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Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution

Neveu, Marc and Desch, Steven J. and Castillo-Rogez, Julie C. (2015) Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution. Journal of Geophysical Research: Planets, 120 (2). pp. 123-154. ISSN 2169-9100. http://resolver.caltech.edu/CaltechAUTHORS:20160222-151108794

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Abstract

Observations and models of Ceres suggest that its evolution was shaped by interactions between liquid water and silicate rock. Hydrothermal processes in a heated core require both fractured rock and liquid. Using a new core cracking model coupled to a thermal evolution code, we find volumes of fractured rock always large enough for significant interaction to occur. Therefore, liquid persistence is key. It is favored by antifreezes such as ammonia, by silicate dehydration which releases liquid, and by hydrothermal circulation itself, which enhances heat transport into the hydrosphere. The effect of heating from silicate hydration seems minor. Hydrothermal circulation can profoundly affect Ceres' evolution: it prevents core dehydration via “temperature resets,” core cooling events lasting ∼50 Myr during which Ceres' interior temperature profile becomes very shallow and its hydrosphere is largely liquid. Whether Ceres has experienced such extensive hydrothermalism may be determined through examination of its present-day structure. A large, fully hydrated core (radius 420 km) would suggest that extensive hydrothermal circulation prevented core dehydration. A small, dry core (radius 350 km) suggests early dehydration from short-lived radionuclides, with shallow hydrothermalism at best. Intermediate structures with a partially dehydrated core seem ambiguous, compatible both with late partial dehydration without hydrothermal circulation, and with early dehydration with extensive hydrothermal circulation. Thus, gravity measurements by the Dawn orbiter, whose arrival at Ceres is imminent, could help discriminate between scenarios for Ceres' evolution.


Item Type:Article
Related URLs:
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http://onlinelibrary.wiley.com/doi/10.1002/2014JE004714/abstractPublisherArticle
http://dx.doi.org/10.1002/2014JE004714DOIArticle
Additional Information:©2014. American Geophysical Union. Received 18 AUG 2014. Accepted 20 DEC 2014. Accepted article online 29 DEC 2014. We thank Everett Shock for discussions on cracking phenomena that helped improve this paper. Comments from two referees and the Associate Editor greatly helped improve this manuscript. This study was funded by the NASA Astrobiology Institute team at Arizona State University and by the NASA Outer Planets Research and Earth and Space Science Fellowship programs. Part of this work has been carried out at the Keck Institute for Space Studies and at the Jet Propulsion Laboratory, California Institute of Technology. The code used in this study is freely available at https://github.com/MarcNeveu/IcyDwarf.
Group:Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
NASANNX10AQ05G
NASA Earth and Space Science FellowshipUNSPECIFIED
Keck Institute for Space Studies (KISS)UNSPECIFIED
JPL/CaltechUNSPECIFIED
Record Number:CaltechAUTHORS:20160222-151108794
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160222-151108794
Official Citation:Neveu, M., S. J. Desch, and J. C. Castillo-Rogez (2015), Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution. J. Geophys. Res. Planets, 120, 123–154. doi: 10.1002/2014JE004714.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64657
Collection:CaltechAUTHORS
Deposited By: Colette Connor
Deposited On:22 Feb 2016 23:25
Last Modified:22 Feb 2016 23:25

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