The Lithosphere of Earth Igneous Processes and Volcanic Activity

1. Why study?• Thermal state• Thermal history• Composition of interior• Geothermal / Hazards• Comparative planetology

2. Volcanism and plate boundaries• Divergent

- Continental breakup (Flood basalts)- Mid-ocean ridge

• Convergent- Domes, flows, explosive, composite volcanoes

• Intraplate Volcanism- Strombolian style- Hawaiian style

The Lithosphere of Earth - Volcanism

Strombolian

Hawaiian Plinian

Volcanic Styles

Strombolian Activity

Hawaiian Activity

Plinian Activity

Dome Growth

Spatter Cone

Bubble Rise Rate > Magma Rise Rate

Cinder Cone

Magma Rise Rate > Gas Rise Rate

Produces turbulent, buoyant cloud,

Rises to great heights

Atmosphere sucked in, heated

Exit velocity high

Low viscosity gas-clast mixture

Pressure greatly exceeds atmospheric pressure

Cloud collapses to pyroclastic flows

Brittle lid

DegassesFracture & Growth

Viscous gas-rich magma