Creation, Aging and Recycling of the Ocean Floor How is the ocean floor made?. Why does the ocean floor get deeper with age?. Formation of Ocean Lithosphere... Formation of Ocean Lithosp
Trang 1Creation, Aging and Recycling
of the Ocean Floor
How is the ocean floor made?
Why does the ocean floor get deeper with age? How are volcanic arcs made and why are they
so dangerous?
Trang 2Formation of Ocean Lithosphere
Trang 3Formation of Ocean Lithosphere
Mid-ocean ridges
global circuit of plate divergence youngest ocean floor
shallowest ocean floor
Architecture of oceanic plates
seismic profiling
ocean drilling
fossil slivers of ocean floor
Trang 4Seismic Profiling (sound energy)
Trang 5Ocean Drilling
International program
(20 nations; began 1968) 2-month cruises
Deepest hole: 2 km
But, new vessel will drill
to >6km!
Trang 6Fast vs Slow Spreading
Fast Spreading Ridge (10-20 cm/yr)
Slow Spreading Ridge (1-5 cm/yr)
Trang 8Ocean Crust Layering
Trang 11Mineralized Volcanic
Breccia (1027-1029 mbsf)
Trang 12Sea floor deepens with distance from the spreading ridges why?
Trang 13Plate Aging involves heat loss through Conductive Cooling
Relation: Depth increases with the
square root of age
Trang 14A New View on Plate Cooling
Adam & Vidal, Science , April 2, 2010
Trang 15And, heat loss through
Hydrothermal Circulation
Trang 16Hydrothermal Circulation
Trang 17Hydrothermal Circulation
hot rock and seawater
Trang 18Hydrothermal Vent Sites
Trang 19Hydrothermal Vents Video
Trang 20The ocean floor ages and accumulates sediments
Trang 21Plate Aging and Recycling
Slab sinking denser than
asthenosphere
Trang 22Plate Subduction and Melting
Trang 23Pacific NW
Trang 25Krakatoa (1883) Tambora (1815)
Trang 26- May have reduced human population to <5000!
Trang 27Mt Hood
Trang 28Broken Top
Trang 29Three Sisters
Trang 30Crater Lake (Mt Mazama)
Trang 31Volcanic ash (tephra)