2023 CSDMS meeting-070

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Fluvial reworking eliminates small craters, but does not meaningfully bias the Mars interbedded-crater record

Andrew Moodie, (he/him),University of Texas at Austin Austin Texas, United States. amoodie@utexas.edu

Timothy Goudge, The University of Texas at Austin Austin Texas, United States.

The accumulated history of crater production and destruction is recorded in crater size-frequency distributions (CSFDs), which can be leveraged to understand the evolution of planetary surfaces and atmospheres. For example, researchers used the size-frequency distribution of craters interbedded with fluvial deposits to provide an upper-bound of ~1.9 bar on paleo-atmospheric pressure at the time of river activity on Mars. Interpretations of paleo-atmospheric pressure are most sensitive to preservation and mapping of smaller craters (<50 m), which may be influenced by fluvial reworking. We simulated river-delta development with coeval crater production; river-delta simulation is completed with pyDeltaRCM and craters 10 to 300 m are generated according to an imposed crater production function and placed randomly and with a parameterized geometry. We quantified preservation of craters in the stratigraphy after 1, 10, or 100 Ma of coupled landscape evolution. Our results indicate that crater preservation is highly variable (ranging fully eroded to fully preserved), but preserved fraction generally increases with crater diameter. Despite rivers removing a substantial portion of smaller craters (>40% of craters <50 m are at least partially eroded); exponential increase in crater counts with decreasing size overwhelms any meaningful fluvial preservation bias. Our findings bolster previous studies that assert fluvial reworking is a secondary controls to atmospheric ablation on CSFDs, indicating that paleo-atmospheric pressure upper-bounds may be translated into estimates (with uncertainty).