The Modification History of Large Craters in the Martian Polar Layered Deposits

Using the Planum Boreum and Planum Australe Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) 3D radargrams (Foss et al., 2017, 2024; Putzig et al., 2018, 2022), we have mapped the subsurface radar stratigraphy in the vicinity of six large craters in the North and South Polar Layered Deposits (PLD) – which exhibit striking cross-circumpolar similarities. For example, both Crotone crater in the North PLD and Crater S3 in the South PLD show an almost complete lack of subsurface radar layering. In contrast, Boola crater in the North PLD and McMurdo crater in the South PLD each exhibit significant subsurface stratigraphy below well-preserved surface features (a sizable ejecta blanket and a large secondary field, respectively). Similarly, the regions around both Udzha crater in the North PLD and Elim crater in the South PLD reveal extensive subsurface layering proximal to possible intra-crater deposition. We will estimate columnar radar dielectric properties in the vicinity of all six of these North and South PLD craters to constrain the effects of possible bulk composition variations upon surface crater preservation and subsurface layer stratigraphy. We will then input our subsurface stratigraphic mapping and dielectric radar property estimates into MARSSIM landform evolution modeling (Howard, 2020) of the modification history in and around these craters to assess the origins of the North and South PLD – could these circumpolar deposit complexes share a common genesis that dates back more than several hundred million or perhaps even over a billion years? References:Foss, F.J. et al., 2017, 3D imaging of Mars' polar ice caps using orbital radar data, The Leading Edge, 36(1), 43-57.Foss, F.J. et al., 2024, Producing 3D radargrams from orbital radar sounding data at Mars: History, results, methods, lessons and plans. Icarus, 419, 115793Howard, A.D., 2020, Evolution of glacial landscapes of the Martian mid-latitudes, GSA Meeting, Abs #355189, 249-10.Putzig, N.E. et al., 2018, Three-dimensional radar imaging of structures and craters in the Martian polar caps, Icarus, 308, 138-147.Putzig, N.E. et al., 2022, New views of the internal structure of Planum Boreum from enhanced 3D imaging of Mars Reconnaissance Orbiter Shallow Radar data, The Planetary Science Journal, 3(11), 259.