Why is there such a variety of lavas in the Basin & Range province?
Simplified deformation and volcanism in an extensional regime that characterizes a basin and range province. Shows the basic processes that lead to eruptions in the region, and what type of eruptions occur. Includes lava flows, ash flow, dome building and cinder cones. During Basin & Range extension, the plates pull apart, the mantle rises and melts due to lower pressures near the surface. The style of eruption depends on how long the magma sits in the crust and undergoes processes such as crystallization and melting and assimilation of wall rock.
Thinned extended crust yields these eruptions:
- Basalt magma erupts as thin lava flows
- Basalt magma at depth melts the crust and makes gas-rich high-silica melt
- Low-gas rhyolite forms lava domes
- Gas-rich basalt forms cinder cones.