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C. Barnhart, E. Asphaug, S. Tulaczyk, E. Kraal (UCSC), J. Moore (NASA Ames)
A number of studies have examined from first principles the thermal evolution and residence time of liquid water and ice cover in martian environments (McKay et al [1985]; Moore et al. [1995]; Krevslavsky and Head [2002]). However, the linked geomorphic evolution of such a system has yet to be adequately characterized. We explore the geomorphic effects of thick glacial ice cover under martian conditions. Ice sheet longevity depends, critically, on the sublimation rate. The sublimation rate is sensitive to solar irradiation, atmospheric pressure, and winds. A sediment veneer blanketing ice can lower sublimation rates by many orders of magnitude. A simple 1D thermal model show that under a sublimation rate of 1 mm/yr a 1km column of water will freeze in ~40,000yrs and sublime in 1 Mys—spanning orbital cycles responsible for climatic forcing.
A lake with thick ice cover will experience volumetric strain from ice/water/brine density variations as the systerm responds to temperature variation. Thermal expansion and freeze-out leads to strain accommodation and slip, resulting in mass wasting and erosional deformation at the ice margin. The mechanism could repeat with climate cycles. We present a 1D thermodynamical ice-lake model with energy and sediment inputs and brine-ice interactions. 1D results are adopted for 2D modified finite element models of ice evolution within evolving crater lake boundary and thermal conditions, coupled to models for margin deformation and erosion.
This effort is supported by NASA’s Mars Fundamental Research Program and by the University Affiliated Research Center (UARC) at NASA Ames.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.