Stable methane hydrate above 2 GPa and the source of Titan's atmospheric methane

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DOIResolve DOI: http://doi.org/10.1038/35070513
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TypeArticle
Journal titleNature
ISSN0028-0836
Volume410
Issue6829
Pages661663; # of pages: 3
AbstractMethane hydrate is thought to have been the dominant methane-containing phase in the nebula from which Saturn, Uranus, Neptune and their major moons formed1. It accordingly plays an important role in formation models of Titan, Saturn's largest moon. Current understanding1, 2 assumes that methane hydrate dissociates into ice and free methane in the pressure range 1�2 GPa (10�20 kbar), consistent with some theoretical3 and experimental4, 5 studies. But such pressure-induced dissociation would have led to the early loss of methane from Titan's interior to its atmosphere, where it would rapidly have been destroyed by photochemical processes6, 7. This is difficult to reconcile with the observed presence of significant amounts of methane in Titan's present atmosphere. Here we report neutron and synchrotron X-ray diffraction studies that determine the thermodynamic behaviour of methane hydrate at pressures up to 10 GPa. We find structural transitions at about 1 and 2 GPa to new hydrate phases which remain stable to at least 10 GPa. This implies that the methane in the primordial core of Titan remained in stable hydrate phases throughout differentiation, eventually forming a layer of methane clathrate approximately 100 km thick within the ice mantle. This layer is a plausible source for the continuing replenishment of Titan's atmospheric methane.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
Identifier10084666
NPARC number12338699
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Record identifier6e517462-cec0-417a-b447-e6ccc132567d
Record created2009-09-10
Record modified2016-05-09
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