Modeling of ice pinnacle formation on Callisto. Issue 1 (16th January 2016)

• Record Type: Journal Article
• Authors: White, Oliver L.; Umurhan, Orkan M.; Moore, Jeffrey M.; Howard, Alan D.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 1(2016:Jan.)
• Page Start: 21
• Page End: 45
• Publication Date: 2016-01-16
• Subjects: Callisto -- pinnacle -- sublimation -- ice -- modeling; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1002/2015JE004846
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: Callisto's pinnacle terrain has been interpreted to form through sublimation weathering of bedrock and subsequent deposition of the sublimated ice in local cold traps on peaks and crater rims. To investigate how these processes are affected by environmental parameters, including solar illumination and the composition and concentration of ices in the crust, we employ the MARSSIM landform evolution model and advance its treatment of the physics that underlies the relevant processes. Both ice sublimation and deposition are controlled by surface temperature, which we calculate based on energy contributions from both insolation and thermal reradiation from the surrounding landscape. We perform 4.5 Gyr duration simulations whereby we separately consider and model CO2 and H2 O as the crustal ice species. We find that sublimating a crustal content of 10% CO2 ice (a reasonable but arbitrarily selected value) yields present‐day landform degradation and regolith coverage that is comparable to what is observed on Callisto. In our H2 O ice simulations we reproduce the essential features of pinnacle ice distribution at both the equator and midlatitudes. Our present nominal crustal H2 O ice content is 33%, which produces a maximum pinnacle ice thickness of 64 m. Pinnacle height is likely limited by collapse or mass wasting of the ice once it reaches a certain thickness. Key Points: We use a physics‐based model to study evolution of Callisto's pinnacle terrain Landform degradation is mainly the result of sublimation of crustal CO2 ice We reproduce pinnacle morphology via sublimation and deposition of H2 O ice