GEOSC 040 Lecture Notes - Lecture 25: Paleomagnetism, Oahu, Pacific Plate
Document Summary
Origins of ocean basin, plate tectonics, and sea floor spreading. Earth"s surface is in motion: evidence = continental drift. Earthquakes define the plate boundaries: 3 types. Changes with age and distance from the spreading center. With increasing distance from the ridge crest . Plates are youngest at the ridge crest. Using the paleomagnetic timescale, we can calculate long-term seafloor spreading rates. For typical spreading rate oceans will open about 12 inches in 4 years. Ocean depth varies systematically with distance from spreading ridge. Emperor seamount chain 70 ma near end. Hawaii is a stationary hotspot plume: delivers magma in the same spot over its history. We can use this to calculate the velocity of the pacific plate. Abyssal plains: flat expanses of sediment-covered seafloor, water depth generally 4-6 km, sea mounts and extinct volcanoes that extend up through the sediments.
