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Published March 13, 1992 | public
Journal Article

Water in Earth's Mantle: The Role of Nominally Anhydrous Minerals

Abstract

Most minerals of Earth's upper mantle contain small amounts of hydrogen, structurally bound as hydroxyl (OH). The OH concentration in each mineral species is variable, in some cases reflecting the geological environment of mineral formation. Of the major mantle minerals, pyroxenes are the most hydrous, typically containing ∼200 to 500 parts per million H_2O by weight, and probably dominate the water budget and hydrogen geochemistry of mantle rocks that do not contain a hydrous phase. Garnets and olivines commonly contain ∼1 to 50 parts per million. Nominally anhydrous minerals constitute a significant reservoir for mantle hydrogen, possibly accommodating all water in the depleted mantle and providing a possible mechanism to recycle water from Earth's surface into the deep mantle.

Additional Information

© 1992 American Association for the Advancement of Science. This research was supported by National Science Foundation grants EAR 88-16006 and EAR 91-04059. D.R.B. acknowledges financial support from the Harry Crossley Foundation and the American Federation of Mineralogical Societies. We thank our numerous sample donors, in particular J. J. Gurney, for their generosity, De Beers Consolidated Mines Ltd. for access to xenolith localities and collections, and G. S. Mattioli for help in the field. We are grateful to D. Endisch and F. Rauch at the University of Frankfurt for willingness to share unpublished nuclear reaction analysis data relevant to the calibrations used here. We have benefited from discussions with P. D. Ihinger, G. S. Mattioli, and E. M. Stolper, and we thank T. J. Ahrens, D. L. Anderson, J. E. Dixon, R. B. Hanson, P. J. Wyllie, and two anonymous reviewers for comments on drafts of this paper. This is Division of Geological and Planetary Sciences contribution no. 5071.

Additional details

Created:
August 20, 2023
Modified:
October 23, 2023