Modeling ammonia–ammonium aqueous chemistries in the Solar System’s icy bodies

Marion, G. M.; Kargel, Jeffrey S.; Catling, David C.; Lunine, Jonathan I.

doi:10.1016/j.icarus.2012.06.016

Cited by 59 publications

(57 citation statements)

References 106 publications

(162 reference statements)

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“…The Pitzer (Pitzer, 1973) and HKF (Helgeson et al, 1981, and references therein) equations are commonly used. The former equation has been used down to 173 K in the FREZCHEM code (Marion et al, 2012), but is derived from polynomial fits to experimental data. Thus, it has little predictive power and is restricted to species for which data are available at given T and P. The semi-empirical HKF equation models interactions between solute molecules in water, and does have predictive capabilities.…”

Section: Modeling At Low Temperature and High Pressurementioning

confidence: 99%

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Prerequisites for explosive cryovolcanism on dwarf planet-class Kuiper belt objects

Neveu

Desch

Shock

et al. 2015

Icarus

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Explosive extrusion of cold material from the interior of icy bodies, or cryovolcanism, has been observed on Enceladus and, perhaps, Europa, Triton, and Ceres. It may explain the observed evidence for a young surface on Charon (Pluto's surface is masked by frosts). Here, we evaluate prerequisites for cryovolcanism on dwarf planet-class Kuiper belt objects (KBOs). We first review the likely spatial and temporal extent of subsurface liquid, proposed mechanisms to overcome the negative buoyancy of liquid water in ice, and the volatile inventory of KBOs. We then present a new geochemical equilibrium model for volatile exsolution and its ability to drive upward crack propagation. This novel approach bridges geophysics and geochemistry, and extends geochemical modeling to the seldom-explored realm of liquid water at subzero temperatures. We show that carbon monoxide (CO) is a key volatile for gas-driven fluid ascent; whereas CO 2 and sulfur gases only play a minor role. N 2 , CH 4 , and H 2 exsolution may also drive explosive cryovolcanism if hydrothermal activity produces these species in large amounts (a few percent with respect to water). Another important control on crack propagation is the internal structure: a hydrated core makes explosive cryovolcanism easier, but an undifferentiated crust does not. We briefly discuss other controls on ascent such as fluid freezing on crack walls, and outline theoretical advances necessary to better understand cryovolcanic processes. Finally, we make testable predictions for the 2015 New Horizons flyby of the Pluto-Charon system.

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Section: Modeling At Low Temperature and High Pressurementioning

confidence: 99%

“…Very low temperatures (below 200 K) are required to prevent significant hydrolysis of CO over the age of the solar system. However, exceptionally cold NH 3 -H 2 O oceans may not preserve CO, as they could be highly alkaline (Marion et al, 2012).…”

Section: Fate Of Co In a Subsurface Oceanmentioning

confidence: 99%

Prerequisites for explosive cryovolcanism on dwarf planet-class Kuiper belt objects

Neveu

Desch

Shock

et al. 2015

Icarus

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“…FREZCHEM model FREZCHEM is an equilibrium chemical thermodynamic model parameterized for 5 concentrated electrolyte solutions (to ionic strengths = 20 molal) using the Pitzer approach (Pitzer, 1991(Pitzer, , 1995 for the temperature range from 173 to 298 K (CHEMCHAU version has temperature range from 273 to 373 K) and the pressure range from 1 to 1000 bars (Marion and Farren, 1999;Marion, 2001Marion, , 2002Marion et al, 2003Marion et al, , 2005Marion et al, , 2006Marion et al, , 2009aMarion et al, , 2009bMarion et al, , 2010aMarion et al, , 2010bMarion et al, , 2011Marion et al, , 2012Marion et al, , 2013Marion et al, , 2014. Pressure above 1 bar was first added in Marion et al (2005).…”

Section: Methodsmentioning

confidence: 99%

“…There have been numerous studies in recent years dealing with the chemistries of subsurface fluids on Titan, especially with respect to (NH 4 ) 2 SO 4 , NH 3 , and CH 4 •6H 2 O (Osegovic and Max, 2005;Atreya et al, 2006;Fortes et al, 2007;Spencer and Grinspoon, 2007;Grindrod et al, 2008;Tobie et al, 2009;Fortes and Choukroun, 2010;Sohl et al, 2010;Norman and Fortes, 2011;Fortes, 2012;Marion et al, 2012Marion et al, , 2014Vance et al, 2012;Glein, 2015). Cassini has discovered a subsurface water ocean on Titan (less et al, 2012), which was previously predicted by many interior models (Fortes, 2000;Baker et al, 2005;Tobie et al, 2005;Fortes et al, 2007;Lorenz et al, 2008;Sotin and Tobie, 2008;Tobie et al, 2009;Sohl et al, 2010).…”

Section: Applications To Titanmentioning

confidence: 95%

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Modeling nitrogen and methane with ethane and propane gas hydrates at low temperatures (173–290K) with applications to Titan

Marion

Kargel

Tan

2015

Icarus

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

2015

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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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Modeling ammonia–ammonium aqueous chemistries in the Solar System’s icy bodies

Cited by 59 publications

References 106 publications

Prerequisites for explosive cryovolcanism on dwarf planet-class Kuiper belt objects

Prerequisites for explosive cryovolcanism on dwarf planet-class Kuiper belt objects

Modeling nitrogen and methane with ethane and propane gas hydrates at low temperatures (173–290K) with applications to Titan

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

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