Components Of The Lithosphere

Topics: Plate tectonics, Earth, Lithosphere Pages: 13 (2881 words) Published: April 24, 2015

Components of the Lithosphere
-Rigid Outer Layer
-Crust and upper mantle
-tectonic plates
Theory of Plate Tectonics
-Theory that Earth's surface is composed of large, thick plates that move and change in size

-Combined hypotheses of continental drift and seafloor spreading, plus new observations using geophysics superconinents
Pangea: super continent

-Godwana: (Permian), southern super continent, south America, Australia, new guinea

Lavrasia: northern super continent
Types of Plate Boundaries
Divergent(constructive)

Convergent(destructive)

Transform(conservative)
Preservation:
-Permineralization: petrified wood
-Minerals and cast: impression in material filled in by another -Carbonization and empression: when carbon film is lost
-Amber: harder resin of ancient trees
Divergent Boundary
-Tension creates rifting
-Creates new ocean basins
-Uplift due to hot, rising, less dense magma
-Shallow earthquakes
-Grabens= normal faulting
Paleontology
study of fossils
Transform Boundaries
-two plates slide past each other
-Offset along other types of plate boundaries
-Shear motion along faults
-May occur as a single fault, or groups of parallel faults
Convergent Boundaries
-two plates coming together
-One subducts and is damages
-Oceanic plate is older, colder, denser, gets subducted
-Characteristics depend on collision type
              -Ocean-ocean   
              -Continent-continent
              -Ocean continent           
Ocean Ocean Convergence
-subduction causes a benioff zone
-creates a deep broad trench
-Accretionary Wedging: marine sediments are scraped off
-Partial melting of the asthenosphere(due to flux melting)
Magma forms an island arc
Continent-Continent
-Oceanic crust is first subducted until ocean closes
-Neither plate wants to subduct(least buoyant does)
-Forms Suture zone plate boundary(in middle)
-Crust is greatly thickened, creates a large mountain belt and shallow focus earthquakes -Continental collision, mountain belts, thrust faults, and detached subducting plates involved Ocean- Continent convergence

-Oceanic plate subducts below less dense cont. crust creating a benioff zone -magma forms and creates magmatic arcs of andesitic volcanoes -Inc. heat causes metamorphism
-Isostatic uplift of Cont. Crust
-Subsidence creates an inland basin
-***Same features as ocean-ocean except volcanoes are built on continental crust, and sometimes backarc thrust belts can form Benioff zone
Tilted zone of earthquakes associated with subduction zones
Ocean-Continent Convergence Continued
Volcanoes(magmatic arc): more silicic form addition of continental material, batholiths form at depth

-Backarc thrust belt: thrust faults form behind arc in response to convergence, cause stickiness between plates Thrust Fault

Internal Forces in the earth that drive plate tectonics/What causes Plate motion -Ridge Push: sliding of lithosphere away from ridge crest, GRAVITY DRIVEN FORCE THAT RESULTS FROM THE ELEVATED POSITION OF THE RIDGE  -Slab pull: Subducting cold, dense, oceanic lithosphere pulls the plate away from ridge crest, MAJOR DRIVING FORCE OF PLATE MOTION, mantle drag and friction resist subduction -Trench Suction: steep subduction can cause overlying plate to be pulled horizontally

Driving Forces of Plate Motion COnt.
-Mantle Convection is the most likely candidate, but it could be either the cause of effect of ridge push and slab pull

-Convection in the mantle enhances plate motion when the velocity of the asthenosphere exceeds that of the overlying plate Paleomagnetism
-Study of earth's magnetic pull over time
-reconstruct paleomagnetic poles form the alignment of magnetic minerals in rocks -When magnetite containing basaltic rocks cool below the curie point, the magnetite aligns toward the position of the north pole -The magnetite is frozen in position and indicates the position of the north pole at the time of solidification Magnetic reversal...
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