A geological context of the honeycomb terrain on Mars and its constraints on its formation mechanisms
The formation process of the unique honeycomb terrain in Hellas basin on Mars is poorly understood. Yet, understanding its origin has significant implications for unraveling the climate histories of Hellas basin in particular and Mars in general. Currently, salt and ice diapirism have been invoked by researchers to explain the observed surface morphology. However, this proposed process predicts extrusive salt and ice glacier flows on the surface, which have not been observed. A major obstacle that hinders our current understanding of the honeycomb terrain formation is the lack of a geologic context that relates the honeycomb structures to the surrounding boundary conditions. This study employs photogeologic mapping to establish the geologic setting of the honeycomb terrain. Our analysis shows that the honeycomb structures generally have a consistent direction of elongation parallel to the rim of Hellas basin, which implies that gravitational sliding from basin margins to basin interior may have also been a driver for the formation of the honeycomb structures. The results of this study suggest that while salt or ice diapirism may provide a partial explanation for the observed surface morphology associated with the honeycomb structures, the formation of giant desiccation polygons and gravitational slumping along a detachment fault from the basin rim towards the basin center may have also contributed to the development of the unique honeycomb terrain on Mars.