ESS105H1 Lecture Notes - Lecture 3: Mantle Convection, Continental Crust, Ultramafic Rock
Document Summary
The unique physical properties of the earth"s interior allow for tectonic plates to move above the mantle. The crust, mantle, and core boundaries are defined by chemical composition. The crust: oceanic (10km): mafic composition and avg rock type is basal/gabbro, continental crust (20-90km): felsic composition and avg rock type = granite. The mantle is a solid rock layer between the crust and the core: below ~100-150 km, the rock is hot enough to flow. It convects: hot mantle rises, cold mantle sinks: mantle composition = ultramafic rock called peridotite, the moho discontinuity is the lower boundary that separates the crust from the upper mantle. Marked by a change in the velocity of seismic p waves. Lithosphere = brittle portion of earth"s interior: behaves as a non-flowing, rigid material, comprises both crust and upper mantle, broken into plates which move in response to mantle convection. It does not take part in mantle convection.
