605895
Description
Flashcards by holliebishop1996, updated more than 1 year ago
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Created by holliebishop1996
over 12 years ago
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| Question | Answer |
| Classification of magma/ Igneous Rocks | Composition(mineral Content) = Chemical composition- % of silica Mineral composition- 99% of igneous rocks are made of silicates. Bowen's reaction series |
| Bowen's Reaction Series |
Image:
Bowen_sII (image/jpg)
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| Variation in Igneous rock types Why? | Different sources of magma, magmatic differentiation, contamination |
| Generation of Melt- Heat | Most Igneous rocks will melt between 700-1200 degrees at the earth's surface. Pressure and temperature increase with depth.(30 degrees for 1km), melting occors in places of high heat e.g Hot spots. |
| Generation of Melt- Pressure | Melting does not normally occur due to pressure, occurs due to decompression as magma rises pressure falls. |
| Generation of melt- Flux Melting | Water acts as a flux, causes rocks to melt at lower temperatures. |
| Fractional Crystallization | As magma cools the minerals crystallise out according to their crystallization/melting points. this means that some minerals crystallize out first and if they are denser sink to the bottom of the magma causing the magma to become depleted. In theory process is called magmatic differentiation. |
| Magmatic Differentiation | Only occurs when the melting of magma is very slow, so that the early formed crystals can sink to the bottom of the magma. The edges of the melt cool rapidly so is closest to the original composition of the magma. |
| Hypothetical magma chamber |
Image:
WP_20140305_004 (image/jpg)
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| Why does Magmatic Differentiation occur? | Due to different minerals crystallizing out at different temperatures, though a process called Fractional crystallization. |
| Movement of magma | Rises due to pressure (convection currents), will not rise if it is not under pressure. |
| Movement of magma: Doming |
Image:
WP_20140305_006 (image/jpg)
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| Movement of magma: Stoping |
Image:
WP_20140305_010 (image/jpg)
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| Movement of Magma: Subduction |
Image:
WP_20140305_009 (image/jpg)
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| Movement of magma: Extension |
Image:
WP_20140305_011 (image/jpg)
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