Glacial-like landforms in Nilosyrtis Mensae, Mars: A geomorphological study of ice-rich landforms in the fretted terrain of the northern mid-latitudes

The prospect of life on Mars has been a driving factor for the exploration and studies of the planet, based on the geochemical and geomorphological evidence for liquid water found on its surface. However, under current cold and arid climatological conditions, liquid water cannot be sustained. The current water inventory left on the planet is mainly locked as water ice on the surface and subsurface, at the poles and in the mid-latitudes. This geomorphological study investigates the region of Nilosyrtis Mensae (34°-28°N, 68°-75°E), located at the dichotomy boundary in the northern mid-latitudes and consisting of characteristic fretted terrain. Features and deposits were mapped using data from the Context Camera (CTX) mosaic of 6m/px, MOLA DEM of 100m/px, and High Resolution Stereo Camera (HRSC) imagery of 10-20m/px. This study shows the regional distribution and preservation of glacial-like landforms and their topographical context, with evidence found for cold-base glaciation. These features are similar to those found through previous studies in neighbouring regions, and are most abundant in the valley systems of the northern half of the region. There is a presence of ice-rich features in the south, but they can only be found within narrow valleys where sufficient insolation can be found. The map classification of this study shows the presence of an amplitude of ice-rich features at different degradational stages, indicating local climatological conditions affecting the conditions for the preservation of ice. These features show a prevalence on northern-facing slopes and in valleys of north-south orientation, and consist of flow-features such as viscous flow features, glacial-like forms, lobated debris aprons, lineated valley fill and concentric crater fill. Ice-rich non-flow features were also identified such as dipping layered deposits and crater-associated irregular cellular structures. Observations of escarpment erosion and asymmetrical permafrost degradation offer insights into local preservation conditions. Gravitational features such as avalanche-like deposits with ice-rich content found on poleward-facing slopes may be indicators for tectonic activity in the region’s vicinity. Similarly, deposits from mass wasting events can be found in the study area, further indicating previous tectonic activity. Evidence for past fluvial activity was identified through fan-shapes and sedimentary deposits in large parts of the area, with the strongest prevalence in the southern part of the study area largely due to the flat topographic setting. The mapping of the study thus highlights the importance of Nilosyrtis Mensae for understanding regional climatological conditions and Martian glacial processes. Future studies may aid in further understanding the correlation between past climate evolution and the regional geomorphology, by providing refined interpretations from more detailed investigations on the basis of the identifications made in this study.