Widespread excess ice in Arcadia Planitia, Mars

The distribution of subsurface water ice on Mars is a key constraint on past climate, while the volumetric concentration of buried ice (pore‐filling versus excess) provides information about the process that led to its deposition. We investigate the subsurface of Arcadia Planitia by measuring the de...

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Bibliographic Details
Published in:Geophysical research letters 2015-08, Vol.42 (16), p.6566-6574
Main Authors: Bramson, Ali M., Byrne, Shane, Putzig, Nathaniel E., Sutton, Sarah, Plaut, Jeffrey J., Brothers, T. Charles, Holt, John W.
Format: Article
Language:English
Subjects:
Accumulation
Climate
Climate models
Concentration (composition)
Craters
Deposition
Depth
Dielectric constant
digital terrain models
Excess water
Geophysics
Ground ice
Ice
Information dissemination
Information processing
layered subsurface
Layering
Mapping
Mars
Mars craters
Mars ice
Mars midlatitude ice
Permittivity
Plains
Preservation
Radar
Reflection
Saturn
Sounding
Soundings
Space exploration
spacecraft observations
subsurface radar
Subsurface water
Terraced
terraced craters
Terraces
Terracing
Water ice
Water scarcity
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Summary:The distribution of subsurface water ice on Mars is a key constraint on past climate, while the volumetric concentration of buried ice (pore‐filling versus excess) provides information about the process that led to its deposition. We investigate the subsurface of Arcadia Planitia by measuring the depth of terraces in simple impact craters and mapping a widespread subsurface reflection in radar sounding data. Assuming that the contrast in material strengths responsible for the terracing is the same dielectric interface that causes the radar reflection, we can combine these data to estimate the dielectric constant of the overlying material. We compare these results to a three‐component dielectric mixing model to constrain composition. Our results indicate a widespread, decameters‐thick layer that is excess water ice ~104 km3 in volume. The accumulation and long‐term preservation of this ice is a challenge for current Martian climate models. Key Points Terraced craters: abundant in Arcadia Planitia, indicate subsurface layering A widespread subsurface interface is also detected by SHARAD Combining data sets yields dielectric constants consistent with decameters of excess water ice
ISSN:0094-8276
1944-8007
DOI:10.1002/2015GL064844