Fire and Water - The Subsurface Perspective of Mars' Elysium Region

Elysium Planitia, the youngest volcanic province on Mars, has been built by lava flows over the last half a billion years. The regular cadence of eruptions over this time period strongly suggests volcanism is very much an ongoing processes on Mars, with lava likely to flow on the planet's surface in the future. The accumulation of basalt though, is only half of the Elysium story. Between eruptions, or possibly accompanying them, outflow channels were carved into the landscape. The concurrence of volcanism with liquid water is of consequence to our assessment of martian habitability and raises questions about the potential for associated climatic effects.

Incorporating over a decade's worth of data collected by the SHAllow RADar (SHARAD) on the Mars Reconnaissance Orbiter, we will present a perspective of Elysium only possible from the use of radar sounder data. Extracting subsurface information from >1000 SHARAD tracks, we are able to three dimensionally visualize the upper >100 m of the entire volcanic province, including reconstructing multiple overlapping flow complexes, many of which are completely buried by younger lavas. Through our subsurface visualizations we are able to test image based mapping efforts and 'peel back' the lava that fills the large scale flood channels.

Recovering the original channel forms of the outflow channels has revealed that previous studies have underestimated the full extent of erosion, suggesting that the floods responsible carried a greater volume of water than was previously appreciated. Radar studies therefore, offer a means to better constrain the liquid water inventory of late Mars.

Finally, our detailed overview of the geologic history of Elysium will provide excellent context for the InSight Mission, which is due to touch down within the region in November.