12_marine_SFspread_10_post

12_marine_SFspread_10_post - afloor Spreading: afloor...

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Unformatted text preview: afloor Spreading: afloor Spreading: 1 12. Marine Geology & Seafloor Spreading afloor Spreading: afloor Spreading: 2 Why this is important The topographic features of the ocean basins are prime evidence of plate tectonics. afloor Spreading: afloor Spreading: 3 Continental margins Portions of ocean floor extending from shoreline to landward edge of abyssal plain Fig. 4.3 Fig. 4.3 Continental shelf : broad, very gently sloping platform underlain by marine sediments (commonly very thick) overlying continental crust; may be exposed during periods of low sea level (e.g., ice ages) afloor Spreading: afloor Spreading: 4 Moving away from the shoreline: 1. Continental shelf : broad, very gently sloping platform underlain by marine sediments (commonly very thick) overlying continental crust; may be exposed during periods of low sea level (ice ages) 2. Continental slope : inclined at 2-4; marine sediments overlie thinner continental crust 3. Continental rise : more gently inclined region adjacent to the continental slope overlying very thin continental crust and/or oceanic crust Fig. 18.5 Fig. 18.5 Continental margins Rise afloor Spreading: afloor Spreading: 5 Trench : large depression, commonly partially filled with sediments, adjacent to many continental margins Continental margins Fig. 18.5b Fig. 18.5b afloor Spreading: afloor Spreading: 6 Ocean basins Abyssal plains : relatively flat parts of ocean floor (between continental margins and mid-ocean ridge system) Fig. 18.6c Fig. 18.6c Fig. 3.7b Fig. 3.7b afloor Spreading: afloor Spreading: 7 Mid-ocean ridge (spreading center) : large-scale, laterally continuous elevated feature, sometimes capped by an axial graben (depression), associated with basaltic pillow lavas, normal faults, and black smokers Map by: Marie Tharp & Bruce Heezen Ocean basins afloor Spreading: afloor Spreading: 8 Fig. 3.10 Fig. 3.10 Ocean basins Mid-ocean ridge : large-scale, laterally continuous, elevated feature, sometimes capped by an axial graben (depression) , associated with basaltic pillow lavas, normal faults , and black smokers Fig. 3.9 Fig. 3.9 afloor Spreading: afloor Spreading: 9 Fig. 4.10 Fig. 4.10 Videos Videos Photo: D.B. Foster Mid-ocean ridge : large-scale, laterally continuous, elevated feature, sometimes capped by an axial graben (depression), associated with basaltic pillow lavas, normal faults, and black smokers Ocean basins Black smokers : eruptions of hot water (undersea geysers) containing abundant dissolved minerals afloor Spreading: afloor Spreading: 10 10 Seamounts Seamounts : elevated features underlain by volcanic rock; not laterally continuous. : elevated features underlain by volcanic rock; not laterally continuous....
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This note was uploaded on 02/25/2012 for the course 460 100 taught by Professor Schlsche during the Spring '09 term at Rutgers.

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12_marine_SFspread_10_post - afloor Spreading: afloor...

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