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99 Cards in this Set
- Front
- Back
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What seismic waves cannot travel through liquid?
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Secondary/Shear waves
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What is the shadow zone?
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An area where no seismic waves go
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What do the velocities of P and S waves depend on?
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Density
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Where do minerals change their coordination number and structures?
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In the transition zone
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What three minerals dominate the lower mantle?
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Magnesium-silicate perovskite (Mg, Fe)SiO3
Magnesio wustite (Mg, Fe)O Stishovite SiO2 |
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Why might silicate perovskite be the most abundant mineral on earth?
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Because it makes up ~80% of the lower mantle
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The study of earthquakes and seismic waves they produce
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Seismology
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What does experimental petrology do?
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Simulates geologic conditions in lab, using high pressures and temperatures
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Seismic discontinuities lead us to defining earth in terms of three very different parts:
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Core
Mantle Crust |
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How do oceanic and continental crust differ?
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Composition and thickness
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How many major tectonic plates are in constant motion due to mantle convection?
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12
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What is the upper mantle dominated by?
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Olivine and pyroxenes
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Where does the olivine structure change to denser packaging?
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Transition zone
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In the transition zone, olivine is in a ___________ structure and pyroxenes adopt a __________ structure
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Spinel, garnet
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The greatest volume of the earth resides where?
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Lower mantle
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Silica is in __________ coordination in the lower mantle
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6-fold
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What is the CN for crustal polymorphs?
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4
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How much of the earths mass does the core represent?
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30%
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How much of the earths volume does the core take up?
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17%
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What is the liquid outer core made of?
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Primarily iron, ~2% nickel
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What is the solid inner core made of?
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Fe-Ni alloy, 20% Ni
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What is petrology?
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study of the processes that create rocks
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What is a rock?
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An aggregate of minerals/mineraloids
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How do you make a rock melt?
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Lower the melting point of raise the temperature of the environment
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What is decompression melting?
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Hot material from deep depths convect and rise, reducing the melting point because of a decrease in pressure.
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How do plutonic (intrusive) rocks cool?
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Slowly
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How do volcanic (extrusive) rocks cool?
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Rapidly
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What is tuff?
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A rock composed of volcanic clasts
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How are intrusive rocks formed?
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from magma that cools and solidifies within the crust, surrounded by country rock
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What does slow cooling of magmas produce in respect to crystals?
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Large crystals easily seen by eye
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How are intrusive rocks classified?
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Classified based on modal proportions of quartz, plagioclase, K-Spar
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What is magma called when it is extruded onto the surface
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lava
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How are extrusive rocks classified?
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Classified based on modal mineralogy or more commonly chemical composition
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Where does volcanism occur?
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Hotspots, divergent and convergent boundaries
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What is magma behaviour goverened by?
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Viscosity
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Hight temperature basalt is ________ in silica, called ________, and behaves like thick oil
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low, mafic
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What does adding more Si to magma do?
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Increases viscosity and decreases eruption temperature
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High silica eruptions, known as ________, have viscosity like molasses in january
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felsic
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Why are mafic eruptions dangerous?
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Lava flows
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How would you describe a felsic eruption?
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Violent, releases gases explosively
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What is explosive pyroclastic material called?
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Tephra
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Phaneritic is characteristic to what type of igneous rock?
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intrusive
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What does phaneritic mean?
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Large crystals
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Aphantic is characteristic to what type of igneous rock?
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Extrusive
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What does aphantic mean?
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small crystals
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A rock that undergoes 2 phase cooling had a _________ texture.
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Porphyritic
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Felsic magmas are ___________ and high in SiO2
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acidic
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Intermediate magmas have 52-66% wt% of __________
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SiO2
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What are mafic and ultramafic magma compositions also known as?
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basic and ultrabasic
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What did Norman Bowen develop?
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Bowen's Reaction Series
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What does IUGS stand for?
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International Union of Geological Sciences
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How much land surface to sedimentary rocks cover?
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80% of land surface
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What are five processes to developing sedimentary rocks?
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Weathering
Erosion Transport Deposition Lithification |
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What kind of weathering is jointing and exfoliation?
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Mechanical
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What is the difference between physical and chemical weathering?
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Physical weathering mechanically breaks down materials
Chemical weathering involves chemical reactions that break down materials. |
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Oxidation and dissolution are what types of weathering?
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Chemical weathering
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What is hydrolysis?
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The chemical breakdown of a compound due to a reaction with water.
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List from fastest to slowest weathering rates:
Mafics/Sulfides Quartz Feldspars Micas |
1. Mafics/Sulfides
2. Feldspars 3. Micas 4. Quartz |
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How do chemical and physical weathering work together?
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Chemical weathering weakens the rock, making it more susceptable to physical weathering.
Physical weathering increases the surface area of a rock, speeding up chemical weathering processes. |
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What grain has the size >256mm or 2^8mm?
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Boulders
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What grain has the size 64-256mm?
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Cobbles
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What grain has the size 2-64mm?
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Pebbles
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What grain has the size 1/16 - 2mm?
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Sand
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What grain has the size 1/256 - 1/16mm?
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Silt
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What grain has the size <1/256 or 2^-8mm?
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Mud or clay
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What does 'clastic' texture mean?
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Having fragments of pre-existing rock
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Sandstones and Shales have _________ texture.
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Clastic
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Sandstones are _________ while shales are ___________.
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Cemented, Compacted
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Evaporites are examples of what kind of texture?
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Chemical / Precipitate
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What does biochemical clastic mean?
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Accumulation of shell debris
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What are the four textural groupings in sedimentary rocks?
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Organic
Biochemical Clastic Clastic Chemical/Precipitates |
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What is chert?
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Biochemical clastic rock
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What is the inorganic replacement material of chert?
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flint
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What are metamorphic rocks?
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Rocks transformed from protolith (pre-existing rock)
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True or False:
Weathering is required in the transformation of protolith into metamorphic rock. |
False
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True or False:
Metamorphic rocks are transformed in the solid state |
True
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What does isochemical mean in regards to metamorphism?
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No chemical change
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What does metasomatism mean in regards to metamorphism?
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Elements are added
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Limestone metamorphoses into what rock?
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Marble
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Limestone and Marble are dominantly what mineral?
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Calcite
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Clay minerals in shale metamorphoses into what rock?
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Mica Schist
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What characteristic is dominant in mica schists?
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foliation
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________________ occurs when fluid is added.
________________ occurs when CO2 is released. ________________ occurs when H2O is released. |
Metasomatism
Decarbonation Dehydration |
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Metamorphism that is just heating, has little or no strain, and does not create foliation.
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Contact metamorphism
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Metamorphism that occurs on a huge scale, occurs usually in subduction zones, near batholiths and mountain roots. Develops foliation.
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Regional metamorphism
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Subduction related metamorphism has ________ pressure and __________ temperature.
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high, low
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Regional metamorphism (mountain building) has _________ pressure and __________ temperature
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medium, medium
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Contact metamorphism (intrusion-related) has ________ pressure and ___________ temperature.
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low, high
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Progressively higher grade assemblages eg. due to hydration and heating
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Prograde metamorphism
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Progressively lower grade assemblages eg. upon cooling or fluid influxes
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Retrograde metamorphism
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Chlorite replacing garnet is an example of __________ metamorphism.
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Retrograde
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Serpentine dehydrating to olivine and pyroxene is an example of ___________ metamorphism.
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Prograde
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What is an index mineral?
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A key mineral that marks a reaction that is related to metamorphic grade
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What is an isograd?
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The first appearance of an index mineral.
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The metamorphic facies diagram resembles what polymorph phase diagram?
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Aluminosilicate phase diagram
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What facies do these minerals belong to?
Chlorite, epidote, actinolite, albite |
Greenschist
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What facies do these minerals belong to?
Hornblende, plagioclase, garnet |
Amphibolite
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What facies do these minerals belong to?
Garnet, jadeite-diopside |
eclogite
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What facies do these minerals belong to?
chlorite, muscovite, zeolite minerals |
Zeolite
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