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The co-evolution of life and the environment stands as a cornerstone in Earth's 4.5-billion-year history. Environmental fluctuations have wielded substantial influence over biological evolution, while life forms have, in turn, reshaped Earth's surface and climate. This dissertation centers on a critical period in Earth's history—the Neoproterozoic Era—when profound environmental shifts potentially catalyzed pivotal eukaryotic evolutionary events. By delving deeper into Neoproterozoic paleoenvironments, I aim at a clearer understanding of life-environment co-evolution in this crucial era. The first chapter focuses on an important juncture—the transition from prokaryote to eukaryote dominance in marine ecosystems during the Tonian Period (1000 Ma to 720 Ma). To assess whether the availability of nitrate, an important macro-nutrient, played a critical role in this evolutionary event, nitrogen isotope compositions (δ15N) of marine carbonates from the early Tonian (ca. 1000 Ma to ca. 800 Ma) Huaibei Group in North China were measured. The data indicate nitrate limitation in early Neoproterozoic oceans. Further, a compilation of Proterozoic sedimentary δ15N data, together with box model simulations, suggest a ~50% increase in marine nitrate availability at ~800 Ma. Limited nitrate availability in early Neoproterozoic oceans may have delayed the ecological rise of eukaryotes until ~800 Ma when increased nitrate supply, together with other environmental and ecological factors, may have contributed to the transition from prokaryote-dominant to eukaryote-dominant marine ecosystems. Recognizing the spatial and temporal variations in Neoproterozoic oceanic environments, the second chapter lays the groundwork for a robust stratigraphic framework for the early Tonian Period. Employing the dynamic time warping algorithm, I constructed a global stratigraphic framework for the early Tonian Period using δ13Ccarb data from the North China, São Francisco, and Congo cratons. This exercise confirms the generally narrow range of δ13Ccarb fluctuations in the early Tonian, but also confirms the presence of a negative δ13Ccarb excursion of notable magnitude (~9 ‰) at ca. 920 Ma in multiple records, suggesting that it was global in scope. This negative excursion, known as the Majiatun excursion, is likely the oldest negative excursion in the Neoproterozoic Era and marks the onset of the dynamic Neoproterozoic carbon cycle. Shifting focus to the late Neoproterozoic, the third chapter delves into the origins of Neoproterozoic superheavy pyrite, whose bulk-sample δ34S values are greater than those of contemporaneous seawater sulfate and whose origins remain controversial. Two supervised machine learning algorithms were trained on a large LA-ICP-MS pyrite trace element database to distinguish pyrite of different origins. The analysis validates that two models built on the co-behavior of 12 trace elements (Co, Ni, Cu, Zn, As, Mo, Ag, Sb, Te, Au, Tl, and Pb) can be used to accurately predict pyrite origins. This novel approach was then used to identify the origins of pyrite from two Neoproterozoic sedimentary successions in South China. The first set of samples contains isotopically superheavy pyrite from the Cryogenian Tiesi'ao and Datangpo formations. The second set of samples contains pyritic rims from the Ediacaran Doushantuo Formation; these pyrite rims are associated with fossiliferous chert nodules and do not have superheavy sulfur isotopes. For the superheavy pyrite, the models consistently show high confidence levels in identifying its genesis type, and three out of four samples were inferred to be of sedimentary origins. For the pyritic nodule rims, the models suggest that early diagenetic pyrite was subsequently altered by hydrothermal fluids and therefore shows mixed signals. The third chapter highlights the importance of pyrite trace elements in deciphering and distinguishing the origins of pyrite in sedimentary strata.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is an established element analysis technique and can provide the element composition and concentration of solid materials from major to trace elements. In combination with spatial resolved sampling called element imaging, the element distribution can be accessed. In earth science, spatially resolved element analysis of minerals and rocks can give insights into geological processes and contribute to the understanding of the genesis. Especially the combination of small volume, low dispersion, fast washout ablation cells and the inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) significantly extended the gain of information from the element imaging analysis. Fast washout ablation cells deliver high density aerosol packages and short signals. This increases the signal to noise ratio and therefore improves the limit of detection. This allows to apply small laser spots for high resolution analysis with still sufficient sensitivity. The fast detection of the ICP-TOFMS allows to detect the full element mass spectrum quasi-simultaneously at high frequency. The acquisition of the full element mass spectrum gives the full picture of element distributions. Often, it allows also to uncover unexpected incorporation of elements into minerals as there is no need to limit the pallet of analytes. The delivery of high density aerosol packages and the high frequency detection allow to measure individual laser pulses and sample positions without aerosol mixing. A high sampling frequency is of major importance for element imaging to be applicable, as often hundreds of thousands of sample position are required for an analysis. In this thesis, the focus was on extending the applicability of LA-ICP-TOFMS element imaging. In Chapter 2 a new configuration of a fast washout ablation cell is presented and investigated. The parallel flow ablation cell (PFAC) is a modification of the tube cell design and provides shortest signal duration published so far. It provides further advantages compared to other fast washout ablation cell as for example a larger inner cell to sample surface distance (CSD) and a higher tolerance to variations in the CSD to achieve shortest signal durations. The short and reproducible signals revealed a present mass dependent shift of ion transport from light to heavy ions. A collision and reaction cell filled with H2 slightly reduced the mass dependent shift but did not allow to fully correct the different traveling speeds by collisional cooling. The fast and robust washout in a wide range of CSD makes the PFAC a promising ablation cell to increase the speed for element imaging analysis while maintaining the possibility for pulse-to-pulse signal separation. In Chapter 3 the first study of a nitrogen based inductively coupled plasma mass spectrometry system in conjunction with laser ablation (LA-(N2-ICP)-MS) is evaluated. N2 as the plasma gas has the potential to remove Ar plasma species leading to less interferences and to reduce the costs of the gas supply. The built prototype instrument achieved similar sensitivities compared to LA-(Ar-ICP)-MS. Ar plasma species were strongly reduced and nitrogen plasma species were more pronounced. The limits of detection for LA-(N2-ICP)-MS and LA-(Ar-ICP)-MS were similar or even lower for most elements using LA-(N2-ICP)-MS. Glass reference materials were quantified and could be determined within the uncertainty of the reference values. Overall, the nitrogen plasma source coupled to a mass spectrometer could challenge the argon-sustained ICP-MS in element analysis in the near future. In Chapter 4 an imaging control system (ICS) is presented and its capabilities are demonstrated. It synchronizes the control of the sample translational stage, the laser and the TOFMS data acquisition. This allows a virtually automated data acquisition. The triggered data acquisition for every ablation position leads to binned pixel data in relation to the sample position. This simplifies and reduces the time for data evaluation. Different imaging modes can be applied and allow for example the ablation of a custom shaped ablation area or to analyze a large area in multiple sections. Ablation modes can be applied according to the application. A single pulse mode allows the fast scanning of the area of interest or a hole-drilling mode provides higher pixel sensitivity and lower limits of detection while maintaining the same lateral resolution. A surface cleaning pulse can be applied at every sample position to reduce the influence of surface contamination and redeposited material from previous ablation spots. Overall, in this thesis the applicability of LA-ICP-TOFMS element imaging was extended by improving the reliability of the analysis system, extending the capabilities for further applications and reducing the costs for the analysis.

Abstract: The transport and depositional controls of ore-forming elements such as Ag, Au, Bi, Cu, Mo, Pb, Pt, and Zn has been extensively studied in crustal environments, but the behaviour of these elements within Earth’s mantle require further study. This thesis presents new petrographic and geochemical data on the abundance of these and other trace and major elements for a suite of mantle peridotites from the subcontinental lithospheric mantle beneath northern Canada. Better constraining the behaviour and residence of base- and precious-metals in the lithospheric mantle will help develop new models for the transport of these ore-forming components from the mantle to the crust. The samples studied were collected from drill-core from the Jericho, Muskox, and Voyageur kimberlites that erupted through the northern Slave Craton in Nunavut, Canada. The mid-Jurassic Jericho kimberlite cluster was used due to the relatively low level of metasomatism of the kimberlites and their entrained xenoliths, the abundance of mantle xenoliths, and the relatively close proximity (∼30 km) to the former Lupin gold mine and three VMS deposits (30–50 km). The selected sample suite is comprised of peridotites with varying modal mineralogy and mantle xenocrysts (i.e., lherzolite, harzburgite, and wehrlite). Major-, minor- and trace-elements were analyzed by electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry. Single-grain Al-in-olivine thermometry was used to estimate temperatures of formation, which were then projected onto a well-constrained xenolith-based mantle geotherm to estimate pressure and equilibration depth. The trace element composition of olivine from different depths was then used to reconstruct the “mantle stratigraphy” in this part of the northern Slave Craton. The equilibration conditions experienced by the peridotites, prior to kimberlite sampling, range from ∼100–200 km deep and ∼810–1210 ◦C, i.e., a large fraction of the garnet-bearing lithospheric mantle was sampled. Depth profiles were constructed for the analyzed elements to reveal the vertical distribution of trace elements within the lithosphere mantle. QEMScan analysis was used to quantify peridotite modal mineral abundances, which combined with mineral geochemical data to perform mass balance calculations, to estimate whole-rock concentrations. Notable features in the trace element data include high field strength element (i.e., Nb, Ta) enrichment at ∼130 km depth, a systematic enrichment in Cu with depth towards the base of the lithosphere, and a variably depleted mantle composition. Trace element trends found in the northern Slave Craton are consistent with those documented previously in the sub-continental lithospheric mantle below the Superior Craton, suggesting consistency in geochemical behaviour in the depth-related variability of some trace elements (i.e., Cu). The results from the mass balance calculations demonstrate the mantle sample suite yield depleted (e.g., high modal olivine Mg#’s) and/or enriched trace element concentrations (e.g., Cu, Zn, Nb, Ta) compared to depleted mantle estimates. The variations found are most likely the product of the complex, multi-stage metasomatic history, where enrichment is produced through protokimberlitic and carbonatite melt metasomatism re-fertilizing rocks that were previously depleted through melt extraction. Depending on the composition of the metasomatic agent different element groups were re-fertilized. HFSE were determined to be enriched in the mantle through carbonatitic metasomatism, resulting in a substantial reservoir hosted in the lithosphere. As shown by the systematic variation with depth, elements of economic interest (e.g., V, Cr, Cu) were re-enriched in the lithosphere by the metasomatic fluids and/or melts and incorporated into silicate minerals through substitution mechanisms. Inconsistent enrichment trends in precious metals and ore-forming elements make determining the metasomatic source, if any, problematic. Elements enriched in the northern Slave peridotites were found to be incorporated into the host minerals through multiple mechanisms. Those elements with moderate compatibility into mantle silicates, were found to be included though substitution (e.g., Cu2+ and Mg2+) based mechanisms. Whereas incompatible elements, such as Au, are incorporated as micro-inclusions, that were not observed during microscopy. The mode of incorporation is reflected in the time-resolved mass spectrometer signal intensity. Substitution mechanisms produce smooth spectra even at low signal intensities; whereas inclusions produce irregular and spikey spectra that are orders of magnitude above background. Trace element systematics in kimberlite derived mantle xenoliths and xenocrysts demonstrate that silicate minerals can host significant concentrations of ore-forming elements and contain a plethora of information about the metasomatic history of the mantle source region.

The Round Mountain gold mine located in northern Nye county Nevada is one of the most economically important low-sulfidation, volcanic-hosted epithermal type gold-silver deposits in North America. The association of gold with pyrite is well established in Carlin type and in other epithermal type deposits, however no comprehensive characterization on the distribution and/or abundance of disseminated gold at the Round Mountain deposit exists. This study presents the first detailed microgeochemical characterization of pyrite from the Type 2 ore unit using energy dispersive X-ray spectroscopy (EDS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Elemental EDS maps revealed heterogeneous arsenic (As) zonation throughout all sampled pyrites, with arsenic enriched in the rims of many grains. While there is complexity to apparent pyrite growth zones, trace elemental mapping via LA-ICP-MS corroborated the EDS As zonation patterns, and revealed a spatial correlation with gold, with gold concentrations up to 66.2 ppm. Additionally, all pyrites studied appear to have porous and inclusion rich microtextures, consistent with boiling. This study reports the first documented occurrence of gold-bearing arsenian pyrite at the Round Mountain gold mine and could have implications for gold recovery in heap leaching and the exploration of future ore.

Abstract: Gahcho Kué is a diamond mine in the Northwest Territories of Canada that opened in 2016. This is the first study into the morphology, N systematics, and stable isotope (C and N) composition of the Gahcho Kué diamonds, and the mineral chemistry of the associated inclusions. The resulting data are used to provide insight into the poorly understood and characterised mantle of the Southern Slave Craton, and the mantle conditions that gave rise to the diamond association within the area. Results from 88 inclusion-bearing diamond samples show that diamond formation beneath the Gahcho Kué mine occurred primarily in depleted peridotitic mantle (84%), with some minor contribution from eclogitic (15%) and websteritic (1%) mantle. Assessment by geothermobarometry revealed relatively cold lithospheric conditions compared to other diamondiferous localities within the Slave craton. The trace element chemistry of associated garnets revealed the standard sinusoidal pattern of depletion and re-enrichment by metasomatic fluids/melts in peridotitic source regions, and the pattern of LREE-depletion typical of eclogitic mantle sources. Temperature estimates from the assessment of N concentrations and aggregation states show largely consistent temperatures between mantle residence and formation conditions. Stable isotope data are largely within the expected mantle ranges for δ13C, whilst δ15N values are largely enriched relative to mantle values. Rare more negative δ13C and positive δ15N values were found, reflecting the influence of a subduction-related component, including a specimen with the highest δ15N value observed to date (+25.12‰) in a diamond.

Polished thin sections of ten eucrites, meteorites originating from the asteroid Vesta, were examined using polarized light microscopy, photomicrograph mapping, and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to investigate their compositions, with particular emphasis on elements known to be volatile at planetary formation conditions. The samples were assessed for pristinity and grouped into impact melts, granular, and subophitic textures. LA-ICP-MS analysis was performed on selected samples for individual pyroxene and plagioclase grains – the main silicate phases - as well as fusion crust, to measure major and trace element abundances, with an emphasis on moderately volatile elements (MVE’s) such as Cs, Zn, K, Rb, and Pb. Incompatible trace element abundances are in generally good agreement between samples, and both plagioclase and pyroxene grains show depletions in the MVE’s. Modal reconstructions were done using plagioclase and pyroxene and compared to bulk rock data. They fairly accurately recreate the bulk rock, besides the most incompatible elements, which must exist in minor accessory minerals known to occur in eucrites (e.g., apatite, zircon, baddeleyite). Fusion crust measurements, along with ALHA 81001 (a fine-grained impact melt,) are almost identical to the bulk rock data, confirming their usefulness as a proxy for bulk rock composition. Volatile abundances were assessed using Rb/Ba, Rb/Sr, and Zn/Fe ratios, which compare an MVE to a refractory element. These show eucrites having similar levels of volatile depletion to the Moon. Finally, normalized elemental abundances were plotted versus the element’s volatility, in which volatile elements fall along a downward trend, with the slope indicating the level of volatiles present. From this perspective, eucrite volatile abundances fall in between those of the Earth and the Moon.

Fluid inclusions are the only available samples of paleo-fluids responsible for crystallization of hydrothermal minerals including ore phases. Analysis of fluid inclusions implicitly assumes that the inclusions have preserved their chemical composition since the time of their entrapment. There is, however, an increasing evidence from experimental work and analytical studies of natural samples showing that inclusions hosted in quartz – a ubiquitous host in many ore-forming systems – can experience post-entrapment modification. The contents of small monovalent cations, e.g. Cu, can be enhanced up to several orders of magnitude in vapor-dominated fluid inclusions by diffusional exchange for hydrogen. In this study, I focus on chemical analysis of fluid inclusions hosted by various minerals that co-precipitated with quartz and host the same fluid, in order to compare their compositional consistency and address existence and extent of post-entrapment modification. The fluid inclusions were analyzed by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) and I explore analytical possibilities and challenges when applied to analysis of ultra-trace quantities of elements in small amounts of fluid, such as Au contents of magmatic vapor. I use representative samples from mineralization settings at convergent plate boundaries, namely granite-related Sn-W deposit (Mole Granite, Eastern Australia) and porphyry Cu deposit (Bingham Canyon, Utah, USA). In these systems, highly saline brines are important carriers of chloride-complexed metals and coexist with sulfur-rich vapors containing sulfide-complexing metals, e.g. As, Au, and, arguably, to various degree Cu. In the Mole Granite Sn-W deposit in Eastern Australia brine and vapor coexist in hydrothermal quartz, topaz, and beryl. Fluid inclusions in these three minerals show consistent salinities of 28–39 wt. % NaCleq in brine and 1–6 wt. % NaCleq in vapor at formation temperatures above 380 °C. These two fluid types have nearly identical concentrations of trace elements such as B, Na, K, S, and Cs, but reveal significant discrepancies in Cu abundances. The Cu concentrations in the quartz-hosted vapor inclusions are in the range of 5–50 000 ppm, in contrast to 20–2000 ppm Cu found in topaz- and beryl-hosted vapor inclusions. Partition coefficients of Cu between brine and vapor recorded by the topaz- and beryl-hosted fluids are in agreement with experimental results for magmatic-hydrothermal conditions, and in favor of the brine. The quartz-hosted fluids, however, show partitioning coefficients of Cu that exceed those found in all available experiments in sulfur-bearing systems. The vapor inclusions preserved in quartz are thus interpreted to have undergone significant post-entrapment modification, facilitated by their initially high sulfur content. By contrast, Au in the brine and vapor inclusions has been detected as erratic values only, despite that the detection limits of Au achieved by the LA-ICP-MS analysis were as low as single ppb. This extreme depletion in Au has been addressed by thermodynamic modeling indicating that saturation of the fluid with liquid bismuth can cause effective and essentially complete removal of Au from the fluid, and precipitates both metals as Bi-Au alloy. In the Bingham Canyon Cu-Mo-Au deposit (Utah, USA), garnet, pyroxene and quartz coexist in carbonate-replacement skarns that trapped brine, vapor as well as initial single-phase fluid prior to its separation. The single-phase intermediate-density fluid with an average salinity of 15 wt. NaCleq was trapped above approx. 550 °C and 800 bar. Salinities of brine and vapor inclusions are 32–42 and 2–7 wt. % NaCleq, respectively, and they formed at 420–380 °C and approx. 200 bar. The characteristics of corresponding fluid types in garnet, quartz, and to some degree in pyroxene remain nearly identical including their metal and other trace element contents. With improved analytical configuration, reliable Au signals were obtained from the fluid inclusions. Both Cu and Au have approximately equal content relative to Na in vapor and brine. This contrasts with previous fluid analyses from the porphyry quartz stockwork suggesting that majority of Cu and Au was transported by vapor. The new data suggest that the Cu concentrations in the vapor from the quartz stockwork were likely enhanced after inclusion entrapment, while the Au concentrations in the vapor phase require verification using lower instrumental detection limits. The Cu, Au and S concentration in the fluids from the porphyry quartz stockwork are consistently higher (0.2–5 ppm Au, 0.05–3 wt. % Cu) than those from the skarn minerals (0.02–0.4 ppm Au, 0.006–0.3 wt. % Cu), in contrast to ore grades that vary in an opposite manner (Au/Cu of 10-5 in the porphyry vs. 5∙10-5 in the skarn). This dichotomy was likely caused by chemical reactivity of carbonate precursor to the skarns and fluid focusing promoted by porosity and permeability enhancement during its decarbonation. In broader context, post-entrapment modification of vapor inclusions appears to be related to acidic and sulfur-rich fluids such as those preserved in granite- or porphyry-hosted pathways. By contrast, skarn-forming reactions appear to effectively neutralize acidity and together with low sulfur concentrations, the skarn-hosted fluids lack the principal driving forces that allow chemical-potential coupling and metal diffusion between fluid and host mineral, hence control the extent of post-entrapment modification. This study illustrates novel approaches to analysis of ultra-low metal concentrations in small volumes of fluids and analysis of fluid inclusions in non-traditional silicate minerals. I have identified and addressed several outstanding challenges of the LA-ICP-MS analytics, specifically effects of contamination on reliable analysis of elements close to their detection limits, strategies for reduction of the analytical data, and estimation of average concentrations for fluid inclusion populations.

Abstract: Asteroids are considered to be rich sources of precious metals, water, and essential volatiles for life. Such a consideration has been derived from the study of meteorites and asteroid reflectance spectra which have both been vital to our understanding of asteroid compositions. The vast amount of valuable resources in asteroids that are in close proximity to Earth (Near-Earth Asteroids; NEAs) has designated such asteroids as prime targets for extra-terrestrial mining. Of the resources that can be extracted from asteroids, the platinum group elements (PGEs) and water are two of the most sought-after materials. The PGEs are highly valuable given their rarity on Earth, while having an available water source in space can help facilitate future space exploration (i.e., rocket fuel, radiation shielding, drinking water, etc.). Before mining of these resources can commence, asteroid miners must develop a detailed understanding of how the different compositions of asteroids can affect the distribution of such resources. Since it is an expensive endeavor to visit asteroids for such an assessment, meteorite studies take precedence in obtaining the necessary information for selecting an asteroid target to mine. The premise of this master’s thesis is to provide insight into the PGE and water resources that can be mined from asteroids through the study of chondritic meteorites. In the first study of this thesis, PGE concentrations have been determined in situ in ordinary chondrite metal via laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This is the first study to provide a detailed account of in situ PGE concentrations in the metal phases among a suite of ordinary chondrites. In situ results reveal that PGE concentrations in ordinary chondrite metal are similar among the different ordinary chondrite groups (H, L, and LL). This discovery is a significant contribution to the asteroid mining industry regarding which ordinary chondrite parent body is most ideal to mine considering that previous studies have claimed that PGE concentrations vary among the three ordinary chondrite groups. The findings from this PGE study are also pertinent to understanding the formation of metal in ordinary chondrites; the minimal variability of PGEs suggest that metal was formed as nebular condensates. The second part of this thesis addresses the effects aqueous alteration has on the abundance of water in carbonaceous material. For this investigation, the unique Tagish Lake carbonaceous chondrite was selected for analysis given that variable aqueous alteration degrees have been reported for three pristine specimens (TL5b < TL11h < and TL11i; Herd et al., 2011; Blinova et al., 2014). Thermogravimetric analysis (TGA), infrared transmission spectroscopy, and X-ray diffraction (XRD) were used to quantify the extent of aqueous alteration in the Tagish Lake specimens based on how much water they contained and their phyllosilicate/olivine ratio. The findings from this study are congruent with the previously reported alteration sequence (Herd et al., 2011; Blinova et al., 2014), allowing for the addition of two new Tagish Lake specimens (TL4 and TL10a) to be incorporated into the sequence. Reflectance spectra of Tagish Lake were also acquired to re-visit the Tagish Lake parent body connection. This Tagish Lake investigation is relevant to the material processing of asteroid mining given that the TGA method records the temperatures at which minerals break down and release water. Furthermore, investigating the meteorite-parent body connection is pertinent for selecting suitable asteroid targets. The findings of this thesis provide valuable insight into the type of asteroids that are suitable for mining PGEs and water. On this basis, I propose that H chondrite parent bodies are ideal for the extraction of PGEs, while CI and CM carbonaceous chondrite parent bodies are best for water resources.

The Ertsberg-Grasberg District in Papua, Indonesia, hosts two of the world’s largest intrusion-related Cu-Au deposits: the Ertsberg Intrusive System, a hybrid porphyry-skarn deposit, and the Grasberg Igneous Complex, a high-grade porphyry deposit. Cu mineralization within the Grasberg porphyry and Ertsberg skarn systems consists primarily of bornite and chalcopyrite, whereas native gold occurs as inclusions within, or along boundaries of these minerals. Experimental studies by other researchers have shown that at hydrothermal ore-forming temperatures (~300-700°C) and elevated sulfur activity, bornite and chalcopyrite can host 1000s ppm Au within the sulfide lattice or as nano-inclusions. Upon retrograde cooling of the hydrothermal system, the capacity of the Cu-Fe sulfides to host Au significantly decreases to ~10 ppm, suggesting that the Au becomes unstable within the Cu-Fe sulfide matrix and may passively migrate out of the sulfides and coalesce to form native gold grains. These data suggest that Cu-Fe sulfides could exert a strong control on the gold contents of porphyry deposits. However, the traditional model for native gold deposition in large hydrothermal systems relies primarily on fluid pulses, and does not consider gold contributions from the exsolution of previously precipitated gold within Cu-Fe sulfides. To assess the role of Au-bearing Cu-Fe sulfides in the concentration of native gold in this setting, High Resolution X-ray Computed Tomography was used to measure the native gold grains’ shapes, textures, and occurrence modes, and map the extent of contiguous Cu-sulfides. HRXCT data were used to 3D modified Voronoi regions within the Cu-sulfides, as an estimate of diffusional domains that may have provided gold to the Au-grains during cooling. The modified Voronoi volumes are defined for each Au-grain as the set of points within the Cu-sulfide network that are closer to that Au-grain than any other, when measured along a path through the Cu-sulfide. HRXCT data for 11 Ertsberg-Grasberg District ore samples were processed with two different threshold criteria, which produced 16 linear correlation values between modified Voronoi volumes and gold grain volumes. Of these 16 correlation coefficients, none show statistically significant correlations. Because of the paucity of gold grains within our samples, calculated drainage regions commonly extended to the physical edge of the core samples, rendering their actual volumes ambiguous and the correlations associated with them un-interpretable. In cases where numerous gold grains were identified, correlation values were not statistically significant. In general, however, this analysis was impaired by the necessity of interpreting whether all grains in a sample were created by a single event and mechanism. Complementary Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to assess and compare trace element variation within the Cu-Fe sulfides in the district and to constrain spatial variation of Au within Cu-Fe sulfides that contain native gold grains. LA-ICP-MS data show a strong positive correlation between Bi and Ag, and a moderate, positive correlation between Bi and Au, throughout the data. Au occurrences are scattered rather than uniform, where Au concentrations appear in patches throughout the sulfides. This may imply that the majority of non-visible gold exists in Au nanoparticles, rather than solid solution with the Cu-Fe sulfides. Spot analyses and 2D maps indicate the presence of an “enrichment halo” of elevated Au contents in Cu-Fe sulfides surrounding the gold grains. This “enrichment halo” can be interpreted as evidence in support of a hybrid Ostwald-type ripening process that coarsens gold inclusions in chalcopyrite at high-temperatures in porphyry-skarn systems.

The Ertsberg-Grasberg District in Papua, Indonesia, hosts two of the world’s largest intrusion-related Cu-Au deposits: the Ertsberg Intrusive System, a hybrid porphyry-skarn deposit, and the Grasberg Igneous Complex, a high-grade porphyry deposit. Cu mineralization within the Grasberg porphyry and Ertsberg skarn systems consists primarily of bornite and chalcopyrite, whereas native gold occurs as inclusions within, or along boundaries of these minerals. Experimental studies by other researchers have shown that at hydrothermal ore-forming temperatures (~300-700°C) and elevated sulfur activity, bornite and chalcopyrite can host 1000s ppm Au within the sulfide lattice or as nano-inclusions. Upon retrograde cooling of the hydrothermal system, the capacity of the Cu-Fe sulfides to host Au significantly decreases to ~10 ppm, suggesting that the Au becomes unstable within the Cu-Fe sulfide matrix and may passively migrate out of the sulfides and coalesce to form native gold grains. These data suggest that Cu-Fe sulfides could exert a strong control on the gold contents of porphyry deposits. However, the traditional model for native gold deposition in large hydrothermal systems relies primarily on fluid pulses, and does not consider gold contributions from the exsolution of previously precipitated gold within Cu-Fe sulfides. To assess the role of Au-bearing Cu-Fe sulfides in the concentration of native gold in this setting, High Resolution X-ray Computed Tomography was used to measure the native gold grains’ shapes, textures, and occurrence modes, and map the extent of contiguous Cu-sulfides. HRXCT data were used to 3D modified Voronoi regions within the Cu-sulfides, as an estimate of diffusional domains that may have provided gold to the Au-grains during cooling. The modified Voronoi volumes are defined for each Au-grain as the set of points within the Cu-sulfide network that are closer to that Au-grain than any other, when measured along a path through the Cu-sulfide. HRXCT data for 11 Ertsberg-Grasberg District ore samples were processed with two different threshold criteria, which produced 16 linear correlation values between modified Voronoi volumes and gold grain volumes. Of these 16 correlation coefficients, none show statistically significant correlations. Because of the paucity of gold grains within our samples, calculated drainage regions commonly extended to the physical edge of the core samples, rendering their actual volumes ambiguous and the correlations associated with them un-interpretable. In cases where numerous gold grains were identified, correlation values were not statistically significant. In general, however, this analysis was impaired by the necessity of interpreting whether all grains in a sample were created by a single event and mechanism. Complementary Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to assess and compare trace element variation within the Cu-Fe sulfides in the district and to constrain spatial variation of Au within Cu-Fe sulfides that contain native gold grains. LA-ICP-MS data show a strong positive correlation between Bi and Ag, and a moderate, positive correlation between Bi and Au, throughout the data. Au occurrences are scattered rather than uniform, where Au concentrations appear in patches throughout the sulfides. This may imply that the majority of non-visible gold exists in Au nanoparticles, rather than solid solution with the Cu-Fe sulfides. Spot analyses and 2D maps indicate the presence of an “enrichment halo” of elevated Au contents in Cu-Fe sulfides surrounding the gold grains. This “enrichment halo” can be interpreted as evidence in support of a hybrid Ostwald-type ripening process that coarsens gold inclusions in chalcopyrite at high-temperatures in porphyry-skarn systems.

Abstract: This thesis applies microanalytical tools to the geochemical investigation of different mineral components in the volcanic rock kimberlite. This work significantly advances the application of one of these tools, deep UV (193 nm) laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to the investigation of the most common mineral in kimberlite and the upper mantle – olivine. The investigation is focused on, but not limited to, samples from the Lac de Gras kimberlite field in the Central Slave Craton, Canada. The overall aim is to further illuminate the applicability of clinopyroxene, garnet, and olivine as petrogenetic and exploration indicator minerals using advanced analytical techniques of electron microprobe microanalysis (EPMA), quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and secondary ion mass spectrometry (SIMS). One petrogenetic topic of interest is the formation of megacrysts, large (> 1 cm) crystals commonly found in kimberlites. Cr-diopside clinopyroxene and Cr-pyrope garnet megacrysts from Lac de Gras kimberlites, Slave Craton, Canada, are investigated. Based on their large crystal size and compositional overlap with lherzolitic phases, the samples can be classified as Cr-rich megacrysts, constituting the first report of such megacrysts in Lac de Gras kimberlites. While trace element systematics and Sr isotope isotopes suggest a genetic link to kimberlite-like melts, a strictly cognate relationship is ruled out, based on evidence for disequilibrium with the transporting kimberlite. Instead, an older metasomatic origin is adopted for their formation, presumably linked to precursor kimberlite melts that stalled at mantle depths and reacted with the wall rocks. The Cr-rich megacrysts also contain fully crystallized former melt inclusions. A detailed petrographical and geochemical study suggests that these polymineralic inclusions constitute an early snapshot of the transporting kimberlite melt which infiltrated the megacrysts during ascent. Within Cr-diopsides, polymineralic inclusions are dominated by calcite and olivine and are commonly surrounded by reaction rims with abundant fluid inclusions (CO2-rich). This mineralogy appears to record long-proposed decarbonation reactions that may play an important role in the evolution of calcite-bearing kimberlites, such as: diopside + dolomite (melt) = olivine + calcite + CO2. In examining new applications of olivine geochemistry using LA-ICP-MS to kimberlite evolution and mantle studies, it is necessary to develop a strict protocol for the measurement of trace elements in olivines. Comparative experiments reveal a more pronounced and complex beam-size dependent inter-element fractionation behavior for olivine that requires careful optimization of ablation parameters and calibration strategies. Methods developed in this thesis have been externally verified in laboratories at the University of Melbourne and at the Geological Survey of Canada. A main conclusion of this study is that matrix-matched calibration is necessary in order to avoid inaccuracies caused by calibration and fractionation effects, especially when using small (< 100 μm) laser spot sizes. Thus, an important output of this study is the characterization of appropriate olivine standards for matrix-matched LA-ICP-MS calibration. The development of a fast and accurate method for analyzing trace elements in olivine opens up new possibilities to pinpoint the different origins of olivine in kimberlite and to explore its potential as a petrogenetic indicator mineral and as a possible diamond exploration tool. Using natural samples, this investigation presents new trace element discriminators to distinguish between olivines derived from spinel- and garnet-peridotites. Using the high-pressure, high-temperature experiments performed by Brey et al. (1990), it is possible to derive the first experimental calibration of the Al-in-olivine thermometer at upper mantle conditions and hence evaluate the empirical thermometer of De Hoog et al. (2010). Al measurements in the experiments are performed at high spatial resolution (~8 μm) by SIMS, including SIMS mapping in order to investigate element distribution in the experiments. Based on Al concentrations in the experimental olivines, an improved and simplified calibration of the Al-in-olivine geothermometer applicable to garnet peridotites can be derived. Evaluation of this thermometer against olivine from natural garnet peridotites indicates that it may be the most reliable geothermometer currently available for garnet harzburgites.

This dissertation examines straying in Lake Erie steelhead (Oncorhynchus mykiss) and investigates how stocking practices can influence the propensity of steelhead to stray. The Lake Erie steelhead fishery generates millions of dollars in revenue each year for local economies in New York, Ohio, Pennsylvania, Michigan, and the province of Ontario. This fishery is overwhelmingly dominated by stocking from each of the four contiguous US states, and approximately 1.8 million juvenile steelhead are stocked each year to sustain population numbers. River-spawned salmonids generally exhibit high rates of philopatry, while for stockedfish straying rates of up to 15% are common. In Chapter I, we quantify the proportion of straying adult steelhead in five Lake Erie tributaries using state-hatchery specific otolith chemical signatures to identify sources. We also investigate the prevalence of naturally produced fish and identify spatial differences in the proportion of strays at different stream locations within two Lake Erie tributaries. Because straying proportions were found to be high in New York, in Chapter II an otolith back-calculation method was used to investigate the influence of size at stocking on the survival of juvenile steelhead released by the New York hatchery program. In Chapter III, we investigate additional drivers of straying by using dual-frequency identification sonar (DIDSON) to estimate survival and tributary residence time of juvenile steelhead stocked into a small Lake Erie tributary. Patterns in emigration, and the role of environmental factors and individual size on emigration timing were also investigated. In Chapter IV, we identify the prevalence of aragonite versus vaterite sagittal otoliths in steelhead raised in Lake Erie hatcheries. We then present a technique to use sagittal otoliths that have transitioned from aragonite to vaterite to help develop otolith chemistry signatures of steelhead from different hatchery sources in Lake Erie. This research was an attempt to identify potential drivers of straying in Lake Erie steelhead. From an applied management perspective, we attempted to identify straying proportions in different Lake Erie tributaries and examine how differential stocking practices may influence overall survival and return rates. Straying is a complex process driven by a number of different biotic and abiotic factors. The identification of mechanisms that increase straying, especially those which can be controlled by hatchery managers, would be invaluable and greatly advance our ability to manage steelhead populations.

The primary aim of this thesis is to develop image processing algorithms to quantitatively determine the link between traumatic brain injury (TBI) severity and chronic traumatic encephalopathy (CTE) neuropathology, specifically looking into the role of blood-brain barrier disruption following TBI. In order to causally investigate the relationship between the tau protein neurodegenerative disease CTE and TBI, mouse models of blast neurotrauma (BNT) and impact neurotrauma (INT) are investigated. First, a high-speed video tracking algorithm is developed based on K-means clustering, active contours and Kalman filtering to comparatively study the head kinematics in blast and impact experiments. Then, to compare BNT and INT neuropathology, methods for quantitative analysis of macroscopic optical images and fluorescent images are described. The secondary aim of this thesis focuses on developing methods for a novel application of metallomic imaging mass spectrometry (MIMS) to biological tissue. Unlike traditional modalities used to assess neuropathology, that suffer from limited sensitivity and analytical capacity, MIMS uses a mass spectrometer -- an analytical instrument for measuring elements and isotopes with high dynamic range, sensitivity and specificity -- as the imaging sensor to generate spatial maps with spectral (vector-valued) data per pixel. Given the vector nature of MIMS data, a unique end-to-end processing pipeline is designed to support data acquisition, visualization and interpretation. A novel multi-modal and multi-channel image registration (MMMCIR) method using multi-variate mutual information as a similarity metric is developed in order to establish correspondence between two images of arbitrary modality. The MMMCIR method is then used to automatically segment MIMS images of the mouse brain and systematically evaluate the levels of relevant elements and isotopes after experimental closed-head impact injury on the impact side (ipsilateral) and opposing side (contralateral) of the brain. This method quantifiably confirms observed differences in gadolinium levels for a cohort of images. Finally, MIMS images of human lacrimal sac biopsy samples are used for preliminary clinicopathological assessments, supporting the utility of the unique insights MIMS provides by correlating areas of inflammation to areas of elevated toxic metals. The image processing methods developed in this work demonstrate the significant capabilities of MIMS and its role in enhancing our understanding of the underlying pathological mechanisms of TBI and other medical conditions.

Recent scholarship demonstrates growth in archaeological analysis of Spanish colonial reducciones in Andean South America. Critical to understanding the impact of reducciones on indigenous populations is examining production and circulation of craft goods after Spanish conquest. Because it characterizes the elemental composition of archaeological pottery, Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is an invaluable tool for examining resource procurement and long distance exchange. In this thesis, I report data derived from XRF and LA-ICP-MS analyses of pottery from two sites in the Moquegua Valley, Peru: Torata Alta and Sabaya. Both sites were founded during Inca control of the valley (c. 1450-1535) but were also occupied into the seventeenth century and have strong Spanish colonial components. Comparing the data with an existing ICP-MS database on locally available clays, I examine differential resource procurement as well as access to imported goods among indigenous and Spanish communities in early colonial Moquegua.

The Eagle Ford Shale of South Texas is an organic-rich, calcareous mudrock succession which was deposited on the Comanche Platform during the earliest Late Cretaceous. Many academic and industry sponsored Eagle Ford studies over the past 10 years have concentrated their efforts on trying to understand the rock fabrics, facies architecture and heterogeneities present in the succession. However, despite heavy economic and academic interest in the system, few studies focus on trying to understand timing and source of the many bentonite ash beds present in the Eagle Ford; which serve as regional chronostratigraphic markers across South Texas. One of the primary goals of the study is the determination of U-Pb age dates in bentonite-rich ash beds from a group of subsurface cores that penetrate the Eagle Ford Formation in Atascosa County, Texas. Absolute age dates provide a chronostratigraphic framework that is used to estimate the depositional timing of variable Eagle Ford facies, as well as define the timing, duration and magnitude of isotopic events in the region. Secondly, age estimates are utilized to determine and calculate Eagle Ford accumulation rates across South Texas. Absolute age dates are incorporated with lithofacies definitions to better 1) understand the cyclic relationship between dominant Eagle Ford lithologies, 2) identify the controls responsible for the cyclic mode of deposition, and 3) determine the lateral continuity of key lithofacies and lithologic units. Lastly, elemental (XRF) data are utilized to describe the subtle paleoceanographic and sediment source conditions that persisted across the entire Eagle Ford section. These findings are integrated with stable carbon (δ13C) isotopic data, which allow for the accurate definition of Ocean Anoxic Event 2 (OAE 2) in the study area and provide a basis for regional correlation with previous studies. Recent studies have suggested that anoxic conditions experienced within the Western Interior Seaway during this time were asynchronous with the well-documented global OAE 2 event. The present study compares local U-Pb age dates, isotopic and elemental results with regional studies to better define the onset timing and paleoceanograpic conditions associated with Eagle Ford Shale deposition.

The Eagle Ford Shale of South Texas is an organic-rich, calcareous mudrock succession which was deposited on the Comanche Platform during the earliest Late Cretaceous. Many academic and industry sponsored Eagle Ford studies over the past 10 years have concentrated their efforts on trying to understand the rock fabrics, facies architecture and heterogeneities present in the succession. However, despite heavy economic and academic interest in the system, few studies focus on trying to understand timing and source of the many bentonite ash beds present in the Eagle Ford; which serve as regional chronostratigraphic markers across South Texas. One of the primary goals of the study is the determination of U-Pb age dates in bentonite-rich ash beds from a group of subsurface cores that penetrate the Eagle Ford Formation in Atascosa County, Texas. Absolute age dates provide a chronostratigraphic framework that is used to estimate the depositional timing of variable Eagle Ford facies, as well as define the timing, duration and magnitude of isotopic events in the region. Secondly, age estimates are utilized to determine and calculate Eagle Ford accumulation rates across South Texas. Absolute age dates are incorporated with lithofacies definitions to better 1) understand the cyclic relationship between dominant Eagle Ford lithologies, 2) identify the controls responsible for the cyclic mode of deposition, and 3) determine the lateral continuity of key lithofacies and lithologic units. Lastly, elemental (XRF) data are utilized to describe the subtle paleoceanographic and sediment source conditions that persisted across the entire Eagle Ford section. These findings are integrated with stable carbon (δ13C) isotopic data, which allow for the accurate definition of Ocean Anoxic Event 2 (OAE 2) in the study area and provide a basis for regional correlation with previous studies. Recent studies have suggested that anoxic conditions experienced within the Western Interior Seaway during this time were asynchronous with the well-documented global OAE 2 event. The present study compares local U-Pb age dates, isotopic and elemental results with regional studies to better define the onset timing and paleoceanograpic conditions associated with Eagle Ford Shale deposition.

Laser Ablation Inductively coupled plasma mass spectrometry (LA-ICP-MS) and Raman spectroscopy are both powerful imaging techniques. Their applications are numerous and extremely potential in the field of biology. In order to improve upon LA-ICP-MS an in-house built cold cell was developed and its effectiveness studied by imaging Brassica napus seeds. To further apply LA-ICP-MS and Raman imaging to the field of entomology a prong gilled mayfly (Ephemeroptera: Leptophlebiidae) from the Róbalo River, located on Navarino Island in Chile, was studied. Analysis of both samples showcased LA-ICP-MS and Raman spectroscopy as effective instruments for imaging trace elements and larger molecules in biological samples respectively.

Abstract: Following ATAC Resources Ltd.’s 2010 discovery of the gold prospects in the Nadaleen Trend (Central Yukon), company geologists and consultants determined that Precambrian carbonate rocks within the trend contain large endowments of gold located in the hinges of anticlines and fault zones. Subsequent studies revealed that additional gold mineralization is found away from these structures, spatially associated with “dolomitization fronts”, i.e. lithological contacts between dolomite and other units. Geochemical studies reveal that the carbonate host rocks of the Nadaleen Trend precipitated in anoxic, ferruginous seawater during the Ediacaran Period. Large volumes of dolomite and pyrite were generated during near-surface diagenesis, and the pyrite became enriched in trace metals. During further burial, calcite veining and stylolitization occurred. This preceded a base metal mineralization event in which a second generation of dolomite formed; this process created significant new porosity and permeability in the host rocks. Further calcite veining and a second generation of stylolitization subsequently occurred. This was post-dated by the ore stage which consisted of the precipitation of gold-bearing arsenian pyrite and a third generation of dolomite. Ore fluids travelled vertically along faults and laterally into Permeable zones associated with saddle dolomite and stylolites. Gold-bearing fluids travelled through these conduits until they encountered pyrite grains, at which point a sulfidation reaction occurred. This reaction resulted in deposition of gold-bearing arsenian pyrite on the pre-existing grains of pyrite. Since the first two generations of pyrite occur most commonly in dolomite rather than limestone, gold mineralization occurred preferentially in dolomite. A post-ore stage occurred consisting of calcite, realgar, and orpiment. Electron microprobe analysis and laser ablation inductively coupled plasma mass spectrometry reveals that the hydrothermal fluids were reducing and acidic, and thus were capable of dissolving carbonates to create porosity. Carbon, oxygen, and strontium isotopic data on calcite and dolomite indicate that the hydrothermal fluids isotopically equilibrated with the host rocks. The mineralization present in the Nadaleen Trend has geological features similar to those of world-class Carlin-type gold deposits, a class of gold deposits modelled after the Carlin Trend in Nevada.

The Eagle Ford Shale and equivalent Boquillas Formation (Late Cretaceous) contain abundant volcanic ash beds of varying thickness. These ash beds represent a unique facies that displays a range of sedimentary structures, bed continuity, and diagenetic alteration. They are prominent not only in West Texas outcrops, but also in the subsurface of South Texas where hydrocarbon production is actively occurring. The ash beds have the potential to be used for stratigraphic correlation for understanding early diagenesis and — most importantly — for obtaining high-resolution geochronology, which can then be used for defining depositional rates and chronostratigraphy. Study of the ash beds was conducted at outcrops along U.S. 90, west of Comstock, Texas, the subsurface in Atascosa and Karnes County, and at a construction site in South Austin. Bed thicknesses range from 0.1–33 cm and were collected throughout the entirety of the Eagle Ford succession. Mineral separation yielded abundant non-detrital zircons for U-Pb dating. Dating was conducted using LA-ICP-MS at The University of Texas at Austin, to attain a base level understanding of the age range for the Eagle Ford. High-resolution ages for the base and top of the Eagle Ford were obtained, in addition to radioisotopically defining the Cenomanian-Turonian boundary within the section. U-Pb ages for the Eagle Ford Shale range from Early Cenomanian to Late-Coniacian near Comstock, Mid-Cenomanian to the Turonian-Coniacian boundary in the subsurface, and Early Cenomanian to Late Turonian in Austin area. These findings contrast with many of the regional biostratigraphic studies across the Eagle Ford and indicate a more prolonged period of Eagle Ford deposition than previously observed.

The Eagle Ford Shale and equivalent Boquillas Formation (Late Cretaceous) contain abundant volcanic ash beds of varying thickness. These ash beds represent a unique facies that displays a range of sedimentary structures, bed continuity, and diagenetic alteration. They are prominent not only in West Texas outcrops, but also in the subsurface of South Texas where hydrocarbon production is actively occurring. The ash beds have the potential to be used for stratigraphic correlation for understanding early diagenesis and — most importantly — for obtaining high-resolution geochronology, which can then be used for defining depositional rates and chronostratigraphy. Study of the ash beds was conducted at outcrops along U.S. 90, west of Comstock, Texas, the subsurface in Atascosa and Karnes County, and at a construction site in South Austin. Bed thicknesses range from 0.1–33 cm and were collected throughout the entirety of the Eagle Ford succession. Mineral separation yielded abundant non-detrital zircons for U-Pb dating. Dating was conducted using LA-ICP-MS at The University of Texas at Austin, to attain a base level understanding of the age range for the Eagle Ford. High-resolution ages for the base and top of the Eagle Ford were obtained, in addition to radioisotopically defining the Cenomanian-Turonian boundary within the section. U-Pb ages for the Eagle Ford Shale range from Early Cenomanian to Late-Coniacian near Comstock, Mid-Cenomanian to the Turonian-Coniacian boundary in the subsurface, and Early Cenomanian to Late Turonian in Austin area. These findings contrast with many of the regional biostratigraphic studies across the Eagle Ford and indicate a more prolonged period of Eagle Ford deposition than previously observed.

Tooth enamel is among the most durable substances in the human body and as such has high recoverability in forensic anthropology cases. Its crystalline hydroxyapatite matrix has a slightly variable chemical composition which incorporates biologically available trace elements. The trace elements are derived from an individual's diet and the water he or she consumes during the period of enamel formation. As a result, trace element profiles of enamel can reflect the geology, pollution, and certain cultural dietary factors of the area in which the individual resided during this period. This research examines a sample of teeth with known demographic information from the Antioquia Modern Skeletal Reference Collection in Medellin, Colombia. A sample set of 75 teeth from 61 individuals born in areas throughout northwestern Colombia were analyzed using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), a minimally destructive, semi-quantitative technique. Analysis was performed at the Center for Archaeology, Materials, and Applied Spectroscopy (CAMAS) at Idaho State University. 33 elements were analyzed in the sample. Nonparametric methods were used to assess the relationship between elemental profiles and region of origin. Sr, Mo, Ag, Ba, Eu, and Tm concentration profiles were found to vary among regional groups. Al, Ni, Cr, Mn, Co, Sr, Cd, Sb, Sm, Eu, and U were found to predict region of origin. Differences in municipality were classified with 72% accuracy, variation across the department of Antioquia was classified with 67% accuracy, and the age of the geologic substrate was classified with 67% accuracy. The results suggest that trace element analysis of permanent tooth enamel may be of some use in estimating an individual's region of origin in forensic anthropological contexts. Further research with both larger sample sizes and more geographic variation is necessary.

The Arizona Strip and adjacent areas in Utah and Nevada are in a very marginal environment. This dissertation investigates how small-scale farmers who survived more than 1000 years in this area coped with the challenges of this marginal environment by examining how and why social interaction patterns varied over time in different parts of the region. Artifact assemblages from this area that date between A.D. 200 and 1350 are characterized by widely distributed ceramics tempered with olivine, a volcanic mineral. Sources of olivine lie in the vicinity of Mt. Trumbull and Tuweep, near the northwestern part of the Grand Canyon. The olivine-tempered ceramics were distributed mostly westward from Mt. Trumbull, up to 100 km to the lowland Virgin area in southern Nevada. Ultimately, the goal of this study is to understand why ceramic production and circulation patterns changed during the Ancestral Pueblo occupation of this peripheral area of the American Southwest. I hypothesize that ceramic production and regional interaction patterns were shaped in part by the need to minimize subsistence risk in this marginal agricultural environment. To reconstruct ceramic production and consumption pattern, laser-ablation inductively couple plasma mass spectrometry (LA-ICP-MS) was conducted on 1,069 sherds from the Mt. Trumbull/Tuweep and the lowland Virgin areas, along with source clay samples collected from the same areas. To examine how the use of clay resources changed over time, optically stimulated luminescence (OSL) dating was conducted on 113 sherd samples with compositional information. The data presented here suggest that different environmental conditions favored different social interaction and local ceramic production patterns. In Mt. Trumbull, under unstable climatic conditions and low population density, near the beginning of the Puebloan occupation, pots moved along with human migration. Later, when populations were higher and environmental conditions were equally unstable, pots were moved through interregional trade. In addition, clay resource specialization was favored early but was replaced later by exclusive use of optimal clays when population numbers were higher. In the lowland Virgin area, exchange played an important role as a risk minimization strategy throughout the Puebloan occupation, but clay-resource specialization gained importance later on, when populations increased.

In this research, electrochemical methods are used to synthesize the inorganic fraction of bone, hydroxyapatite, for application in biological implants and as a calibration material for elemental analysis in human bone. Optimal conditions of electrochemically deposited uniform apatite coatings on stainless steel were investigated. Apatite is a ceramic with many different phases and compositions that have beneficial characteristics for biomedical applications. Of those phases hydroxyapatite (HA) is the most biocompatible and is the primary constituent of the inorganic material in bones. HA coatings on metals and metal alloys have the ability to bridge the growth between human tissues and implant interface, where the metal provides the strength and HA provides the needed bioactivity. The calcium apatites were electrochemically deposited using a modified simulated body fluid adjusted to pH 4-10, for 1-3 hours at varying temperature of 25-65°C while maintaining cathodic potentials of -1.0 to -1.5V. It was observed that the composition and morphology of HA coatings change during deposition by the concentration of counter ions in solution, pH, temperature, applied potential, and post-sintering. The coatings were characterized by powder x-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The precipitated powders from the experiment were also characterized, with results showing similarities to biological apatite. There is a need for quantitative elemental analysis of calcified biological matrices such as bone and teeth; however there are no suitable calibration materials commercially available for quantitative analysis. Matrix-matched standards are electrochemically synthesized for LA-ICP-MS analysis of human bone. The synthetic bioapatite is produced via a hydrothermal electrochemical process using a simulated body fluid solution to form hydroxyapatite. Additional bioapatite standards are synthesized containing trace amounts of metals. The x-ray diffraction of the synthesized standards shows an increase in cell volume for the crystal structure from 0.534 to 0.542 nm3 with the substitution of metals into the crystal structure. The analyte concentration and recoveries for the synthesized standards and reference materials were determined by ICP-MS with % RSD below 6.3% and limits of detection below 1.2 ng/mL for trace metals. The electrochemically synthesized bioapatite was also compared to standard reference materials with X-ray diffraction, FTIR, and Raman spectroscopy. Optimum laser ablation parameters were determined for the standards and human bone. The synthesized standards were homogeneous and the reproducibility for the isotope concentrations determined by LA-ICP-MS was between 3-10 % compared to 10-35% for SRM 1486 Bone Meal and SRM 1486 Bone Ash. A quantitative method has been developed for 2D mapping using LA-ICP-MS and the matrix-matched standards of metal-doped biopaptite to characterize metal concentrations in human bone. Laser ablation parameters for the method are refined resulting in concentration (ug/g) contour map measurements for each isotope measured in the human bone. Essential and non-essential metals, Al, Ca, Cu, Fe, Pb, and Zn are quantitatively mapped using these parameters. Limit of detection for the metals in the bone range from 0.001 to 0.08 ug/g. The LA-ICP-MS analysis method developed proves to be a straightforward and simple method for quantitative analysis of human bone.

Understanding the different igneous processes that magmas undergo is important for a variety of reasons including potential hazards associated with volcanoes in populated regions, magmatic hydrothermal ore deposition, and tectonic processes. One method of obtaining geochemical data that can help constrain petrogenetic processes is through the study of melt and fluid inclusions. The research presented here examines melt inclusions through experimental, analytical and field studies to better understand igneous petrogenesis. One potential problem associated with melt inclusions is water-loss during laboratory heating. A Raman spectroscopic technique was developed to determine water contents of silicate glasses, and this technique was applied to monitor water loss from natural melt inclusions that were heated for varying lengths of time. The results suggest that water loss is insignificant when heated for less than 12 hours but significant water loss can occur with longer duration heating. The distribution of trace elements between silicate melts and phenocrysts growing from that melt can constrain igneous processes such as fractional crystallization, assimilation, and partial melting. Partition coefficients were determined for syngenetic clinopyroxene, orthopyroxene, and plagioclase in equilibrium with a dacitic melt using the Melt Inclusion-Mineral (MIM) technique. Melt inclusion chemistry is the same regardless of mineral host phase, suggesting that the melt inclusions have not been subjected to re-equilibration processes or boundary layer development. Partition coefficients from this study are similar but typically lower than published values. Three closely-spaced monogenetic eruptive units from the active Campi Flegrei volcanic system (Italy) with similar eruptive styles were examined to better understand the evolution of the magmatic system. Results suggest fractional crystallization as the dominant process taking place over time but that magma mixing was significant for one of the eruptions. Trace element geochemical data suggest a mixed magma source of within-plate and volcanic arc components, and still retain a T-MORB signature from the subducting slab.

Elemental analysis in forensic laboratories can be tedious and many trace evidence items are not analyzed to determine their elemental composition. Presently, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) is the primary analytical tool for determining the elemental composition of trace evidence items. However, due to the time it takes to obtain the required vacuum and the limited number of samples that can be analyzed at any one time, SEM-EDS can be impractical for a high volume of evidence items. An alternative instrument that can be used for this type of analysis is laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). While LA-ICP-MS is a very precise and quantitative analytical method that determines elemental composition based on isotopic mass measurements; however, the instrumentation is relatively expensive and therefore is budgetarily prohibitive for many forensic laboratories. It is the purpose of this research to evaluate an inexpensive instrument that can potentially provide rapid elemental analysis for many forensic laboratories. Laser induced breakdown spectroscopy (LIBS) is an analytical method that meets these requirements and offers information about the elemental composition based on ionic, atomic and diatomic molecular emissions.