Water generation and transport below Europa's strike-slip faults

Kalousová, Klára; Souček, Ondřej; Tobie, G.; Choblet, G.; Čadek, O.

doi:10.1002/2016je005188

Cited by 43 publications

(63 citation statements)

References 75 publications

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“…; Kalousová et al, 2016;Neveu et al, 2015;Quick & Marsh, 2016;Showman et al, 2004). Future models could examine more complex chemical systems, melt transport through fractures, and Rayleigh-Taylor instabilities, as well as the influence of topographically induced pressure gradients (cf.…”

Section: Discussionmentioning

confidence: 99%

Compaction and Melt Transport in Ammonia‐Rich Ice Shells: Implications for the Evolution of Triton

2018

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Ammonia, if present in the ice shells of icy satellites, could lower the temperature for the onset of melting to 176 K and create a large temperature range where partial melt is thermally stable. The evolution of regions of ammonia‐rich partial melt could strongly influence the geological and thermal evolution of icy bodies. For melt to be extracted from partially molten regions, the surrounding solid matrix must deform and compact. Whether ammonia‐rich melts sink to the subsurface ocean or become frozen into the ice shell depends on the compaction rate and thermal evolution. Here we construct a model for the compaction and thermal evolution of a partially molten, ammonia‐rich ice shell in a one‐dimensional geometry. We model the thickening of an initially thin ice shell above an ocean with 10% ammonia. We find that ammonia‐rich melts can freeze into the upper 5 to 10 km of the ice shell, when ice shell thickening is rapid compared to the compaction rate. The trapping of near‐surface volatiles suggests that, upon reheating of the ice shell, eutectic melting events are possible. However, as the ice shell thickening rate decreases, ammonia‐rich melt is efficiently excluded from the ice shell and the bulk of the ice shell is pure water ice. We apply our results to the thermal evolution of Neptune's moon Triton. As Triton's ice shell thickens, the gradual increase of ammonia concentration in Triton's subsurface ocean helps to prevent freezing and increases the predicted final ocean thickness by up to 50 km.

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Section: Discussionmentioning

confidence: 99%

Compaction and Melt Transport in Ammonia‐Rich Ice Shells: Implications for the Evolution of Triton

2018

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“…The fate of these putative melt pockets is, however, difficult to determine. For such shallow depths, it is possible that part of the melt reaches the surface (Lesage et al, 2020;Mitri et al, 2008;Showman & Han, 2004), while most of the melt probably sinks to the subsurface ocean via percolation through the solid ice matrix (Kalousová et al, 2014(Kalousová et al, , 2016. The occurrence of these melt pockets may therefore favor material exchange between the subsurface ocean, the ice layer, and potentially the surface.…”

Section: Occurrence Of Meltingmentioning

confidence: 99%

Tidally Heated Convection and the Occurrence of Melting in Icy Satellites: Application to Europa

et al. 2020

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Observations of icy satellites have revealed widespread marks of cryovolcanism. Because aqueous cryomagmas are negatively buoyant, two processes are required to explain these observations: one mechanism to generate melt close enough to the surface and another one to transport this melt to the surface. Here, we investigate the generation of melting in a systematic way, using a set of 85 numerical simulations where we vary the viscosity contrast, Rayleigh number, and tidal heating rate. Applied to Europa, considering a hydrosphere composed of pure water, our simulations suggest that isolated melt pockets can be generated close to the surface ( ∼5 km) as long as the ice layer thickness ( d*) remains modest ( 15≤d*≤35 km). However, the generation of melting becomes increasingly difficult as the amount of antifreeze compounds in the subsurface ocean increases. Furthermore, the proportion of melting increases very sharply with increasing tidal heating rate. In particular, when the tidal heating rate exceeds a threshold, an asymptotic regime is reached where the surface heat flux remains constant indicating that the tidal heat generated above this threshold is only used for melting the ice shell. In that regime, we found a direct relationship between the surface heat flux and d*. Finally, we provide a new assessment of Europa's thermal state. Based on available constraints, we propose that the ice shell thickness should exceed 15 km. However, d*∼15–35 km implies a tidal power ( >2 TW) much larger than expected. An extrapolation of the trends suggested by our results indicates that a more reasonable tidal power ( ∼1 TW) would involve d*∼50–90 km.

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“…Studies that leverage numerical predictions of mid-ocean ridge evolution to interpret observed seafloor morphology have illuminated the processes of melting and deformation and identified key controls on seafloor morphology and faulting (e.g., Behn & Ito, 2008;Buck et al, 2005;Howell et al, 2016;Olive et al, 2015;Tian & Choi, 2017). brittle layer (lithosphere) for simplified rheologies (e.g., Mitri & Showman, 2005), and of melt migration beneath imposed tectonic features (Kalousová et al, 2016). brittle layer (lithosphere) for simplified rheologies (e.g., Mitri & Showman, 2005), and of melt migration beneath imposed tectonic features (Kalousová et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Band Formation and Ocean‐Surface Interaction on Europa and Ganymede

Howell

Pappalardo

2018

Geophysical Research Letters

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Geologic activity in the outer H2O ice shells of Europa and Ganymede, Galilean moons of Jupiter, may facilitate material exchange between global water oceans and the icy surface, fundamentally affecting potential habitability and the future search for life. Spacecraft imagery reveals surfaces rich with tectonic bands, predominantly attributed to the extension of brittle ice overlaying a convecting ice layer. However, the details of band‐forming processes and links to potential ocean‐surface exchange have remained elusive. We simulate ice shell faulting and convection with two‐dimensional numerical models and track the movement of “fossil” ocean material frozen into the base of the ice shell and deformed through geologic time. We find that distinct band types form within a spectrum of extensional terrains correlated to lithosphere strength, governed by lithosphere thickness and cohesion. Furthermore, we find that smooth bands formed in weak lithosphere promote exposure of fossil ocean material at the surface.

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Water generation and transport below Europa's strike-slip faults

Cited by 43 publications

References 75 publications

Compaction and Melt Transport in Ammonia‐Rich Ice Shells: Implications for the Evolution of Triton

Compaction and Melt Transport in Ammonia‐Rich Ice Shells: Implications for the Evolution of Triton

Tidally Heated Convection and the Occurrence of Melting in Icy Satellites: Application to Europa

Band Formation and Ocean‐Surface Interaction on Europa and Ganymede

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