Term
Tectonics, Earthquakes, and
Volcanism |
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Definition
| Earth’s Surface Relief Features |
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Term
| Earth’s Surface Relief Features |
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Definition
Relief refers to vertical elevation
differences in the landscape |
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Definition
refers to the undulating form of
Earth’s surface |
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Definition
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Definition
Broadest category that includes
continental platforms and ocean basins |
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Definition
Includes mountain masses,
plains and lowlands |
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Definition
Most detailed and includes
individual mountains, cliffs, valleys, hills and
other small scale landforms |
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Term
| Crustal Formation Processes |
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Definition
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Term
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Definition
Nuclei of ancient crystalline rocks
– Found on all continents
– Date to the Precambrian (> 600 m.y. old)
– Regions of thickest lithosphere |
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Term
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Definition
Region where a craton is exposed at the
surface |
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Term
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Definition
Dominantly
igneous and
metamorphic rocks
> 1 billion years old |
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Term
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Definition
ancient crustal
rocks that have been significantly
deformed and metamorphosed in
various ways: |
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Term
Cratons represent ancient crustal
rocks that have been significantly
deformed and metamorphosed in
various ways: |
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Definition
Continental margin and oceanic material
squeezed within the collision zones of
ancient proto-continents
– Oceanic crust caught up in subduction
zones or extensional basins behind
volcanic arcs
– Root zones of once vast mountain ranges |
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Term
| Earliest continents started out as |
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Definition
protocontinents over 4 billion years
ago: |
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Term
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Definition
Were much smaller than continents today
– Probably granitic in composition
– Served as sources of ancient zircon
minerals
– Preserved today within ancient gneiss
complexes of Archean (>2.5 billion year old)
cratons |
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Term
| Earliest Protocontinents May Have Formed Through |
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Definition
Partial Melting Of Mantle Peridotite And Overlying Basaltic
Crust By Rising Mantle Plumes, Followed By
Differentiation Of The Magma |
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Term
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Definition
Continued convection and partial
melting of the underlying mantle
resulted in growth of protocontinents
in both extent and thickness through
addition of siliceous plutons |
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Term
| Archean (>2.5 B.Y. Old) Gneisses Such As In Greenland |
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Definition
| May Preserve Relicts Of Ancient Protocontinents |
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Term
| Eventually continents grew from |
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Definition
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Term
| These continents continued to grow by: |
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Definition
– Addition of igneous material through partial
melting of underlying mantle
– Erosion of uplifted areas, followed by sediment
deposition around periphery
– Accretion of arc terranes and micro-continents
around periphery
– Collision and assembly with other continents |
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Term
| Crustal formation is a complex process |
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Definition
– Sea floor spreading and formation of oceanic
crust along a divergent plate boundary (midocean
ridge)
– Movement of oceanic crust away from divergent
boundary
– Subduction of oceanic crust at convergent plate
boundaries
– Melting of subducted crust to form magma
– Addition of magma to overlying crust |
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Term
| Continental crust is constructed along |
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Definition
convergent plate boundaries as a product
of the tectonic cycle |
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Term
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Definition
Two major supercontinents existed
over the last 1 billion years:
Both may be products of the
supercontinent cycle |
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Term
Two major supercontinents existed
over the last 1 billion years: |
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Definition
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Term
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Definition
Assembled by ~1 b.y. ago and
began to break apart ~600 m.y. ago |
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Term
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Definition
Assembled by 230 m.y. years
ago and began to break apart ~200 m.y.
ago |
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Term
Late Proterozoic(~750
M.Y. Ago) Supercontinent
Of Rodinia |
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Definition
Some possible
arrangements of
continents during
the Late
Proterozoic to form
Rodinia |
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Term
| Crustal Deformation Processes |
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Definition
Rocks subjected to powerful tectonic
forces, deep burial, and gravity can
eventually deform |
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Term
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Definition
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Definition
| Rocks are bent and contorted |
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Term
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Definition
Rocks break and slip along a plane of
dislocation |
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Term
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Definition
typically sites of
crustal deformation |
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Term
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Definition
– That which tends to put stationary objects
in motion or changes the motions of
moving objects |
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Term
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Definition
| Force applied to a given area (F/A) |
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Term
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Definition
Stress applied unequally in different
directions |
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Term
Three Types of Differential
Stress |
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Definition
Compressional Stress
Tensional Stress
Shearing Stress |
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Term
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Definition
| – Squeeze and shorten a body |
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Term
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Definition
| – Stretch the body and pull it apart |
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Term
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Definition
– Push different parts of body in opposite
directions |
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Term
| Tensional Stress and Strain |
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Definition
| Common along divergent plate boundaries |
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Term
| Compressional Stress and Strain |
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Definition
| Common along convergent plate boundaries |
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Term
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Definition
| Common along transform plate boundaries |
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Term
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Definition
| Folds are twists and bends in rocks |
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Term
Result from ductile deformation of
rocks in response to external forces: |
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Definition
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Term
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Definition
layered rocks that were
folded into arches |
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Term
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Definition
layered rocks folded into
troughs |
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Term
| Folding in the Zagros Crush Zone |
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Definition
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Term
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Definition
an anticlinal structure
where the flanking strata dip away
from the center in all directions |
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Term
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Definition
a synclinal structure
appearing as a bowl-shaped
depression where rock layers dip
towards the center in all directions |
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Term
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Definition
plane of dislocation
where rocks on one side of the
fault have moved relative to
rocks on the other side |
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Term
Faults can form in response to any of
the three types of stresses: |
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Definition
– Compressional
– Tensionial
– Shear |
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Term
The type of fault produced depends
on the |
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Definition
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Term
| Reverse Versus Thrust Faults |
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Definition
For both types, the hanging wall moves
upward relative to footwall |
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Term
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Definition
| Fault angles greater than 45o |
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Term
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Definition
| Faults angles less than 45o |
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Term
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Definition
Convergent plate boundaries often
are sites of accretion (addition) of
crustal pieces that include: |
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Term
Convergent plate boundaries often
are sites of accretion (addition) of
crustal pieces that include: |
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Definition
Microcontinents broken off from other
continents
– Volcanic island arcs
– Pieces of ocean floor called ophiolites |
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Term
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Definition
A collage is an assemblage of
micro-continents, arcs, and
other crustal fragments
accreted along the edge of a
continent adjacent to a
subduction zone |
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