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