HR: 1340h
AN: V33C-1474    [Abstracts]
TI: Erosion by Flowing Martian Lavas: Insights from Modeling Constrained by MER and Mars Express Data
AU: * Williams, D A
EM: david.williams@asu.edu
AF: Arizona State University, Department of Geological Sciences, Box 871404, Tempe, AZ 85287-1404 United States
AU: Greeley, R
EM: greeley@asu.edu
AF: Arizona State University, Department of Geological Sciences, Box 871404, Tempe, AZ 85287-1404 United States
AU: Hauber, E
EM: Ernst.Hauber@dlr.de
AF: Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Institut fuer Planetenforschung, Rutherfordstr. 2, Berlin, 12489 Germany
AU: Neukum, G
EM: gneukum@zedat.fu-berlin.de
AF: Freie Universitaet Berlin, Department of Earth Sciences, Institute of Geosciences, Remote Sensing of the Earth and Planets, Malteserstr. 74-100, Building D, Berlin, D-12249 Germany
AU: The HRSC CoInvestigator Team, .
EM: gneukum@zedat.fu-berlin.de
AF: Freie Universitaet Berlin, Department of Earth Sciences, Institute of Geosciences, Remote Sensing of the Earth and Planets, Malteserstr. 74-100, Building D, Berlin, D-12249 Germany
AB: Low-viscosity lava flows, particularly mafic and ultramafic lavas, have a great potential to degrade underlying substrates by thermo-mechanical erosion during tube- or channel-fed flow emplacement. We used data returned by the recent Mars Exploration Rovers (MER) and {\it Mars Express} missions to provide new constraints to evaluate the potential of Martian lavas to form lava tubes and channels by erosion of flowing lava. Recently published geochemical information on basaltic rocks at Gusev Crater from the Mars rover {\it Spirit} indicates that the dust- and coating-free interiors of the rocks Adirondack, Humphrey, and Mazatzal are primitive, high-Mg basalts (MgO = 11.6-12.8 wt%: {\it McSween et al.}, 2004). Liquidus temperatures of silicate liquids of these compositions would have been $\sim$1250-1270$\deg$C, and liquid dynamic viscosities would have been $\sim$2.5-3.8 Pa s (similar to cold motor oil), suggesting that Martian lavas had the potential for turbulent flow emplacement. From the HRSC experiment on the {\it Mars Express} orbiter comes high-resolution stereo data of Martian lava flows and channels, which provide information on slopes, channel depths, and flow thicknesses at better resolutions than previously available from MOLA data. We have adapted the lava erosion model of {\it Williams et al.} (1998) to Martian conditions and used the MER-based compositions to assess the erosional potential of Martian lava flows. Our first test case is a long lava channel on Hecates Tholus in Elysium Planitia, in which HRSC data show is $>$ 66 km long (from caldera top to base of volcano) and emplaced on slopes between 1.4-8.3$\deg$. Our computer modeling results suggest turbulent emplacement (assuming initially 7.5 m thick flows) with maximum erosion rates of 85-170 cm/day, depending upon the ice content of the basaltic substrate. Further study and application will provide a better understanding of lava emplacement processes on Mars.
DE: 8429 Lava rheology and morphology
DE: 5464 Remote sensing
DE: 5480 Volcanism (8450)
DE: 6225 Mars
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting