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29 Cards in this Set
- Front
- Back
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igneous |
born of fire |
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igneous rocks |
- formed via crystallization from magma (+700degrees) - magma cools as it rises - different minerals crystallize at different temperatures - magmas have different chemical compositions |
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intrusive igneous rock (3) |
- plutonic - magma cools deep in Earth's crust - large, interlocking crystals due to slow cooling [ eg. granite ] |
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extrusive igneous rocks (3) - other name, how it forms, appearance |
- volcanic (Vulcan god of fire) - form when magma reaches surface through volcanoes - very fine-grained or glassy textures due to rapid cooling [ basalt ] |
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magma |
- igneous rocks form from molten rock - rocks melted |
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where do rocks melt |
anywhere the T is high enough to melt the minerals present, different rocks melt at different temperatures
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factors that cause melting |
- increase in temperature - decrease pressure - increase in volatile compounds |
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three components of magma |
1. solid - minerals crystals suspended in melt 2. liquid - melted rock 3. gas/volatiles |
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partial melt |
rocks usually don't melt completely |
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how is magma mobile |
less dense than surrounding solids, so it wants to rise |
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what happens when magma cools |
crystals begin to form and settle out, location and rate of crystal formation determine type of igneous rock |
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phaneritic texture |
- only applies to igneous rocks - crystals visible to naked eye - intrusive, cools slow |
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aphanitic |
- igneous - tiny crystals invisible to naked eye - extrusive, cools fast |
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porphyritic |
- variable cooling rates, two stage - big crystals and tiny crystals |
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glassy |
igneous rocks with very rapid cooling rate, cools so fast, that no mineral crystals can form |
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mafic and felsic minerals (7, oxygen missing) |
- mafic (Mg, Fe, Ca rich) - felsic (Si, Al, Na, K rich) |
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felsic rocks |
- rich in Si, Na, K - found in subduction zones and continental crust - lighter |
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mafic rocks |
- rich in Fe, Mg, Ca - found at divergent plate boundaries and hot spots - darker |
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intermediate rocks |
- chemical composition between felsic and mafic - dominant in igneous rock in subduction zones |
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ultramafic rocks |
- Si-poor and Fe/Mg-rich - make up most of the mantle |
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bowen's reaction series |
predicts order that minerals will crystallize out of a magma melt, or the order in which minerals will melt |
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felsic pair with same chemical and mineralogical compostion |
granite and rhyolite |
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mafic pair with same chemical and mineralogical compostion |
gabbro and basalt |
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intermediate pair with same chemical and mineralogical compostion |
diorite and andesite |
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four layers of the ocean crust system |
1. sediments 2. basalt 3. gabbro 4. peridotite |
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composition of island arc volcanoes |
mafic to intermediate |
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continental hotspot continental (2) |
- mantle basalts can rise through continental crust - mantle hot-spots under continental crust can cause melting of felsic crust = rhyolite |
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oceanic hot spot volcanism |
similar to volcanic rock types from a mid ocean ridge: magma rises from the mantle = basalt |
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continental subduction zone |
convergent margin volcanoes are mafic to felsic -- lots of modification to original basaltic magmas |
