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Plate tectonics bs 1st year

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Awais Bakshy
Awais Bakshy

The document summarizes key concepts about tectonic plates and continental drift. It describes how tectonic plates consist of rigid continental and oceanic crust that moves due to convection currents in the underlying mantle. It outlines Alfred Wegener's early 20th century proposal of continental drift, which provided evidence that continents were once joined together before drifting apart. It also summarizes the three main types of plate boundaries: divergent boundaries where plates move apart, convergent boundaries where they move together, and transform boundaries where they slide past one another.

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Plate tectonics bs 1st year
A tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.
Plates are made of rigid lithosphere. The lithosphere is made up of the crust and the upper part of the mantle.
Below the lithosphere (which makes up the tectonic plates) is the asthenosphere.
 “Plates” of lithosphere are moved around by the underlying hot mantle convection cells
Plate tectonics bs 1st year
Proposed in 1911 All evidence found on the continents Mechanism for moving the continents was not known
 Alfred Wegener proposed the hypothesis of continental drift in 1911  He gathered information from many different sources and used it as evidence for his hypothesis
Fit of the continents Fossil evidence Ancient mountain ranges Past climate evidence Glaciers formed at the south pole
 The continental drift hypothesis proposes that the continents were assembled to form the super continent Pangaea.  Moved through time 3:20
 Antonio Snider-Pelligrini (1858), a geographer cut out a map of Africa and South America suggesting they were connected at one time  Other physical evidence based on observation was used by Wegener
 Similar terrestrial species were found on many continents now separated by oceans.  Information collected by paleontologists
The same sequence of rocks is found in North America, Great Brittan, and Norway. The pattern does not make sense with the continents in their current configuration.
Swamps 300 million years ago
•Glaciers carve the rock as they move. •Scientists can determine the direction of movement (notice the direction of movement noted in South America) •As South America sits today, the pattern would not make sense. (glaciers do not move from sea level to higher elevations)
Plate tectonics bs 1st year
Divergent Three types of plate boundary Convergent Transform
Continuing divergence • Widening sea • Mid-oceanic ridge system • New crust formed at mid-oceanic ridge
During break up of a continent • Rifting, basaltic eruptions (Flood Basalts), uplifting • Shallow focus earthquakes Continental crust separates • Oceanic crust created
Plate tectonics bs 1st year
Plate tectonics bs 1st year
Plate tectonics bs 1st year
Plate tectonics bs 1st year
Plates move toward each other One plate overrides the other • Subduction zone
Plate tectonics bs 1st year
 Oceanic-Oceanic Convergence • Oceanic trench  curved convex to subducting plate • Benioff zone (Dipping 200-900; average 450) • Magma generated at depth  Andesitic volcanism  Batholith emplacement • Island arc • Accretionary wedge forms (formed from sediments that are accreted onto the non- subducting tectonic plate at a convergent plate boundary) • Trench migration in time
Subducting Plate
Plate tectonics bs 1st year
Oceanic-Continental Convergence • Active continental margin  Subduction of oceanic lithosphere beneath continental lithosphere • Magmatic arc- volcanoes & plutons • Crustal thickening and mountain belts • Regional metamorphism • Thrust faulting & folding on continental side
Plate tectonics bs 1st year
Continental-Continental convergence • Two continents approach each other and collide  Sea floor subducted on one side  Ocean becomes narrower and narrower • Crust thickened  Thrust belts • Mountain belt in interior of continent
Plate tectonics bs 1st year
Boundary between two plates that are sliding past each other EARTHQUAKES along faults
San Andreas Fault, CA
Plate tectonics bs 1st year

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Plate tectonics bs 1st year

  • 2. A tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.
  • 3. Plates are made of rigid lithosphere. The lithosphere is made up of the crust and the upper part of the mantle.
  • 4. Below the lithosphere (which makes up the tectonic plates) is the asthenosphere.
  • 5.  “Plates” of lithosphere are moved around by the underlying hot mantle convection cells
  • 7. Proposed in 1911 All evidence found on the continents Mechanism for moving the continents was not known
  • 8.  Alfred Wegener proposed the hypothesis of continental drift in 1911  He gathered information from many different sources and used it as evidence for his hypothesis
  • 9. Fit of the continents Fossil evidence Ancient mountain ranges Past climate evidence Glaciers formed at the south pole
  • 10.  The continental drift hypothesis proposes that the continents were assembled to form the super continent Pangaea.  Moved through time 3:20
  • 11.  Antonio Snider-Pelligrini (1858), a geographer cut out a map of Africa and South America suggesting they were connected at one time  Other physical evidence based on observation was used by Wegener
  • 12.  Similar terrestrial species were found on many continents now separated by oceans.  Information collected by paleontologists
  • 13. The same sequence of rocks is found in North America, Great Brittan, and Norway. The pattern does not make sense with the continents in their current configuration.
  • 15. •Glaciers carve the rock as they move. •Scientists can determine the direction of movement (notice the direction of movement noted in South America) •As South America sits today, the pattern would not make sense. (glaciers do not move from sea level to higher elevations)
  • 17. Divergent Three types of plate boundary Convergent Transform
  • 18. Continuing divergence • Widening sea • Mid-oceanic ridge system • New crust formed at mid-oceanic ridge
  • 19. During break up of a continent • Rifting, basaltic eruptions (Flood Basalts), uplifting • Shallow focus earthquakes Continental crust separates • Oceanic crust created
  • 24. Plates move toward each other One plate overrides the other • Subduction zone
  • 26.  Oceanic-Oceanic Convergence • Oceanic trench  curved convex to subducting plate • Benioff zone (Dipping 200-900; average 450) • Magma generated at depth  Andesitic volcanism  Batholith emplacement • Island arc • Accretionary wedge forms (formed from sediments that are accreted onto the non- subducting tectonic plate at a convergent plate boundary) • Trench migration in time
  • 29. Oceanic-Continental Convergence • Active continental margin  Subduction of oceanic lithosphere beneath continental lithosphere • Magmatic arc- volcanoes & plutons • Crustal thickening and mountain belts • Regional metamorphism • Thrust faulting & folding on continental side
  • 31. Continental-Continental convergence • Two continents approach each other and collide  Sea floor subducted on one side  Ocean becomes narrower and narrower • Crust thickened  Thrust belts • Mountain belt in interior of continent
  • 33. Boundary between two plates that are sliding past each other EARTHQUAKES along faults