ESS105H1 Lecture 3: Plate Tectonics and Minerals
Document Summary
Unique physical properties of earth"s interior allow for tectonic plates to move above the mantle. Outermost skin of earth with variable thickness. Oceanic crust (~10km), ma c composition, average rock - basalt. Continental crust (~20-90 km), felsic composition, average rock - granite. Solid rock layer between crust and core. Below, rock is hot enough to ow (~100-150km) It convects: hot mantle rises, cold mantle sinks. Mantle composition = ultrama c rock called peridotite. The moho discontinuity is the lower boundary that separated the crust from the upper mantle. Marked by a change in the velocity of seismic p waves. Crust, mantle and core boundaries are de ned by chemical composition. Lithosphere = brittle portion of earth"s interior. Broken into plates which more in response to mantle convection. It does not take part in mantle convection. Asthenosphere = ductile portion of earth"s interior. De ned by seismic discontinuity indicating signi cant change in composition.
