Reading Material (see website for course)Who Cares?Ocean BasinsSlide 4Earth’s SurfacePlate Tectonics – mechanism that moves crustSlide 7Slide 8Slide 9Slide 10BathymetrySub-Environments on Continental MarginsSlide 13Slide 14Slide 15Central California area of Monterey CanyonMonterey CanyonSlide 18Slide 19Slide 20Slide 21Slide 22Continental MarginsSlide 24Slide 25Slide 26Materials filling ocean basinsClassification of marine sedimentsSlide 29Slide 30Slide 31Reading Material(see website for course)“Ocean Basins”, from “Oceanography”M.G. Gross, Prentice-HallWho Cares?Indonesia earthquake landslide tsunamiNew Orleans, hurricane wind storm surgeGalvestonOil & GasMinerals (metals, fertilizer)Sand and Gravel for concreteFate of contaminated sedimentsHarbor siltationBeach erosionSea-level riseCarbon burial, greenhouse gases, global warmingHistory of Earth recorded by marine sedimentary depositsOcean BasinsWhat creates the Earth’s surface?What is the shape of the surface below sea level (the seafloor)?What types of sediment are burying the seafloor?Hypsographic CurveEarth’s SurfaceHypsographic Diagram30% land10% continental margins (boundary)60% deep seaTwo distinct levels for Earth surface0-1000 m above sea level4000-5000 m below sea levelThese represent two distinct types of crust (Earth’s rigid upper layer)continental crust – thick, granite, not so denseoceanic crust – thin, basalt, denserPlate Tectonics – mechanism that moves crustPlatesseparate pieces of crustmove due to convection of heat in underlying layer (Mantle)plates can move in different directions, and collideCollisionsa) two continental plates collide, form high mountain rangese.g., Himalayasb) two ocean plates collide, form island arc and submarine trenche.g., Aleutian Islands, Aleutian Trenchc) ocean and continental plates collide, form mountains and trenche.g., Andes and Peru-Chile TrenchSubductionoccurs when ocean crust carried down into Mantle (e.g., b and c above)basalt and sediment heated to form volcanic magmaOpening of new ocean and formation of mid-ocean ridgePlate Tectonics – mechanism that moves crustPlatesseparate pieces of crustmove due to convection of heat in underlying layer (Mantle)plates can move in different directions, and collideCollisionsa) two continental plates collide, form high mountain rangese.g., Himalayasb) two ocean plates collide, form island arc and submarine trenche.g., Aleutian Islands, Aleutian Trenchc) ocean and continental plates collide, form mountains and trenche.g., Andes and Peru-Chile TrenchSubductionoccurs when ocean crust carried down into Mantle (e.g., b and c above)basalt and sediment heated to form volcanic magmaBathymetryMid-Ocean Ridges (underwater mountain ranges)water depth – 2000-4000 mcan be less – where islands occur (e.g., Iceland)volcanic eruptions create new ocean crusthot basalt, thermal expansion creates elevationmoves away from ridge axis in both directionsAbyssal basinswater depth – 4000-6000 m (only trenches are deeper)abyssal hills, include rough relief from volcanic formationabyssal plains, smooth surface due to burial by sedimentContinental marginscreated by sediment from land that builds into ocean basinsSub-Environments on Continental MarginsContinental shelfsmooth, gently dipping (less than 0.1 degrees)land surface during lowstand of sea levelglacial ice melted and flooded portion of continentContinental slopesteep (more than 4 degrees), rough topographyedge of continental crustsubmarine canyons, larger than canyons on landnot eroded by rivers directly (too deep), but by slurry of sedimentContinental risemore gentle gradient and reliefsediment from land piled on ocean crustTrenches (collision of plates, deepest places in ocean)Abyssal plains (sediment from land buries abyssal hills)Trailing-Edge MarginSub-Environments on Continental MarginsContinental shelfsmooth, gently dipping (less than 0.1 degrees)land surface during lowstand of sea levelglacial ice melted and flooded portion of continentContinental slopesteep (more than 4 degrees), rough topographyedge of continental crustsubmarine canyons, larger than canyons on landnot eroded by rivers directly (too deep), but by slurry of sedimentContinental risemore gentle gradient and reliefsediment from land piled on ocean crustTrenches (collision of plates, deepest places in ocean)Abyssal plains (sediment from land buries abyssal hills)Trailing-Edge MarginCentral California area of Monterey CanyonMonterey CanyonSub-Environments on Continental MarginsContinental shelfsmooth, gently dipping (less than 0.1 degrees)land surface during lowstand of sea levelglacial ice melted and flooded portion of continentContinental slopesteep (more than 4 degrees), rough topographyedge of continental crustsubmarine canyons, larger than canyons on landnot eroded by rivers directly (too deep), but by slurry of sedimentContinental risemore gentle gradient and reliefsediment from land piled on ocean crustTrenches (collision of plates, deepest places in ocean)Abyssal plains (sediment from land buries abyssal hills)Trailing-Edge MarginFormation of Submarine FanSediments accumulate at base of canyon, on oceanic crustContinental MarginsTwo types:Trailing-edge marginscontinental and oceanic plates move in same direction at same speedexamples – margins around Atlantic Oceancontain: coastal plain (was continental shelf during higher sea level)broad continental shelfcontinental slope and riseCollision marginscontinental and oceanic plates move toward each otherexamples – margins around Pacific Oceancontain: coastal mountain range, volcanoes, earthquakesnarrow, steep continental shelfcontinental slope and submarine trenchTrailing-Edge MarginContinental MarginsTwo types:Trailing-edge marginscontinental and oceanic plates move in same direction at same speedexamples – margins around Atlantic Oceancontain: coastal plain (was continental shelf during higher sea level)broad continental shelfcontinental slope and riseCollision marginscontinental and oceanic plates move toward each otherexamples – margins around Pacific Oceancontain: coastal mountain range, volcanoes, earthquakesnarrow, steep continental shelfcontinental slope and submarine trenchCollision MarginMaterials filling ocean basinsDissolved chemicalsespecially from rivers and mid-ocean ridges (volcanic eruptions)some remain dissolved (e.g., producing salt water)some precipitate inorganically (e.g., producing Manganese
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