Grid Mapping the Northern Plains of Mars: Geomorphological, Radar, and Water‐Equivalent Hydrogen Results From Arcadia Plantia

Abstract

A project of mapping ice‐related landforms was undertaken to understand the role of subsurface ice in the northern plains. This work is the first continuous regional mapping from CTX (ConTeXt Camera, 6 m/pixel; Malin et al., ) imagery in Arcadia Planitia along a strip 300 km across stretching from 30°N to 80°N centered on the 170°W line of longitude. The distribution and morphotypes of these landforms were used to understand the permafrost cryolithology. The mantled and textured signatures occur almost ubiquitously between 35°N and 78°N and have a positive spatial correlation with inferred ice stability based on thermal modeling, neutron spectroscopy, and radar data. The degradational features into the LDM (latitude‐dependent mantle) include pits, scallops, and 100‐m polygons and provide supporting evidence for subsurface ice and volatile loss between 35 and 70°N in Arcadia with the mantle between 70 and 78°N appearing much more intact. Pitted terrain appears to be much more pervasive in Arcadia than in Acidalia and Utopia suggesting that the Arcadia study area had more widespread near‐surface subsurface ice and thus was more susceptible to pitting or that the ice was less well buried by sediments. Correlations with ice stability models suggest that lack of pits north of 65–70°N could indicate a relatively young age (~1 Ma); however, this could also be explained through regional variations in degradation rates. The deposition of the LDM is consistent with an air fall hypothesis; however, there appears to be substantial evidence for fluvial processes in southern Arcadia with older, underlying processes being equally dominant with the LDM and degradation thereof in shaping the landscape.

Grid Mapping the Northern Plains of Mars: A New Overview of Recent Water‐ and Ice‐Related Landforms in Acidalia Planitia

“…In summary, the enigmatic pits were only observed in Chryse/Acidalia Planitiae in our mapping studies (Ramsdale et al, 2018;Séjourné et al, 2018) and are very rare elsewhere (Kuznetsov et al, 2005), thus we suggest that specific conditions in southern Acidalia Planitia, perhaps related to the accumulation of large amounts of fine-grained volatile-rich sediments, favor their origin. They may belong to a suite of landforms that may all be related to volatile release, and their specific locations are locally controlled by slope aspect (orientation).…”

“…LDM and textured terrain occur ubiquitously from 44°N to 78°N in Acidalia Planitia further north than in Arcadia and Utopia Planitiae (Ramsdale et al, 2018, Séjourné et al, 2018. The origin of ice by air fall deposition is most likely, as LDM and its degraded varieties are draped over the terrain regardless of topography and are uncorrelated with geologic boundaries, outflow channels, or tectonic features, as would be expected if the ice had a fluvial or groundwater origin.…”

“…This technique (described in detail below) was successfully applied to the Hellas impact basin (Voelker et al, 2017) and results in a consistent and comparable database of landform locations, which can subsequently be statistically interrogated for different spatial relationships. We report on the results of the grid mapping as well as any serendipitous science observations in three separate studies covering Acidalia Planitia (this study), Arcadia Planitia (Ramsdale et al, 2018), and Utopia Planitia (Séjourné et al, 2018). In the following, we provide first an overview on the context and the geology of Acidalia Planitia (sections 1.2).…”

“…After processing we compiled a mosaic with a resolution of 6 m/pixel. We also used images from the MRO High-Resolution Imaging Science Experiment (HiRISE,25 Overview map of the three main basins of the northern lowlands: Acidalia (this study), Utopia (Séjourné et al, 2018), and Arcadia Planitiae (Ramsdale et al, 2018).…”

Grid Mapping the Northern Plains of Mars: Using Morphotype and Distribution of Ice‐Related Landforms to Understand Multiple Ice‐Rich Deposits in Utopia Planitia

“…We used a grid mapping approach (e.g., Ramsdale et al, 2017) with the latest middle-to high-resolution images of Mars to study its northern large basins (Arcadia, Acidalia, and Utopia Planitiae). The aims were to compare and to contrast the assemblages of landforms and their latitudinal distribution across these three regions and to attempt to determine the origin of some of these materials Ramsdale et al, 2018). Grid mapping is an efficient method to deal with the problems of mapping small landforms over large areas by providing a consistent and standardized approach to spatial data collection (Ramsdale et al, 2017;Voelker et al, 2017).…”