ARCTIC DELTAS: A PROXY FOR MARTIAN DELTAS?

Mars’ paleoclimate is a hotly debated topic. Ancient Martian deltas might help us better understand the history of Mars’ climate. Arctic deltas on Earth provide insights about how ice cover affects depositional patterns, potentially holding clues to determining if Martian deltas may have formed under the influence of ice. We used numerical models simulating Arctic deltas to examine how the presence and thickness of ice impacted delta stratigraphy. We found that offshore deposition increased with the presence of ice, which aligned with findings of previous studies; however, as ice thickness increased, offshore deposition decreased. The fraction of sand present throughout the subaqueous regions followed the same pattern, increasing with the presence of ice but decreasing with increasing ice thickness. High sand fractions were more prevalent throughout the main (subaerial) delta regions where sediments were likely deposited in inactive channels. 3m-thick ice models and 0.5m-thick ice models had lower sand fractions than no ice and 4.5m-thick ice models throughout the main delta region, with 3m-thick-ice models having the lowest average sand fraction. When comparing deltas with no ice and deltas with 4.5m-thick-ice, the deltas were similar in terms of depositional area and sand fraction throughout the whole domain. However, 4.5m ice models showed signs of overbank sand deposition and relatively fewer channels while deltas with no ice had channel deposits reaching farther toward the shoreline. Most of our findings correspond closely to the dynamics associated with different conditions. We found that overbank sand deposits were typically found only in ice-covered deltas, likely due to increased flooding, while deltas with no ice present consistently had more channel fills, likely associated with their higher channel mobility in the absence of ice. Future work will apply these findings to martian delta stratigraphies to determine whether Martian deltas may have formed in an icy environment.