2 & 3 plate tectonic, gerak dan sifat interaksi
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Transcript of 2 & 3 plate tectonic, gerak dan sifat interaksi
Modul 2Modul 2Plate TectonicsPlate Tectonics
THE NEW GLOBAL THE NEW GLOBAL TECTONICTECTONIC
PLATE TECTONICSPLATE TECTONICS
Continental driftContinental drift The theory that the continents have moved in The theory that the continents have moved in
relation to one anotherrelation to one another
Plate tectonicsPlate tectonics The theory of global dynamics in which the The theory of global dynamics in which the
lithosphere is believed to be broken into lithosphere is believed to be broken into individual plates that move in response to individual 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 geologic the plates are sites of considerable geologic activity.activity.
Crust Mantle Core (CMC)-sphere
Crust Mantle Core (CMC)-sphere
Dep
th (
km)
cold, rigid, brittle
hot, plastic
Δ = 3,3– 4,3 g/cm3
hot, high pressure,rigid, brittle
Liquid
45000 C
solid
rocks
ultrabasicigneous rocks
(MgO, SiO2)
Fe, Ni
Crust Mantle Core (CMC)-sphere
Plate Tectonic TheoryPlate Tectonic Theory
• Lithosphere is broken into individual pieces Lithosphere is broken into individual pieces called called platesplates
• Plates move over the asthenosphere Plates move over the asthenosphere – as a result of underlying as a result of underlying convection cellsconvection cells
Antonio Snider-Pelligrini’ Map (1858)Antonio Snider-Pelligrini’ Map (1858)
Continental DriftContinental Drift
Alfred Wegener’ Map (1915)Alfred Wegener’ Map (1915)
Continental DriftContinental Drift
Wegener’s Concept of Continental Drift and OrogenesisWegener’s Concept of Continental Drift and Orogenesis
Note:Note:Most geologists and geophysicists rejected Wegener’s ideasMost geologists and geophysicists rejected Wegener’s ideasbecause they violated what was known about the because they violated what was known about the STRENGTH STRENGTH OF ROCKSOF ROCKS..Also, centrifugal force (from Earth’s rotation) along with tidal Also, centrifugal force (from Earth’s rotation) along with tidal forcesforces were deemed to be were deemed to be TOO SMALLTOO SMALL to move the continents! to move the continents!
Continental DriftContinental Drift
Continents Fit Continents Fit TogetherTogether
Evidence on ContinentEvidence on Continent
Best fit at 100 m below sea levelBest fit at 100 m below sea level
Evidence on ContinentEvidence on Continent
Rocks andRocks andStructures Match UpStructures Match Up
Evidence on ContinentEvidence on Continent
AppalachiansAppalachians
AppalachiansAppalachiansCaledonides
Mauritanides
Mountain Belts ofMountain Belts ofthe Same Agethe Same Age
Evidence on ContinentEvidence on Continent
Evidence on ContinentEvidence on Continent
Glacial FeaturesGlacial Features
Direction of ice flowDirection of ice flow
Evidence on ContinentEvidence on Continent
FossilsFossils
LystrosaurusLystrosaurus
GlossopterisGlossopteris
CynognathusCynognathus
MesosaurusMesosaurus
Permian-PennsylvanianPermian-Pennsylvanian
Early TriassicEarly Triassic
PermianPermian
Evidence on ContinentEvidence on Continent
PaleoclimatePaleoclimateof Pangeaof Pangea
Evidence on SeafloorEvidence on Seafloor
Seafloor Seafloor MorphologyMorphology
Evidence on SeafloorEvidence on Seafloor
Paleomagnetism and Paleomagnetism and seafloor spreadingseafloor spreading
Magnetic Time ScaleMagnetic Time Scale Magnetic Stripe Formation at Ridge CrestMagnetic Stripe Formation at Ridge Crest
Evidence on SeafloorEvidence on Seafloor
Paleomagnetism and Paleomagnetism and seafloor spreadingseafloor spreading
Evidence on SeafloorEvidence on Seafloor
Seafloor Age MapSeafloor Age Map
Mantle Plume Hot Spot TracksMantle Plume Hot Spot Tracks
Evidence on SeafloorEvidence on Seafloor
ReconstructionReconstruction
MODUL 03
GERAK DAN SIFAT INTERAKSI
Directions of Motion and Plate Velocities Determined by Directions of Motion and Plate Velocities Determined by Mantle Plume Hot Spot Tracks and Age-Dating of Rocks Mantle Plume Hot Spot Tracks and Age-Dating of Rocks
Plate TectonicsPlate Tectonics
Directions of Motion and Plate Velocities Determined by GPS Directions of Motion and Plate Velocities Determined by GPS (Global Positioning System) Satellites(Global Positioning System) Satellites
Plate TectonicsPlate TectonicsDirections of Motion and Plate Velocities Determined Directions of Motion and Plate Velocities Determined
by GPS (Global Positioning System) Satellitesby GPS (Global Positioning System) Satellites
Earth’s Tectonic PlatesEarth’s Tectonic Plates
North American
South American
Juan de Fuca
Cocos
Pacific
Nazca
Antarctic Antarctic
Caribbean
Scotian
African
Eurasian
Arabian
IndoAustralian
Pacific
Philippine
North American
Plate TectonicsPlate Tectonics
Plate TectonicsPlate Tectonics
What drivesWhat drivesPlate Tectonics???Plate Tectonics???
What drives plate motions• Forces that drive plate
motion – Slab-pull
• Cold, dense slabs of subducted oceanic lithosphere pull the plate towards the subduction zone
– Ridge-push• The higher elevation of
spreading centers result in oceanic lithosphere wanting to move “downhill”, away from the ridge
• Far less important than slab-pull
– Mantle drag and plate resistance
• Can act to increase or decrease plate motion
Mantle convection providesthe primary drive forplate tectonics
What drives plate motions• Models of plate-mantle
convection • Any model must be consistent
with observed physical and chemical properties of the mantle
• Horizontal movement of plates causes mantle upwelling
• Models – Layering at 660 km– Explains why basalts
erupted at mid-ocean ridges are different (more evolved, relatively shallow source) compared to those erupted at hot-spots (more primitive, deeper source).
– We know that subducting slabs descend beneath 660 km
What drives plate motions• Whole-mantle convection
– Would mix the entire mantle in the space of a few hundred million years, removing heterogeneities
What drives plate motions• Deep-layer model
– “Lava lamp model”
– Two layers swell and shrink in a complex fashion in response to heat from the Earth’s interior
Internal HeatInternal Heat
Plate TectonicsPlate Tectonics
Arc-Trench systems 35
Arc-Trench systems 36
Trench roll-back
Arc-Trench systems 37
Types of arc-trench system
Results in the formation of Oceanic CrustResults in the formation of Oceanic Crust
Plate TectonicsPlate Tectonics
Divergent BoundaryDivergent Boundary
Transform BoundaryTransform Boundary
Plate TectonicsPlate Tectonics
Results in the formation & growth of Continental CrustResults in the formation & growth of Continental Crustand destruction of Oceanic Crustand destruction of Oceanic Crust
Melting Produces
More Felsic
Magma
Plate TectonicsPlate Tectonics
Convergent Boundary: SubductionConvergent Boundary: Subduction
Results in the growth of Continental CrustResults in the growth of Continental Crust
Convergent Boundary: CollisionConvergent Boundary: Collision
Plate TectonicsPlate Tectonics
BASIC PLATE TECTONICS – RevisedBASIC PLATE TECTONICS – Revised
• Earth’s lithosphere is broken into 12-24 Earth’s lithosphere is broken into 12-24 rigid platesrigid plates
• Plates move about 1-10 cm/yr on the plastic Plates move about 1-10 cm/yr on the plastic AsthenosphereAsthenosphere
• ““Geology happens” where the plates Geology happens” where the plates interact with one another along Divergent, interact with one another along Divergent, Transform, Subduction and Collisional Transform, Subduction and Collisional BoundariesBoundaries