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11 Cards in this Set
- Front
- Back
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How do igneous rocks form?
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they form from the cooling and solidification of hot molten rock material either on or below the Earth's surface.
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What are the most common elements in igneous rocks?
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oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium
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What are the types of magmas?
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Felsic and Mafic
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Felsic Magma
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(sialic) are magmas rich in silica and aluminum.
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Characteristics of Felsic
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They produce quartz, potassium (orthoclase) feldspar, and sodium plagioclase. They are generally light colored and usually intrusive.
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Mafic Magmas
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magmas rich in iron, magnesium, and calcium
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Characteristics of Mafic
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they produce greater quantities of olivine, pyroxene, amphibole, and calcium plagioclase. Generally dark colored because of abundant dark ferromagnesian minerals.
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At what temperatures do minerals from magma crystalize?
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1200 and 600 degrees celsius
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Geothermal Gradient
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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. |
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Radioactive Minerals
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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. |
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Friction
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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. |
