EPSS Colloquium winter-2014

Why is there volcanism in the Basin and Range? Cinder cones have popped up from California to Utah, bringing mantle melts and xenoliths to the surface. Some of these volcanic vents are clearly related to active deformation in the Basin and Range, while others are not. Recent work points to small-scale convective phenomena in the mantle, such as lithospheric drips or edge-driven convection, to drive melting. What is the role of prior subduction and hydration of the lithosphere in generating magmas? These questions are fundamental to how the continent evolves in regions of active extension, and yet there are no consensus answers. The first data on the water contents of Basin and Range magmas are combined with mantle melt thermobarometers and seismic shear wave velocities to provide a new view of melting beneath the Western US.