Cryovolcano (original) (raw)

Type of volcano that erupts volatiles such as water, ammonia or methane, instead of molten rock

An image of two large cryovolcanoes

Leviathan Patera (center) and Ruach Planitia (upper left), two large cryovolcanic features on Neptune's moon Triton

A cryovolcano (sometimes informally referred to as an ice volcano) is a type of volcano that erupts gases and volatile material such as liquid water, ammonia, and hydrocarbons. The erupted material is collectively referred to as cryolava; it originates from a reservoir of subsurface cryomagma. Cryovolcanic eruptions can take many forms, such as fissure and curtain eruptions, effusive cryolava flows, and large-scale resurfacing, and can vary greatly in output volumes. Immediately after an eruption, cryolava quickly freezes, constructing geological features and altering the surface.

Although rare in the inner Solar System, past and recent cryovolcanism is common on planetary objects in the outer Solar System, especially on the icy moons of the giant planets and potentially amongst the dwarf planets as well. As such, cryovolcanism is important to the geological histories of these worlds, constructing landforms or even resurfacing entire regions. Despite this, only a few eruptions have ever been observed in the Solar System. The sporadic nature of direct observations means that the true number of extant cryovolcanoes is contentious.

Like volcanism on the terrestrial planets, cryovolcanism is driven by escaping internal heat from within a celestial object, often supplied by extensive tidal heating in the case of the moons of the giant planets. However, isolated dwarf planets are capable of retaining enough internal heat from formation and radioactive decay to drive cryovolcanism on their own, an observation which has been supported by both in situ observations by spacecraft and distant observations by telescopes.

Etymology and terminology

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The term cryovolcano was coined by Steven K. Croft in a 1987 conference abstract at the Geological Society of America (GSA) Abstract with Programs. The term is ultimately a combination of cryo-, from the Ancient Greek κρῠ́ος (krúos, meaning cold or frost), and volcano.[1][2]: 492 In general, terminology used to describe cryovolcanism is analogous to volcanic terminology:

As cryovolcanism largely takes place on icy worlds, the term ice volcano is sometimes used colloquially.[8]

Types of cryovolcanism

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Explosive eruptions

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A diagram of Enceladus's interior structure

Diagram of Enceladus's south polar plumes, an example of explosive cryovolcanism, and Enceladus's internal ocean

Explosive cryovolcanism, or cryoclastic eruptions, is expected to be driven by the exsolvation of dissolved volatile gasses as pressure drops whilst cryomagma ascends, much like the mechanisms of explosive volcanism on terrestrial planets. Whereas terrestrial explosive volcanism is primarily driven by dissolved water (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2), explosive cryovolcanism may instead be driven by methane (CH4) and carbon monoxide (CO). Upon eruption, cryovolcanic material is pulverized in violent explosions much like volcanic ash and tephra, producing cryoclastic material.[4]: 768

Effusive cryovolcanism takes place with little to no explosive activity and is instead characterized by widespread cryolava flows which cover the pre-existing landscape. In contrast to explosive cryovolcanism, no instances of active effusive cryovolcanism have been observed. Structures constructed by effusive eruptions depend on the viscosity of the erupted material. Eruptions of less viscous cryolava can resurface large regions and form expansive, relatively flat plains, similar to shield volcanoes and flood basalt eruptions on terrestrial planets. More viscous erupted material does not travel as far, and instead can construct localized high-relief features such as cryovolcanic domes.[3]: 199–200

For cryovolcanism to occur, three conditions must be met: an ample supply of cryomagma must be produced in a reservoir, the cryomagma must have a force driving ascent, and conduits need to be formed to the surface where cryomagma is able to ascend.[3]: 180–181

A major challenge in models of cryovolcanic mechanisms is that liquid water is substantially denser than water ice, in contrast to silicates where liquid magma is less dense than solid rock. As such, cryomagma must overcome this in order to erupt onto a body's surface.[3]: 180–182 A variety of hypotheses have been proposed by planetary scientists to explain how cryomagma erupts onto the surface:

In addition to overcoming the density barrier, cryomagma also requires a way to reach the surface in order to erupt. Fractures in particular, either the result of global or localized stress in the icy crust, providing potential eruptive conduits for cryomagma to exploit. Such stresses may come from tidal forces as an object orbits around a parent planet, especially if the object is on an eccentric orbit or if its orbit changes. True polar wander, where the object's surface shifts relative to its rotational axis, can introduce deformities in the ice shell. Impact events also provide an additional source of fracturing by violently disrupting and weakening the crust.[3]: 185

An alternative model for cryovolcanic eruptions invokes solid-state convection and diapirism. If a portion of an object's ice shell is warm and ductile enough, it could begin to convect, much as the Earth's mantle does.[11] As the ice convects, warmer ice becomes buoyant relative to surrounding colder ice, rising towards the surface. The convection can be aided by local density differences in the ice due to an uneven distribution of impurities in the ice shell. If the warm ice intrudes on particularly impure ice (such as ice containing large amounts of salts), the warm ice can lead to the melting of the impure ice. The melting may then go on to erupt or uplift terrain to form surface diapirs.[3]: 189–190

Cryomagma reservoir generation

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A diagram of Europa's internal structure

A diagram of Europa's probable internal structure, with a hot core tidally heated by Jupiter's influence. A global subsurface ocean exists underneath Europa's surface, with localized melting possibly occurring within its ice shell

Cryovolcanism implies the generation of large volumes of molten fluid in the interiors of icy worlds. A primary reservoir of such fluid are subsurface oceans.[3]: 167 Subsurface oceans are widespread amongst the icy satellites of the giant planets[3]: 167 and are largely maintained by tidal heating, where the moon's slightly eccentric orbit allows the rocky core to dissipate energy and generate heat.[12]: 675 Evidence for subsurface oceans also exist for the dwarf planets Pluto[13] and, to a lesser extent, Ceres,[14][15] Eris, Makemake,[16]: 8 Sedna, Gonggong, and Quaoar.[17]: 8 In the case of Pluto and the other dwarf planets, there is comparatively little, if any, long-term tidal heating. Thus, heating must largely be self-generated, primarily coming from the decay of radioactive isotopes in their rocky cores.[3]: 171

Reservoirs of cryomagma can hypothetically form within the shell of an icy world as well, either from direct localized melting or the injection of cryomagma from a deeper subsurface ocean. A convective layer in the ice shell can generate warm plumes that spread laterally at the base of the brittle icy crust. The intruding warm ice can melt impure ice, forming a lens-shaped region of melting.[18][3]: 173 Other proposed methods of producing localized melts include the buildup of stress within strike-slip faults, where friction may be able to generate enough heat to melt ice; and impact events that violently heat the impact site.[3]: 174 Intrusive models, meanwhile, propose that a deeper subsurface ocean directly injects cryomagma through fractures in the ice shell, much like volcanic dike and sill systems.[3]: 173–174

Cryomagma composition

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Water is expected to be the dominant component of cryomagmas. Besides water, cryomagma may contain additional impurities, drastically changing its properties.[3]: 162 Certain compounds can lower the density of cryomagma. Ammonia (NH3) in particular may be a common component of cryomagmas, and has been detected in the plumes of Saturn's moon Enceladus. A partially frozen ammonia-water eutectic mixture can be positively buoyant with respect to the icy crust, enabling its eruption.[4]: 766–767 Methanol (CH3OH) can lower cryomagma density even further, whilst significantly increasing viscosity.[3]: 178 Conversely, some impurities can increase the density of cryomagma. Salts, such as magnesium sulfate (MgSO4) and sodium sulfate (Na2SO4) significantly increases density with comparatively minor changes in viscosity. Salty or briny cryomagma compositions may be important cryovolcanism on Jupiter's icy moons, where salt-dominated impurities are likely more common.[10][3]: 183 Besides affecting density and viscosity, the inclusions of impurities—particularly salts and especially ammonia—can encourage melting by significantly lowering the melting point of cryomagma.[4]: 766

Properties of hypothesized cryomagmas[19][3]: 178

Cryomagma composition, mass % Melting point (K) Liquid density (g/cm3) Liquid viscosity (Pa·s) Solid density (g/cm3)
Pure water100% H2O 273 1.000 0.0017 0.917
Brine81.2% H2O, 16% MgSO4, 2.8% Na2SO4 268 1.19 0.007 1.13
Ammonia and water67.4% H2O, 32.6% NH3 176 0.946 4 0.962
Ammonia, water, and methanol47% H2O, 23% NH3, 30% CH3OH 153 0.978 4,000 –
Nitrogen and methane86.5% N2, 13.5% CH4 62 0.783 0.0003 –
Basaltic lava (comparison)[20]: 23–25 – – ~10-100 –

Although there are broad parallels between cryovolcanism and terrestrial (or "silicate") volcanism, such as the construction of domes and shields, the definitive identification of cryovolcanic structures is difficult. The unusual properties of water-dominated cryolava, for example, means that cryovolcanic features are difficult to interpret using criteria applied to terrestrial volcanic features.[3]: 162 [2]: 487

Bright spots inside Occator

Bright faculae on the floor of the Occator impact basin on Ceres, with Cerealia Facula at center

Ceres is the innermost object in the Solar System known to be cryovolcanically active. Upon the arrival of the Dawn orbiter in March 2015,[21] the dwarf planet was discovered to have numerous bright spots (designated as faculae) located within several major impact basins, most prominently in the center of Occator Crater. These bright spots are composed primarily of various salts, and are hypothesized to have formed from impact-induced upwelling of subsurface material that erupt brine to Ceres's surface. The distribution of hydrated sodium chloride on one particular bright spot, Cerealia Facula, indicates that the upwelling occurred recently or is currently ongoing. That brine exists in Ceres's interior implies that salts played a role in keeping Ceres's subsurface ocean liquid, potentially even to the present day.[22]: 786 Dawn also discovered Ahuna Mons and Yamor Mons (formerly Ysolos Mons), two prominent isolated mountains which are likely young cryovolcanic domes.[23][3]: 213,215 It is expected that cryovolcanic domes eventually subside after becoming extinct due to viscous relaxation, flattening them. This would explain why Ahuna Mons appears to be the most prominent construct on Ceres, despite its geologically young age.[23]

Europa receives enough tidal heating from Jupiter to sustain a global liquid water ocean. Its surface is exceedingly young, at roughly 60 to 90 million years old.[24]: 452 [25] Its most striking features, a dense web of linear cracks and faults termed lineae, appear to be the sites of active resurfacing on Europa, proceeding in a manner similar to Earth's mid-ocean ridges.[26] In addition to this, Europa may experience a form of subduction, with one block of its icy crust sliding underneath another.[25]

Despite its young surface age, few, if any, distinct cryovolcanoes have been definitively identified on the Europan surface in the past.[3]: 193–194 Nevertheless, observations of Europa from the Hubble Space Telescope (HST) in December 2012 detected columns of excess water vapor up to 200 kilometres (120 miles) high, hinting at the existence of weak, possibly cryovolcanic plumes. The plumes were observed again by the HST in 2014. However, as these are distant observations, the plumes have yet to be definitively confirmed as eruptions.[27][28] Recent analyses of some Europan surface features have proposed cryovolcanic origins for them as well. In 2011, Europa's chaos terrain, where the crust appears especially disrupted, was interpreted by a team of researchers as the site of very shallow cryomagma lakes. As these subsurface lakes melt and refreeze, they fracture Europa's crust into small blocks, creating the chaos terrain.[18] Later, in 2023, a field of cryovolcanic cones was tentatively identified near the western edge of Argadnel Regio, a region in Europa's southern hemisphere.[29][30]

Ganymede's surface, like Europa's, is heavily tectonized yet appears to have few cryovolcanic features.[31] By 2009, at least 30 irregularly-shaped depressions (termed paterae) were identified on Ganymede's surface from Voyager and Galileo imagery. The paterae have been hypothesized by several teams of planetary scientists as caldera-like cryovolcanic vents. However, conclusive evidence for a cryovolcanic origin of these structures remains elusive in imagery.[32][33]: 863–864

Image of Enceladus's plumes

Enceladus's south polar plumes

Saturn's moon Enceladus is host to the most dramatic example of cryovolcanism yet observed, with a series of vents erupting 250 kg of material per second that feeds Saturn's E ring.[34][35] These eruptions take place across Enceladus's south polar region, sourced from four major ridges which form a region informally known as the Tiger Stripes.[36] Enceladus's cryovolcanic activity is sustained by a global subsurface ocean.[37][38]

Other regions centered on Enceladus's leading and trailing hemispheres—the hemispheres that "face" towards or against the direction of Enceladus's orbit—exhibit similar terrain to that of the Tiger Stripes, possibly indicating that Enceladus has experienced discrete periods of heightened cryovolcanism in the past.[37]: 42

Saturn's moon Titan has a dense atmospheric haze layer which permanently obscures visible observations of its surface features, making the definitive identification of cryovolcanic structures especially difficult. Titan has an extensive subsurface ocean,[39] encouraging searches for evidence of cryovolcanism. From Cassini radar data, several features have been proposed as candidate cryovolcanoes, most notably Doom Mons, a mountain reminiscent of a shield or dome edifice; and the neighoring Sotra Patera, an ovular depression that resembles a caldera.[40]: 423 Several round lakes and depressions in Titan's polar regions show structural evidence of an explosive origin, including overlapping depressions, raised rims (or "ramparts"), and islands or mountains within depression rim.[41]: 1 These characteristics led to a 2020 hypothesis by planetary scientists Charles A. Wood and Jani Radebaugh that they form from either maar-like eruptions—forming by explosions of boiling subsurface liquid as it is rapidly heated by magma (in this case, cryomagma)[41]: 6 —or the flooding of collapse calderas.[41]: 13

On 24 January 1986, Uranus and its system of moons were explored for the first time by the Voyager 2 spacecraft.[42] Of Uranus's five major satellites, Miranda and Ariel appear to have unusually youthful surfaces indicative of relatively recent activity. Miranda in particular has extraordinarily varied terrain, with striking angular features known as the coronae cutting across older terrain. Inverness Corona is located near Miranda's south pole and is estimated to be less than 1 billion years old,[43] and broad similarities between Miranda's coronae and Enceladus's south polar region have been noted. These characteristics have led to several teams of researchers to propose a cryovolcanic origin of the coronae, where eruptions of viscous cryomagma form the structures with some tectonic involvement.[44]: 11 Ariel also exhibits widespread resurfacing, with large polygonal crustal blocks divided by large canyons (chasmata) with floors as young as ~0.8 ± 0.5 billion years old, while relatively flat plains may have been the site of large flood eruptions.[44]: 9–10

Evidence for relatively recent cryovolcanism on the other three round moons of Uranus is less clear. Titania hosts large chasms but does not show any clear evidence of cryovolcanism.[44]: 6 Oberon has a massive ~11 km (6.8 mi) high mountain that was observed on its limb at the time of Voyager 2's flyby; the precise origins of the mountain is unclear, but it may be of cryovolcanic origin.[44]: 4

Neptune and its largest moon Triton were explored by the Voyager 2 spacecraft on 25 August 1989,[42] revealing Triton's surface features up close for the first time.[45] With an estimated average surface age of 10–100 million years old, with some regions possibly being only a few million years old, Triton is one of the most geologically active worlds in the Solar System.[46] Large-scale cryovolcanic landforms have been identified on Triton's young surface, with nearly all of Triton's observed surface features likely related to cryovolcanism.[6]: 919 One of Triton's major cryovolcanic features, Leviathan Patera, the apparent primary vent of the Cipango Planum cryovolcanic plateau which is one of the largest volcanic or cryovolcanic edifices in the Solar System.[47][48][a]

Triton hosts four walled plains: Ruach Planitia and Tuonela Planitia form a northern pair, and Sipapu Planitia and Ryugu Planitia form a southern pair. The walled plains are characterized by crenulated, irregularly-shaped cliffs that enclose a flat, young plain with a single group of pits and mounds.[6]: 886 The walled plains are likely young cryovolcanic lakes and may represent Triton's youngest cryovolcanic features.[6]: 920–921 [50]: 870; 872 The regions around Ruach and Tuonela feature additional smaller subcircular depressions, some of which are partially bordered by walls and scarps. In 2014, a team of planetary scientists interpreted these depressions as diapirs, caldera collapse structures, or impact craters filled in by cryolava flows.[51] To the south of Tuonela Planitia, isolated conical hills with central depressions have been noted as resembling terrestrial cinder cones, possibly pointing to cryovolcanic activity beyond Tuonela Planitia's plains.[6]: 922

Triton's southern polar ice cap is marked by a multitude of dark streaks, likely composed of organic tholins deposited by wind-blown plumes. At least two plumes, the Mahilani Plume and the Hili Plume, have been observed, with the two plumes reaching 8 kilometres (5.0 miles) in altitude.[50]: 873 These plumes have been hypothesized by numerous teams of researchers in the early 1990s to be driven by the buildup of nitrogen gas underneath solid nitrogen ice through a sort of solid greenhouse effect; however, more recent analysis in 2022 disfavors the solid greenhouse effect model. An alternative cryovolcanic model, first proposed by R. L. Kirk and collaborators in 1995, instead suggests that the plumes represent explosive cryovolcanic eruption columns—an interpretation supported by the estimated observed output rate of ~200 kg/s, comparable to the output of Enceladus's plumes.[52]: 3–4

Wright Mons, a cryovolcano on Pluto

Edifice of Wright Mons, a likely cryovolcano on Pluto. Coleman Mons can be seen just southwest of Wright Mons

The dwarf planet Pluto and its system of five moons were explored by the New Horizons spacecraft in a flyby on 14 July 2015, observing their surface features in detail for the first time.[53] The surface of Pluto varies dramatically in age, and several regions appear to display relatively recent cryovolcanic activity. The most reliably identified cryovolcanic structures are Wright Mons and Piccard Mons, two large mountains with central depressions which have led to hypotheses that they may be cryovolcanoes with peak calderas.[54][55] The two mountains are surrounded by an unusual region of hilly "hummocky terrain", and the lack of distinct flow features have led to an alternative proposal in 2022 by a team of researchers that the structures may instead be formed by sequential dome-forming eruptions, with nearby Coleman Mons being a smaller independent dome.[56]

Virgil Fossae, a large fault within Belton Regio, may also represent another site of cryovolcanism on Pluto. An estimated 300 kilometres (190 miles) of Virgil Fossae's western section was likely the site of a fountaining eruption, spewing and dispersing material that covered surrounding terrain up to 200 kilometres (120 miles) away.[57]: 166 More recently, in 2021 Hekla Cavus was hypothesized to have formed from a cryovolcanic collapse by a team of two researchers, C. J. Ahrens and V. F. Chevrier.[58]: 7 Similarly, in 2021 a team of planetary scientists led by A. Emran proposed that Kiladze, a feature that is formally classified as an impact crater, is actually a cryovolcanic caldera complex.[59]

Although Sputnik Planitia represents the youngest surface on Pluto, it is not a cryovolcanic structure; Sputnik Planitia continuously resurfaces itself with the convective overturning of glacial nitrogen ice, fuelled by Pluto's internal heat and sublimation into Pluto's atmosphere.[60]

Charon's surface dichotomy indicates that a large section of its surface may have been flooded in large, effusive eruptions, similar to the Lunar maria. These floodplains form Vulcan Planitia and may have erupted as Charon's internal ocean froze.[61]

Other dwarf planets

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In 2022, low-resolution near-infrared (0.7–5 μm) spectroscopic observations by the James Webb Space Telescope (JWST) detected light hydrocarbons and complex organic molecules on the surfaces of the dwarf planets Quaoar, Gonggong, and Sedna. The detection indicated that all three have experienced internal melting and planetary differentiation in their pasts. The presence of volatiles on their surfaces indicates that cryovolcanism may be resupplying methane.[17]: 13 JWST spectral observations of Eris and Makemake revealed that hydrogen-deuterium and carbon isotopic ratios indicated that both dwarf planets are actively replenishing surface methane as well, possibly with the presence of a subsurface ocean.[16]: 8

These observations, combined with the discoveries in the Pluto system by the New Horizons spacecraft, indicate that icy worlds are capable of sustaining enough heat on their own to drive cryovolcanic activity. In contrast to the icy satellites of the giant planets, where many benefit from extensive tidal heating from their parent planets, the dwarf planets must rely on heat generated primarily or almost entirely by themselves. Leftover primordial heat from formation and radiogenic heat from the decay of radioactive isotopes in their rocky cores likely serve as primary sources of heat. The serpentinization of rocky material or tidal heating from interactions with their satellites .[62][17]: 8 [63]: 245

Various examples of probable cryovolcanic structures in the Solar System

  1. ^ Using an estimated surface area of at least 490,000 km2 for Cipango Planum,[48] this significantly surpasses Olympus Mons's area of roughly 300,000 km2.[49] As Cipango Planum extended beyond Triton's terminator during Voyager 2's closest approach, its true extent is uncertain and may be significantly larger

  2. ^ Liddell, Henry George; Scott, Robert (1940). "κρύος". A Greek–English Lexicon. Clarendon Press. Archived from the original on 12 January 2024. Retrieved 13 May 2024.

  3. ^ a b c d e Hargitai, Henrik; Kereszturi, Ákos, eds. (2015). Encyclopedia of Planetary Landforms (first ed.). Springer New York. doi:10.1007/978-1-4614-3134-3. ISBN 978-1-4614-3133-6.

  4. ^ a b c d e f g h i j k l m n o p q r s t u v Gregg, Tracy K. P.; Lopes, Rosaly M. C.; Fagents, Sarah A. (December 2021). Planetary Volcanism across the Solar System. doi:10.1016/B978-0-12-813987-5.00005-5. ISBN 978-0-12-813987-5. S2CID 245084572. Retrieved 12 March 2024.

  5. ^ a b c d Geissler, Paul (2015). The Encyclopedia of Volcanoes (Second ed.). pp. 763–776. doi:10.1016/B978-0-12-385938-9.00044-4. ISBN 978-0-12-385938-9. Retrieved 12 March 2024.

  6. ^ Fortes, A. D.; Gindrod, P. M.; Trickett, S. K.; Vočadlo, L. (May 2007). "Ammonium sulfate on Titan: Possible origin and role in cryovolcanism". Icarus. 188 (1): 139–153. Bibcode:2007Icar..188..139F. doi:10.1016/j.icarus.2006.11.002.

  7. ^ a b c d e Croft, S. K.; Kargel, J. S.; Kirk, R. L.; et al. (1995). "The geology of Triton". Neptune and Triton: 879–947. Bibcode:1995netr.conf..879C.

  8. ^ Schenk, P. M.; Beyer, R. A.; McKinnon, W. B.; Moore, J. M.; Spencer, J. R.; White, O. L.; Singer, K.; Nimmo, F.; Thomason, C.; Lauer, T. R.; Robbins, S.; Umurhan, O. M.; Grundy, W. M.; Stern, S. A.; Weaver, H. A.; Young, L. A.; Smith, K. E.; Olkin, C. (November 2018). "Basins, fractures and volcanoes: Global cartography and topography of Pluto from New Horizons". Icarus. 314: 400–433. Bibcode:2018Icar..314..400S. doi:10.1016/j.icarus.2018.06.008. S2CID 126273376.

  9. ^ Sohn, Rebecca (1 April 2022). "Ice volcanoes on Pluto may still be erupting". Space.com.

  10. ^ Moore, M. H.; Ferrante, R. F.; Hudson, R. L.; Stone, J. N. (September 2007). "Ammonia–water ice laboratory studies relevant to outer Solar System surfaces". Icarus. 190 (1): 260–273. Bibcode:2007Icar..190..260M. doi:10.1016/j.icarus.2007.02.020.

  11. ^ a b Manga, M.; Wang, C. -Y. (April 2007). "Pressurized oceans and the eruption of liquid water on Europa and Enceladus". Geophysical Research Letters. 34 (7). Bibcode:2007GeoRL..34.7202M. doi:10.1029/2007GL029297. Retrieved 12 March 2024.

  12. ^ Moresi, Louis; Solomatov, Viatcheslav (1998). "Mantle convection with a brittle lithosphere: thoughts on the global tectonic styles of the Earth and Venus". Geophysical Journal International. 133 (3): 669–82. Bibcode:1998GeoJI.133..669M. CiteSeerX 10.1.1.30.5989. doi:10.1046/j.1365-246X.1998.00521.x.

  13. ^ "Tidal heating and the long-term stability of a subsurface ocean on Enceladus" (PDF). Archived from the original (PDF) on 21 July 2010. Retrieved 14 October 2011.

  14. ^ McGovern, J. C.; Nguyen, A. L. (April 2024). "The role of Pluto's ocean's salinity in supporting nitrogen ice loads within the Sputnik Planitia basin". Icarus. 412. Bibcode:2024Icar..41215968M. doi:10.1016/j.icarus.2024.115968. S2CID 267316007. Retrieved 13 March 2024.

  15. ^ McCord, Thomas B. (2005). "Ceres: Evolution and current state". Journal of Geophysical Research. 110 (E5): E05009. Bibcode:2005JGRE..110.5009M. doi:10.1029/2004JE002244.

  16. ^ Castillo-Rogez, J. C.; McCord, T. B.; Davis, A. G. (2007). "Ceres: evolution and present state" (PDF). Lunar and Planetary Science. XXXVIII: 2006–2007. Archived (PDF) from the original on 24 February 2011. Retrieved 25 June 2009.

  17. ^ a b Glein, Christopher R.; Grundy, William M.; Lunine, Jonathan I.; Wong, Ian; Protopapa, Silvia; Pinilla-Alonso, Noemi; Stansberry, John A.; Holler, Bryan J.; Cook, Jason C.; Souza-Feliciano, Ana Carolina (April 2024). "Moderate D/H ratios in methane ice on Eris and Makemake as evidence of hydrothermal or metamorphic processes in their interiors: Geochemical analysis". Icarus. 412. arXiv:2309.05549. Bibcode:2024Icar..41215999G. doi:10.1016/j.icarus.2024.115999. S2CID 261696907. Retrieved 12 March 2024.

  18. ^ a b c Emery, J. P.; Wong, I.; Brunetto, R.; Cook, R.; Pinilla-Alonso, N.; Stansberry, J. A.; et al. (March 2024). "A Tale of 3 Dwarf Planets: Ices and Organics on Sedna, Gonggong, and Quaoar from JWST Spectroscopy". Icarus. 414 (116017). arXiv:2309.15230. Bibcode:2024Icar..41416017E. doi:10.1016/j.icarus.2024.116017.

  19. ^ a b Schmidt, Britney; Blankenship, Don; Patterson, Wes; Schenk, Paul (24 November 2011). "Active formation of 'chaos terrain' over shallow subsurface water on Europa". Nature. 479 (7374): 502–505. Bibcode:2011Natur.479..502S. doi:10.1038/nature10608. PMID 22089135. S2CID 4405195.

  20. ^ Kargel, J. S. (1995). "Cryovolcanism on the Icy Satellites". Earth, Moon, and Planets. 67 (1–3): 101–113. Bibcode:1995EM&P...67..101K. doi:10.1007/BF00613296. S2CID 54843498. Retrieved 12 March 2024.

  21. ^ Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. pp. 53–55. ISBN 9780521880060.

  22. ^ Landau, Elizabeth; Brown, Dwayne (6 March 2015). "NASA Spacecraft Becomes First to Orbit a Dwarf Planet". NASA. Archived from the original on 7 March 2015. Retrieved 6 March 2015.

  23. ^ De Sanctis, M; Ammannito, E; Raponi, A; Frigeri, A; Ferrari, M; Carrozzo, F; Ciarniello, M; Formisano, M; Rousseau, B; Tosi, F.; Zambon, F.; Raymond, C. A.; Russell, C. T. (10 August 2020). "Fresh emplacement of hydrated sodium chloride on Ceres from ascending salty fluids". Nature Astronomy. 4 (8): 786–93. Bibcode:2020NatAs...4..786D. doi:10.1038/s41550-020-1138-8. S2CID 225442620.

  24. ^ a b Sori, Michael T.; Sizemore, Hanna G.; et al. (December 2018). "Cryovolcanic rates on Ceres revealed by topography". Nature Astronomy. 2 (12): 946–950. Bibcode:2018NatAs...2..946S. doi:10.1038/s41550-018-0574-1. S2CID 186800298. Archived from the original on 17 August 2021. Retrieved 17 August 2021.

  25. ^ Schenk, Paul M.; Chapman, Clark R.; Zahnle, Kevin; and Moore, Jeffrey M. (2004) "Chapter 18: Ages and Interiors: the Cratering Record of the Galilean Satellites" Archived 24 December 2016 at the Wayback Machine, pp. 427 ff. in Bagenal, Fran; Dowling, Timothy E.; and McKinnon, William B., editors; Jupiter: The Planet, Satellites and Magnetosphere, Cambridge University Press, ISBN 0-521-81808-7.

  26. ^ a b Kattenhorn, Simon A. (March 2018). "Commentary: The Feasibility of Subduction and Implications for Plate Tectonics on Jupiter's Moon Europa". Journal of Geophysical Research: Planets. 123 (3): 684–689. Bibcode:2018JGRE..123..684K. doi:10.1002/2018JE005524.

  27. ^ Figueredo, Patricio H.; Greeley, Ronald (February 2004). "Resurfacing history of Europa from pole-to-pole geological mapping". Icarus. 167 (2): 287–312. Bibcode:2004Icar..167..287F. doi:10.1016/j.icarus.2003.09.016.

  28. ^ Fletcher, Leigh (12 December 2013). "The Plumes of Europa". The Planetary Society. Archived from the original on 15 December 2013. Retrieved 17 December 2013.

  29. ^ "NASA's Hubble Spots Possible Water Plumes Erupting on Jupiter's Moon Europa". NASA. 26 September 2016. Retrieved 13 May 2015.

  30. ^ Bradák, Balázs; Kereszturi, Ákos; Gomez, Christopher (November 2023). "Tectonic analysis of a newly identified putative cryovolcanic field on Europa". Advances in Space Research. 72 (9): 4064–4073. Bibcode:2023AdSpR..72.4064B. doi:10.1016/j.asr.2023.07.062. S2CID 260798414.

  31. ^ "Argadnel Regio". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program. (Center Latitude: -14.60°, Center Longitude: 208.50°)

  32. ^ Showman, Adam P.; Malhotra, Renu (1 October 1999). "The Galilean Satellites" (PDF). Science. 286 (5437): 77–84. doi:10.1126/science.286.5437.77. PMID 10506564. Archived (PDF) from the original on 14 May 2011. Retrieved 17 January 2008.

  33. ^ Solomonidou, Anezina; Malaska, Michael; Stephan, Katrin; Soderlund, Krista; Valenti, Martin; Lucchetti, Alice; Kalousova, Klara; Lopes, Rosaly (September 2022). Ganymede paterae: a priority target for JUICE. 16th Europlanet Science Congress 2022. Palacio de Congresos de Granada, Spain and online. doi:10.5194/epsc2022-423.

  34. ^ Patterson, G. Wesley; Collins, Geoffrey C.; Head, James W.; Pappalardo, Robert T.; Prockter, Louise M.; Lucchitta, Baerbel K.; Kay, Jonothan P. (6 December 2009). "Global geological mapping of Ganymede". Icarus. 207 (2): 845–867. Bibcode:2010Icar..207..845P. doi:10.1016/j.icarus.2009.11.035.

  35. ^ "Enceladus rains water onto Saturn". ESA. 2011. Archived from the original on 23 November 2017. Retrieved 14 January 2015.

  36. ^ Spahn, F.; et al. (10 March 2006). "Cassini Dust Measurements at Enceladus and Implications for the Origin of the E Ring". Science. 311 (5766): 1416–8. Bibcode:2006Sci...311.1416S. CiteSeerX 10.1.1.466.6748. doi:10.1126/science.1121375. PMID 16527969. S2CID 33554377.

  37. ^ Porco, C. C.; Helfenstein, P.; Thomas, P. C.; Ingersoll, A. P.; Wisdom, J.; West, R.; Neukum, G.; Denk, T.; Wagner, R. (10 March 2006). "Cassini Observes the Active South Pole of Enceladus". Science. 311 (5766): 1393–1401. Bibcode:2006Sci...311.1393P. doi:10.1126/science.1123013. PMID 16527964. S2CID 6976648. Archived from the original on 16 June 2024. Retrieved 13 March 2024.

  38. ^ a b Thomas, P. C.; Tajeddine, R.; et al. (2016). "Enceladus's measured physical libration requires a global subsurface ocean". Icarus. 264: 37–47. arXiv:1509.07555. Bibcode:2016Icar..264...37T. doi:10.1016/j.icarus.2015.08.037. S2CID 118429372.

  39. ^ Berne, A.; Simons, M.; Keane, J.T.; Leonard, E.J.; Park, R.S. (29 April 2024). "Jet activity on Enceladus linked to tidally driven strike-slip motion along tiger stripes". Nature Geoscience. 17 (5): 385–391. Bibcode:2024NatGe..17..385B. doi:10.1038/s41561-024-01418-0. ISSN 1752-0908.

  40. ^ Iess, L.; Jacobson, R. A.; Ducci, M.; Stevenson, D. J.; Lunine, Jonathan I.; Armstrong, J. W.; Asmar, S. W.; Racioppa, P.; Rappaport, N. J.; Tortora, P. (2012). "The Tides of Titan". Science. 337 (6093): 457–9. Bibcode:2012Sci...337..457I. doi:10.1126/science.1219631. hdl:11573/477190. PMID 22745254. S2CID 10966007.

  41. ^ Lopes, R. M. C.; Kirk, R. L.; Mitchell, K. L.; LeGall, A.; Barnes, J. W.; Hayes, A.; Kargel, J.; Wye, L.; Radebaugh, J.; Stofan, E. R.; Janssen, M. A.; Neish, C. D.; Wall, S. D.; Wood, C. A.; Lunine, Jonathan I.; Malaska, M. J. (19 March 2013). "Cryovolcanism on Titan: New results from Cassini RADAR and VIMS" (PDF). Journal of Geophysical Research: Planets. 118 (3): 416–435. Bibcode:2013JGRE..118..416L. doi:10.1002/jgre.20062. Archived (PDF) from the original on 1 September 2019. Retrieved 2 September 2019.

  42. ^ a b c Wood, C.A.; Radebaugh, J. (2020). "Morphologic Evidence for Volcanic Craters near Titan's North Polar Region". Journal of Geophysical Research: Planets. 125 (8): e06036. Bibcode:2020JGRE..12506036W. doi:10.1029/2019JE006036. S2CID 225752345.

  43. ^ a b Bolles, Dana (March 2024). "Voyager 2". NASA. Archived from the original on 18 May 2024. Retrieved 21 May 2024.

  44. ^ Leonard, Erin Janelle; Beddingfield, Chloe B.; Elder, Catherine M.; Nordheim, Tom Andrei (December 2022). The Geologic History of Miranda's Inverness Corona. AGU Fall Meeting 2022. Chicago, Illinois. Bibcode:2022AGUFM.P32E1872L.

  45. ^ a b c d Schenk, Paul M.; Moore, Jeffrey M. (December 2020). "Topography and geology of Uranian mid-sized icy satellites in comparison with Saturnian and Plutonian satellites". Philosophical Transactions of the Royal Society A. 378 (2187). Bibcode:2020RSPTA.37800102S. doi:10.1098/rsta.2020.0102. PMID 33161858.

  46. ^ Sulcanese, Davide; Cioria, Camilla; Kokin, Osip; Mitri, Giuseppe; Pondrelli, Monica; Chiarolanza, Giancula (March 2023). "Geological analysis of Monad Regio, Triton: Possible evidence of endogenic and exogenic processes". Icarus. 392. Bibcode:2023Icar..39215368S. doi:10.1016/j.icarus.2022.115368. S2CID 254173536. Retrieved 12 March 2024.

  47. ^ Schenk, Paul M.; Zahnle, Kevin (December 2007). "On the negligible surface age of Triton". Icarus. 192 (1): 135–149. Bibcode:2007Icar..192..135S. doi:10.1016/j.icarus.2007.07.004.

  48. ^ Martin-Herrero, Alvaro; Romeo, Ignacio; Ruiz, Javier (2018). "Heat flow in Triton: Implications for heat sources powering recent geologic activity". Planetary and Space Science. 160: 19–25. Bibcode:2018P&SS..160...19M. doi:10.1016/j.pss.2018.03.010. S2CID 125508759.

  49. ^ a b Schenk, Paul; Beddingfield, Chloe; Bertrand, Tanguy; et al. (September 2021). "Triton: Topography and Geology of a Probable Ocean World with Comparison to Pluto and Charon". Remote Sensing. 13 (17): 3476. Bibcode:2021RemS...13.3476S. doi:10.3390/rs13173476.

  50. ^ Frankel, C.S. (2005). Worlds on Fire: Volcanoes on the Earth, the Moon, Mars, Venus and Io; Cambridge University Press: Cambridge, UK, p. 132. ISBN 978-0-521-80393-9.

  51. ^ a b McKinnon, William B.; Kirk, Randolph L. (2014). Encyclopedia of the Solar System (Third ed.). pp. 861–881. doi:10.1016/C2010-0-67309-3. ISBN 978-0-12-415845-0. Retrieved 12 March 2024.

  52. ^ Martin-Herrero, A.; Ruiz, J.; Romeo, I. (March 2014). Characterization and Possible Origin of Sub-Circular Depressions in Ruach Planitia Region, Triton (PDF). 45th Lunar and Planetary Science Conference. The Woodlands, Texas. Bibcode:2014LPI....45.1177M. Archived (PDF) from the original on 12 March 2024. Retrieved 13 March 2024.

  53. ^ Hofgartner, Jason D.; Birch, Samuel P. D.; Castillo, Julie; Grundy, Will M.; Hansen, Candice J.; Hayes, Alexander G.; Howett, Carly J. A.; Hurford, Terry A.; Martin, Emily S.; Mitchell, Karl L.; Nordheim, Tom A.; Poston, Michael J.; Prockter, Louise M.; Quick, Lynnae C.; Schenk, Paul (15 March 2022). "Hypotheses for Triton's plumes: New analyses and future remote sensing tests". Icarus. 375: 114835. arXiv:2112.04627. Bibcode:2022Icar..37514835H. doi:10.1016/j.icarus.2021.114835. ISSN 0019-1035.

  54. ^ "NASA's Three-Billion-Mile Journey to Pluto Reaches Historic Encounter". Johns Hopkins University Applied Physics Laboratory. 14 July 2015. Archived from the original on 14 November 2021. Retrieved 18 May 2024.

  55. ^ "At Pluto, New Horizons Finds Geology of All Ages, Possible Ice Volcanoes, Insight into Planetary Origins". New Horizons News Center. The Johns Hopkins University Applied Physics Laboratory LLC. 9 November 2015. Archived from the original on 4 March 2016. Retrieved 9 November 2015.

  56. ^ Witze, A. (9 November 2015). "Icy volcanoes may dot Pluto's surface". Nature. Nature Publishing Group. doi:10.1038/nature.2015.18756. S2CID 182698872. Archived from the original on 17 November 2015. Retrieved 9 November 2015.

  57. ^ Singer, Kelsi N. (29 March 2022). "Large-scale cryovolcanic resurfacing on Pluto". Nature Communications. 13 (1): 1542. arXiv:2207.06557. Bibcode:2022NatCo..13.1542S. doi:10.1038/s41467-022-29056-3. PMC 8964750. PMID 35351895.

  58. ^ Cruikshank, Dale P.; Umurhan, Orkan M.; Beyer, Ross A.; Schmitt, Bernard; Keane, James T.; Runyon, Kirby D.; Atri, Dimitra; White, Oliver L.; Matsuyama, Isamu; Moore, Jeffrey M.; McKinnon, William B.; Sandford, Scott A.; Singer, Kelsi N.; Grundy, William M.; Dalle Ore, Cristina M.; Cook, Jason C.; Bertrand, Tanguy; Stern, S. Alan; Olkin, Catherine B.; Weaver, Harold A.; Young, Leslie A.; Spencer, John R.; Lisse, Carey M.; Binzel, Richard P.; Earle, Alissa M.; Robbins, Stuart J.; Gladstone, G. Randall; Cartwright, Richard J.; Ennico, Kimberly (15 September 2019). "Recent cryovolcanism in Virgil Fossae on Pluto". Icarus. 330: 155–168. Bibcode:2019Icar..330..155C. doi:10.1016/j.icarus.2019.04.023. S2CID 149983734.

  59. ^ Ahrens, C. J.; Chevrier, V. F. (March 2021). "Investigation of the morphology and interpretation of Hekla Cavus, Pluto". Icarus. 356. Bibcode:2021Icar..35614108A. doi:10.1016/j.icarus.2020.114108.

  60. ^ Emran, A.; Dalle Ore, C. M.; Cruikshank, D. P.; Cook, J. C. (March 2021). "Surface composition of Pluto's Kiladze area and relationship to cryovolcanism". Icarus. 404. arXiv:2303.17072. Bibcode:2023Icar..40415653E. doi:10.1016/j.icarus.2023.115653.

  61. ^ McKinnon, W. B.; et al. (1 June 2016). "Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigour". Nature. 534 (7605): 82–85. arXiv:1903.05571. Bibcode:2016Natur.534...82M. doi:10.1038/nature18289. PMID 27251279. S2CID 30903520.

  62. ^ Desch, S. J.; Neveu, M. (2017). "Differentiation and cryovolcanism on Charon: A view before and after New Horizons". Icarus. 287: 175–186. Bibcode:2017Icar..287..175D. doi:10.1016/j.icarus.2016.11.037. Archived from the original on 1 October 2017. Retrieved 13 March 2024.

  63. ^ Witze, Alexandra (2015). "Ice volcanoes may dot Pluto's surface". Nature. doi:10.1038/nature.2015.18756. S2CID 182698872. Archived from the original on 17 November 2015. Retrieved 15 November 2015.

  64. ^ Saxena, Prabal; Renaud, Joe P.; Henning, Wade G.; Jutzi, Martin; Hurford, Terry (March 2018). "Relevance of tidal heating on large TNOs". Icarus. 302: 245–260. arXiv:1706.04682. Bibcode:2018Icar..302..245S. doi:10.1016/j.icarus.2017.11.023.