Ammonium sulfate on Titan: possible origin and role in cryovolcanism
Fortes, Andrew Dominic and Grindrod, Peter M. and Trickett, S.K. and Vočadlo, L. (2007) Ammonium sulfate on Titan: possible origin and role in cryovolcanism. Icarus 188 (1), pp. 139-153. ISSN 0019-1035.
Abstract
We model the chemical evolution of Titan, wherein primordial NH3 reacts with sulfate-rich brines leached from the silicate core during its hydration. The resulting differentiated body consists of a serpentinite core overlain by a high-pressure ice VI mantle, a liquid layer of aqueous ammonium sulfate, and a heterogeneous shell of methane clathrate, low-pressure ice Ih and solid ammonium sulfate. Cooling of the subsurface ocean results in underplating of the outer shell with ice Ih; this gravitationally unstable system can produce compositional plumes as ice Ih ascends buoyantly. Ice plumes may aid in advection of melt pockets through the shell and, in combination with surface topography, provide the necessary hydraulic pressure gradients to drive such melts to the surface. Moreover, contact between the magma and wall rock (methane clathrate) will allow some methane to dissolve in the magma, as well as eroding fragments of wall rock that can be transported as xenoliths. Upon rising to the clathrate decomposition depth (∼ 2 MPa, or 1700 m), the entrained xenoliths will break down to ice + methane gas, powering highly explosive eruptions with lava fountains up to several kilometers high. Hence we predict that Titan is being resurfaced by cryoclastic ash consisting of ice and ammonium sulfate (or its tetrahydrate), providing an abundance of sedimentary grains, a potential source of bedload for fluvial transport and erosion, and of sand-sized material for aeolian transport and dune-building. The infrared reflectance spectrum of ammonium sulfate makes it a plausible candidate for the 5 μm-bright material on Titan's surface. © 2006 Elsevier Inc. All rights reserved.
Metadata
| Item Type: | Article |
|---|---|
| Keyword(s) / Subject(s): | Titan, Volcanism, Interiors, Ices |
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Depositing User: | Dr Peter Grindrod |
| Date Deposited: | 27 Aug 2015 12:12 |
| Last Modified: | 02 Aug 2023 17:18 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/12865 |
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