Plate Tectonics
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Transcript of Plate Tectonics
Plate TectonicsPlate TectonicsEarth layersEarth layers
History of plate tectonicsHistory of plate tectonics
Plate movement and marginsPlate movement and marginsPassive margins, spreading margins, Passive margins, spreading margins, and the Ring of Fireand the Ring of Fire
Ocean floor topography and plate tectonicsOcean floor topography and plate tectonics
Ocean floor effects: horizontal and vertical zonationsOcean floor effects: horizontal and vertical zonationsLifeLifeCirculationCirculation
CrustCrust4-60km4-60km
MantleMantle2885km2885km
Outer coreOuter core2270km2270km
Inner coreInner core1216km1216km
LithosphereLithosphere100km100km
AsthenosphereAsthenosphere250km250km
Lower mantleLower mantle25502550
Outer CoreOuter CoreInner coreInner core
Layers of the EarthLayers of the Earth
Earth topographyEarth topography
Movement of Movement of ContinentsContinents
Old views: Geosyncline cycleOld views: Geosyncline cycleno continent movementno continent movement
Instead, continent growth through sediment accretionInstead, continent growth through sediment accretion
Movement of Movement of ContinentsContinents
Alfred Wegener: Plate Tectonics: 1912Alfred Wegener: Plate Tectonics: 1912Continents like “puzzle pieces”Continents like “puzzle pieces”Fossils on different continentsFossils on different continents
Carey and the Southern Hemisphere geologistsCarey and the Southern Hemisphere geologists
Movement of Movement of ContinentsContinents
Morey: CanadaMorey: CanadaHess: mantle convection and sea floor spreadingHess: mantle convection and sea floor spreadingContinental Drift: theoryContinental Drift: theory
Movement of Movement of ContinentsContinents
Vine and Matthews: tested Continental DriftVine and Matthews: tested Continental DriftMagnetic “stripes” Magnetic “stripes” Magnetic reversalsMagnetic reversalsSymmetrial Symmetrial
Theory of Plate tectonics accepted.Theory of Plate tectonics accepted.
IstostacyIstostacyDensity differencesDensity differences
Density: closeness of moleculesDensity: closeness of moleculesMass/volumeMass/volume
Istostacy: Crustal floatation on the mantleIstostacy: Crustal floatation on the mantleLike ice cube: Like ice cube:
part above the mantle surface part above the mantle surface part beneathpart beneath
““Root” balances “top”: floats in equilibriumRoot” balances “top”: floats in equilibrium
Ocean crust more dense, floats lowerOcean crust more dense, floats lower
Plate Movement: Cross Plate Movement: Cross SectionSection
Active MarginActive MarginDivergent Plate BoundariesDivergent Plate Boundaries
Crustal formation, spreadingCrustal formation, spreading
Mid-ocean ridgesMid-ocean ridgesmantle convection upwardmantle convection upwardvolcanismvolcanismnew crust madenew crust madeBegin in continentBegin in continent
Africa/South AmericaAfrica/South AmericaAfrican rift valleyAfrican rift valley
Volcanoes, earthquakesVolcanoes, earthquakes
African Rift Valley
Gondwana
RiftingRifting
Active MarginActive MarginConvergent Convergent
PlatePlate Boundaries Boundaries
Subduction: destructiveSubduction: destructive
Ocean - oceanOcean - oceanIsland arcIsland arcJapanJapan
Ocean-continentContinent-continent
Volcanoes, earthquakes, Volcanoes, earthquakes, trenchestrenches
Active MarginActive MarginConvergent Convergent
PlatePlate Boundaries Boundaries
Subduction: destructiveSubduction: destructive
Ocean - oceanContinent - oceanContinent - ocean
Volcanic arcVolcanic arcAndes, CascadesAndes, Cascades
Continent - continent
Volcanoes, earthquakes, trenchesVolcanoes, earthquakes, trenches
Active MarginActive MarginConvergent Convergent
PlatePlate Boundaries Boundaries
Subduction: destructiveSubduction: destructive
Ocean - oceanContinent - oceanContinent - continent: Continent - continent:
tall mountainstall mountainsTibetan plateauTibetan plateau
Volcanoes, earthquakes, trenchesVolcanoes, earthquakes, trenches
Neither Neither constructive constructive nor destructivenor destructive
Strike-slip,Strike-slip, shear: shear: 2 plates slide 2 plates slide San AndreasSan Andreas
Earthquakes Earthquakes no volcanoesno volcanoes
Active Margins: Transform Active Margins: Transform BoundariesBoundaries
Passive MarginsPassive Margins
Stable marginsStable margins
Development of wide Development of wide continental shelfcontinental shelf or or rampramp
East coast North AmericaEast coast North America
Mountains from previous Mountains from previous continent-continent collisionscontinent-continent collisions
Small earthquakes from ancient Small earthquakes from ancient faultsfaultsBut no effects from marginBut no effects from margin
Hot SpotsHot SpotsMantle plumes: “stationary” as Mantle plumes: “stationary” as plates move over themplates move over themRecord of plate movementRecord of plate movement
Land or oceanLand or oceanLand: YellowstoneLand: YellowstoneOcean: island formationOcean: island formation
HawaiiHawaii
Hot SpotsHot Spots
Superplumes in Cretaceous: Superplumes in Cretaceous: High rates of sea floor spreading:High rates of sea floor spreading:Ocean crust warm --> sea level much higherOcean crust warm --> sea level much higher
Sundance SeaSundance SeaCO2 into atmosphere: greenhouse effectCO2 into atmosphere: greenhouse effect
Ocean DepthsOcean Depths
Ocean DepthsOcean DepthsSupralittoral zone: “spray Supralittoral zone: “spray zone”: zone”: terrestrialterrestrialLittoral zone: tidal rangeLittoral zone: tidal rangeSublittoral zoneSublittoral zone
Inner sublittoral zone: 0-Inner sublittoral zone: 0-50m50m
Outer sublittoral Outer sublittoral zone:50-zone:50- 200m200mBathyal zone: 50m - 4kmBathyal zone: 50m - 4kmAbyssal zone: 4km - 6kmAbyssal zone: 4km - 6kmHadal zone: 6km + (deepest: Hadal zone: 6km + (deepest: Mariana Trench: 11km)Mariana Trench: 11km)
Provinces: shallowProvinces: shallowContinental shelfContinental shelf
Wide: passive margins; narrow: active marginsWide: passive margins; narrow: active marginsShelf break ~135m, but wide rangeShelf break ~135m, but wide range
Continental slope:Continental slope:Submarine canyonsSubmarine canyonsTurbidity currentsTurbidity currents
Continental Rise: Continental Rise: deep sea fansdeep sea fans
Provinces: DeepProvinces: DeepAbyssal plainAbyssal plain
>4km>4kmOcean ridges, topography on plainOcean ridges, topography on plainSeamounts, guyots: other volcanic activitySeamounts, guyots: other volcanic activityTrenches >6.7kmTrenches >6.7km
D L WJapan Trench 10.5 2200 120Mariana Trench 11.0 2550 70Philippine Trench 10.8 1400 55Aleutian Trench 7.7 3700 50Peru-Chile Trench 8.1 5900 100Puerto Rico Trench 8.4 1550 120Java Trench 7.5 4500 80
Horizontal zonation: Horizontal zonation: Geographic rangeGeographic rangeProximity to resourcesProximity to resourcesLatitude (Temperature)Latitude (Temperature)Circulation patternsCirculation patternsSalinitySalinity
Vertical zonation (water column)Vertical zonation (water column)ResourcesResourcesPressurePressureTemperatureTemperatureLightLight Water ChemistryWater Chemistry
Geographic range + vertical zonationGeographic range + vertical zonationResources, life history, habitat constraints determineResources, life history, habitat constraints determine
Life in the oceanLife in the ocean