This proposal is for the acquisition of a multi-anvil press for the primary purpose of studying mineralogical reactions and mineral-composition variations relevant to ultra-high-pressure (UHP) metamorphism. Several projects have been identified that will be the initial focus of research. First, the upper-pressure stability of glaucophane, which breaks down to talc and jadeite, will be examined to try to resolve existing discrepancies in the location of this boundary. This reaction boundary defines the upper-pressure limit of the blueschist metamorphic facies and may correspond in pressure to the onset of UHP metamorphism (defined by the presence of coesite). Second, univariant reactions defining the conversion of the low-pressure assemblage zoisite + diopside-rich clinopyroxene to the high-pressure assemblage lawsonite + grossular-rich garnet in the system CaO-MgO-Al2O3-SiO2-H2O will be investigated to better understand the pressures at which lawsonite-bearing eclogites occur. Third, the possible expansion of the stability field of zoisite-bearing eclogites, limited by the reaction 6 zoisite = 4 grossular + 5 kyanite + coesite + 3 H2O, resulting from the addition of ferric iron to the above system will be examined. The latter two projects will help delimit the stability field of zoisite (or epidote) in eclogites from UPH terranes. This mineral may be an important host for returning water to Earth's mantle. The multi-anvil press requested in this proposal will support research on many other projects relevant to UHP metamorphism. The broader impacts of this proposal are (1) improving the research infrastructure at this institution by allowing research at pressures and temperatures that were not previously attainable and (2) by providing undergraduate and graduate students opportunities to conduct research relevant to planetary interiors.
