Plate Tectonics
Plate Tectonics
Margin Types
Divergent Margins : Spreading Centers Tension - New
Oceanic Crust
Convergent Margins : Compression
Ocean/Ocean
Ocean/Continent
Continent
Transform : Shear - lithosphere neither created
nor distroyed
Historical Perspective
Wegner -- Continental Drift
Pangea -- Beginning of the Jurassic
Laurasia and Gondwanaland
Evidence strongest for the southern
hemisphere continents
Divergent Margins
Tensile Stresses
Shallow Earthquakes
Grabens and Horsts
Oceanic Lithosphere - basalts and gabbros
Magnetic "stripes"
Ophiolites
Convergent Margins
Shallow, intermediate, and deep focus earthquakes
high heat flows, active continental margins
molasse deposits
turbedites
Mechanisms -- Driving Forces
Variations in margin types
Mechanisms
Hot Spots