15 Questions
What is the primary source of heat that contributes to the formation of magma?
Heat leftover from Earth's violent past and the decay of radioactive elements
What happens when magma reaches the surface of the Earth?
It is referred to as lava
What is a characteristic of magma that causes it to rise from within the Earth?
It is less dense than the surrounding solid rock
What can vary in magma composition?
Mineral composition
What can be present in magma besides molten rock?
Dissolved gases such as carbon dioxide and hydrogen sulfide
What is the characteristic of magma in terms of its composition?
It is a liquid with solids and semi-liquids within it
What is the primary location of magma within Earth?
Within the Earth's crust and upper mantle
What is the temperature range of magma beneath the Earth's surface?
1060 to 1600 degrees Celsius
What is the primary mechanism for magma formation in the upper mantle?
Decompression of rising heat and material from mantle plumes
What is the result of the subduction of plate material in terms of magma formation?
The formation of magma
What is the primary reason for the formation of magma at subduction zones?
Increasing temperature gradient within the interior of Earth
What is the role of water in the formation of magma at subduction zones?
It lowers the melting point of crust material
What is the characteristic of felsic magma in terms of its composition and temperature?
High silica content, temperature range of 800-1200°C
What is the main difference between magma and lava?
Magma is beneath the Earth's surface, while lava is on the Earth's surface
What is the type of igneous rock that forms when magma solidifies while inside Earth's crust?
Intrusive igneous rock
Study Notes
What is Magma?
- Magma is liquid rock found beneath Earth's surface, formed when rocks melt.
- It is less dense than solid rock, so it rises to the surface, where it's referred to as lava.
- Magma forms within the interior of Earth, mainly in the crust and upper mantle, due to heat and radioactive decay.
- It can vary in composition, containing dissolved gases like carbon dioxide and hydrogen sulfide.
Formation of Magma
- Magma forms through decompression of rising heat and material from mantle plumes or convection currents.
- Subduction of plate material colliding with another also creates the circumstances for solid rock to melt.
- Mantle plumes rise over long geological timeframes, eventually reaching the base of the lithosphere, where they spread out and melt.
- Decrease in pressure as mantle plume and convection current material rises allows for particles to spread out, melt, and form magma.
Characteristics of Magma
- Temperature range: 1060-1600°C (besides rare carbonatite magmas at 490°C).
- Viscosity and resistance to flow vary depending on the type of magma.
- Some magmas are more viscous, while others flow quickly.
Types of Magma
- Felsic magma: high silica content (>63%), low iron content, highly viscous, and relatively low temperature (800-1200°C).
- Mafic magma: lower silica content (<45%), higher iron content, less viscous, and higher temperature (1100-1600°C).
- Ultramafic magma: very low silica content, high iron content, and high temperature.
Difference between Magma and Lava
- Magma is liquid rock beneath Earth's surface.
- Lava is magma that has reached Earth's surface, where it cools and solidifies into rock.
- Igneous rocks form from the solidification of lava or magma.
Magma is a liquid formed from the heat within the Earth's interior, created from the decay of radioactive elements and leftover heat from Earth's violent past. It can reach temperatures hot enough to melt solid rock.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
