Plate Tectonics and Earth’s Interior

Pangea

Distribution of Late Paleozoic Fossils

Conventional Wisdom: Animals Migrated Across Land Bridges

Late Paleozoic Glaciation

Distribution of Ancient Mountain Belts

Patterns Fit, But Is It Possible? Tremendous amount of energy needed to move continents around the globe Tremendous amount of energy needed to move continents around the globe Wegener proposed that centrifugal force on the spinning Earth pushed continents from the south pole to the equator Wegener proposed that centrifugal force on the spinning Earth pushed continents from the south pole to the equator Modeling/simulation indicated that this would be insufficientModeling/simulation indicated that this would be insufficient Wegener proposed that the moving continents plowed through the oceans like an icebreaker Wegener proposed that the moving continents plowed through the oceans like an icebreaker Experiments indicated that oceanic rock is stronger than continental rock, and so oceans would have cut through the continentsExperiments indicated that oceanic rock is stronger than continental rock, and so oceans would have cut through the continents Continental Drift was a Model without a Mechanism!

Bathymetry of the Ocean Floor

Volcanoes of the World

Volcanoes Correlate Globally with Deep Earthquakes

Benioff Zone of Seismicity

Plate Tectonic Model

Tectonic Plates

Seismic Waves

Seismic Wave Velocities

Seismic Wave Paths S-WavesP-Waves

Layers Within Earth

Convection Cells and Plate Movements

Plate Tectonic Model

Differentiation: Basalt Partial melting of peridotite will form basaltic magma Partial melting of peridotite will form basaltic magma Basaltic magmas are formed from melting mantle due to upwelling heat

Differentiation: Andesite Partial melting of basalt will form an andesitic or granitic magma Partial melting of basalt will form an andesitic or granitic magma Andesitic magmas are formed from melting oceanic crust Subducting plate releases water (a flux) into mantle Magma pools under crust and partially melts the oceanic crust

Differentiation: Granite Partial melting of andesite will form granitic magma Partial melting of andesite will form granitic magma Granitic magmas are formed from melting of continental crust Subducting plate releases water (a flux) into mantle Magma pools under crust and partially melts the continental crust

Sources of Heat for Metamorphism Heat from Earth’s interior Heat from Earth’s interior Geothermal gradient is the increase in temperature with depth Geothermal gradient is the increase in temperature with depth Typical continental geothermal gradient is °C/kmTypical continental geothermal gradient is °C/km Volcanically active areas have geothermal gradients of °C/kmVolcanically active areas have geothermal gradients of °C/km Oceanic trenches have geothermal gradients as low as 5-10°C/kmOceanic trenches have geothermal gradients as low as 5-10°C/km