Cold-climate modification of Martian landscapes: A case study of a spatulate debris landform in the Hellas Montes Region, Mars

Abstract

We use spaceborne image and topographic data of Mars for a geomorphological study of the origin, development, and postemplacement modification of a 30-km-long spatulate landform in the Hellas Montes area, east of Hellas Planitia. The area is characterized by an abundance of lobate debris aprons, all of which have been interpreted as a result of creep and viscous deformation of rock and ice mixtures that make the eastern Hellas Planitia assemblages a type location for possible Martian rock glaciers. The spatulate landform has been discussed controversially in the past. Explanations range from a rock glacier to a wet debris avalanche or debris flow origin. This work scrutinizes arguments provided in earlier works and presents evidence that a landslide origin of the spatulate landform, connected with a sector collapse of a volcanic construct, is conceivable. We also find extensive observational evidence that the landslide has recently undergone or is still undergoing significant postemplacement modifications, which are characteristic of rock glaciers in periglacial environments. Creep deformation as well as disintegration of the original surface by thermokarstic degradation is considered to have obliterated impact craters and, in consequence, create a seemingly younger age. Similar processes are considered to be common on Mars under current climatic conditions. Our results imply that the strong and possible long-term modification of landforms on Mars by cold-climate processes often hinders the identification of their original nature and complicates the assessment of true ages.