HR: 1340h
AN: V33C-1473    [Abstracts]
TI: Topographic Attributes of Three Hawaiian Lava Flows: Implications for Evaluation of Lava Flow Emplacement on Mars
AU: * Zimbelman, J R
EM: zimbelmanj@nasm.si.edu
AF: Smithsonain Institution, P.O. Box 37012, CEPS/NASM MRC 315, Washington, DC 20013-7012 United States
AB: Differential Global Positioning System surveys were carried out recently across portions of three lava flows on the Big Island of Hawaii. Transects crossed an entire flow in several cases, and in other cases provided detailed information about selected flow margins. The 1907 basalt (a'a) flow from the southwestern rift zone of Mauna Loa has easy access at several points via the Ocean View Estates road system; flow thickness ranges from about 1 m near the middle of the eastern flow lobe to more than 10 m toward the distal end of this flow. Several components of a benmoreite (alkali-rich basaltic andesite) flow complex from Mauna Kea were examined near the small community of Mana (with permission of the Parker Ranch management), on the western flank of the volcano. The flows are more than 14,000 years old and completely covered with soil more than a meter thick, but flow morphology at the decameter scale remains very evident in aerial photographs; some benmoreite flows have up to 30 m of relief along their middle reaches. A trachyte flow more than 100,000 years old extends down slope from Puu Waawaa, on the northern flank of Hualalai; Puu Anahulu represents a very advanced stage of magmatic differentiation that resulted in a flow complex with more than 120 m of relief at its southern margin. Width/thickness represents a good discriminator between these three Hawaiian lava flows. Unfortunately, width is often the most difficult parameter to measure remotely for flows on other planets. Recent imaging data from the Thermal Emission Imaging System on the Mars Odyssey spacecraft reveal important new details of lava flows in the Tharsis region of Mars, some of which can be combined with elevation information from the Mars Orbiter Laser Altimeter. The precise topographic characteristics of diverse Hawaiian lava flows provide a new tool for evaluating the potential emplacement conditions for some Martian lava flows, which appear to be more consistent with the basalt to basaltic andesite lava flows than with the highly evolved trachyte flows. Future work, supported by a grant from the NASA Planetary Geology and Geophysics Program, will obtain additional precise topographic information for several Hawaiian flows to expand the topographic data set for comparison with the Martian flows, as well as lava flows on other planetary bodies.
DE: 8400 VOLCANOLOGY
DE: 8429 Lava rheology and morphology
DE: 8450 Planetary volcanism (5480)
DE: 5480 Volcanism (8450)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting