A depth versus diameter scaling relationship for the best-preserved melt-bearing complex craters on Mars

Abstract

We use topographic data to show that impact craters with pitted floor deposits are among the deepest on Mars. This is consistent with the interpretation of pitted materials as primary crater-fill impactite deposits emplaced during crater formation. Our database consists of 224 pitted material craters ranging in size from ~1 to 150 km in diameter. Our measurements are based on topographic data from the Mars Orbiter Laser Altimeter (MOLA) and the High-Resolution Stereo Camera (HRSC). We have used these craters to measure the relationship between crater diameter and the initial post-formation depth. Depth was measured as maximum rim-to-floor depth, (dr), but we also report the depth measured using other definitions. The database was down-selected by refining or removing elevation measurements from "problematic" craters affected by processes and conditions that influenced their dr/D, such as pre-impact slopes/topography and later overprinting craters.We report a maximum (deepest) and mean scaling relationship of dr = (0.347±0.021)D 0.537±0.017 and dr = (0.323±0.017)D 0.538±0.016 , respectively. Our results suggest that significant variations between previously-reported MOLA-based dr vs. D relationships may result from the inclusion of craters that: 1) are influenced by atypical processes (e.g., highly oblique impact), 2) are significantly degraded, 3) reside within highstrength regions, and 4) are transitional (partially collapsed). By taking such issues into consideration and only measuring craters with primary floor materials, we present the best estimate to date of a MOLA-based relationship of dr vs. D for the least-degraded complex craters on Mars. This can be applied to crater degradation studies and provides a useful constraint for models of complex crater formation.

Deriving Morphometric Parameters and the Simple‐to‐Complex Transition Diameter From a High‐Resolution, Global Database of Fresh Lunar Impact Craters (D ≥ ~ 3 km)

“…However, the goodness of fit in terms of the R 2 value strongly increases for complex craters, if they are not combined with transitional craters. Similar observations were made for Martian transitional and complex craters by Tornabene et al ().…”

Transitional impact craters on the Moon: Insight into the effect of target lithology on the impact cratering process

“…Indeed, Tornabene et al. () did not find a preference for the best‐preserved (i.e., with preserved melt deposits) deepest complex craters toward volcanic plain units nor heavily cratered terrains.…”

Degradation of 100‐m‐Scale Rocky Ejecta Craters at the InSight Landing Site on Mars and Implications for Surface Processes and Erosion Rates in the Hesperian and Amazonian

“…Because the initial morphometry of Martian impact craters is well understood (e.g., Basilevsky et al, ; Daubar et al, ; Garvin & Frawley, ; Garvin et al, ; R. J. Pike, , ; Tornabene et al, ; Watters et al, ), measurements of depth, diameter, and rim height can be used to constrain the types and rates of surface processes involved in their degradation and thus can be used to infer past Martian climate conditions (e.g., Craddock & Howard, ; Golombek, Warner, et al, ; Warner et al, ). The preservation state of the global Martian crater population is, however, spatially variable due to the variety of surface processes that have occurred and the complexities in local geology and climate conditions.…”

“…Until recently, quantitative studies of crater degradation have been limited to kilometer‐sized craters on the Moon and Mars and span large, geologically diverse regions due to the large grid size of available digital elevation models (DEMs). However, the observed degradational sequence of simple and complex kilometer‐sized craters (Craddock & Howard, ; Craddock & Maxwell, ; Forsberg‐Taylor et al, ; Irwin et al, ; Mangold et al, ), and the surface modification rates derived from their preservation relative to a pristine crater model (e.g., Garvin & Frawley, ; Garvin et al, ; Tornabene et al, ), may not be appropriate for smaller, <1‐km‐sized craters. The morphology of craters of this size is far more sensitive to both target properties (e.g., Gault et al, ; Mizutani et al, ; Moore, ; Robbins & Hynek, ) and surface modification, even during the Hesperian and Amazonian, where low erosion rates caused global obliteration of small craters (e.g., Golombek, Warner, et al, ; Irwin et al, ; Warner et al, ).…”