Ancient alluvial plains at Oxia Planum, Mars

The geologic origin of the ancient, phyllosilicate-bearing bedrock at Oxia Planum, Mars, ExoMars rover landing site, is unknown. phyllosilicates record ancient aqueous processes, but processes that formed host remain elusive. Here, we use high-resolution orbital and topographic datasets from HiRISE, CaSSIS CTX instruments to investigate characterize fluvial sinuous ridges (FSRs), found across Planum region. FSRs form segments up 70 km long, are 20-600 m wide, 9 in height, with sub-horizontal layering common ridge margins. Some comprise multi-story systems; many embedded within bedrock. We interpret as deposits episodically active, alluvial river systems (channel-belt overbank deposits). Thus, least some was by rivers, active wider region, though do not exclude other contributing its formation well. presence floodplains increases chances detecting signs life. Future exploration can verify interpretation provides an opportunity oldest Solar System.