dc.contributor.author | Hilchie, Luke Jonathan | |
dc.contributor.author | Hilchie, Luke | |
dc.date.accessioned | 2011-08-25T12:25:22Z | |
dc.date.available | 2011-08-25T12:25:22Z | |
dc.date.issued | 2011-08-25 | |
dc.identifier.uri | http://hdl.handle.net/10222/14103 | |
dc.description | This thesis includes an Electronic Appendix, available at http://dalspace.library.dal.ca | en_US |
dc.description.abstract | Volatiles are fundamental to many aspects of kimberlite magmatism. However, the volatile compositions and concentrations are poorly defined. Enrichment of H in kimberlitic olivines, many of which are xenocrysts, suggests high water content, but the extent to which H exchanges between these xenocrysts and kimberlite magmas remains unclear. This study investigates zonation of H in kimberlite-hosted xenolith and macrocrystic olivines using Fourier transform infrared spectroscopy to constrain the extent of re-equilibration. Data show that, depending on locality, xenolith olivines exhibit either no H-zonation, or substantial H-depletion in their rims. Macrocrysts feature similar trends to xenolith olivines from the same intrusion. In terms of the rim:core ratio of H, strongly zoned olivines average ~0.5, whereas poorly zoned olivines average at ~0.9 (macrocrysts) or 1.0 (xenolith olivines). Locality-specific H-zonation could result from different magmatic thermal regimes, water concentrations, or ascent durations. If the magmas that contained weakly zoned olivines were anhydrous, their restricted zoning requires ascent durations (< 20 min at 1100 °C) that are considerably shorter than published estimates (~1-24 hr at 1100 °C). These findings suggest that elevated magmatic water concentrations minimized loss of H from olivine in these kimberlites, showing that non-equilibrated xenocrysts could indirectly record high water concentrations in the form of weak H-zonation. Strong H-depletion patterns in olivines from other kimberlites may reflect lower initial magmatic water concentrations, or loss of fluid to country rocks. Future studies could compare H-zonation to temperature and ascent rate estimates, and field relationships to better elucidate the causes of locality-specific H-zonation. An apparent correlation between diamond grade and H-zonation warrants further investigation. | en_US |
dc.language.iso | en | en_US |
dc.subject | Kimberlite | en_US |
dc.subject | olivine | |
dc.subject | hydrogen | |
dc.subject | water | |
dc.subject | diffusion | |
dc.subject | zonation | |
dc.subject | mantle | |
dc.subject | peridotite | |
dc.subject | xenocryst | |
dc.title | Zonation of Hydrogen in Kimberlitic and Mantle Olivines: A Possible Proxy for the Water Content of Kimberlite Magmas | en_US |
dc.date.defence | 2011-08-08 | |
dc.contributor.department | Department of Earth Sciences | en_US |
dc.contributor.degree | Master of Science | en_US |
dc.contributor.external-examiner | Cliff Shaw | en_US |
dc.contributor.graduate-coordinator | Nicholas Culshaw | en_US |
dc.contributor.thesis-reader | D. Barrie Clarke | en_US |
dc.contributor.thesis-reader | Alan Anderson | en_US |
dc.contributor.thesis-supervisor | Yana Fedortchouk | en_US |
dc.contributor.ethics-approval | Not Applicable | en_US |
dc.contributor.manuscripts | Not Applicable | en_US |
dc.contributor.copyright-release | Not Applicable | en_US |