Topographic and geomorphologic analyses of volcanic and impact-related landforms on Earth and Mars
Abstract
In this work, high-resolution topography and imaging datasets are utilized to illuminate the formation processes of enigmatic surface features on Mars and lava flows on Kilauea Volcano. Thermally distinct craters are identified on a deposit flanking Hrad Vallis, Elysium Planitia, Mars. In THEMIS IR nighttime images, the craters have cool interiors surrounded by warm ejecta haloes and in daytime IR the craters have warm interiors surrounded by cool ejecta, suggesting coarser material in the ejecta than in the surrounding terrain. The craters exhibit varying degrees of concentric fracturing and blocks up to several meters across are visible in HiRISE images. The distribution and morphology of the craters suggest that they are the result of interaction between a hot deposit and ice.
Previous studies of the one-dimensional roughness characteristics of volcanic surfaces indicate that information regarding the formation and evolution of the surface may be gleaned from roughness statistics. In this work, the 1D technique is carried into the second dimension, where roughness statistics are mapped using topography at varying resolutions. Lava flows in Kilauea caldera, emplaced by a variety of processes, provide a useful location to apply the 2D model. The 2D model results indicate that features formed during emplacement and modification of the flows exhibit statistically distinct roughness signatures and provides a tool for unit mapping based on surface roughness. Four candidate examples of impact melt flows and debris flows have been identified on the southern rim and interior wall at Tooting crater, a young, 29 km diameter impact crater in Amazonis Planitia, Mars. The flows are analyzed using HiRISE, CTX, and THEMIS VIS images, and a stereo-derived HiRISE DEM. The impact melt flows are fractured on the meter- to decameter scale, have ridged, leveed lobes and flow fronts. The debris flows exhibit varying morphologies, from a channelized, leveed flow with arcuate ridges in the channel, to a rubbly flow with a channel but no obvious levees. Extensive structural failure has modified the northern half of the crater and is interpreted to have caused the destruction of both the volatile-rich wall rock and any impact melt emplaced.- Publication:
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Ph.D. Thesis
- Pub Date:
- 2008
- Bibcode:
- 2008PhDT........38M
- Keywords:
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- Mars;
- Impact craters;
- Lava flows;
- Volcanic surfaces;
- Debris flows