PALEOMAGNETIC CORRELATION OF LATE QUATERNARY LAVA FLOWS IN THE LOWER EAST RIFT-ZONE OF KILAUEA VOLCANO, HAWAII

Paleomagnetic data reflecting paleosecular variation (PSV) of the geomagnetic field are used to correlate individual lava flows in the lower east rift zone of Kilauea Volcano. This area has been recently mapped based on petrography, stratigraphy, soil development, and degree of weathering of the flows; eight C-14 dates also provide a framework for the relative age assignments. Site-mean directions of remanent magnetization for historic flows in this region indicate that local magnetic anomalies do not mask the PSV signal, that within-flow angular differences are generally < 5 degrees, and that temporal resolution of the paleomagnetic directions is of the order of 100 years. The paleomagnetic correlations do not conflict with the observed stratigraphic relationships, and PSV reference curves from dated lava flows and lake sediments have also been used to help determine the sequence of directional groups. Paleomagnetic grouping of flows into eruptive events indicates a different and perhaps more refined eruptive history for the lower east rift zone than implied by the geologic mapping alone. The number of individual flows based on petrographic distinctions is likely the same, but the frequency of events (including petrographically distinct flows) is apparently lower than previously thought. Flows from ridge crest vents bifurcated by the rift indicate formation of the central graben in this region after similar to 300 years ago, possibly related to the 1790 eruptions along dual fractures.