2009 Annual Research Report

Chuang's research conducted over the past few years has been focused on the geologic mapping of the Deuteronilus Mensae region of Mars and analyses of HiRISE images of Martian slope streaks. The research from these studies have recently been published.

The principle goal from the geologic mapping was to assess the characteristic landforms, superpositional relationships of defined units, and overall evolution of terrains near the dichotomy boundary in Deuteronilus Mensae. Results from this work shows that the region has been influenced by a variety of processes including formation of depressions from collapse of ancient highland materials, development of fretted valleys along possible pre-existing weaknesses in ancient highland materials, and modification of the dichotomy boundary region from erosion and mass-wasting of highland materials. Ice was likely incorporated into the mass-wasted materials as they appear to flow away from source areas such as crater walls, highland escarpments, and isolated mesas. Characteristic flow features observed in the region include lobate debris aprons, lineated valley fill, and concentric crater fill. Overall, a wide range of geologic processes appears to have modified the Deuteronilus Mensae region spanning a time period from the middle Noachian to late Amazonian on Mars.

The goal in the study of slope streaks was to identify and interpret features observed within the floors of these features. Analyses of HiRISE images showed that transverse bedforms within the floor had relatively consistent wavelengths (i.e., spacing between individual bedforms). The heights of the bedforms were estimated to be a few meters using photoclinometry techniques. The heights, wavelengths, and morphologies of the bedforms are all consistent with terrestrial fine or coarse-grained aeolian ripples. Because the slope streaks with ripples occur in dust-rich regions of Mars, it is hypothesized that the material forming the ripples are likely dust aggregates, possibly mixed with a smaller proportion of terrestrial sand-sized particles. A first-order estimate of the winds using Mars GCM models and reasonable terrestrial analog particle densities suggests that dust aggregates are capable of saltation to form the ripples. From the results of this study, we hypothesize a sequence of events in a slope streak formation and modification cycle where grains saltate to form ripples, airfall dust mantling causes fading of the streak, and infill material buries the ripples, which eventually reaches the pre-streaked surface level, removing all traces of relief.

Current research is focused on studying intracrater layered deposits in Arabia Terra. Using datasets from the Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter missions, our initial results show that the deposits have a variety of forms and layering styles in an area between 330-30 E longitude and 0-30 N latitude. The deposit forms and layering styles also show a regional transition from east to west-southwest across the study region. Details on the deposit characteristics and their overall distribution will be submitted to the Journal of Geophysical Research-Planets in spring of 2010.

Papers:

Chuang, F.C., R.A. Beyer, and N.T. Bridges, Modification of Martian slope streaks by eolian processes, Icarus, 205, 154-164, 2010.

Chuang, F.C. and D.A. Crown, Geologic map of MTM 35337, 40337, and 45337 quadrangles, Deuteronilus Mensae region of Mars, U.S. Geol. Surv. Scientific Invest. Series Map 3079, 1:1,000,000 scale, 2009.