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14 Cards in this Set
- Front
- Back
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What are the characteristics of Ultra-mafic rocks?
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-Less than 45% SiO2
-Represents the mantle -Mostly Magnesium and Iron -minerals like olivine and pyroxene form |
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What are the characteristics of Mafic rocks?
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-between 45-52% SiO2
-basalt/gabbro -mostly magnesium and calcium Calcium rich plagioclase, Olivine, pyroxene, hornblende |
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What are the characteristics of Intermediate Mafic rocks?
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-More 53-65% SiO2
-andesite/diorite -mostly Sodium, and Magnesium -Sodium rich plagioclase, hornblende, biotite |
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What are the characteristics of Felsic rocks?
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-More than 65% SiO2
-Rhyolite/granite -mostly Aluminum, Potassium, Silica -K-spar, quartz |
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How do you form magma?
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(Gabbroic Melt)
Two ways that magma forms 1) Outer Core. Pressure and heat melt the rock 2) Subducting slab is pushed up fast enough by convection currents. This reduces pressure while maintaining temperature |
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What is the difference between mafic and felsic magma?
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Mafic magma flows more slowly (Mid-Ocean ridges)
Felsic magma flows more quickly (convergent zones) |
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How do Granites form?
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Start as gabbroic magmas and assimilates through the continental crust.
Water cools it off |
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What are volatiles in the magma?
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1)CO2
2)H2S 3)H2O |
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What three type of materials erupt from volcanoes?
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1)Lava (Basalt, Andesite, Rhyolite)
2)Pyroclastic debris (Lapilli) 3)Lahar (Thick volcanic mud) |
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What gasses come from volcanoes?
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1)CO2
2)SO2 3)H2O |
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Types of Volcanoes?
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1)Shield (effusive)
-Formed by basalts that flow 2)Stratovolcanoes -formed by rhyolite and/or andesite -explosive eruptions 3)Cinder Cones -Made of fine pyroclastic material |
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What is the difference between Effusive vs. Explosive?
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Effusive volcanoes are lava flowing
Explosive volcanoes explode |
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What is a Pyroclastic Flow?
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Hot cloud of debris; moves quickly
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What is a lahar flow?
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Fluidized debris flow
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