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Plate Tectonics
Chapter 2 in the book EARTH: An Introduction to Physical Geology 9th Edition.
37
Geology
Undergraduate 1
04/06/2010

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Term
asthenosphere
Definition
(asthenos=weak; sphere=ball)

the mantle that is underneath the lithosphere
Term
continental drift
Definition
theory made by Alfred Wegener

Pangea began breaking apart into smaller continents about 200 millionn years ago.
Term
continental volcanic arc
Definition
Mountains such as ANDES are produced in part by volcanic activiy associated with the subduction of oceanic lithosphere.
Term
convergent boundary
Definition
plate boundaries moving towards eachother where subduction zones are produced with oceanic lithosphere always submerging underneath another oceanic/continental.
lithosphere is destroyed.
cause DEEP OCEAN TRENCHES.
3 convergences: oceanic-oceanic; continental-oceanic; continental-continental.
Term
curie point
Definition
a point of temperature where depending on whether it is high or lovw, magnetic minerals are either gained or lost.
Term
deep-ocean trench
Definition
expression produced by a plate descending underneath another one.
Term
divergent boundary
Definition
plates moving apart from one another.
occur along the crest of oceanic ridges.
also called "spreading centers" because seafloor spreading occurs at these boundaries.
Term
fossil magnetism
Definition
rocks that were formed millions of years ago and contain a "record" of the direction of the magnetic polesat the time of their formation.
Term
fracture zone
Definition
linear breaks in the oceanic crust.
include both the active transform faults as well as their inactive extentions into the plate interior.
Term
geomagnetic reversal
Definition
the Earth's magnetic field periodically reverse polarity.
Term
hot-spot
Definition
an area of volcanism
Term
hot-spot tracks
Definition
shows the age of each volcano indicating the time when it was situated over the mantle plume.
traces the direction of the plate motion.
Term
island arc
Definition
arshaped chain of small volcanic islands
Term
lithosphere
Definition
(lithos=stone;sphere=ball)
uppermost mantle along with the overlying crust behaves as a strong ridid layer
Term
lithospheric plate
Definition
lithosphere broken into numerous segments.
Term
magnetometer
Definition
magnetic surveys that map variations in the strength of Earth's magnetic field that arise from differences in the magnetic properties of the underlying crustal rocks.
Term
magnetic time scale
Definition
measures the magnetic polarity of hundresds of lava flows and use radiometric dating techniques to establish their ages.
Term
mantle plume
Definition
hot, buoyant upward flowing arms of mantle convection.
Term
normal polarity
Definition
when rocks exhibit the same magnetism as the present magnetic field
Term
oceanic ridge system
Definition
large expanses of the seafloor slowy emerging. down the middle of the Atlantic Ocean.
Term
paleomagnetism
Definition
rocks that were formed millions of years ago and contain a "record" of the direction of the magnetic polesat the time of their formation.

same as fossil magnetism.
Term
Pangea
Definition
a supercontinent that was broken apart due to continental drift.
Term
partial melting
Definition
when the mantle is sufficiently hot, the introduction of water leads to some melting.
Term
plate
Definition
lithosphere broken into smaller pieces.
Term
plate tectonics
Definition
continental drift and seafloor spreading were united to encompass this theory.
Term
reverse polarity
Definition
rocs exhibiting opposite magnetism.
Term
ridge push
Definition
results when gravity sets the elevated slabs astride oceanic ridges in motion.
Term
rift or rift valley
Definition
ridge segments in a deep down faulted structure.
Term
seafloor spreading
Definition
states that new seafloor is continually being generated at mid-ocean ridges and old, dense seafloor is being consumed at the deep-ocean trenches.
Term
slab pull
Definition
occurs where cold, dense oceanic lithosphere is subducted and pulls the trailing lithosphere along
Term
slab suction
Definition
mantle flows being "sucked" in nearby plates.
Term
spreading center
Definition
another name for divergent boundaries.
Term
subduction zone
Definition
also called convergent boundaries
Term
tectonic plate
Definition
lithosphere broken into numerous segments.
Term
transform fault
Definition
plates slide horizontally past one another without the production or destruction of lithosphere.
Term
transform fault boundary
Definition
plates grind past each other without production or destruction of lithosphere.
Term
volcanic island arc
Definition
oceanic-oceanic convergence resulting in an arc shaped chain of volcanic islands.
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