Shared Flashcard Set

Details

Rocks Midterm Spring 2005
Rocks
48
Geology
Undergraduate 1
01/30/2011

Additional Geology Flashcards

 


 

Cards

Term
Match magma type with appropriate tectonic setting where it likely forms: Cascade Mountains
Definition
andesite
Term
Match magma type with appropriate tectonic setting where it likely forms: plutons under the himilaya mountains
Definition
granite
Term
Match magma type with appropriate tectonic setting where it likely forms: Japan
Definition
andesite
Term
the athsenosphere is composed of rock rich in
Definition
peridotite (>90% olivine)
Term
as a granitic magma (wet melt) rises toward the surface
Definition
its melting temp will increase

it will crystalize before it reaches the surface
Term
a partial melt in the asthenosphere will tend to rise toward the surface because
Definition
the melt is less dense than the surrounding rock
Term
pillow basalts form when
Definition
when the basalt flow is erupted into water
Term
when two ocean plates converge
Definition
the older plate will be subducted
Term
the most widely accepted explanation for the earths magnetic field
Definition
movement of electrons in the molten iron of its outer core
Term
what kind of plate margin existed when the appalachian mountains formed during the Paleozoic era
Definition
collision margin (continent-continent)
Term
what type of volcanic rock would incorporate would lithic fragments during the eruption
Definition
volcanic breccia
Term
why does quartz develop six cleavage planes?
Definition
this mineral does not cleave
Term
why are andesitic rocks usually porphyritic
Definition
two staged cooling history for andesitic magmas
Term
diamond is harder than graphite becasue
Definition
diamonds have covalent bonds between its constituent atoms while graphite has vanderwahl bonds
Term
the silicate tetrahedron (SiO4) has a net charge of
Definition
-4
Term
how does the silicate tetrahedron acheive charge balance
Definition
it will share electrons
it will form ionic bonds wiht available cations
it willl form metallic bonds with available cations
Term
why do the terrestrial planets have so little molecular (gaseous) hydrogen
Definition
the terrestrial planets are close to the suna and the low density hydrogen was lost to space
Term
how many oxygen atoms are being shared between the silicate tetrahedral muscovite sheets
Definition
three
Term
why does muscovite cleave between its silicate sheets
Definition
the bonds are stronger within the silicate sheets compared to between silicate sheets
Term
what is the significance of (OH) in the muscovite crystal structure
Definition
it is water likely incorporated during the subduction process
Term
why does the topographic expression of the hawaiian island become progressively lower from the big island to the island lying northwest
Definition
the ocean lithosphere is the lighter over the hotspot and it floats higher
Term
arrange the compositional zones of the earth according to their respective density (densest to lightest)
Definition
inner core, outer core, mantle, ocean crust, continental crust
Term
what kind of plate margin is represented by the andes mountains
Definition
convergent margin (ocean to ocean subduction)
Term
meteorites are thought to be composed of
Definition
materials that are simiilar in composition to those found in the solid earth
Term
which zone of the earth is also described as the 'low velocity zone'
Definition
asthenosphere
Term
the melting temperature of ____ must be reached in order for the earth to become compositionally zone
Definition
metallic fe and ni
Term
why will the juan de fuca spreading ridge eventually be subducted under north american plate
Definition
the rate of teh sea floor spreading is less than the rate of subduction at teh convergent margin
Term
transform plate boundaries are typically associated with
Definition
divergent margins when the rate of spreading is the same along segments of the spreading ridge
Term
the cause of volcanism observed at yellowstone national park is similar to that of
Definition
the hawaiian islands
Term
a shield volcano has a lower slope angle than a strato (composite) volcano
Definition
its basaltic lava flows that have lower viscosities than the andesitic flows of strato volcanoes
Term
what is the significance of the change in the direction of the hawaiian island chain and the emperor seamount chain
Definition
the tectonic plate on which both island chains sit changed direction
Term
which tectonic margin would tend to have deep and shallow focused earthquakes
Definition
convergent
Term
basaltic composition magma can form
Definition
at sea floor spreading zones
at continental rift zones
above hotspots
back are spreading basins
Term
S-waves _____ as they travel through the outer core
Definition
are absorbed
Term
How can we best explain the fact that teh inner and outer cores are both composed of metallic iron and nickel yet the outer core is liquid and the inner core is solid
Definition
the melting temp for iron nickel is lower than the geothermal gradient temp in the outer core
Term
what makes the asthenosphere unique relative to teh lowermost lithosphere and the uppermost mesosphere (upper mantle)
Definition
the asthenosphere is at the pressure melting temp for the upper mantle composition
Term
a phaneritic (plutonic) rock composed of 5% quartz, 55% plagioclase, 25% amphibole, and 5% pyroxene would be classified as ____
Definition
granite
Term
a plutonic rock composed of predominantly calcium rich plagioclase and pyroxene would be classified as
Definition
gabbro
Term
granite contains ____ olivine.
Definition
0%
Term
Magma is being erupted from a hotspot:
What type of magma is produced atthe setting
Definition
basalt
Term
Magma is being erupted from a hotspot:
this type of tectonic setting can be found __
Definition
beneath teh ocean basins and continents
Term
Magma is being erupted from a hotspot:
what is the main source of erupted lava
Definition
partial melt of the asthenosphere
Term
magmas are divided into three compositional ranges based mainly on _____ content
Definition
silica content
Term
why is there a low velocity zone for seismic waves entering teh asthenosphere
Definition
the asthenosphere is a partial melt and seismic wave decelerate as tehy enter teh phase change
Term
In the geologic techniques lab each group completed a topographic cross section of yosemite valley. what profile shape was indicitive of a glaciated valley
Definition
u shaped
Term
in the plate tectonics lab we observed that the magnetic polarity stripes south of alaska were uni directional. how could you even explain the fact that half the magnetic stripes were missing
Definition
the spreading that created stripes were subducted under washingotn
Term
in the metallics lab the main diagnosic criteria for identifying the metallic mineral hermite was its _____
Definition
reddish brown streak
Term
In the igneous rock lab we observed two volcanic rocks at the front of the lab. they were collected from ______
Definition
Hawaii and mt saint helens
Supporting users have an ad free experience!