Tiny Melt Inclusions from 2009 Redoubt Tephra Samples

Graduate student Allison Payne (USGS ARRA student appointment) uses a binocular microscope to pick out minerals that contain tiny melt inclusions from 2009 Redoubt tephra samples. Melt inclusions are then analyzed with a SHRIMP - Sensitive High Resolution Ion Microprobe - for their volatile (H2O and CO2) content. Determining volatile content of the melt allows petrologists to constrain the pressure, and therefore the depth, of a magma at various stages in the magma's migration toward the surface.