Formation of lenticulae on Europa by saucer-shaped sills

Manga, Michael; Michaut, Chloé

doi:10.1016/j.icarus.2016.10.009

Cited by 66 publications

(114 citation statements)

References 59 publications

Supporting

Mentioning

106

Contrasting

Order By: Relevance

“…Fracturing by overpressure that develops in water confined by a freezing ice shell has also been invoked for icy satellites, for water confined both in a global ocean (e.g., Manga & Wang, 2007) and possibly in isolated pockets of water (e.g., Fagents, 2003;Manga & Michaut, 2017). Fracturing by overpressure that develops in water confined by a freezing ice shell has also been invoked for icy satellites, for water confined both in a global ocean (e.g., Manga & Wang, 2007) and possibly in isolated pockets of water (e.g., Fagents, 2003;Manga & Michaut, 2017).…”

Section: Discussionmentioning

confidence: 99%

Squeezing Marsquakes Out of Groundwater

Manga

Zhai

Wang

2019

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Pore pressure in aquifers confined below a cryosphere will increase as Mars cools and the cryosphere thickens. Increased pore pressure decreases the effective stress and hence promotes seismicity. We calculate the rate of pore pressure change from cooling of Mars's interior and the modulation of pore pressure from solar and Phobos tides and barometric loading. Using the time‐varying pressure and tidal stresses, we compute Coulomb stress changes and the expected seismicity rate from a rate‐and‐state friction model. Seismicity rate will vary by several tens of percent to 2 orders of magnitude if the mean pore pressure is within 0.2 and 0.01 MPa of lithostatic, respectively. Seismic events promoted by high pore pressure may be tremor‐like. Documenting (or not) tidally modulated shallow seismicity would provide evidence for (or against) water‐filled confined aquifers, that pore pressure is high, and that the state of stress is close to failure—with implications for processes that can deliver water to the Martian surface.

show abstract

Section: Discussionmentioning

confidence: 99%

Squeezing Marsquakes Out of Groundwater

Manga

Zhai

Wang

2019

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, even for an extreme thickness of 50 km of ice, freezing of a few kilometers of water in the ocean would induce a 1-10 kPa overpressure, which is enough to propagate a fracture over the ice crust thickness (Manga and Wang, 2007;Neveu et al, 2015) but not to bring water from the ocean to the surface: a few MPa are necessary to drive the water past the level of neutral buoyancy. On the other hand, recent literature demonstrated the possibility of the emplacement of common geological features at Europa's surface, such as double ridges (Dombard et al, 2013;Johnston and Montési, 2014;Dameron and Burr, 2018), chaos (Greenberg et al, 1999;Schmidt et al, 2011) and lenticulae (Manga and Michaut, 2017) by the presence of near-surface liquid water reservoirs. Although Craft et al (2016) found emplacement of horizontal water sills to be challenging through hydrofracturing mechanisms, the morphological studies of the features cited above remain in good agreement with models taking into account warm water lenses at shallow depths.…”

Section: Introductionmentioning

confidence: 99%

Cryomagma ascent on Europa

Lesage

Massol

Schmidt

2020

Icarus

View full text Add to dashboard Cite

Europa's surface exhibits morphological features which, associated with a low crater density, might be interpreted to have formed as a result of recent cryovolcanic activity. In particular, the morphology of smooth deposits covering parts of the surface, and their relationship to the surrounding terrains, suggest that they result from liquid extrusions. Furthermore, recent literature suggests that the emplacement of liquid-related features, such as double ridges, lenticulae and chaos could result from the presence of liquid reservoirs beneath the surface. We model the ascent of liquid water through a fracture or a pipe-like conduit from a subsurface reservoir to Europa's surface and calculate the eruption time-scale and the total volume extruded during the eruption, as a function of the reservoir volume and depth. We also estimate the freezing time of a subsurface reservoir necessary to trigger an eruption. Our model is derived for pure liquid water and for a briny mixture outlined by Kargel (1991): 81 wt% H 2 O + 16 wt% MgSO 4 + 3 wt% Na 2 SO 4 . Considering compositional data for salt impurities for Europa, we discuss the effect of MgSO 4 and Na 2 SO 4 on the cryomagma freezing time-scale and ascent. For plausible reservoir volumes and depths in the range of 10 6 m 3 ≤ V ≤ 10 10 m 3 and 1 km ≤ H ≤ 10 km respectively, the total extruded cryolava volume ranges from 10 3 m 3 to 10 8 m 3 and the duration of the eruptions varies from few minutes to few tens of hours. The freezing time-scale of the cryomagma reservoirs varies with cryomagma composition and the temperature gradient in the ice shell: from a few days to a thousand years for pure water cryomagma, and from a few months to a 10 4 years for briny cryomagma.

show abstract

“…It has been suggested that some landforms on Enceladus and Ganymede may be the resulting of convectiondriven yielding (Showman & Han 2005, Barr & Hammond 2015, but this is uncertain. Small-scale "domes" and "pits" on Europa might be the result of convection, but are more plausibly caused by the intrusion of liquid water (Manga and Michaut 2017). The most convincing example of convection in the outer solar system is the nitrogen plains of Sputnik Planitia, Pluto, which display a cellular pattern almost certainly indicative of convection ).…”

Section: Convectionmentioning

confidence: 99%

“…Higher-viscosity flows might be responsible for the smooth plains of Charon and the two large, enigmatic mounds imaged at Pluto (Moore et al 2016). Cryovolcanic intrusions are even harder to identify, although Manga and Michaut (2017) make a strong case that the pits, spots and domes seen on Europa are likely of intrusive origin.…”

Section: Emplacement Of Low-viscosity Cryovolcanic Surface Flows Hasmentioning

confidence: 99%

Icy Satellites: Interior Structure, Dynamics, and Evolution

Nimmo¹

2018

Oxford Research Encyclopedia of Planetary Science

View full text Add to dashboard Cite

This article consists of three sections. The first discusses how we determine satellite internal structures, and what we know. The primary probes of internal structure are measurements of magnetic induction, gravity and topography, and rotation state and orientation. Enceladus, Europa, Ganymede, Callisto, Titan and (perhaps) Pluto all have subsurface oceans; Callisto and Titan may be only incompletely differentiated. The second section describes dynamical processes that affect satellite interiors and surfaces: tidal and radioactive heating, flexure and relaxation, convection, cryovolcanism, true polar wander, non-synchronous rotation, orbital evolution and impacts. The final section discusses how the satellites formed and evolved. Ancient tidal heating episodes and subsequent refreezing of a subsurface ocean are the likeliest explanation for the deformation observed at Ganymede, Tethys, Dione, Rhea, Miranda, Ariel and Titania.The high heat output of Enceladus is a consequence of Saturn's highly dissipative interior, but the dissipation rate is strongly frequency-dependent and does not necessarily imply that Saturn's moons are young. Major remaining questions include the origins of Titan's atmosphere and high eccentricity, the regular density progression in the Galilean satellites, and the orbital evolution of the Saturnian and Uranian moons.

show abstract

Formation of lenticulae on Europa by saucer-shaped sills

Abstract: Saucer shaped sills may create pits, domes, spots and small chaos on Europa. • Sills are predicted to be 1-5 km below Europa's surface. • Liquid water is predicted to exist presently under pits, and some domes and small chaos.

Cited by 66 publications

References 59 publications

Squeezing Marsquakes Out of Groundwater

Squeezing Marsquakes Out of Groundwater

Cryomagma ascent on Europa

Icy Satellites: Interior Structure, Dynamics, and Evolution

Contact Info

Product

Resources

About