Geologically recent gully–polygon relationships on Mars: Insights from the Antarctic Dry Valleys on the roles of permafrost, microclimates, and water sources for surface flow

• Published in: Icarus
• Main Authors: Levy, J. S., Head, J. W., Marchant, D. R., Dickson, J. L., Morgan, G. A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2009
• Subjects: Mars surface; Earth; Geological processes; Ices; Regoliths; Antarctic; The Antarctic; Antarc*; Ice; permafrost; wedge*
• Online Access: https://doi.org/10.1016/j.icarus.2008.12.043

We describe the morphology and spatial relationships between composite-wedge polygons and Mars-like gullies (consisting of alcoves, channels, and fans) in the hyper-arid Antarctic Dry Valleys (ADV), as a basis for understanding possible origins for martian gullies that also occur in association with polygonally patterned ground. Gullies in the ADV arise in part from the melting of atmospherically-derived, wind-blown snow trapped in polygon troughs. Snowmelt that yields surface flow can occur during peak southern hemisphere summer daytime insolation conditions. Ice-cemented permafrost provides an impermeable substrate over which meltwater flows, but does not significantly contribute to meltwater generation. Relationships between contraction crack polygons and sedimentary fans at the distal ends of gullies show deposition of fan material in polygon troughs, and dissection of fans by expanding polygon troughs. These observations suggest the continuous presence of meters-thick ice-cemented permafrost beneath ADV gullies. We document strong morphological similarities between gullies and polygons on Mars and those observed in the ADV Inland Mixed microclimate zone. On the basis of this morphological comparison, we propose an analogous, top–down melting model for the initiation and evolution of martian gullies that occur on polygonally-patterned, mantled surfaces. © 2009 Elsevier Inc. Received 29 May 2008; Revised 17 October 2008; Accepted 22 December 2008; Available online 21 January 2009. This work was made possible with support of JSL by the Rhode Island Space Grant Consortium, by NSF Grant ANT-0338291 to D.R.M. and J.W.H., NASA MDAP Grants NNG04GJ99G and NNG05GQ46G to J.W.H., NASA MFRP Grant NNX06AE32G to D.R.M. and J.W.H., and NASA Applied Information Systems Research Grant NNG05GA61G to J.W.H. Thanks are extended to Caleb Fassett and James Dickson for HiRISE image processing and to James Dickson, Douglas Kowalewski, Gareth Morgan, David Shean, and Kate Swanger for field support. Also, thanks to the ...