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Stability of ice/rock mixtures with application to a partially differentiated Titan

O'Rourke, Joseph G. and Stevenson, David J. (2014) Stability of ice/rock mixtures with application to a partially differentiated Titan. Icarus, 227 . pp. 67-77. ISSN 0019-1035. https://resolver.caltech.edu/CaltechAUTHORS:20140206-082750899

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Abstract

Titan’s moment of inertia, calculated assuming hydrostatic equilibrium from gravity field data obtained during the Cassini–Huygens mission, implies an internal mass distribution that may be incompatible with complete differentiation. This suggests that Titan may have a mixed ice/rock core, possibly consistent with slow accretion in a gas-starved disk, which may initially spare Titan from widespread ice melting and subsequent differentiation. A partially differentiated Titan, however, must still efficiently remove radiogenic heat over geologic time. We argue that compositional heterogeneity in the major saturnian satellites indicates that Titan formed from planetesimals with disparate densities. The resulting compositional anomalies would quickly redistribute to form a vertical density gradient that would oppose thermal convection. We use elements of the theory of double-diffusive convection to create a parameterized model for the thermal evolution of ice/rock mixtures with a stabilizing compositional gradient. To account for large uncertainties in material properties and accretionary processes, we perform simulations for a wide range of initial conditions. Ultimately, for realistic density gradients, double-diffusive convection in the ice/rock interior can delay, but not prevent, ice melting and differentiation, even if a substantial fraction of potassium is leached from the rock component. Consequently, Titan is not partially differentiated.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.icarus.2013.09.010 DOIArticle
http://www.sciencedirect.com/science/article/pii/S0019103513003904PublisherArticle
https://arxiv.org/abs/1210.5280arXivDiscussion Paper
ORCID:
AuthorORCID
O'Rourke, Joseph G.0000-0002-1180-996X
Stevenson, David J.0000-0001-9432-7159
Additional Information:© 2013 Elsevier Inc. Received 18 October 2012; Revised 15 July 2013; Accepted 10 September 2013; Available online 19 September 2013. J. G. O’Rourke thanks A.C. Barr, W.B. McKinnon, and I. Mosqueira for helpful discussions and the NASA Planetary Geology & Geophysics Undergraduate Research Program for support. Constructive comments from one reviewer improved the content and clarity of this manuscript. J. G. O’Rourke is supported by a National Science Foundation Graduate Research Fellowship.
Funders:
Funding AgencyGrant Number
NASA Undergraduate Student Research ProgramUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:Titan, interior; Saturn, satellites; Jupiter, satellites; Thermal histories
Record Number:CaltechAUTHORS:20140206-082750899
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140206-082750899
Official Citation:Joseph G. O’Rourke, David J. Stevenson, Stability of ice/rock mixtures with application to a partially differentiated Titan, Icarus, Volume 227, 1 January 2014, Pages 67-77, ISSN 0019-1035, http://dx.doi.org/10.1016/j.icarus.2013.09.010. (http://www.sciencedirect.com/science/article/pii/S0019103513003904)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43684
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:11 Feb 2014 22:28
Last Modified:03 Oct 2019 06:10

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