GEO 1111 Lecture Notes - Lecture 10: Mantle Convection, Seafloor Spreading, Asthenosphere

• School: University of Ottawa
• Department: Geology
• Course: GEO 1111
• Professor: David Schneider

Document Summary

Theory of plate tectonics: composite of ideas that explain the observed motion of earth s lithosphere thru mechanisms of sea-floor spreading & subduction which generate continents & ocean basins. 1965 j. tuzo wilson: earth is composed of lithospheric plates that move on asthenosphere due to thermal convection in mantle, convection is circulation driven by rising hot material and/or sinking cooler material. 1962 harry hess proposed seafloor spreading: seafloor moves away from the mid-oceanic ridge due to mantle convection, hot mantle rock rises under mid-oceanic ridge. Plate tectonics: seafloor rocks & mantle rocks beneath them, cool and become more dense with distance from mid-oceanic ridge when sufficiently cool & dense, these rocks may sink back into the mantle at subduction zones. Transform / conservative margins plates slide horizontally past one another (shear) no igneous or metamorphic activity can mark offset of: two offset segments of mid-oceanic ridge, a mid-oceanic ridge and a trench, two trenches.