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Published byWilfred Whitehead Modified over 8 years ago
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Chapter 4: Marine Provinces
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Seismic profiling Fig. 4-4
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Hypsographic curve Average depth of ocean 3729 m Average height of continents 840 m Fig. 4-5
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Continental margins Shallow ocean close to land Underlain by continental crust Classified as passive or active
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Passive margins Not a plate boundary Not tectonically active Continental shelf Continental slope Continental rise
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Active margins At plate boundaries Tectonically active Classified by type of plate boundary
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Continental shelf Coast to shelf break (average depth 135m) Generally flat May be narrow or wide Average width 70 km Active margin narrower Passive margin wider
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Continental slope Extends from shelf break to deep ocean Gradient ranges from 1-25 o Average gradient 4 o Relief greater at active margin Submarine canyons Turbidity currents
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Fig. 4-9a
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Continental rise Transition between continental margin and deep ocean Sediments deposited by waning turbidity currents Not common convergent active margins Rise only exists where sediments can accumulate
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Deep ocean basin Underlain by oceanic crust Seaward of continental margin Abyssal plains very flat Fine-grained sediments deposited Volcanic seamounts, tablemounts, abyssal hills
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Mid-ocean ridge 75,000 km long Covers 23% of Earth’s surface Rift valley at crest Site of magma (pillow basalts) Hydrothermal vents Warm water White smokers Black smokers
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Fig. 4-17a
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Hot vent communities Chemosynthetic autotrophs Metal sulfide deposits
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Ocean ridge Steeper, rugged, prominent rift valley Ocean rise Gentler, less rugged, less well-defined rift valley Fracture zones Aseismic scars, extensions of transform faults
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End of Chapter 4: Marine Provinces
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