D. Crown, Planetary Science Institute, Tucson, AZ

S. Anderson, Black Hills State University, Spearfish, SD

J. Byrnes, U.S. Geological Survey, Astrogrology Team, Flagstaff, AZ

M. Ramsey, Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA

This investigation examines the significance of lava transport in features intermediate in scale to small, toe-dominated pahoehoe lobes and large lava tubes to assess controls on flow field development. Field observations show that channel systems of moderate size are responsible for emplacement of a significant portion of the final surface lava of the Mauna Ulu flow field (1969-1974) at Kilauea Volcano (HI). Channel networks and individual channels with segment widths of a few meters across or less control the distribution and morphology of flow surface units in parts of the medial zone of the Mauna Ulu flow field. Complex flow surface unit patterns can be interpreted in terms of local conduit evolution, including generation of sequences of lateral levees, production of zones with slabby and clinkery lava textures along flow fronts and margins, and later stage breakouts of pahoehoe at flow margins and within interior zones, sometimes burying the primary channel. In order to understand conduit evolution, breakout history, and local flow stratigraphy, morphometric and topographic surveys of flow conduit systems (channels, levees, and breakouts) were completed to quantitatively characterize levees and breakout lobes and measure channel dimensions, flow thicknesses, and levee volumes. This work utilized a dGPS unit coupled with a high-resolution laser profiling system providing sub-meter horizontal (~10 cm) and vertical (~30 cm) accuracy. Preliminary analyses of areal resurfacing from four conduit systems with channel segments between 55 and 166 m in length have been completed. Total resurfaced areas are between ~500 and 2500 square meters, with 70 percent or more in levees and lateral and distal rubble zones and the remainder in late-stage pahoehoe breakouts. Along a given channel segment, ~10-30 square meters are resurfaced for each meter of channel length, suggesting the duration of activity in small to moderate conduits can be a key factor in understanding flow field evolution.

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Submitted: American Geophysical Union Fall Meeting
Date: December 5 - 9, 2004