Tidal dissipation in Europa's silicate mantle undergoing partial melting
Abstract
The presence of a subsurface ocean on Europa (Khurana et al. 1998; Kivelson et al., 2000) in direct contact with the silicate mantle, along with the spectacular volcanic activity exhibited by its neighboring satellite Io (e.g. Carr, 1986; McEwen et al., 1998; Lopes and Williams 2005), raise the possibility of seafloor volcanic activity (Thomson and Delaney, 2001; Travis et al. 2012), which has significant implications for Europa's ocean habitability.
Observational constraints concerning the heat budget of satellites exist only in the case of Io. The total power emitted through its surface is estimated to about 100 TW at present (e.g. Veeder et al. 1994), which is several orders of magnitude higher than can be explained by radiogenic heating alone. Tidal dissipation in a partially molten layer at the top of the silicate mantle appears consistent with the prodigious heat flux emitted from Io (e.g. Segatz et al. 1988), but it is still unclear how Io reached such a highly dissipative state. Unlike Io, the surface heat flux of Europa is unknown. Due to a larger distance from Jupiter and a smaller size, dissipation in Europa's mantle is expected to be considerably smaller than on Io, but still could be comparable to present-day radiogenic heating. Combined radiogenic heating and tidal heating sustain partial melting in Europa's mantle during billions of years (B ěhounková et al.2020), especially during periods of enhanced eccentricity, which may lead to melt accumulation in the asthenosphere. Evaluating the coupling between melt generation and tidal heat production is thus essential to assess the possibility of seafloor volcanism on Europa. We model the viscoelastic deformation of Europa's mantle using Andrade rheology. We test the influence of a partially molten layer, assuming rheological laws including the effect of melt on anelastic properties of rocks. A simplified parameterization for melt production and extraction is used to determine whether an equilibrium between heat generation and extraction can be reached or not. We estimate the maximal heat and melt production that could be generated as a function of time, assuming different scenarios for the eccentricity evolution.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP042.0015K
- Keywords:
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- 1039 Alteration and weathering processes;
- GEOCHEMISTRY;
- 5220 Hydrothermal systems and weathering on other planets;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 5419 Hydrology and fluvial processes;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5455 Origin and evolution;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS