Investigating Potential Ancient Inverted Valley Networks on Mars

Abstract:

Mars has been a long sought after target due to the potential habitable environments it may have harbored in the past. In order to help understand the potential duration over which Mars may have been capable to support life, it is vital to understand the current and past states of the Martian environment. To better constrain the condition of these past and present environments, we constructed a global map of small-scale exposures of olivine across the Martian surface, as the distribution and context of these exposures can help provide an understanding of the current chemical weathering history, as olivine is readily susceptible to such types weathering. To map these olivine exposures, we utilized a red-green-blue decorrelation stretch (DCS) in bands 8,7, and 5, as olivine has a signature purple hue associated with it.

While constructing this global map, we have identified a unique olivine-enriched deposit near Novara Crater, centered at 347.582E, -24.967N. In addition to an olivine spectral signature, the feature is characterized by elevated thermal inertia, a branching/dendritic pattern, and raised topography with a central depression. This feature occurs near the bottom of a larger topographic low, which appears to be an area of active erosion. In an effort to constrain the origin of this unit, we examined several characteristics of the feature including: thermophysical properties of the center “channel” and surrounding terrain, stream order, feature scale, topography, etc. As a result of this analysis, we interpret this feature to be an ancient, inverted, valley network that was perhaps filled by olivine-rich materials and has since been exhumed. In the surrounding terrain on overlying units, other valley networks have been observed lending to the interpretation that this potential valley network may be older than others identified, due to the preservation from the olivine deposit. If true, this could be one of the oldest preserved valley networks on Mars that could provide us with contextual clues about the timing of liquid water on the Martian surface, thus contributing to evidence for past potential habitable environments.