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 Plinian Activity
Strombolian Activity Spatter Cone
Hawaiian Activity
Produces turbulent, buoyant cloud, Rises to great heights
Cinder Cone Bubble Rise Rate > Magma Rise Rate
Dome Growth Brittle lid
Degasse s Fracture & Growth
Viscous gas-rich magma
Magma Rise Rate > Gas Rise Rate
Cloud collapses to pyroclastic flows
Atmosphere sucked in, heated Exit velocity high Low viscosity gas-clast mixture Pressure greatly exceeds atmospheric pressure