Modul 11 - Plate Tectonics

7/27/2019 Modul 11 - Plate Tectonics

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ModulModul 1111

Plate TectonicsPlate Tectonics



PLATE TECTONICSPLATE TECTONICS

Continental driftContinental drift

The theory that the continents have moved inThe theory that the continents have moved in

relation to one another relation to one another

Plate tectonicsPlate tectonics

The theory of global dynamics in which theThe theory of global dynamics in which the

lithosphere is believed to be broken intolithosphere is believed to be broken intoindividual plates that move in response toindividual plates that move in response to

convection in the (upper) mantle. The margins of convection in the (upper) mantle. The margins of

the plates are sites of considerable geologicthe plates are sites of considerable geologic

activity.activity.



Crust Mantle Core (CMC)-sphere






D e p t h (

k m )

cold, rigid, brittle

hot, plastic

∆ = 3,3– 4,3 g/cm3

hot, high pressure,rigid, brittle

Liquid

45000 C

solid


rocks

ultrabasicigneous rocks

(MgO, SiO2)

Fe, Ni



Continental DriftContinental Drift

Antonio Snider Antonio Snider --PelligriniPelligrini’’ Map (1858)Map (1858)


http://slidepdf.com/reader/full/modul-11-plate-tectonics 7/31AlfredAlfred Wegener Wegener ’’ Map (1915)Map (1915)





Wegener Wegener ’’s Concept of Continental Drift and Orogenesiss Concept of Continental Drift and Orogenesis

Note:Note:Most geologists and geophysicists rejected Wegener Most geologists and geophysicists rejected Wegener ’’s ideass ideas

because they violated what was known about thebecause they violated what was known about the STRENGTHSTRENGTH

OF ROCKSOF ROCKS..

Also, centrifugal force (from EarthAlso, centrifugal force (from Earth’’s rotation) along with tidals rotation) along with tidal

forcesforces were deemed to bewere deemed to be TOO SMALLTOO SMALL to move the continents!to move the continents!



Evidence on ContinentEvidence on Continent

Continents FitContinents FitTogether Together

Best fit at 100 m below sea levelBest fit at 100 m below sea level

E id C ti t




Rocks andRocks andStructures Match UpStructures Match Up

E id C ti tE id C ti t








AppalachiansAppalachians

AppalachiansAppalachiansCaledonides

Mauritanides

Mountain Belts of Mountain Belts of the Same Agethe Same Age





Glacial FeaturesGlacial Features

Direction of ice flowDirection of ice flow

E id C ti tE idence on Continent




FossilsFossils

LystrosaurusLystrosaurus

GlossopterisGlossopteris

CynognathusCynognathus

MesosaurusMesosaurus

PermianPermian--PennsylvanianPennsylvanian

Early TriassicEarly Triassic

PermianPermian

E idence on ContinentEvidence on Continent




PaleoclimatePaleoclimateof of PangeaPangea

Evidence on SeafloorEvidence on Seafloor



Evidence on Seafloor Evidence on Seafloor

Seafloor Seafloor MorphologyMorphology





PaleomagnetismPaleomagnetism andand

seafloor spreadingseafloor spreading

Magnetic Time ScaleMagnetic Time Scale Magnetic Stripe Formation at Ridge CrestMagnetic Stripe Formation at Ridge Crest





PaleomagnetismPaleomagnetism andand

seafloor spreadingseafloor spreading





Seafloor Age MapSeafloor Age Map





Mantle Plume Hot Spot TracksMantle Plume Hot Spot Tracks

ReconstructionReconstruction



ReconstructionReconstruction





Directions of Motion and Plate Velocities Determined byDirections of Motion and Plate Velocities Determined by

Mantle Plume Hot Spot Tracks and AgeMantle Plume Hot Spot Tracks and Age--Dating of RocksDating of Rocks




Directions of Motion and Plate Velocities Determined by GPSDirections of Motion and Plate Velocities Determined by GPS

(Global Positioning System) Satellites(Global Positioning System) Satellites


Directions of Motion and Plate Velocities DeterminedDirections of Motion and Plate Velocities Determined

by GPS (Global Positioning System) Satellitesby GPS (Global Positioning System) Satellites





EarthEarth’’s Tectonic Platess Tectonic Plates

North American

South

American

Juan de

Fuca

Cocos

Pacific

Nazca

Antarctic Antarctic

Caribbean

Scotian

African

Eurasian

Arabian

Indo

Australian

Pacific

Philippine

North

American





What drivesWhat drives






Internal HeatInternal Heat





Divergent BoundaryDivergent Boundary

Results in the formation of Oceanic CrustResults in the formation of Oceanic Crust




Transform BoundaryTransform Boundary

Plate Tectonicsate ecto cs




ate ecto cs

Convergent Boundary:Convergent Boundary: SubductionSubduction

Results in the formation & growth of Continental CrustResults in the formation & growth of Continental Crust

and destruction of Oceanic Crustand destruction of Oceanic Crust

Melting

Produces

More

Felsic

Magma




Convergent Boundary: CollisionConvergent Boundary: Collision

Results in the growth of Continental CrustResults in the growth of Continental Crust



BASIC PLATE TECTONICSBASIC PLATE TECTONICS – – RevisedRevised

•• EarthEarth’’s lithosphere is broken into 12s lithosphere is broken into 12--2424rigid platesrigid plates

•• Plates move about 1Plates move about 1--10 cm/yr on the plastic10 cm/yr on the plastic

AsthenosphereAsthenosphere•• ““Geology happensGeology happens”” where the plateswhere the plates

interact with one another along Divergent,interact with one another along Divergent,

Transform,Transform, SubductionSubduction andand CollisionalCollisionalBoundariesBoundaries

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Modul 11 - Plate Tectonics