Abstract by Katelyn Wheldon
Determining Magma Storage Pressure with DERP: An Example from the Snake River Plain, Idaho
Knowing the pressure (or depth) of magma crystallization allows for inferences about magma genesis and potential for catastrophic eruption. Using new experiments, Wilke et al. (2017) created DERP (DEtermining Rhyolite Pressures) a program to estimate pressure using glass compositions in rhyolite. Because volcanic glass is difficult to analyze, we are testing DERP with rhyolites from the Snake River Plain. We analyzed the composition of glass in the same thin sections used by Wilke by electron microprobe at BYU and used the data to calculate pressure with DERP. The pressures calculated with BYU data are almost 200 MPa higher than those from Wilke’s analysis—implying the magmas crystallized at greater depths. The biggest differences in composition are Si, Al, and Na being on average 1.3% higher and 0.43% and 0.25% lower than Wilke’s values respectively. Further work will be done to investigate the discrepancies between the glass analyses done at BYU and by Wilke.