1 / 25

What Lies Beneath

What Lies Beneath. Pre Solar Nebula—4.6 Billion yrs ago. Protoplanetary Disk—50 million years later. Formation of the moon. Return of the Volatiles. Comets and Asteroids -lingering remnants of planetary formation. Oceans and Basalt. Oceans cover 71% of Earth’s surface

phoebe
Télécharger la présentation

What Lies Beneath

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What Lies Beneath

  2. Pre Solar Nebula—4.6 Billion yrs ago

  3. Protoplanetary Disk—50 million years later

  4. Formation of the moon

  5. Return of the Volatiles Comets and Asteroids -lingering remnants of planetary formation

  6. Oceans and Basalt • Oceans cover 71% of Earth’s surface • 5 km deep on average, up to 11 km in trench

  7. If the ocean floor is so deep, how do we study it?

  8. Sampling Methods • Collecting sediment/rock directly • Dredge • Large net dragged along ocean floor • Sediment Core • Weighty hollow pipe dropped to ocean floor—sediment sample • Drilling • Cylindrical cores of sediment/rock

  9. Remote Sensing • Remote “sampling” • Magnetometers • Instrument that measures a magnetic field • Magnetic stripes • Echo sounders • Sound signal from a ship—deeper stuff=longer time to return to ship

  10. Deep-sea Submersibles

  11. Features of the Ocean Floor

  12. Mid-Ocean Ridge System Continuous, submarine mtn chain 80,000 km long rising an average of 2- 3 km above the surrounding sea floor

  13. Rift valley Transform Faults

  14. How Oceans Form

  15. Life on the Seafloor? • Black smokers • Hot water dissolves materials as it passes through rock • Black color: fine- grained metals that precipitate in “cool” ocean water • 400°C sulfurous H2O • Chemosynthesis • Bacteria feed on H2S Hydrothermal vents at a mid-ocean ridge.

  16. Ocean Trenches, Island Arcs • Accreted Terranes • Do the continents grow?

  17. Seamounts and Guyots • Basaltic seafloor features • Seamount: Submarine mountain, ≥1 km above sea floor created by a hot spot • Guyot: a flat-topped seamount cut by waves

  18. Wh Atoll Is It Made Of? • Atoll: Circular coral reef forming a ring of islands around a lagoon • Lagoon: shallow, enclosed water basin • Living coral keep up with rate of sinking

  19. “Young” Oceans, Thin Sediments • Why aren’t the seafloors as old as the continents? • Structure of the ocean floor

  20. Passive Continental Margins • Contin. Shelf • Sedimentation and Isostasy • Contin. Slope • Thinner cont. crust • Contin. Rise • Apron of debris

  21. Carbonate Platforms • In warm areas lacking terrigenous sediment • Thriving reef- building organisms • Thick limestone beds accumulate

  22. Active Continental Margins • Note thickness of shelf • Why is it only this size?

More Related