Constraining the Hydration State of the Phyllosilicate Deposits of Eastern Valles Marineris Mars

A study has found that the bound water of clay deposits on Mars render radar observations ineffective, as the water presence absorbs the radar signal beyond detection (Stillman & Grimm 2011). However, at Aurorae Planum, basal reflections are still observed, despite the presence of widespread clay deposits in the region. We conduct dielectric laboratory experiments on a terrestrial analog clay sample to constrain dielectric properties sufficient enough to allow transmission of SHARAD radar. In addition, we utilize HiRISE and CRISM data to draw correlations between the clays and the radar observations. Our study finds that a catastrophic flooding event is a sufficient and plausible explanation for this contradiction. Leftover pooled water from the flood was left to alter shallow sediment deposits, and upon evaporating, provided the necessary mechanism for desiccation due to water table retreat to occur, minimizing the influence of bound water on the incident radar waves.