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Test #3
The Ocean Floor
27
Geology
Undergraduate 1
04/01/2014

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Term
Mapping the Sea Floor
Definition
1.Echo Sounding
2.Multibeam Systems
3.Seismic reflection profiles
4.Satellite Altimetry
Term
Satellite Altimetry
Definition
satellites measure variations in the elevation of the ocean surface which are caused by the gravitational pull of large underwater features
Term
Seismic reflection profiles
Definition
reveals rock structure beneath seafloor sediment
Term
Multibeam Systems
Definition
uses multiple sound beams to reveal a more complete picture of the bottom
Term
Echo Sounding
Definition
A pulse of sound is directed at the bottom and the reflection (echo) is detected. The time required for this can be correlated to distance.
Term
3 Major areas of the seafloor
Definition
1.Continental margins
2.Deep-ocean basins
3.Oceanic ridges
Term
Continental Margins
Definition
submerged edge of the continents
Term
Types of Continental Margins
Definition
1. Passive Continental Margins
2. Active Continental Margins
Term
Passive Continental Margins
Definition
not situated along an active plate boundary
Term
Active Continental Margins
Definition
situated along a (subduction zone type) convergent plate boundary
Term
Types of Passive Continental Margins
Definition
1.Continental shelf
2.Continental slope
3.Continental rise
Term
Types of Active Continental Margins
Definition
1.continental shelf narrow or nonexistent
2.deep-ocean trench forms between plates
3.accretionary wedge
Term
Continental shelf
Definition
is long and gently sloping (1 degree); thick layers of sediment;area of much ocean life.
Term
Continental Slope
Definition
(5-25 degrees); marks the edge of the continent
Term
Continental Rise
Definition
(1/3 of a degree); region of sediments deposited from continental shelf.
Term
Accretionary Wedge
Definition
rock and sediment are scraped from subducting plate and plastered to edge of
continent
Term
Deep-Ocean Basins
Definition
1. Trenches
2. Volcanic Island Archs
4. Abyssal Plains
5. Volcanic Peaks of the Abyssal Plains
6. Oceanic plateaus
Term
Trenches
Definition
1.deep arc-shaped troughs which form at subduction-type convergent plate boundaries
2.deepest places in the oceans
3.no continental rise because sediment is deposited in the trench
Term
Volcanic Island Archs
Definition
1.Curving line of volcanic islands
2.Parallel to trenches
3.Magma forms due to partial melting of mantle above subducting slab
Term
Abyssal Plains
Definition
1.Deep (4-6 km), flat regions of sediment-covered seafloor
2.Thick layer of fine sediment covering irregularities in underlying crust
3.Most occur in Atlantic and Indian Oceans (passive continental margins)
4.Fewer located in Pacific (active continental margins–trenches trap sediment from land)
Term
Volcanic Peaks of the Abyssal Plains
Definition
1.Seamounts
2.Guyots
Term
Guyots
Definition
1.flat-top.
2.Seamount high enough to rise above sea level and form an island.
3.Wave erosion flattened the top.
Term
Seamounts
Definition
1.higher than 1000m
2.pointy top.
3.Created above hot spots and along oceanic ridges
Term
Oceanic plateaus
Definition
thick flows of basaltic lava
Term
Oceanic Ridges
Definition
1.form along divergent plate boundaries
2.elevated due to hot,upward moving mantle
3.broken into ridge segments,offset by transform faults
4.tensional stress causes normal faulting
5.deep sea hydrothermal vents occur in some locations
Term
Continental Rifting
Definition
1.Birth of a new ocean basin
2.tensional stress causes normal faulting
3.young, narrow oce
an basin develops where rifting continue
Term
Destruction of Oceanic Lithosphere
Definition
1.subduction occurs at convergent plate boundaries where one or both plates have oceanic crust
2.occurs because overall density of lithosphere is greater than underlying mantle (asthenosphere)
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