Constraints on the formation and properties of a Martian lobate debris apron: Insights from high-resolution topography, SHARAD radar data, and a numerical ice flow model

Lobate debris aprons (LDAs) are midlatitude deposits of debris-covered ice formedduring one or more periods of glaciation during the Amazonian period. However, little is known about theclimate conditions that led to LDA formation. We explore a hypothesis in which a single, extended period of precipitation of ice on the steep slopes of Euripus Mons (45 degrees S, 105 degrees Eeast of the Hellas Basin)produced a flowing ice deposit which was protected from subsequent ablation to produce the LDA found at this location. We test this hypothesis with a numerical ice flow model using an ice rheology based on low-temperature ice deformation experiments. The model simulates ice accumulation and flow for the northern and southern lobes of the Euripus Mons LDA using basal topography constrainedby data from the Shallow Radar (SHARAD) and a range of ice viscosities (determined by ice temperature and ice grain size).Simulations for the northern lobe of the Euripus LDA produce good fits to the surface topography. Assuming an LDA age of approximate to 60Myr and an expected temperature range of 200 to 204K (forvariousobliquities) gives an ice grain size of approximate to 2mm. Simulations of the southern section produce poor fits to surface topography and result in much faster flow timescales unless multiple ice deposition events or higher ice viscosities are considered.