Geology Midterm
Earth And Space Sciences 101 with Swanson at University of Washington - Seattle Campus
About this deck
By: Adrienne Ton
Created: 2011-01-31
Size: 102 flashcards
Views: 189
Created: 2011-01-31
Size: 102 flashcards
Views: 189
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Basaltic composition magma can form ________
At sea floor spreading zones, at continental rift zones, above hotspots, back arc spreading basins.
What kind of plate margin is represented by the San Andreas fault?
Transform margin
Why do you think that there is very little evidence for the accretion of the planetismals at the surface of the earth?
Weathering and the subduction of the tectonic plates
What is the main source of heat driving convection cells in the asthenosphere today?
Radioactive heating
The melting temperature of what substance must be reached in order for the earth to become compositionally zoned?
Fe (iron)
True or False: Spreading ridges can never be subducted.
False
Seismic wave data shows that the outer core is liquid and the inner core is solid; yet the actual temperature of the outer core is lower than the inner core's actual temperature. Why is it that the inner and outer cores are composed of similar metallic iron and nickel yet the outer core is liquid?
The melting temperature curve for iron nickel is LESS THAN the geothermal gradient temperature in the outer core.
What makes the asthenosphere unique relative to the lowermost lithosphere and the uppermost mesosphere (upper mantle)?
The asthenosphere is at the pressure melting temperature for the upper mantle composition.
A shield volcano is formed of alternating layers of what?
Basaltic lava flow
What is the significance of the change in direction of the Hawaiian Island chain and the Emperor Seamount chain?
The tectonic plate on which both island chains sit changed directions.
(Because some other plate was subducted, thus removing a vector and changing the direction)
What is the coarse-grained igneous rock that would be composed of approximately 25% quartz, 20% sodium rich plagioclase, 50% potassium feldspar, and 5% biotite and amphibole?
Granite
What is the fine-grained igneous rock that would be composed of approximately 60% calcium rich plagioclase, 30% pyroxene, and 10% of either amphibole or olivine?
Basalt
Which of the combination of mineral assemblages shown below would not naturally occur in igneous rocks?
Quartz, pyroxene, olivine.
Meaning the combinations (quartz, biotite, potassium feldspar), (amphibole, potassium feldspar, and quartz), and (calcium-rich plagioclase, pyroxene, and olivine) would naturally occur.
Why are andesitic rocks usually porphyritic?
Two staged cooling history for andesitic magmas
Which tectonic margin would tend to have deeper focused earthquakes?
Convergent
The Andes Mountains formed at a _____ tectonic margin
Convergent (Ocean continent)
S-waves do what as they travel through the outer core?
are absorbed
When two ocean plates converge, what happens?
The older plate will be subducted
Magma is being erupted along a divergent margin. What type of magma is erupted on the surface?
Basalt
Where can you find a divergent type of margin (along which basaltic magma is being erupted)?
In ocean basins and continents.
What causes the divergence (along a divergent type of margin in which basaltic magma is being erupted)?
Upwelling due to convection in the asthenosphere
Magmas are divided into three compositional ranges based mainly on _________ content?
silica content
Most igneous rocks are predominantly composed of what?
Silicon and oxygen
What is the appropriate tectonic setting where basalt most likely forms?
Mid ocean hotspot
What is the appropriate tectonic setting where granite most likely forms?
Continent-continent collision
What is the appropriate tectonic setting where andesite most likely forms?
Ocean ocean convergence or continent continent collision
The asthenosphere is composed of rock rich in
Peridotite (>90% olivine)
A GRANITIC MAGMA formed by wet partial melting will tend to solidify and form an igneous rock underground because:
Because they have a high silica content and because the effectiveness of water in reducing the melting temperature is greatly reduced
A partial melt of the asthenosphere will tend to rise toward the surface because______
The melt is less dense than the surrounding rock
Answer based on three pie diagrams showing average compositions of the three principal kinds of magma. What type of lava or magma would Chart A represent?
Granitic
Answer based on three pie diagrams showing average compositions of the three principal kinds of magma. Which of the above lavas or magmas would have the lowest viscosity?
Basaltic
Answer based on three pie diagrams showing average compositions of the three principal kinds of magma. Which of the above lavas or magmas would have the highest quartz content?
Granitic
Answer based on three pie diagrams showing average compositions of the three principal kinds of magma. Which of the above magmas would you expect to represent the composition of the mesosphere (middle and lower mantle)?
NONE (not granitic, andesitic, or basaltic)
What are three types of lava or magma?
Granitic, andesitic, basaltic
Diamond is harder than graphite because:
Diamonds have covalent bonds between its constituent atoms while graphite has vanderwahl bonds
How does the silicate tetrahedrom achieve charge balance? (3 reasons)
It will share electrons between oxygen atoms, it will form ionic bonds with available cations, and it will form metallic bonds with available cations.
The inert gases (i.e. helium, neon, argon) rarely bond with other atoms because??
They have no electron shell valencies.
The compositional zonation of the earth is best described as what?
Density gradient
Angular momentum is mathematically described as Velocity x Radius x Mass. What would happen to the rotational velocity of the sun if it condensed from a gas cloud that extended beyond the orbit of Pluto?
Its rotational velocity would speed up during condensation.
Why does the sun have less angular momentum than the planets yet it contains 99% of the solar system's mass?
The sun's magnetic field is applying a drag on its atmosphere
How many oxygen atoms are being shared between the silicate tetrahedra in quarts?
Four
What is the significance of OH in the muscovite crystal structure?
It is water likely incorporated during the subduction process
If the pyroxene chains are formed from silicate tetrahedra of four oxygen atoms to every silicon atom, why is the formula shown as SiO3
Two of the oxygen atoms are shared with another silicon atom
Why does muscovite develop cleavage planes?
The mineral cleaves between ionic bonds separating sheet pairs
BONUS QUESTIONS: What mineral group represents our major sources of iron?
Oxides
Lead, mercuty, and zinc ores are smelted (refined) from which mineral group?
Sulfides
Paleomagnetism cannot provide geologists with information
About the longitudinal position of tectonic plates over geologic time
Match the magma type with the appropriate tectonic setting where it likely forms. Cascade Mountains?
Andesite
Match the magma type with the appropriate tectonic setting where it likely forms. Plutons under the Himalayas?
Granite
Match the magma type with the appropriate tectonic setting where it likely forms. Japan?
Basalt
The asthenosphere is composed of rock rich in what?
Peridotite (>90% olivine)
As a granitic magma rises to the surface, what two things happen?
Its melting temperature will increase and it will tend to crystallize before it reaches the surface
A partial melt of the asthenosphere will tend to rise toward the surface because?
the melt is less dense than the surrounding rock
Pillow basalts form when what happens?
When the basalt flow is erupted into water
What happens when two ocean plates converge?
The older one is subducted
What is the most widely accepted explanation for the earth's magnetic field?
The movement of electrons in the molten iron of its outer core
What kind of plate margin existed when the Appalachian Mountains formed during the Paleozoic Era?
Collision margin (continent-continent)
What type of volcanic rock would incorporate lithic fragments during the eruption?
volcanic breccia
Why does quartz develop six cleavage planes?
TRICK QUESTION. Quartz does not cleave.
Why are andesitic rocks usually porphyritic?
Two-staged cooling history for andesitic magmas
Diamond is harder than graphite because:
diamonds have covalent bonds between its constituent atoms while graphite has vanderwahl bonds
How does the silicate tetrahedron achieve charge balance? (THREE ANSWERS)
it will share electrons between oxygen atoms
b. it will form ionic bonds with available cations
c. it will form metallic bonds with available cations
Why do the terrestrial planets have so little molecular (gaseous) hydrogen?
The terrestrial planets are close to the sun and the low density hydrogen was lost to space.
Why does muscovite cleave between its silicate sheets?
the bonds are stronger within the silicate sheets compared to between the silicate sheets
What is the significance of (OH) in the muscovite crystal structure?
. it is water likely incorporated during the subduction process
Why does the topographic expression of the Hawaiian Island become progressively lower from the Big Island to
the island lying northwest?
ocean lithosphere is lighter over the hotspot and it floats higher
Arrange the compositional zones of the earth according to their respective density (densest to lightest).
inner core, outer core, mantle, ocean crust, continental crust
What kind of plate margin is represented by the Andes Mountains?
convergent margin (ocean-continental subduction)
Meteorites are thought to be composed of ____________?
materials that are similar in composition to those found in the solid earth
Which zone of the earth is also described as the “low velocity zone?”
asthenosphere
The melting temperature of _____ must be reached in order for the earth to become compositionally zone:
Metallic Fe and Ni
Why will the Juan de Fuca spreading ridge eventually be subducted under the North American plate?
the rate of sea floor spreading is less than the rate of subduction at the convergent margin
Transform plate boundaries are typically associated with ___________.
divergent margins where the rate of spreading is different along segments of the spreading ridge
The cause of volcanism observed at Yellowstone National Park is similar to that of ________.
the Hawaiian Islands
A shield volcano has a lower slope angle than a strato (composite) volcano because ________.
its basaltic lava flows have lower viscosities than the andesitic flows of strato volcanoes
What is the significance of the change in direction of the Hawaiian Island chain and the Emperor Seamount
chain?
the tectonic plate on which both island chains sit changed directions
Which tectonic margin would tend to have deep and shallow focused earthquakes?
convergent
Basaltic composition magma can form _____ (4 answers)
at sea floor spreading zones
b. at continental rift zones
c. above hotspots
d. back arc spreading basins
S-waves ___________ as they travel through the outer core.
Absorbed
outer core is liquid and the inner core is solid; yet the actual temperature of the outer core is lower than the inner core's actual temp. Why are the inner and outer cores both composed of metallic iron and nickel
yet the outer core is liquid and the inner core solid?
the melting temperature for iron-nickel is lower than the geothermal gradient temperature in the outer core.
What makes the asthenosphere unique relative to the lowermost lithosphere and the uppermost mesosphere
(upper mantle)?
the asthenosphere is at the pressure melting temperature for the upper mantle composition.
Granite
Gabbro
Magma is being erupted from a hotspot.
What type of magma is produced at this setting?
Basalt
Magma is being erupted from a hotspot.This type of tectonic setting can be found _____________?
beneath ocean basins and continents
Magma is being erupted from a hotspot.What is the main source of the erupted lava?
partial melt of the asthenosphere
Magmas are divided into three compositional ranges based mainly on ___________ content.
Silica
Why is there a low velocity zone for seismic waves entering the asthenosphere?
the asthenosphere is a partial melt and seismic wave decelerate as they enter the phase change
In the geologic techniques lab each group completed a topographic cross-section of Yosemite Valley. What
profile shape was indicative of a glaciated valley?
U-shaped
In the plate tectonics lab we observed that the magnetic polarity stripes south of Alaska were uni-directional.
How could you explain the fact that half of the magnetic stripes were missing?
the spreading ridge that created the stripes was subducted under Alaska
In the minerals lab the main diagnostic criteria for identifying the metallic mineral hematite was
its reddish-brown streak
In the igneous rock lab we observed two volcanic rocks at the front of the lab. They were collected from ____.
Hawaii and Mount St. Helens
A phaneritic (plutonic( rock composed of 95% olivine and less than 5% of pyrozene and Ca-rich?
Peridotite
An aphanitic (volcanic) rock composed of predominantly calcium-richplagioclase and pyroxene would be classified as?
Basalt
What are three types of plate boundaries? What are the specific types associated with each?
Convergent: (Ocean, ocean) (continental continental) (ocean continental)
Divergent: spreading ridge
Transform: sliding past one another, usually in conjunction with spreading ridge
About this deck
By: Adrienne Ton
Created: 2011-01-31
Size: 102 flashcards
Views: 189
Created: 2011-01-31
Size: 102 flashcards
Views: 189
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
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“I have used this website for three exams, and I see a huge difference in my test results.”
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