Using martian single and double layered ejecta craters to probe subsurface stratigraphy

Identifying an index of subsurface volatiles on Mars through an analysis of impact crater morphometry using principal component analysis

“…In addition to their key morphological difference (number of ejecta layers), some further distinctions exist between the SLE and DLE crater populations: the average diameter of DLEs is significantly larger than that of SLEs [ Barlow , ]; the outer layer of DLE craters shows higher mobility and sinuosity than both the inner layer and SLE ejecta [ Boyce et al ., ]; DLEs are typically concentrated in the northern lowlands at latitudes >25° (associated with past ice‐bearing units), whereas SLEs are concentrated at lower latitudes [ Barlow and Perez , ; Costard and Kargel , ; Mouginis‐Mark , ]. Within the same region, SLE and DLE craters are distinguished by their ejecta mobility (EM), onset diameter, and EM‐diameter correlation [ Jones and Osinski , ], providing a strong indication that the two morphologies may result from differing properties of the target materials. The distribution and attributes of SLE and DLE craters have a complex relationship with target properties that is not yet fully understood and may be elucidated through the application of multivariate statistical techniques.…”

“…This can occur through the incorporation of volatiles, such as water, or fine grained materials in the ejecta [ Baratoux et al ., ; Barlow and Boyce , ; Barlow , ; Barnouin‐Jha et al ., ; Costard , ; Gault and Greeley , ; Osinski et al ., ; Rager et al ., ; Schultz , ]. Latitudinal and longitudinal trends occur in EM values, with the least mobile ejecta observed in the volcanic provinces (Tharsis, Hesperia, and Elysium) and the most mobile within Utopia, Acidalia, and eastern Arcadia Planitia and eastern Hellas [ Barlow and Perez , ; Jones and Osinski , ]. The occurrence of highly mobile ejecta in the northern lowlands suggests a link between ejecta mobility and present and past ice‐rich substrate [ Feldman et al ., ].…”

“…Boyce et al . [] found that EM did not increase with crater diameter for Martian complex crater morphologies (EM was self‐similar with crater size); however, Jones and Osinski [] found a regional variation between EM and crater size. The correlation between EM and crater diameter suggests a relationship between the effectiveness of the ejecta flow, and the excavation depth of the impact and source depth of the ejecta.…”

“…It is likely that fines [ Barnouin‐Jha et al ., ; Schultz , ] and atmospheric volatiles [ Schultz , ; Sugita and Schultz , ] play a role in the emplacement of Martian ejecta. Despite this, previous studies have shown a strong link between high ejecta mobility and lobateness values and regions of modern ice stability and net ice accumulation within the recent periods of low obliquity (25–35°) [ Barlow et al ., ; Demura and Kurita , ; Jones and Osinski , ]. Whether the attributes of layered ejecta are dominated by particle size distribution and cohesion of the target, or by the melt and volatile content, will likely vary regionally on Mars [ Jones and Osinski , ].…”

“…Despite this, previous studies have shown a strong link between high ejecta mobility and lobateness values and regions of modern ice stability and net ice accumulation within the recent periods of low obliquity (25–35°) [ Barlow et al ., ; Demura and Kurita , ; Jones and Osinski , ]. Whether the attributes of layered ejecta are dominated by particle size distribution and cohesion of the target, or by the melt and volatile content, will likely vary regionally on Mars [ Jones and Osinski , ]. However, both EM and lobateness are morphological parameters, which are likely related to crustal properties, and hence have the potential to provide key information on the composition and physical characteristics of the subsurface with depth.…”