Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth's deep mantle

Creators: Tschauner, O.; Huang, S.; Greenberg, E.; Prakapenka, V. B.; Ma, C.; Rossman, G. R.; Shen, A. H.; Zhang, D.; Newville, M.; Lanzirotti, A.; Tait, K.

Abstract

Water-rich regions in Earth's deeper mantle are suspected to play a key role in the global water budget and the mobility of heat-generating elements. We show that ice-VII occurs as inclusions in natural diamond and serves as an indicator for such water-rich regions. Ice-VII, the residue of aqueous fluid present during growth of diamond, crystallizes upon ascent of the host diamonds but remains at pressures as high as 24 gigapascals; it is now recognized as a mineral by the International Mineralogical Association. In particular, ice-VII in diamonds points toward fluid-rich locations in the upper transition zone and around the 660-kilometer boundary.

Additional Information

© 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. This is an article distributed under the terms of the Science Journals Default License. 5 July 2017; accepted 19 January 2018. We thank four anonymous reviewers for their helpful comments, and H. A. Bechtel for support at the Advanced Light Source. Funding: This work was supported by U.S. Department of Energy (DOE) awards DESC0005278, DE-FG02-94ER14466, and DE-NA0001974, and by NSF grants EAR-1634415, EAR-1128799, EAR-1322082, EAR-0318518, and DMR-0080065. The Advanced Photon Source, a DOE Office of Science User Facility, is operated by Argonne National Laboratory under contract DE-AC02-06CH11357. The Advanced Light Source is supported through contract DE-AC02-05CH11231. Author contributions: O.T. participated in design, interpretation, data collection, and analysis of the reported results, and in drafting and revising the manuscript; S.H. participated in interpretation of the results and in drafting and revising the manuscript; E.G., V.B.P., C.M., G.R.R., A.H.S., D.Z., and K.T. participated in data collection and revising the manuscript; and M.N. and A.L. participated in data collection. The authors have no competing interests. Availability of data and materials: Additional chemical and crystallographic information about ice-VII is provided as supplementary material. Raw data are deposited at Dryad (doi:10.5061/dryad.7145v). Crystallographic and chemical information on type material ice-VII are deposited with the ICSD database.

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