Hydroxide in pyroxene: Variations in the natural environment
Abstract
A suite of 51 pyroxenes from a wide range of geological environments was examined with infrared spectroscopy. Small amounts of OH occur in nearly all the samples, suggesting that OH groups are a minor component of most pyroxenes. The OH concentrations vary (0.002-0.12 wt% OH) as a function of geological setting with the greatest amounts occurring in mantle-derived samples. The intensities of certain OH absorption bands are somewhat correlated with pyroxene composition, in particular with the presence of trivalent cations. This suggests that crystal chemical or compositional factors also control the OH incorporation. The OH incorporated in the pyroxene structure is easily distinguishable from OH owing to amphibole lamellae, which usually occur in diopsides and often in orthopyroxenes. OH in pyroxene is probably a function of the activity of hydrous components during crystallization but may also depend on postcrystallization changes in the geological environment.
Additional Information
© 1990 Mineralogical Society of America. Manuscript received August 14, 1989. Manuscript accepted April 19, 1989. We thank the following individuals for providing samples for this study: J .E. Dixon, P. Dobson (Caltech), W.A. Dollase (UCLA), J. Ito (Univ. Chicago), F.F. Foit (Univ. Washington), J.J. Gurney (Univ. Cape Town), G. Harlow (Amer. Museum Natl. History, NY), D. Johnston (Univ. Oregon), J.L. Rosenfeld (UCLA), J.S. White (Smithsonian Institution), and J.S. Huebner (USGS, Reston, VA) who also provide microprobe analyses of his samples. R. Livi (Porto Alegre) is especially thanked for providing the H analyses by nuclear reaction analyses. The study was supported by the National Science Foundation, Grants EAR 86-18200 and EAR 88-16006, a Harry Crossley Foundation scholarship to D.R.B., and by the Knut and Alice Wallenberg Foundation through a postdoctoral fellowship to H.S. This is contribution number 4782 of the Division of Geological and Planetary Sciences, California Institute of Technology.Additional details
- Eprint ID
- 38518
- Resolver ID
- CaltechAUTHORS:20130515-101542226
- EAR 86-18200
- NSF
- EAR 88-16006
- NSF
- Harry Crossley Foundation scholarship
- Knut and Alice Wallenberg Foundation postdoctoral fellowship
- Created
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2013-05-15Created from EPrint's datestamp field
- Updated
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2019-11-26Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Division of Geological and Planetary Sciences
- Other Numbering System Identifier
- 4782