Recent Tectonic Activity on Pluto Driven by Phase Changes in the Ice Shell

Abstract

The New Horizons spacecraft has found evidence for geologic activity on the surface of Pluto, including extensional tectonic deformation of its water ice bedrock (see Moore et al., 2016). One mechanism that could drive extensional tectonic activity is global surface expansion due to the partial freezing of an ocean. We use updated physical properties for Pluto and simulate its thermal evolution to understand the survival of a possible subsurface ocean. For thermal conductivities of rock less than 3 W m${}^{-1}$ K${}^{-1}$, an ocean forms and at least partially freezes, leading to recent extensional stresses in the ice shell. In scenarios where the ocean freezes and the ice shell is thicker than $260$ km, ice II forms and causes global volume contraction. Since there is no evidence for recent compressional tectonic features, we argue that ice II has not formed and that Pluto's ocean has likely survived to present day.

18 pages, 3 figures. Geophysical Research Letters, in press

References in corpus (4)

• The Pluto system: Initial results from its exploration by New Horizons
• The Geology of Pluto and Charon Through the Eyes of New Horizons
• Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigor
• Tectonic Activity on Pluto After the Charon-Forming Impact

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