Download Chapter 3.4 - 3.5 Marine Provinces

3.4 What features exist in the Deep-ocean
basins?
 Past the continental rise, begins the DEEP OCEAN
basin (floor).
ABYSSAL PLAINS
 ABYSSAL PLAINS are very flat due to deposited
sediments.
 The depth of the abyssal plains ranges from
4500 m to 6000 m. (or 4.5 km to 6 km)
 Any features on the abyssal plain are covered with
LAYERS of sediment that have been deposited
over MILLIONS of years.
Recall????? Hypsographic Curve?
 Approximately 24% of the ocean floor is between 4 – 5 km deep.
Deep Ocean Basin
ABYSSAL PLAINS
 Abyssal plains are more common on the ATLANTIC
sea floor due the PASSIVE continental margin.
 In the PACIFIC where there are ACTIVE
continental margins, abyssal plains are less common
due to deep TRENCHES that swallow up
SEDIMENT.
Abyssal hills covered in sediment
VOLCANIC PEAKS OF THE ABYSSAL PLAIN
 ABYSSAL HILLS rise less that 1000 m (1 km)
above the sea floor.
 Seamounts rise MORE that 1 km above the sea
floor, but are still under SEA LEVEL.
 Abyssal hills are the MOST ABUNDANT feature
on the planet.
VOLCANIC PEAKS OF THE ABYSSAL PLAIN
 Areas dominated by abyssal hills are called
ABYSSAL HILL PROVINCES.
 In the ATLANTIC ocean basin, abyssal hills are
LESS common because they are covered by layers
of sediment.
 The PACIFIC ocean has more than 20,000
volcanic peaks due to less SEDIMENTATION and
more VOLCANIC activity.
The picture to the left
shows the Pacific Ocean
basin with Hawaiian
Islands and surrounding
abyssal hills and
seamounts
The picture to the right
shows the Pacific Ocean
basin off the west coast
of S. American
Abyssal Hills vs. Seamounts
VOLCANIC PEAKS OF THE ABYSSAL PLAIN
 Ocean TRENCHES and volcanic arcs are
commonly found in areas where CONVERGENT
boundaries occur and are more common in the
PACIFIC.
 Trenches occur where SUBDUCTION occurs, two
plates converging.
VOLCANIC PEAKS OF THE ABYSSAL PLAIN
Volcanic arcs
 ISLAND ARC = Oceanic – OCEANIC convergence
(Recall…Aleutian Islands)
And the Marianas Islands/trench
VOLCANIC PEAKS OF THE ABYSSAL PLAIN
Volcanic arcs
 Continental Arc = Oceanic-CONTINENTAL
convergence. (Recall…Andes Mt of S. American)
PACIFIC RING OF FIRE
Volcanic The most active margins are located in the
PACIFIC RING of FIRE in the Pacific Ocean.
VOLCANIC PEAKS OF THE ABYSSAL PLAIN
 In the Atlantic, there are a few active margins,
PUERTO RICO Trench and the SOUTH SANDWICH
trench.
South Sandwich Trench & Islands
3.5 What features Exist in the MidOcean Ridges?
 Mid-ocean ridges are located in the MIDDLE of an ocean
basin.
 They are some of the LONGEST mountain ranges on
Earth.
 RIFT VALLEY is a v-shaped area in the center caused by
sea-floor spreading.
Mid-ocean Ridges
Ridge vs. Rise
 Oceanic ridges are STEEPER due
to SLOWER sea-floor spreading.
 Oceanic rises are LESS steep
areas of a ridge caused by
FASTER sea-floor spreading.
Volcanic Features
 Pillow LAVA or pillow BASALT, which are
underwater flows lava that cool QUICKLY in the
sea water.
Pillow Lava (click here)
Pillow lava eruption (click here)
Volcanic Features
 Hydrothermal Vents


HYDROTHERMAL vents are created when sea
water seeps into the crust, is SUPER-HEATED
and then ERUPTS back through the crust.
Dissolved minerals in the super-heated water
crystallize to form a VENT.
Types of Hydrothermal Vents
 The type of vent that forms is determined by the
TEMPERATURE of the water
 Warm Water Vents = below 30 oC (86 F)
 WHITE Smokers = 30 – 350 oC (662 F)
 BLACK Smokers = above 350 oC
Click Pic for video
Life around a vent.
What do you think????
What kind of organisms live around hydrothermal vents?
If there is no light, what organisms are the base of the food
chain?
How do “producers” of a hydrothermal vent make their food?
What kind of organisms live in the abyssal plain?
What kind of adaptations would an organism need to survive
in the deep ocean?
 Deep Sea Exploration