Ice-rich landforms of the southern mid-latitudes of Mars: A case study in Nereidum Montes

Mapping of Viscous Flow Features (VFFs), a general grouping of ice-rich flow features that includes Lobate Debris Aprons (LDA), Concentric Crater Fill (CCF), Lineated Valley Flow (LW), small lobate flows (i.e., glacier-like flows, or GLFs), and arcuate ridges, in the southern hemisphere of Mars shows a dense concentration in Nereidum Montes, along the northern rim of Argyre basin. Further mapping within a subregion in northwest Nereidum Montes (45.3 degrees-48.5 degrees S, 307 degrees-312 degrees E) shows a large number of well-preserved VFFs and ice-rich mantling deposits. Processed SHARAD data across a VFF within the region indicates that it is composed of nearly pure water ice. Model ages obtained from crater counts and their associated size-frequency distributions (SFDs) on both icerich mantling deposits and small lobate VFFs suggest that the deposits stabilized several to tens of Ma ago in the Late Amazonian Epoch, and that small lobate VFFs likely formed due to the mobilization of mantling deposits. SFD for a larger VFF shows a model age of 100 s of Ma, consistent with ages for LDAs in eastern Hellas. Deposition of ice in Nereidum Montes that led to the formation of VFFs likely occurred during periods of high obliquity in the Late Amazonian. Our results show that VFFs have more complete and diverse preservation states in Nereidum Montes than similar features in other regions on Mars. This region contains uniquely well-preserved mantling deposits above arcuate ridges and beyond the margins of lobate VFFs and gully aprons. This key observation ties arcuate ridges to the flow of mantling deposits, part of a continuum model for mid-latitude ice-rich landforms.

Automated summary

The mapping of Viscous Flow Features (VFFs) in the southern hemisphere of Mars, particularly in the Nereidum Montes region, reveals a dense concentration of well-preserved VFFs and ice-rich mantling deposits. These features likely formed several to tens of millions of years ago during periods of high obliquity in the Late Amazonian Epoch. This region contains a more diverse and complete preservation of VFFs compared to other areas on Mars, providing valuable insights into the formation and evolution of ice-rich landforms in mid-latitude regions.