31st Annual Meeting of the DPS, October 1999
Session 43. Mars Surface: Structure
Contributed Oral Parallel Session, Thursday, October 14, 1999, 10:30am-12:00noon, Sala Plenaria

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[43.04] The Topography and Basin Deposits of the Equatorial Highlands: A MGS–Viking Synergistic Study

J. M. Moore (NASA Ames), A. D. Howard (U. Va.), P. M. Schenk (LPI)

We are using Digital Terrain Models (DTM) to evaluate the sequence and extent of various landform-modifying processes that have shaped the martian equatorial highlands using models that simulates these processes on a three-dimensional synthetic landscape. This modeling emulates the following processes: (1) cratering; (2) fluvial erosion and sedimentation; (3) weathering and mass wasting; (4) aeolian erosion and deposition; (5) groundwater flow and groundwater sapping; and (6) volcanic deposition of different emplacement modes. The models have been successfully used to predict the evolution of terrestrial landscapes. The models provide explicit simulations of landform development and thusly predict the topographic evolution of the surface and final landscape form. We generate combined Viking-MOLA DTMs, so that we have absolute regional and high resolution topographic information. With our DTMs we are able to much more realistically evaluate the evolution of specific locations within the cratered uplands of Mars than would be possible from either data set alone. Results of this analysis have direct import to Mars Surveyor Program landing site selection and science. We have selected three areas for our initial studies: (1) the south edge of the "hematite" deposit detected by TES and observed to be bordered by scarps and knobs exhibiting layers in Viking and MOC SPO images located at ~2°S, 4°W; (2) a typical example of equatorial cratered highlands at ~2°N, 240.5°W; and (3) a site at ~5°S and 264°W just south of the Isidis rim that is heavily dissected by channels. These regions were optimally imaged by Viking for the generation of DTMs, lie within the Mars 2001 landing constraints, and are potential locations for fluvial or lacustrine deposits. Our initial analysis of the later sites indicates that fluvial erosion for large solitary channels probably took the form of sapping, whereas denser networks of small channels may have formed at least in part from runoff, such as from surface ice-melt. Both sites show that channeling took place during a period in which fairly large craters will still forming. The tectonic fabric appears to largely predate the channeling. Aeolian deposition largely post dates the channeling. The deposition event that is responsible for the pervasive layering seen in the highlands in MOC images antedates all the processes responsible for the present topography.

The author(s) of this abstract have provided an email address for comments about the abstract: jmoore@mail.arc.nasa.gov

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