Ridges on martian debris-covered glaciers : deconvolving structural and climate processes
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Debris-covered glaciers on Earth and Mars often exhibit surface ridges transverse to the flow direction of the glacier. The formation mechanism of these ridges is not well established, but some evidence from terrestrial analogues supports the idea that surface ridges may demarcate climate cycles. It is also possible they are induced by thrust faulting, buckle folding, or other compressional mechanisms. This work aims to differentiate climate-related ridges from thrust fault and buckle folding ridges on Mars through mapping, geometric analysis, and flow modelling. We find that martian glaciers exhibit ridges of a variety of amplitudes and wavelengths. Large ridges on martian debris-covered glaciers cannot be explained by buckle folding given their long arclengths and inconsistent inter-ridge spacing, while some smaller ridges are consistent with the expected arclengths for buckle folds on Mars. The smaller ridges also exhibit highly consistent inter-ridge spacing and morphologies similar to terrestrial examples of two-layer buckle folds. Flow modelling results suggest that thrust faulting is a possible explanation for ridges on some debris covered glaciers, but thrust faulting diminishes as temperature decreases. We conclude that it some ridges on martian debris-covered glaciers are likely caused by climate variations however the buckle folding hypothesis is plausible for finely spaced ridges.