Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Anoxic event wikipedia , lookup
Physical oceanography wikipedia , lookup
Deep sea community wikipedia , lookup
Arctic Ocean wikipedia , lookup
Large igneous province wikipedia , lookup
Marine habitats wikipedia , lookup
Geological history of Earth wikipedia , lookup
Plate tectonics wikipedia , lookup
Hotspot Ecosystem Research and Man's Impact On European Seas wikipedia , lookup
The Sea Floor GLG 101 - Physical Geology Bob Leighty These notes and web links are your primary “lecture” content in this class. Additionally, various articles are assigned each week to supplement this “lecture” information. I believe you’ll have enough information to reference without having to purchase a costly textbook. These lecture notes are very similar to the ones I use in my traditional classes. You’ll find they are loaded with imagery and streamlined text that highlight the most essential terms and concepts. The notes provide a framework for learning and, by themselves, are not meant to be a comprehensive source of information. To take advantage of the global knowledge base known as the Internet, I have included numerous hyperlinks to external web sites (like the Wikipedia, USGS, NASA, etc.). Follow the links and scan them for relevant info. The information from linked web sites is meant to supplement and reinforce the lecture notes – you won’t be responsible for knowing everything contained in them. As a distance learning student, you need to explore and understand the content more independently than in a traditional class. As always, I will help guide you through this learning adventure. Remember, email Dr. Bob if you have any questions about today’s lecture ([email protected]). Leave no questions behind! Explore and have fun! Sea Floor The Sea Floor Much of Earth’s surface is underlain by oceanic crust Oceans include >97% of all water on Earth Earth's early history - volcanic “outgassing” & asteroids/comets Sea Floor Mapping Mapped mainly by sonar & satellite radar since WWII Sea Floor Oceanic Sediment Derived from land (terrigenous) – mud & sand Derived from critters (biogenic) – chert & limestone Sea Floor Continental Margins Passive Minimal tectonism; no oceanic trench or volcanic arc Example - east coast of N & S America, west coast of Africa Sea Floor Continental Margins Passive Continental Shelf Shallow water (<135 m deep); affected by waves Gently-sloping; underlain by continental crust Sea Floor Continental Margins Passive Continental Shelf Sea Floor Continental Margins Passive Continental Slope Deeper water (>135 m); not affected by waves Steeper than the shelf; submarine canyons Sea Floor Continental Margins Passive Continental Rise Very deep water; grades into the abyssal plain of the deep ocean Gently-sloping; underlain by oceanic crust Sea Floor Continental Margins Active Lots of tectonism; develop at subduction zones Example - west coast of N & S America Sea Floor Continental Margins Turbidity Currents Dense, “muddy” underwater currents Sea Floor Deep Ocean Basins Abyssal Plains Deep ocean (avg ~5000 m) Flattest places on Earth (deep-sea sediment covers & subdues topography) Sea Floor Deep Ocean Basins Oceanic trenches Deepest parts of the ocean (some >10,000 m) Develop at subduction zones, parallel to volcanic arcs Sea Floor Deep Ocean Basins “Hot spots” Volcanic mountains that form above mantle plumes Example: Hawaiian Island-Emperor Seamount chain Sea Floor Deep Ocean Basins Seamounts Isolated volcanic peaks that may rise above sea level Guyots = old, high seamounts eroded flat Sea Floor Deep Ocean Basins Coral Reefs & Atolls Organisms typically prefer warm, clear, shallow water Sea Floor Deep Ocean Basins Mid-ocean Ridges Divergent plate boundaries (spreading centers) Sea Floor Deep Ocean Basins Mid-ocean Ridges Total >70,000 km long! Sea Floor Deep Ocean Basins Mid-ocean Ridges Rise 2-3 km above ocean basins Sea Floor Deep Ocean Basins Mid-ocean Ridges Mostly mafic rocks (basalt & gabbro); pillow lavas Normal faults & transform faults Sea Floor Deep Ocean Basins Mid-ocean Ridges Black smokers & “weird” critters Tube worms Black smokers Sea Floor WWW Links in this Lecture > Oceanic crust - http://en.wikipedia.org/wiki/Oceanic_crust > Oceanic trench - http://en.wikipedia.org/wiki/Oceanic_trench > Volcanic arc - http://en.wikipedia.org/wiki/Volcanic_arc > Continental crust - http://en.wikipedia.org/wiki/Continental_crust > Continental shelf - http://en.wikipedia.org/wiki/Continental_shelf > Submarine canyon - http://en.wikipedia.org/wiki/Submarine_canyon > Shelf-slope break - http://en.wikipedia.org/wiki/Continental_shelf#Continental_shelf_break.2C_slope.2C_and_rise > Abyssal plain - http://en.wikipedia.org/wiki/Abyssal_plain > Subduction zone - http://en.wikipedia.org/wiki/Subduction > Hot spot - http://en.wikipedia.org/wiki/Hotspot_%28geology%29 > Mantle plume - http://en.wikipedia.org/wiki/Mantle_plume > Hawaii-Emperor seamount chain - http://en.wikipedia.org/wiki/Hawaiian-Emperor_seamount_chain > Seamount - http://en.wikipedia.org/wiki/Seamount > Guyout - http://en.wikipedia.org/wiki/Guyot > Atoll - http://en.wikipedia.org/wiki/Atolls > Mid-ocean ridges - http://en.wikipedia.org/wiki/Mid-ocean_ridges > Pillow lava - http://en.wikipedia.org/wiki/Pillow_lava#Pillow_lava > Black smoker - http://en.wikipedia.org/wiki/Black_smokers