Towards climate reconstruction on Mars using ice-related landforms: insights from landscape analysis and terrestrial analogues

Kurzfassung

Very young latitude-dependent landforms on Mars resemble terrestrial glacial and periglacial surface features in permafrost regions. They include surface mantling, viscous flow features, patterned ground, fractured mounds, and gullies. Collectively, these landforms are hypothesized to represent the geomorphological surface record of Martian ice ages during favourable spin-orbit conditions. We use permafrost landscapes of Svalbard (Norway) as analogues for cold-climate landforms typically found in mid-latitudes on Mars. Although relatively warm and wet as compared to other cold-climate analogues on Earth, Svalbard is a particularly instructive morphological analogue to Mars as it offers many surface features in a close spatial context. Based on this comparison, using remote sensing and field data, we identify similarities as well as differences, both of which are important when establishing testable hypotheses. We then propose possible scenarios which may help to understand the evolution of Martian landforms into their present state. Of particular interest is whether liquid water and freeze-thaw cycles were involved or not. Most phenomena on Mars, but not on Svalbard, can plausibly be explained by “dry” permafrost scenarios without the need to invoke freeze/thaw. Examples of such processes are the slow creep of ice-debris mixtures in permafrost, such as rock glaciers or debris-covered glaciers, or the aggradation and degradation of niveo-aeolian deposits. Other landforms may be explained with and without liquid water. Examples are thermal contraction polygons, which could form as ice-wedge polygons indicating freeze-thaw and liquid water, or, alternatively, as sublimation polygons. Former glaciers could have either been warm-based or cold-based, and therefore do not provide constraints on the history of liquid water. Some landforms such as gullies, however, seem to definitely require at least transient liquid water sometimes in the last ~10 Ma.