The origin of domes on Europa: The role of thermally induced compositional diapirism

Abstract

The surface of Jupiter's moon Europa is peppered by topographic domes, interpreted as sites of intrusion and extrusion. Diapirism is consistent with dome morphology, but thermal buoyancy alone cannot produce sufficient driving pressures to create the observed dome elevations. Instead, diapirs may initiate by thermal convection that induces compositional segregation. Exclusion of impurities from warm upwellings allows sufficient buoyancy for icy plumes to create the observed surface topography, provided the ice shell has a small effective elastic thickness (∼0.2 to 0.5 km) and contains low‐eutectic‐point impurities at the few percent level. This model suggests that the ice shell may be depleted in impurities over time.

Surface, Subsurface and Atmosphere Exchanges on the Satellites of the Outer Solar System

“…Pappalardo and Barr 2004), clathrates of CO 2 or SO 2 (e.g. Prieto-Ballesteros et al 2005), ammonium sulfate (Fortes et al 2007) etc.…”

Thermal Diapirism and the Habitability of the Icy Shellof Europa

“…The most popular explanation for the origin of domes and microchaos features is surface upwarping and disruption by thermal diapirism related to convection in the lower part of the icy shell Pappalardo and Head 2001). In addition, differential tidal heating of warm ice or compositional differences could contribute to the buoyancy of upwelling plumes (Sotin et al 2002;Pappalardo and Barr 2004). In this scenario, large chaos areas would be formed by coalescence of diapirs (Spaun et al 1998;Schenk and Pappalardo 2004).…”

Seeking Europa's Ocean

“…Partial melting in chaotic terrain, in lenticulae, and along ridge axes may allow melt to sink downward through the cold near-surface ice and to the convective zone below on a time scale of ∼10-100 yr (Barr et al, 2002). In turn, convection can circulate material from the top to bottom of the convective zone on a time scale of ∼10 5 yr (Pappalardo and Barr, 2004). Through this indirect route, oxidants may be supplied to Europa's ocean below.…”

“…They are probably the surface expression of upwelling warm ice diapirs, implying that Europa's icy shell is convecting (Barr and Showman, 2004), as Reynolds and Cassen (1979) had first predicted. This implies that diapirs of warm ice apparently risen up from the base of the floating icy shell, and some have impinged on the cold surface layer to warp it upward into domes, while others have pierced the cold surface to flow out onto the surface, though piercing the coldest near-surface ice implies additional processes such as compositional buoyancy of the diapirs (Pappalardo and Barr, 2004). Pits may be locations where warm diapirs have triggered melting within the ice shell, resulting in downwarping of the surface as melt drains downward in the ice shell below (Singer et al, 2010).…”