Ancient deltas on Mars: outstanding targets for martian habitability?

Wednesday, 17 December 2014: 11:50 AM
Sanjeev Gupta, Imperial College London, London, SW7, United Kingdom, Peter Fawdon, Open University, Milton Keynes, United Kingdom, Peter M Grindrod, University College London, London, United Kingdom, Matthew R Balme, Open University, Milton Keynes, MK7, United Kingdom, Ernst Hauber, German Aerospace Centre (DLR), Berlin, Germany, Nicholas H Warner, SUNY at Geneseo, Geneseo, NY, United States and Jan-Peter Muller, University College London, Mullard Space Science Laboratory, London, United Kingdom
The identification of putative ancient deltaic sedimentary systems on Mars has been both exciting and controversial. Our excitement is elicted by the potential provided by deltas as evidence for standing bodies of water associated with the deltas, and the resulting implications for both the ancient climate of Mars and ancient habitability. The controversy stems from how confident can we be in the identification of ancient deltaic systems from orbital data, and how robust are our assertions about the habitability potential of such settings. Delta systems in particular are key astrobiological targets because at their distal toes fine-grained sediment (ie., clays) settle from suspension in a lower energy setting and they are commonly characterised by high rates of sedimentation. This leads to high preservation potential of biosignatures. Targeting of future Mars rovers to investigate deltaic landing sites requires better understanding of these issues to reduce exploration risk. In this presentation, we describe the key criteria that enable us to make robust interpretations of deltaic stratigraphy and constrain delta evolution for martian systems. In particular, the past 10 years has seen in a revolution in our process understanding of terrestrial delta systems through a combination of field, experimental and numerical modelling studies. Analysis of martian deltas has much to gain from these results. We go on to consider why deltaic systems offer potential as astrobiological target paleoenvironments. We use the exhumed delta system (Hypanis delta system) at the termination of Hypanis Vallis, 11.8°N, 314.96°E as a case example. This system, situated in Xanthe Terra, comprises layered sedimentary rocks with an overall multi-lobate geometry and associated inverted channel networks. The Hypanis 'delta' is a proposed landing site for the ExoMars rover and also for the NASA 2020 mission.