This is the continuation of a study to determine the nature and causes of compositional variation in lavas from the eruption of Kilauea Volcano, Hawaii which has been going on since 1983. Mineral and whole-rock compositions will be determined uand used to evaluate the relative importance of crystal fractionation, magma mixing and mantle melting in controlling the composition of the lavas erupted. Lavas collected from the active lava lake 19 km. from the summit of the volcano seem to have a cyclic variation in composition that correlates well (with a time delay) with summit tilt variations. The continued monitoring of this variation will provide the first direct measurement of the rate of movement of magma in the rift zone. It is also planned to evaluate the temporal and spatial variations in the composition of lavas erupted historically at the summit of Kilauea Volcano. This should make clearer the size and location of the summit reservoir which is still poorly known. The petrological and geochemical results from this study will be integrated with field and geophysical measurements and interpretations by the staff of the USGS Hawaiian Volcano Observatory. This collaboration should yield new insights that will have fundamental implications for understanding the plumbing system of Kilauea Volcano and for interpreting petrologic processes in volcanic systems.
