HR: 14:10h
AN: P12C-03    [PDF]
TI: An Emerging Picture of the Volcanic History of Syrtis Major From Multiple Dataset Views
AU: * Ruff, S W
EM: ruff@tes.asu.edu
AF: Arizona State University, Deparment of Geological Sciences, Mars Space Flight Facility Moeur Building, Rm 131, Tempe, AZ 85287 United States
AB: Syrtis Major Planum is a classical low albedo feature on Mars that contains one of the largest shield volcanoes on the planet. It is the only volcano of its size that is nearly free of a spectrally obscuring dust layer, making it an ideal target for investigation using the full range of available Mars datasets. Recent datasets from Mars Global Surveyor and Mars Odyssey provide compositional and morphologic information that has not been incorporated previously. Shaded relief topography from MOLA data presents the clearest view of the overall scale and morphology of the volcano. Lava flows, wrinkle ridges, and structural features all are readily discernable. THEMIS daytime and nighttime IR images supply a new level of detail on the morphology of the lava flows. The nighttime images are especially well suited to identifying flows, which appear slightly warmer than their surroundings. A clear radial pattern is evident emanating from the summit caldera complex. The occurrence of these flows is notably biased toward the western half of the volcano, perhaps indicative of an age or compositional asymmetry. Spectral indices sensitive to compositional variations in TES thermal IR data generally correspond with this asymmetry. Variations in visible/near infrared spectral parameters observed in Phobos 2 ISM data also depict an east/west asymmetry. A picture is emerging in which volcanic processes have varied during the construction of the Syrtis shield. Complicating this picture is the abundant evidence for post-emplacement modification of the upper surface of the volcano. Aeolian processes clearly have been active in redistributing materials across the volcano, generally from east to west. Dunes and wind streaks are evident in most of the imaging datasets, highlighted in great detail by MOC narrow angle images. Color images from the THEMIS visible camera provide dramatic views of reddish wind streaks in the lee of craters, apparently a zone of accumulation for airborne dust. Elsewhere, visibly dark streaks thinly mantle lava flows with material that appears compositionally distinct as shown by THEMIS multi-spectral IR images. While the wealth of information provided by multiple datasets adds complexity, careful scrutiny of the myriad details should create a clearer picture of the volcanic history of Syrtis Major.
DE: 5410 Composition
DE: 5415 Erosion and weathering
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 5480 Volcanism (8450)
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting