Ch9 VOLCANOES AND MAGMA

Which of the following factors makes rocks melt more easily?

• Increasing pressure

• Decreasing temperature

• Addition of water

• Removal of silica

At spreading centers, what causes magma formation?

• Subduction of oceanic crust

• Hot asthenosphere oozing into the spreading ridge

• Frictional heating from plate movement

• Decompression of the lower mantle

Tags

NGSS.HS-ESS1-5

What is the primary cause of magma formation in subduction zones?

• Increasing temperature

• Decreasing pressure

• Addition of water

• Removal of carbon dioxide

Tags

NGSS.HS-ESS2-3

Which type of magma is produced by partial melting of peridotite in the asthenosphere?

• Granitic

• Andesitic

• Rhyolitic

• Basaltic

Tags

NGSS.HS-ESS2-3

Compared to peridotite, basaltic magma is:

• 20 percent richer in silica

• 20 percent poorer in silica

• 50 percent richer in silica

• 50 percent poorer in silica

Why does granitic magma tend to rise in the crust?

• It is denser than surrounding rocks

• It has a higher melting point

• It has a lower melting point

• It contains more water than other magmas

Tags

NGSS.HS-ESS2-3

What keeps magma liquid as it rises through the crust?

• Increasing temperature

• Lower pressure

• Addition of water

• Removal of silica

Tags

NGSS.HS-ESS2-3

Which of the following is NOT a common location for magma formation?

• spreading centers

• subduction zones

• mantle plumes

• transform faults

Tags

NGSS.HS-ESS2-3

What characterizes a mantle plume?

• It's colder than its surroundings

• It's more dense than its surroundings

• It's buoyant relative to its surroundings

• It's more rigid than its surroundings

Tags

NGSS.HS-ESS2-3

How does partial melting affect the composition of magma compared to its source rock?

• The magma has the same composition as the source rock

• The magma is enriched in some elements compared to the source rock

• The magma is depleted in all elements compared to the source rock

• The magma has a random composition unrelated to the source rock