Master of Science
Flemming, Roberta L.
Blamey, Nigel J.F.
23Na Magic Angle Spinning Solid State Nuclear Magnetic Resonance (MAS SS NMR) spectroscopy has been used to study natural geological samples of halite, fluorite, and quartz to evaluate the efficacy of NMR spectroscopy for in situ fluid inclusion analysis. NaCl calibration standards yielded a strong linear correlation (R2=0.9919) for salinity, albeit only over a ~1 ppm breadth of chemical shift. Fluid inclusions were successfully identified in all three types of minerals studied using MAS NMR. Chemical analysis with Inductively Coupled Plasma -- Mass Spectrometry (ICP-MS) was employed to quantify elemental contaminants in halite samples. Powder X-Ray Diffraction (pXRD) analysis was used to verify the mineral identity of the samples and identify any contaminant mineral phases. This research was successful in producing reasonable estimates for fluid salinity within halite samples. Quartz and fluorite samples showed evidence of further influence beyond salinity affecting the chemical shift of fluid peaks. This research was successful as a proof of concept for NMR analysis of fluid inclusions, however, further study is needed to understand the effects of pressure and fluid composition on fluid inclusion behaviour in order for NMR to be a useful technique to identify formation conditions of geological samples.
Summary for Lay Audience
This research seeks to lay the foundation for using sodium-23 Nuclear Magnetic Resonance (23Na NMR) spectroscopy to study microscopic capsules of fluids that have been trapped inside naturally occurring rocks and minerals. These naturally preserved fluids can hold important information about the formation of the mineral, such as the temperature and pressure of formation and the types of fluids involved in its mineralization. Hydrothermal alteration can also be recorded, so changes over time could be monitored to better understand the geological history of the area. These are important to understand when trying to model the processes that contributed to a geological system, and these can be very useful when identifying areas that have a high potential for hosting minerals of economic interest. Current techniques that are used to study fluid inclusions are very time-consuming and labour-intensive, leading to expensive analyses that sometimes require a month or more to complete. By understanding the capabilities of NMR spectroscopy for studying geological samples and their fluid inclusions, there exists the potential to greatly reduce the time needed for sample characterization. Preparation of samples for NMR analysis is fast and efficient, as is the analysis itself; NMR spectroscopy can be completed within hours with the appropriate understanding and resources, instead of weeks or more with standard fluid inclusion analysis. This research investigates the potential for studying fluid inclusions in situ and non-destructively using 23Na NMR spectroscopy within natural samples of halite, fluorite, and quartz.
Pilar, Stephen, "In Situ Study of Geological Fluid Inclusions Using 23Na Nuclear Magnetic Resonance Spectroscopy" (2021). Electronic Thesis and Dissertation Repository. 8353.
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