The effect of Rayleigh–Taylor instabilities on the thickness of undifferentiated crust on Kuiper Belt Objects

Rubin, M.; Desch, S. J.; Neveu, Marc

doi:10.1016/j.icarus.2014.03.047

Cited by 27 publications

(39 citation statements)

References 44 publications

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“…Thermal calculations by Castillo‐Rogez and McCord [] show a temperature gradient at shallow areas. Although dependent on the model assumption, at 10 Myr from accretion, |d T /d z |∼2×10 −3 K m −1 , which is consistent with the estimation for at the early stage by Rubin et al []. After that, the temperature gradient decreases to 0.6 − 1.0×10 −3 K m −1 and becomes stable for a few billion years [ Castillo‐Rogez and McCord , ].…”

Section: Stability Of the Crustsupporting

confidence: 86%

“…For the stability of the crust, we use an equation derived by Rubin et al []. The critical viscosity of the ice for the Rayleigh‐Taylor instability η crit is given by

η_{crit} = ([], {(n - 1)}^{1 / n} \frac{C_{L normalΔρ}}{2 n}) {((), \frac{Z_{0}}{L})}^{(n - 1) / n} normalΔρgLτ,

where C L Δ ρ ≈0.76 is a dimensionless quantity depending on the geometry and rheology [ Rubin et al , ]. Δ ρ and g = 0.27 m s −2 are the density difference between the crust and the pure ice, and the acceleration due to gravity on the surface of Ceres, respectively.…”

Section: Stability Of the Crustmentioning

confidence: 99%

“…The index that relates the stress σ and the strain rate

\overset{ϵ}{true}

through

\overset{ϵ}{true} \propto σ^{n}

is n . At around 150 K, n should be 1.8 because grain boundary sliding dominates the creep of the ice [ Rubin et al , ]. As shown in section 2.3, the critical temperature for the stability of the crust is not so different from 150 K. Thus, we use n = 1.8 in this work.…”

Section: Stability Of the Crustmentioning

confidence: 99%

“…L is given as

L = \frac{nR T_{0}}{E_{a}} \frac{T_{0}}{| normald T / normald z |},

where R and T 0 are the gas constant and the temperature at the interface between the crust and the underlying ice, respectively. The activation energy E a = 49 kJ mol −1 is a reasonable value for grain boundary sliding, which dominates the creep of the ice [ Rubin et al , ]. |d T /d z | is the temperature gradient across the crust with z = 0 at the interface.…”

Section: Stability Of the Crustmentioning

confidence: 99%

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Compositional diapirism as the origin of the low‐albedo terrain and vaporization at midlatitude on Ceres

Dake

Kurita

2014

JGR Planets

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Recent observations of Ceres, made using the Heterodyne Instrument for the Far Infrared on board the European Space Agency's Herschel Space Observatory, have shown that water vapor is emanated from the low‐albedo midlatitude regions. Based on the supposition that some dark spots on Europa may be caused by diapirism, we explored whether Ceres' environment also can induce compositional diapirism, and whether an upwelling diapir could explain the origin and distribution of the dark spots and vaporization of Ceres. If the density of the rock that constitutes Ceres is around 2700 kg m−3, the undifferentiated crust is stable over geological time periods at less than 180 K. At a surface temperature of 170 K, a diapir can reach the surface if the crust is a few tens of kilometers thick. Alternatively, if the surface temperature is 150 K, a large contrast in viscosity would prevent diapirs from reaching the surface. The relatively moderate surface temperature in the midlatitude regions of Ceres may be the reason for the formation of dark terrains occurring only in such areas. Our finite difference calculations do not show that diapirism melts the surface ice because the temperature gradient changes very little. However, if the observed vapor emission is caused by the sublimation of fresh ice, compositional diapirism could be the mechanism that transports the fresh ice to the surface. In addition to other mechanisms such as cryovolcanism, diapirism is a valid hypothesis for explaining the dark terrain and vapor emissions of Ceres.

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Section: Stability Of the Crustsupporting

confidence: 86%

“…For the stability of the crust, we use an equation derived by Rubin et al []. The critical viscosity of the ice for the Rayleigh‐Taylor instability η crit is given by

η_{crit} = ([], {(n - 1)}^{1 / n} \frac{C_{L normalΔρ}}{2 n}) {((), \frac{Z_{0}}{L})}^{(n - 1) / n} normalΔρgLτ,

Section: Stability Of the Crustmentioning

confidence: 99%

“…The index that relates the stress σ and the strain rate

\overset{ϵ}{true}

through

\overset{ϵ}{true} \propto σ^{n}

Section: Stability Of the Crustmentioning

confidence: 99%

“…L is given as

L = \frac{nR T_{0}}{E_{a}} \frac{T_{0}}{| normald T / normald z |},

Section: Stability Of the Crustmentioning

confidence: 99%

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Compositional diapirism as the origin of the low‐albedo terrain and vaporization at midlatitude on Ceres

Dake

Kurita

2014

JGR Planets

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“…Third, chemical interactions between water and rock may leach out radiogenic elements, such as potassium, from core silicates [ Castillo‐Rogez and Lunine , ; Castillo‐Rogez and McCord , ]. Similarly, salt or volatile antifreezes such as ammonia, invoked as a requirement for liquid over the long term [e.g., Desch et al , ; Castillo‐Rogez and McCord , ; Rubin et al , ], may be produced or consumed in water‐rock reactions [ Matson et al , ; Fortes et al , ; Glein et al , ]. Finally, water can circulate through pores or fractures in the core and efficiently transport heat outward in a convective pattern known as hydrothermal circulation [ Young , ; Young et al , ].…”

Section: Introductionmentioning

confidence: 99%

Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution

2015

Self Cite

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Observations and models of Ceres suggest that its evolution was shaped by interactions between liquid water and silicate rock. Hydrothermal processes in a heated core require both fractured rock and liquid. Using a new core cracking model coupled to a thermal evolution code, we find volumes of fractured rock always large enough for significant interaction to occur. Therefore, liquid persistence is key. It is favored by antifreezes such as ammonia, by silicate dehydration which releases liquid, and by hydrothermal circulation itself, which enhances heat transport into the hydrosphere. The effect of heating from silicate hydration seems minor. Hydrothermal circulation can profoundly affect Ceres' evolution: it prevents core dehydration via "temperature resets, " core cooling events lasting ∼50 Myr during which Ceres' interior temperature profile becomes very shallow and its hydrosphere is largely liquid. Whether Ceres has experienced such extensive hydrothermalism may be determined through examination of its present-day structure. A large, fully hydrated core (radius 420 km) would suggest that extensive hydrothermal circulation prevented core dehydration. A small, dry core (radius 350 km) suggests early dehydration from short-lived radionuclides, with shallow hydrothermalism at best. Intermediate structures with a partially dehydrated core seem ambiguous, compatible both with late partial dehydration without hydrothermal circulation, and with early dehydration with extensive hydrothermal circulation. Thus, gravity measurements by the Dawn orbiter, whose arrival at Ceres is imminent, could help discriminate between scenarios for Ceres' evolution.

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Geochemistry, thermal evolution, and cryovolcanism on Ceres with a muddy ice mantle

Neveu

Desch

2015

Geophysical Research Letters

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We present a model of the internal evolution of Ceres consistent with pre‐Dawn observations and preliminary data returned by Dawn. We assume that Ceres accreted ice and both micron‐ and millimeter‐sized rock particles and that micron‐sized fines stayed suspended in liquid during differentiation. We conclude that aqueously altered grains were emplaced on Ceres's surface during the first tens of megayears of its evolution. Our geochemical simulations suggest that Ceres's unusual surface mineralogy is consistent with aqueous alteration of CM material, possibly by NH3‐bearing fluid. Thermal evolution simulations including insulating fines yield present‐day liquid at depth if Ceres has a small core or no core at all; otherwise, they yield temperatures at the core‐mantle boundary of 240–250 K, just warm enough for chloride brines to persist and be freezing today. We hypothesize that ongoing freezing may overpressurize liquid or briny reservoirs, driving cryovolcanic outflow whose surface expression may have been observed by Dawn at Ceres's “bright spots.” These outflows may contribute to the water vapor being produced at Ceres.

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The effect of Rayleigh–Taylor instabilities on the thickness of undifferentiated crust on Kuiper Belt Objects

Cited by 27 publications

References 44 publications

Compositional diapirism as the origin of the low‐albedo terrain and vaporization at midlatitude on Ceres

Compositional diapirism as the origin of the low‐albedo terrain and vaporization at midlatitude on Ceres

Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution

Geochemistry, thermal evolution, and cryovolcanism on Ceres with a muddy ice mantle

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