Ancient Alluvial Plains at Oxia Planum, Mars
- 1Department of Earth and Planetary Sciences, Birkbeck, University of London, UK (joel.davis@bbk.ac.uk)
- 2School of Physical Sciences, The Open University, Milton Keynes, Buckinghamshire, UK
- 3Department of Earth Sciences, Natural History Museum, London, UK
- 4Department of Earth Sciences and Engineering, Imperial College London, London, UK
The geologic origin of the ancient, phyllosilicate-rich bedrock at Oxia Planum, Mars, the landing site of ESA’s ExoMars rover, is unknown. The phyllosilicates record ancient aqueous processes, but the processes that formed the host bedrock remain elusive. Here, we use high-resolution orbital image and topographic datasets (HiRISE, CTX, CaSSIS) to investigate and characterize fluvial sinuous ridges (FSRs), found across the Oxia Planum region. The FSRs form segments up to 70 km long, with sub-horizontal layering commonly exposed in ridge margins. Some FSRs comprise multi-story ridge systems; many are embedded within and are being exhumed from the phyllosilicate-rich bedrock. We interpret the FSRs as deposits of ancient, episodically active, alluvial river systems (channel-belt and overbank deposits) at Oxia Planum. Thus, the phyllosilicate-rich bedrock was formed at least partly by ancient alluvial rivers, active across the wider region. Our alluvial hypothesis does not exclude other sources of sediment playing a role in building the terrain as well. Future exploration by ExoMars can verify this interpretation and provides an opportunity to investigate some of the oldest river deposits in the Solar System.
How to cite: Davis, J., Balme, M., Fawdon, P., Grindrod, P., Favaro, E., and Banham, S.: Ancient Alluvial Plains at Oxia Planum, Mars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-545, https://doi.org/10.5194/epsc2022-545, 2022.
