hot spots generate?
They generate igneous activity
What can hot-spot volcanoes do?
They can track igneous activity
What does the acronym LIPs stand for?
Large Igneous Provinces
What are LIPs?
Large areas of mafic melt that appear periodically over geologic time
What can LIPs result from?
They can result from mantle plumes at the base of the lithosphere that create huge volumes of low-viscosity mafic magma
What are some ways to melt the Earth (or the mantle)?
- Get it hot (add heat)
- Decrease pressure
- Add fluids or volatiles
In slide 12 of lecture 5, what is the green line called?
Solidus
In slide 12 of lecture 5, what is the red line called?
Liquidus
Where does decompression melting occur?
They occur at:
- Mantle plumes
- Continental rifts
- Divergent-plate boundaries
In a subduction zone, what volatiles are driven from the oceanic crust and into the asthenosphere?
H20 and CO2
What are the different types of melt?
- Mafic
- Ultramafic
- Felsic
- Intermediate
The type of melt you make depends on the ….?
Silica content
In the word “felsic” what do the words “fel” and “sic” stand for?
“Fel” stands for felsic
“Sic” stands for silica content
What magma has the highest silica content?
Felsic magma
What magma has the second highest silica content?
Intermediate magma
What magma has the third highest silica content?
Mafic magma
What magma has the fourth highest silica content?
Ultramafic magma
What is resistant to flow called?
Viscosity
How does viscosity work in colder materials?
- They tend to be more viscous (will move more slowly)
- They have a high SiO2 content (they’re more felsic)
- The volatile content is lower
How does viscosity work in hotter materials?
- They tend to be less viscous (will move quicker)
- They have a lower count of SiO2 content (they’re more mafic)
- The volatile content is higher
What does the viscosity of a rock depend on?
- Temperature
- Volatile content
- Silica content
Partial melting of the rocks makes the melt ______ because ___ minerals melt first?
Silica-enriched; felsic
What is assimilation?
As a melt rises, it assimilates the wall rock, changing the
composition of the melt
What type of minerals crystallize first?
Mafic
What type of minerals crystallize last?
Felsic
In the Bowen’s reaction series, the rocks that formed first are called ….?
Mafic
Name a rock that crystallizes first
Olivine
Name a rock that crystallizes last
Quartz
What are pyroclastic flows?
Are deadly fast-moving avalanches of superheated volcanic ash and debris
Dikes tend to run through ___
Vertically
Sills tend to run through ____
Horizontally
What are most sills a result of?
They result in the change in the elevation of a land surface
What do dikes do?
They cut across layers and spread the rock sideways
What are laccoliths?
Magma that usually stays in one area like a blister-shaped intrusion
What are plutons?
Blob-shaped intrusions that solidify from magma chambers
What is a batholith?
A group of plutons that cover a large area
What are xenoliths?
Chunks of wall rock incorporated into the magma
How are igneous rocks formed?
Through cooling and crystallization of magma
