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Characterizing Silicate Materials Via Raman Spectroscopy And Machine Learning: Implications For Novel Approaches To Studying Melt Dynamics, Blake O. Ladouceur

Doctoral Dissertations

Silicate melt characteristics impose dramatic influence over igneous processes that operate, or have operated on, differentiated bodies: such as the Earth and Mars. Current understanding of these melt properties, such as composition, primarily comes from investigations on their volcanic byproducts. Therefore, it is imperative to innovate on modalities capable of constraining melt information in environments where a reliance on laboratory methods is severed. Recent investigations have turned to Raman Spectroscopy and amorphous volcanics as a suitable pairing for exploring these ideas. Silicate glasses are a proxy for igneous melts; and Raman spectroscopy is a robust analytical technique capable of operating …

Optimizing Raman Spectral Collection For Quartz And Zircon Crystals For Elastic Geothermobarometry, Mayara F. Cizina

Boise State University Theses and Dissertations

Raman microspectroscopy is widely used to identify and characterize organic and inorganic compounds. In the geosciences, Raman microspectroscopy has been used to identify mineral and fluid inclusions in host crystals, as well as to calculate pressure-temperature (P-T) conditions using mineral inclusions in host crystals, such as quartz-in-garnet barometry (QuiG). For thermobarometric applications, the reproducibility of Raman peak position measurements is crucial to obtain accurate P-T estimates. In this study, we explored how to optimize Raman spectral collection of quartz and zircon inclusions and reference crystals by monitoring machine stability and by varying spectral parameters. We also monitored a reference Hg …

Raman Spectroscopic Investigation Of The Speciation Of Uranyl (Vi) And Thorium (Iv) Ions In Chloride-Bearing Aqueous Solutions Under Hydrothermal Conditions, Nadib Akram

MSU Graduate Theses

Raman spectra were acquired for a uranyl chloride aqueous solution at temperatures ranging from 25°C to 500°C at the chloride concentration of 6M and uranium (vi) concentration of 0.05M. The measurements were taken by sealing the sample in a hydrothermal diamond anvil cell (HDAC) which enabled spectra acquisition at non-ambient conditions. The pressure inside the cell was measured by estimating the liquid-vapor homogenization temperature (T_H) and using the isochoric equation of state diagram of water. The acquired spectra were then fitted to determine the speciation distribution of the various uranyl chloride species for the mentioned concentration. The developed …

Shock Effects Recorded By The U-Pb Radiometric System In Zircons Of Apollo 17 Impact Breccias And By Raman Spectroscopy In Enstatite Meteorites, Bidong Zhang

Electronic Thesis and Dissertation Repository

Impact cratering processes and formations are ubiquitous on the rocky planets within the Solar System. The Earth-Moon system was formed by a massive planetary impact, and numerous impacts afterwards significantly reshaped the topography and lithology of the Moon surface. This dissertation focuses on studying some specific geochemical, geochronological, and geophysical signatures of impact processes preserved in lunar rocks and asteroidal meteorites.

The zircon U-Pb radiometric system is one of the most reliable geochronometers in measuring geological time. Recently, unsupported radiogenic Pb enrichment has been reported to compromise the accuracy and precision of zircon U-Pb geochronometer in terrestrial rocks. In Chapter …

An In-Situ Study Of The Aqueous Speciation Of Uranium (Vi) Under Hydrothermal Conditions, Diwash Dhakal

MSU Graduate Theses

Rigorous study of the speciation distribution of uranyl-chloride bearing solutions under hydrothermal conditions is important to understand the transport mechanism of uranium underground, which is of uttermost interest to parties studying the geological uranium deposits and those studying the possibilities of geological repositories for spent nuclear waste. I report an in-situ Raman spectroscopic study of the speciation distribution of aqueous uranyl-chloride complexes upto 500°C conducted using a HDAC as the high PT spectroscopic cell. The samples studied contained the species UO₂²⁺, UO₂Cl⁺, UO₂Cl₂⁰ and UO₂Cl₃^{- …}

Local Environmental Controls On Sulfur Isotope Ratios In Marine Sedimentary Iron Sulfide Minerals, Roger Nicholas Bryant

Arts & Sciences Electronic Theses and Dissertations

The controls on the bulk sulfur isotopic composition of marine sedimentary iron sulfides (often referred to simply as pyrite; δ34Spyr) are poorly understood. Nevertheless, many have employed δ34Spyr in efforts to reconstruct the past operation of the biogeochemical sulfur cycle, from the planetary scale down to individual microbial metabolisms. This practice has been thrown into doubt by a growing body of evidence that suggests δ34Spyr is strongly controlled by local environmental conditions. This dissertation describes efforts to determine the mechanisms responsible for the link between local environmental conditions and δ34Spyr. In order to do this, we developed novel laboratory procedures …

Evaluation Of Raman Spectroscopic Geothermometry Of Graphitic Carbon As A Mineral Exploration Tool. A Case Study Of The San Sebastian Au-Ag Mine, Durango, Mexico, Justin Daniel Rumney

Electronic Thesis and Dissertation Repository

While visually similar to graphite, graphitic carbon is disordered rings of carbon whereas graphite is the pure-carbon crystalline form. As graphitic carbon is heated, it undergoes an irreversible graphitization process which can be observed using Raman spectroscopy and determine the maximum temperature that a rock was exposed to. Samples of sedimentary rocks, taken from the Au-Ag San Sebastian mine in Durango Mexico, containing graphitic carbon located from positions in contact with mineralized veins were used in developing a low-cost protocol for Raman spectroscopic analysis of drill core. The samples were cut and then polished to provide a smooth surface, so …

Survey Of ‘Low-Z’ Particles From The Interplanetary Dust Collection In Search Of Idps, Harison Wiesman

Undergraduate Theses—Unrestricted

Micrometeorites are one of the most common types of extraterrestrial material that fall to the Earth, beside meteorites and interplanetary dust particles (IDPs). All of these materials are known to contain presolar grains that, when studied in the laboratory, provide information about the origin of the solar system and help to constrain models of nucleosynthesis in stars. Recent studies of micrometeorites revealed the presence of a group of particles with very high C contents. These ultra-carbonaceous Antarctic micrometeorites (UCAMMs) are fine-grained, fluffy particles dominated by highly disordered carbonaceous matter. The presence of H and N isotopic anomalies, abundant presolar grains, …

Raman Spectroscopic Study Of Solid Solution Spinel Oxides, Brian D. Hosterman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solid solution spinel oxides of composition MgxNi1−xCr2O4, NiFexCr2−xO4, and FexCr3−xO4 were synthesized and characterized using x-ray diffraction and Raman spectroscopy. Frequencies of the Raman-active modes are tracked as the metal cations within the spinel lattice are exchanged. This gives information about the dependence of the lattice vibrations on the tetrahedral and octahedral cations. The highest-frequency Raman-active mode, A1g, is unaffected by substitution of the divalent tetrahedral cation, whereas the lower frequency vibrations are more strongly affected by substitution of the tetrahedral cation. The change in wavenumber of many phonons is nonlinear upon cation exchange. All detected modes of MgxNi1−xCr2O4 and …