geology

Laccolith

A ________ is a mushroom-shaped pluton that forms by injecting magma between sedimentary strata, forcing the upper layers to arch upward.

sill

A ________ is a tabular, concordant pluton that is nearly horizontal and forms when magma exploits a weakness between sedimentary layers.

quartz

According to Bowen's Reaction Series, __________ is one of the first minerals to melt, but last to crystallize.

convergent

Along which tectonic boundary will chains of composite cone volcanoes be located?

the introduction of water

At a subduction zone, melting is triggered by _____.

After the earliest formed minerals have settled, the resulting magma will be more felsic than the original magma.

How do the crystallization and settling of the earliest formed minerals affect the composition of the remaining magma?

When hot, solid mantle rock ascends, it moves to areas of lower pressure. This reduction in pressure allows the hot material to melt into a less compressed liquid phase.

How does decompression melting occur?

water content decreases

How does water content of granitic magmas change as the magmas move towards Earth's surface?

water content increases

How does water content of melt change with increasing pressure?

Basaltic magma partially melts the continental crust, which is more felsic in composition

How is basaltic magma transformed into felsic magma?

Fluids are boiled out of the subducting plate, which lower the melting point of the surrounding mantle

How is magma generated along convergent plate boundaries?

The subducting slab drives water and carbon dioxide into the mantle, which reduces the temperature at which it melts, allowing mantle rock to melt and rise

How is magma generated along convergent plate boundaries?

the melting temperature of mantle rocks to decrease

In a subduction zone, water driven from subducted oceanic crust causes __________.

Felsic magma and mafic residue

Once a source rock partially melts, what does it produce?

iron, magnesium, feldspars, and silica

Peridotite that undergoes partial melting will create a melt enriched in ________.

Decompression melting of the mantle

What causes an elevated geothermal gradient in a divergent plate setting?

Tree roots cracking a sidewalk, potholes forming in the street

What is an everyday example of mechanical weathering?

A dike intrudes across sedimentary layers, and a sill intrudes between sedimentary layers.

What is the difference between a dike and a sill?

Dikes crosscut sedimentary layers; sills pry between horizontal layers.

What is the difference between a dike and a sill?

magma chambers and volcanic conduits

What lies underneath volcanic features at Earth's surface?

Water contained within minerals in the subducting plate is released during metamorphism.

Where does the water involved in melting at subduction zones come from?

decrease in pressure, change in composition, increase in temperature

Which of the following could cause rock to melt?

Continental margins

Which of the following regions will primarily erupt silica-rich lavas?

Higher melting points are determined by higher pressures.

Which of the following statements best describes the relationship between pressure and melting point in the Earth's Interior?

heat from basaltic magma partially melting overlying crust

Which process is thought the generate most felsic magmas?

decompression melting and wet melting (the addition of volatiles)

Which two processes commonly generate magma?

This experiment allows geologists to interpret where granitic rock solidifies beneath Earth's surface

Why is Tuttle and Bowen's experiment useful to geologists?

Magmatic differentiation

________ describes the formation of one or more secondary magmas from a single parent magma.

chemical

________ weathering is when there is a chemical transformation of rock into other compounds.

Rock can remain solid, become partially melted, or melt completely at the same depth within Earth, depending on the temperature

what is true about melting of rocks