Testing for flow in the north polar layered deposits of Mars using radar stratigraphy and a simple 3D ice-flow model

The water-ice-rich north polar layered deposits (NPLD) of Mars play a key role in the Martian climate through an active exchange of water vapor with the atmosphere. Conditions are not currently amenable for flow of the NPLD; however, gross morphological evidence for past flow suggests the possibility of a warmer climate in the past. Here we present the first comparison of internal stratigraphy predicted by a flow model with that observed by an orbital radar sounder. We have analyzed radar data from Gemina Lingula, the southernmost tongue of the NPLD, acquired by the Shallow Radar on board NASA’s Mars Reconnaissance Orbiter. The data shows extensive internal reflections and several radar reflectors were mapped to create gridded surfaces of this part of the NPLD. All the mapped radar reflectors were smooth with no sudden dips towards the surface or the bedrock. The internal radar reflectors were then compared with modeled isochrones in two different areas of Gemina Lingula under the assumption of flow occurring. Results indicate that flow of ice is unlikely to have occurred between the main dome and Gemina Lingula. Furthermore, we found no evidence for the existence of a prior ablation zone in Gemina Lingula as predicted in another study.

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