How are features formed from magma that solidified under Earths surface described What are the different types of intrusive rock bodies What geologic processes result in intrusive rocks that appear at Earths surface ID: 321898
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Essential QuestionsHow are features formed from magma that solidified under Earth’s surface described?What are the different types of intrusive rock bodies?What geologic processes result in intrusive rocks that appear at Earth’s surface?
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Intrusive ActivitySlide2
Reviewigneous rock
New
pluton
batholith
stock
laccolithsilldike
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Vocabulary
Intrusive ActivitySlide3
Intrusive Activity
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Most of Earth’s volcanism happens below the surface because not all magma emerges at the surface. Before it gets to the surface, rising magma can interact with the crust in several ways
.Slide4
Intrusive Activity
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Magma
can force the overlying rock apart and enter the newly formed fissures.
Magma
can cause blocks of rock to break off and sink into the magma.
It
can melt its way through the rock into which it intrudes.Slide5
Intrusive Activity
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Plutons
Plutons
are
intrusive
igneous rock bodies, formed through mountain-building processes and oceanic-oceanic collisions.
They can be exposed at Earth’s surface due to uplift and erosion and are classified based on their size, shape, and relationship to surrounding rocks.Slide6
Intrusive Activity
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Batholiths
and
stocks
Batholiths
, the largest plutons, are irregularly shaped masses of coarse-grained igneous rocks that cover at least 100 km2 and take millions of years to form.
Batholiths are common in the interior of mountains.Slide7
Intrusive Activity
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Batholiths
and
stocks
Irregularly shaped plutons that are similar to batholiths but smaller in size are called
stocks. Both batholiths and stocks cut across older rocks and generally form 5 to 30 km beneath Earth’s surface.Slide8
Intrusive Activity
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Laccoliths
A
laccolith
is a lens-shaped pluton with a round top and flat bottom.
Compared to batholiths and stocks, laccoliths are relatively small; at most, they are 16 km wide.Slide9
Intrusive Activity
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Sills
A
sill
forms when magma intrudes parallel to layers of rock.
Because it takes great amounts of force to lift entire layers of rock, most sills form relatively close to the surface.Slide10
Intrusive Activity
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Dikes
A
dike
is a pluton that cuts across preexisting rocks and often forms when magma invades cracks in surrounding rock bodies.
A volcanic neck occurs when the magma in a volcano conduit solidifies. Dikes are often associated with the conduit but do not always form the neck.Slide11
Intrusive Activity
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Dikes
The coarse-grained texture of most sills and dikes suggests that they formed deep in Earth’s crust, where magma cooled slowly enough for large mineral grains to develop.
Dikes and sills with a fine-grained texture formed closer to the surface where many crystals began growing at the same time.Slide12
Intrusive Activity
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Plutons and Tectonics
Many plutons form as the result of mountain-building processes. In fact, batholiths are found at the cores of many of Earth’s mountain ranges.Slide13
Intrusive Activity
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Scientists
think that some of the collisions along continental-continental convergent plate boundaries might have forced continental crust down into the upper mantle where it melted, intruded into the overlying rocks, and eventually cooled to form batholiths.Slide14
Intrusive Activity
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Plutons
are also thought to form as a result of oceanic plate convergence. When an oceanic plate converges with another plate, water from the
subducted
plate causes the overlying mantle to melt. Plutons often form when the melted material rises but does not erupt at the surface.Slide15
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ReviewEssential QuestionsHow are features formed from magma that solidified under Earth’s surface described?
What are the different types of intrusive rock bodies?What geologic processes result in intrusive rocks that appear at Earth’s surface?
Vocabulary
pluton
batholithstocklaccolithsilldike
Intrusive Activity