Understanding the Sea Floor: Origins, Features, and Study Methods
This comprehensive overview delves into the origins of the ocean floor, impacted by water vapor from early Earth degassing and volcanic activity. It explores methods of studying the sea floor, including rock dredging, coring, and deep-sea drilling. Key features such as continental margins, oceanic trenches, and mid-ocean ridges are examined, alongside sediment types and their deposition processes. The dynamic processes of fringing reefs, abyssal plains, and the geology of hydrothermal systems are discussed, providing insight into the profound influences shaping our oceanic landscapes.
Understanding the Sea Floor: Origins, Features, and Study Methods
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Presentation Transcript
Origin of the Ocean • Water vapor released during degassing of early earth • volcanism • Salt from chemical weathering
Methods of Studying the Sea Floor • Rock Dredge • Corer • Sea-Floor Drilling • Submersibles • Echo Sounder • Seismic Profiler • Surveys - Magnetic, Gravity, Seismic Refraction • Deep Sea Cameras
Features of the Sea Floor • Continental Margins • Passive • Active • Oceanic trench • Mid-oceanic ridge • Seamounts
Continental Shelves and Continental Slopes • Vertical exaggeration in diagrams • Continental shelf • Continental slope • Continental rise
Active Continental Margins • On land- earthquakes, young mountain belt, volcanoes • Continental shelf, continental slope, oceanic trench • Oceanic Trenches • Earthquakes of the Benioff seismic Zones • Volcanoes • Low Heat Flow • Negative Gravity Anomalies
Submarine Canyons • Abyssal Fans • Bottom Currents • Down-canyon movement of sand • Bottom currents • River erosion • Turbidity Currents • Graded bedding • Shallow water fossils
Passive Continental Margins • Continental shelf, slope, rise • The Continental Rise • Types of Deposition • From turbidity currents • From contour currents • Abyssal plains
Fracture Zones • Offset rift valleys • Transform Fault • Portion that has earthquakes
Seamounts, Guyots, and Aseismic Ridges • Seamounts • Guyots • Aseismic ridges
Reefs • Fringing Reefs • Barrier Reefs • Atolls
Sediments of the Sea Floor • Terrigenous Sediment • Pelagic Sediment • thickness increases away from crest of mid-oceanic ridge
Deep-sea sediments, those found at depths greater than about 500 m, cover roughly two-thirds of the Earth. The predominant deep sediment is carbonate ooze, which covers nearly half the ocean floor
The Mid-Oceanic Ridge • Rift Valley • Geologic Activity on the Ridge • Shallow-focus Earthquakes • High Heat Flow • Basalt Eruptions • Hot springs • Black Smokers • Biologic Activity on the Ridge • Geomicrobiology
Oceanic Crust and Ophiolites • Evidence for composition of the oceanic crust • Ophiolite (from top to bottom) • Marine sedimentary rock • Pillow basalt • Sheeted dike complex • Gabbroic intrusions • Ultramafic rock
The Age of the Sea Floor • Younger than 200 million years old • Parts of continents much older
