Ocean Basins Flashcards
What were some of the problems with early forms of bathymetry?
Exact location of the ship wasn’t known
Temperature, pressure and density affect the readings
What is the modern approach to bathymetry?
Multi-beam systems scanning at once to get a clear picture by using multiple angles (ship)
Satillites
Why is the ocean not a flat surface?
The mass of the underwater mountains pulls more water to it, forming a dome of water that can only be seen in space over it
More mass means a stronger pull
What is the continental margin?
submerged outer edge of the continent that encompasses other parts (slope, shelf, etc)
What is the ocean basin?
deep sea floor beyond continental margin
What is the difference between active and passive margins?
passive: face edges of divergent plate boundaries
active: near edges of convergent and/or transform plate boundaries
What are continental shelves?
shallow submerged extension of continents, gentle slope
What is a continental slope?
transition zone between continental shelf and deep-ocean
floor
sediments that reach edge of shelf and are transported
over the side
What is the shelf break?
abrupt transition from continental shelf to continental slope
What are submarine canyons and what do they do?
cut into continental shelf and slope and deposit at sediment fan on deep-sea floor
turbidity currents flow through these and form them
What are turbidity currents?
mass movements of sediment due to slope instability
What is the continental rise?
oceanic crust at base of continental slope is covered by accumulated sediment
what makes up a continental margin in order from shallowest to deepest?
continental shelf, continental slope, continental rise
oceanic ridges are ____ when more active and ___ when less active
wider, steeper
What do transform vaults do?
Connect oceanic ridges when they move
What are hydrothermal vents?
hot springs on active ridges (rocky chimneys (some are black smokers))
How do hydrothermal vents work?
water descends through fissures in sea floor and
comes into contact with hot rocks associated with seafloor
spreading
superheated chemically-active water dissolves
minerals and gases
escape through vents by convection
What are abyssal plains?
flat, featureless expanses of sediment-covered ocean floor found on the periphery of all oceans
What are abyssal hills?
sediment-covered extinct volcanoes
What are island arcs?
long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries
form on overriding side of trench
japan
What 3 things happen to melt rock?
decrease in pressure
addition of volatiles (flux melting (decrease melting temperature)
heat transfer from magma
