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11 Cards in this Set

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  • Back
How do igneous rocks form?
they form from the cooling and solidification of hot molten rock material either on or below the Earth's surface.
What are the most common elements in igneous rocks?
oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium
What are the types of magmas?
Felsic and Mafic
Felsic Magma
(sialic) are magmas rich in silica and aluminum.
Characteristics of Felsic
They produce quartz, potassium (orthoclase) feldspar, and sodium plagioclase. They are generally light colored and usually intrusive.
Mafic Magmas
magmas rich in iron, magnesium, and calcium
Characteristics of Mafic
they produce greater quantities of olivine, pyroxene, amphibole, and calcium plagioclase. Generally dark colored because of abundant dark ferromagnesian minerals.
At what temperatures do minerals from magma crystalize?
1200 and 600 degrees celsius
Geothermal Gradient
Rate of temperature increase with increasing depth (3 degrees Celsius/100 m (30 degrees/km)
At great depth temperature alone would melt rock but high pressure cause it to remain solid.
Radioactive Minerals
Heat byproducts during decay.
High concentration may cause temperatures to increase with depth at a rate greater then the geothermal gradient. common in felsic rocks.
Rock grinding past rock
Active mountain building regions. Friction of moving and shifting rock masses in regions of mountain building may combine with heat from other sources to melt.