Questions and Answers
What are the physical and chemical changes in rocks due to changes in pressure and temperature called?
Metamorphism
Burial metamorphism occurs when sediments are buried deeply enough that the heat and pressure cause minerals to begin to recrystallize and new minerals to grow but does not leave the rock with a foliated appearance.
True
Regional metamorphism refers to large-scale metamorphism, such as what happens to continental crust along convergent tectonic margins.
True
Contact metamorphism happens when a body of magma intrudes into the upper part of the crust.
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Dynamic metamorphism is the result of very high shear stress, as it occurs along fault zones.
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Metamorphism is the change of minerals or geologic texture in pre-existing rocks without the protolith melting into liquid magma.
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Plutonic igneous rock is formed from lithification.
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Scoria is a light-colored and coarse-grained rock.
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Igneous extrusive is also known as plutonic igneous rock.
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Magma that reaches the Earth’s surface during a volcanic eruption is called lava.
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The collision of rock layers causes rocks to be folded, broken, and stacked on each other.
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What is the temperature range that can lead to metamorphism?
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What do we call the original rock that undergoes metamorphism?
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Name one example of a metamorphic rock.
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Rocks formed from regional metamorphism are likely to be foliated because of the strong directional pressure of converging plates.
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At subduction zones, there is a unique combination of relatively low temperatures and very high pressures.
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Study Notes
Metamorphism Overview
- Metamorphism signifies "change in form," transforming existing rocks (protoliths) under heat and pressure.
- Occurs at temperatures over 150-200 °C and pressures exceeding 100 megapascals (1,000 bar).
- Protoliths can be sedimentary, igneous, or existing metamorphic rocks.
Formation and Characteristics of Metamorphic Rocks
- Metamorphic rocks comprise about 12% of the Earth's land surface and are classified by texture and mineral composition (metamorphic facies).
- Form through deep burial under Earth’s crust, high temperatures, and immense pressure from overlying rock layers.
- Can also arise from tectonic processes like continental collisions leading to mountain formation.
Metamorphic Processes
- Burial Metamorphism: Occurs at relatively low temperatures (~300 °C) and pressures; leads to recrystallization without a foliated appearance.
- Regional Metamorphism: Involves large-scale changes, typical along convergent plate margins; results in foliated rocks due to strong directional pressure.
- Contact Metamorphism: Happens when hot magma intrudes crust, causing thermal effects on surrounding rocks.
Unique Conditions in Subduction Zones
- Subduction metamorphism combines low temperatures with high pressures as ocean lithosphere is forced into the mantle.
- High lithostatic pressure increases with depth, influencing metamorphic reactions.
Key Facts about Metamorphic Rocks
- Examples of metamorphic rocks include gneiss, slate, marble, and schist.
- Metamorphism can change minerals and textures without melting the original rock.
- Chemical and physical changes are driven by heat, pressure, and chemically active fluids.
- Certain minerals are stable only under specific pressure and temperature conditions, leading to new assemblages during metamorphism.
True/False Statements Recap
- Burial metamorphism allows for recrystallization without foliation. True
- Regional metamorphism affects continental crust at plate boundaries. True
- Contact metamorphism results from magma intrusion. True
- Dynamic metamorphism occurs due to high shear stress along faults. True
- Metamorphism can happen without melting the protolith. True
- Plutonic igneous rocks are formed through lithification. False
- Scoria is a light-colored and coarse-grained rock. False
- Igneous extrusive rocks are synonymous with plutonic igneous rocks. False
- Lava is magma that reaches the Earth's surface. True
- Rock collisions lead to folding and stacking of rock layers. True
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Description
This quiz explores the fundamental concepts of metamorphism, including the transformation of protoliths, the formation of metamorphic rocks, and the defining characteristics of different metamorphic processes. It covers essential aspects such as temperature, pressure, and geological implications of metamorphic activities.
