Term
| How do igneous rocks form? |
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Definition
| From the crystallization of minerals |
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Term
| What are Intrusive Igneous Rocks? |
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Definition
Igneous rocks that form inside Earth
(will eventually come to Earth's surface) |
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Term
| What are extrusive Igneous Rocks? |
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Definition
| Igneous rocks that form at Earths surface |
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Term
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Definition
| The interaction of plate tectonic and climate systems. (Rocks can skip phases in the cycle, there is no particular order.) |
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Term
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Definition
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Term
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Definition
| An intrusion of magma into pre-existing rock where it may accumulate into an irregularly shaped mass |
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Term
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Definition
| melted rock at Earth's surface |
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Term
| What reasons to geologist study igneous rocks? (4) |
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Definition
-Info about Earth's mantle
-Radiometric dating (tool used to find the age of Earth)
-Ore deposits
-other economic uses (building stones, granite tables) |
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Term
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Definition
| Upper part of asthonosphere and lower crust (100-150 ft deep) |
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Term
| Why do magmas form? (3 terms) |
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Definition
| temperature, pressure, volatiles |
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Term
| One cause of magma formation is decompression melting. What is decompression melting? |
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Definition
| melting of rock due to a decrease in pressure (forms magma inside Earth) |
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Term
Where does decompression melting occur?
Name examples of where this can occur. |
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Definition
| Where hot mantle rock rises to shallower depths in the Earth. This occurs in matle plumes, beneath rifts and beneath mid ocean ridges. |
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Term
| Magma is formed from additon of volatiles. How so? |
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Definition
| When volatiles mix with hot, dry rock they help break chemical bonds so that the rock begins to melt. Adding volatiles decreases a rock's melting temperature. (known as flux melting) |
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Term
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Definition
| Substances such as water and carbon dioxide that evaporate easily and can exist in gaseous forms at the Earth's surface |
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Term
| Where does flux melting occur? |
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Definition
| where volatiles enter hot mantle; at subduction zones |
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Term
| Magma is formed from the melting as a result of heat transfer from rising magma. Explain the process. |
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Definition
When magma from the mantle rises up into the crust it brings heat with it. This heat raises the temperature of the surrounding crustal rock and the rise in temperature may be enough for the crustal rock to begin melting. (known as heat transfer melting)
Example: Imagine injecting hot fudge into ice cream; the fudge transfers heat to the ice cream, raises it's temperature and causes it to melt |
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Term
| What is heat transfer melting? |
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Definition
| the transfer of heat from a hotter material to a cooler one |
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Term
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Definition
| decompression melting, addition of volatiles, heat transfer |
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Term
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Definition
| Silicon, oxygen, aluminum, calcium, sodium, potassium, iron, and magnesium |
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Term
| Because magma is a liquid, how are its molecules arranged? |
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Definition
| grouped in clusters or short chains, relatively free to move with respect to one another |
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Term
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Definition
| Magmas that do not conatin volatiles |
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Term
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Definition
| Magmas that contain volatiles |
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Term
| There are four types of distinguished magmas based on the proportion of silica relative to other metal oxides. What are the four types? |
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Definition
| Mafic magma, ultramafic, Felsic and intermediate magma |
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Term
| What proportion of chemicals to silica does mafic magma contain? |
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Definition
| a relatively high proportion of iron exide and magnesium oxide relative to silica (low silica, 45-52% silica) |
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Term
| What proportion of chemicals to silica does ultramafic rock contain? |
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Definition
| An even higher proportion of magnesium and iron oxides relative to silica. (38-45% silica) (contains least amount of silica of the four types of magmas) |
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Term
| What proportion of chemicals to silica does felsic magma contain? |
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Definition
| a high proportion of silica relative to magnesium and iron oxides (66-76% silica) (highest amount of silica of the four magma types) |
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Term
| what proportion of chemicals to silica does intermediate magma contain? |
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Definition
| It is partway between mafic and felsic. (which is where its name comes from) (52-66% silica) |
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Term
| What factors influence magma composition? (5) |
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Definition
Source rock composition
partial melting
contamination/assimilation
Magma mixing
fractional crystallization
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Term
| What is source rock composition? |
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Definition
| The composition of a melt reflects the compostion of the solid from which it was derived. Not all magmas form from the same source rock, so not all magmas have the same composition. |
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Term
| What is the process of partial melting? |
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Definition
| Only 2%-30% of an original rock can melt to produce magma at a given location, the temperature at sites of magma production never get high enough to melt the entire original rock before the magma has a chance to migrate away from its source. |
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Term
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Definition
| the process by which only part of an original rock melts to produce magma |
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Term
| Magmas formed by partial melting are more felsic than the original rock from which they were derived. give an example. |
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Definition
Partial melting of an ultramafic rock produces a mafic rock.
-mafic rock produces and intermediate rock
-intermediate rock produces a felsic rock |
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Term
| Magma composition is influenced by Contamination/assimilation. How is this process defined? |
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Definition
| Magma incorporates parts of the rock it passes through. . |
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Term
| What is magma mixing? Explain an example. |
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Definition
Different magmas formed in different locations from different sources may enter a magma chamber
Example: mixing a felsic magma witha mafic magma in equal proportions produces an intermediate magma. |
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Term
| What is fractional crystallization? |
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Definition
| Partial melting backwards; different minerals crystallize at different temperatures. (Bowen's Reaction Series) |
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Term
| What is Bowen's Reaction Series? |
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Definition
| The order of crystal formation from magma as cooling occurs. |
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Term
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Definition
| Buoyancy and Speed (Viscosity) |
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Term
| Explain how magma rises through buoyancy. |
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Definition
Buoyancy drives magma upward because magma is less dense than the surrounding rock. Magma also rises because the weight of overlying rock creaes pressure at depth that literally squeezes magma upward.
Example: when you step into a puddle barefoot and mud sqeezes up between your toes |
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Term
| What is viscosity? How does it affect magma/lava? |
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Definition
| resistance to flow, it affects the speed with which magmas or lavas flow |
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Term
| Magmas with low viscosity flow ______ than those with high viscosity. |
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Definition
easier
Example: Water flows more easily than molasses (syrup) |
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Term
| What three factors does viscosity depend on? |
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Definition
| temperature, volatile content, and silica content. |
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Term
| Hotter magma is ____ _____ than cooler magma. Because thermal energy breaks bonds and allows atoms to move more easily |
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Definition
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Term
| Magmas or Lavas containing more volatiles are ____ _____ than dry (volatile-free) magmas. Because the volatiles also tend to break apart silicate molecules and mayu also form gas bubbles. |
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Definition
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Term
| Mafic magmas are ___ _____ than felsic magmas because silicon-oxygen tetrahedra tend to link together in magma to create long melecular chains that can't move past each other easily and there are more of these chains in a felsic magma than in a mafic magma. |
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Definition
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Term
| What three factors control the cooling time of magma that freezes below the surface in the intrusive realm? |
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Definition
the depth of intrusion
the shape/size of a magma body
the presence of circulating groundwater |
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Term
| Igneous rocks crystallize at what range of temperature? |
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Definition
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Term
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Definition
| a tabular intrusion that cuts across pre-existing layering vertically(bedding) |
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Term
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Definition
| a tabular intrusion that injects parallel to layering (horizontally) |
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Term
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Definition
| blob-shaped intrusions that range insize from tens of meters across to tens of kilometers across |
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Term
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Definition
| The intrusion of numerous plutons in a region that creates a vast composit body that my be several hundred kilometers long and over 100 km wide |
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Term
| Where are batholiths in western North America? (4) |
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Definition
| Coast Ranges batholith, Idaho, Sierra Nevada, Peninsular batholith |
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Term
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Definition
| foreign rock (gaps of rock between magma) |
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Term
| How can igneous rocks be classified? (2) |
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Definition
| Texture and mineral/chemical composition |
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Term
| What is aphanitic? Example |
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Definition
| minerals to small to see. Ex. rhyolite |
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Term
| What is phaneritic? Example |
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Definition
| Minerals large enough to see with unaided eye (granite) |
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Term
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Definition
| no obvious minerals (obsidian) |
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Term
| What is pyroclastic? example |
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Definition
| fused, glassy volcanic rock fragments and ash from explosive volcanic eruption (Tuff) |
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Term
| What is vesicular? example |
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Definition
| Many holes or pits in rock surfaced caused by escaping gas (vesicular basalt) |
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Term
| What is porphyrytic? example |
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Definition
| two distinct mineral sizes (porphyritic basalt) |
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Term
| How is texture of an igneous rock measured? |
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Definition
| by using visual grain size depending on crystallization history |
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Term
| Textures of igneous rocks are mainly controlled by the cooling rate. Slow cooling form ____ sized crystals and are _______ igneous rocks. |
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Definition
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Term
| What are the three types of textures of igenous rocks? |
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Definition
| Crystalline, Fragmental and Glassy |
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Term
| Fast cooling igenous rocks form _____ sized crystals and are ________ igneous rocks. |
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Definition
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Term
| Why must texture and composition of igneous rocks be studied? |
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Definition
| Every intrusive rock has an extrusive rock that goes with it. |
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Term
| Which two intrusive and extrusive Felsic Rocks go together? |
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Definition
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Term
| Which two intrusive and extrusive Intermediate Rocks go together? |
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Definition
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Term
| Which two intrusive and extrusive Mafic Rocks go together? |
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Definition
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Term
| Which two intrusive and extrusive Ultramafic Rocks go together? |
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Definition
| Peridotite-------Komatiite |
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Term
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Definition
| a volcanic extrusive rock so light that paper can hold it up |
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Term
| Obisidan and Volcanic Ash are more examples of extrusive igneous rocks |
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Definition
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Term
| All igneous rocks result from what? |
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Definition
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Term
| Where does igneous activity occur? (4) |
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Definition
| subduction zones, continental rifts, hot spots, mid-ocean ridges |
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Term
| Where are intermediate and felsic rocks formed through subduction zones? (2) And what type of igneous rocks are formed in these areas? (3) |
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Definition
Andes, Sierra Nevada
Andesite, Granite, Diorite |
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Term
| Where are Basalt and Rhyolite formed through hot spots? |
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Definition
| Hawaii, Yellowstone, Iceland |
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Term
| What two types of igneous rock is formed from mid-ocean ridges? |
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Definition
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Term
What are flood basalts?
Where has this occured? |
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Definition
thin basaltic lava that can flow very far
East African valley, Basin and Range Province, Clumbia River Plateau |
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