| Whole-rock and olivine phenocryst geochemistry archives the petrologic evolution of the
eastern Snake River Plain (ESRP) basaltic system. This study aims to assess olivine-melt
equilibrium, apply olivine-melt thermometry and hygrometry to evaluate the pre-eruptive
conditions of the melt, and evaluate basalt flow-group correlations between core holes drilled
within the Materials and Fuels Complex region (MFC) of the Idaho National Laboratory (INL) to
aid research efforts by the United States Geological Survey (USGS) to better understand
groundwater migration and volcanic hazards in this region. This work demonstrates that olivine
phenocrysts are in equilibrium with the whole-rock (i.e., melt) compositions; at the onset of
olivine crystallization temperature and dissolved H2O content of the melts was 1,117–1,195 ˚C
and 0.4–2.6 wt%, respectively. Whole-rock data support correlations of flow groups within the
MFC. This work provides information about the stratigraphy beneath the MFC and the petrologic
evolution of ESRP basalts. |