Doctor of Philosophy, University of Akron, 2024, Integrated Bioscience

The scientific reciprocity of environmental geomicrobiology and biotechnology harnessing microbially induced carbonate precipitation (MICP) is epitomized by cave speleothem research; delineating environmental conditions uncovers factors that inform the development of industrial bacteriogenic mineralization processes, with greater control over the end products. Reconciling bacterial metabolism and CaCO3 precipitation has the potential to recontextualize geological precipitation events as microbial byproducts, warranting interdisciplinary investigation. In Wind Cave, South Dakota, I identified a complex weave of speleoclimatic, geochemical, and microbiological dynamics that controls the materialization and polymorphism of CaCO3 secondary deposits known as frostwork. Microclimatic monitoring and analysis suggested an evaporative environment, modelled from detailed temperature, humidity and airflow data. Airflow measurements support a causal link between cave wind directionality and the occurrence of frostwork. Sequential deposition of carbonate phases characterizes bulk frostwork formations according to shifting Mg2+/Ca2+ ratios over the speleothem lifetime, yielding multiaggregate formations consisting of calcite, aragonite, hydromagnesite, dolomite, opal, and smectite. Thin sections showed diagenetic fabrics indicative of oscillating supersaturation conditions in response to surface seasonal climatic changes. Scanning electron microscopy (SEM) analyses identified frostwork's aragonite crystal topography as a microecological niche supporting filamentous Actinomyces bacteria, leaving room for a microbial component to Wind Cave frostwork development. To begin to monitor the impact of factors controlling crystal growth in vitro I developed two parallel techniques for measuring bacteriogenic carbonate precipitation in Escherichia coli cultures, using i) image analysis for agar media, and ii) inductively coupled plasma–optical emission spectroscopy (ICP-OES) ion quantifica (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Earth Sciences

Fuego and Pacaya volcanoes in Guatemala are highly active volcanoes located near dense population centers. Despite this, both volcanoes are understudied, and there is insufficient data to fully understand their magma evolutionary processes and magma plumbing systems, and to adequately constrain eruption triggers. Because these are key components of volcanic hazard mitigation efforts, further investigation of Fuego and Pacaya will provide disaster response agencies with vital information to minimize loss of life and property in vulnerable Guatemalan communities. This research involves a petrological and geochemical study of recent and historical eruptive products from Fuego and Pacaya and will provide insight into the present and past magma storage conditions, recharge processes, and eruption triggers. Mineralogical data presented in this study highlight the complex, polybaric nature of magma storage and eruption at both Pacaya and Fuego Volcanoes. A detailed analysis of mineralogical data from Fuego 2018 eruption finds that this paroxysm was likely sourced from Fuego's extensive magma storage system, and that this eruption involved rapid decompression of these magmas creating the observed variation in crystal compositions and groundmass glass textures observed in these samples. However, because this eruption was a high-volume paroxysm, recharge of the magma plumbing system is necessary. Therefore, future sampling and petrologic monitoring is key for understanding this magma supply problem. Pacaya volcano has extensive evidence for magma mixing, assimilation, and recharge events, and mineralogical data points to magma mixing being an important eruption trigger. This finding, along with geobarometry work indicating that magma storage at Pacaya is generally at shallow depths (0 to 4 km beneath the crater), are both important considerations for future hazard mitigation efforts. This study is part of a larger collaborative, interdisciplinary effort at the Ohio State (open full item for complete abstract)

Master of Science, Miami University, 2024, Geology and Environmental Earth Science

Tonopah NV has a long history of mining operations. Between 1900 - 1947 gold and silver were mined from a multitude of districts with a total value of >$1 billion in today's market value. The mine tailings at Tonopah are poorly understood and have the potential for mineral recovery, critical metal recycling, and the potential for ceramics. Bulk samples are composed of quartz, illite, feldspar, and other minor phases. The clay size fraction is primarily quartz, illite, and kaolinite, with occasional expandable clays. TGA results agree with the XRD composition of the samples and highlights the complexity of heterogeneous clay-rich mine tailings. Overall physical characteristics are promising for use in ceramics as anthropogenic ball clay, expected to be effective in ceramic tiles. There is significant potential for Au and Ag recovery, with samples containing low-grade ore concentrations (Ag~11 ppm, Au~0.20 ppm), equating to ~181 kg of gold (6,400 oz) and ~9,980 kg (352,000 oz) of silver resources. There are also elevated levels of Ba, Pb, As, and Ag that are toxic to human health, and proper care should be taken to ensure no additional harm to the environment or human health results from the reprocessing of the mine tailings.

Master of Science, University of Akron, 2024, Geology

Partial melting of hydrous phases such as amphibole, biotite, and muscovite occurs in orogens where distributed ductile thinning is causing exhumation of mid- to lower-crustal rocks. The partial melting of these hydrous phases contributes significantly to the physical and chemical evolution of the crust, as well as affecting the crust's strength. The Si-rich melts generated from partial melting reactions of mid- to lower-crustal assemblages migrate toward the upper crust leaving a more mafic restite. Previous laboratory experiments conducted on amphibole-, biotite-, or muscovite-bearing rocks performed at rapid strain rates (10-4/s to 10-5/s) result in brittle deformation due to high local pore pressures. These rapid experiments suggest this brittle behavior is the likely mechanism causing melt segregation in the crust. However, field evidence and slower strain rate experiments (10-6/s to 10-7/s) suggest that crystal plastic processes may be dominant during syndeformational partial melting. To investigate grain-scale melt segregation mechanisms in a common lower crustal protolith, I performed a suite of axial compression and general shear experiments on an amphibole-bearing source rock during syndeformational partial melting at T = 800-975°C, Pc = 1.5 GPa, at a strain rate (ε) of 1.6 x 10-6/s. I also performed axial compression experiments on a biotite-bearing gneiss and a muscovite-bearing quartzite at T = 950°C, Pc = 1.5 GPa, at a strain rate (ε) of 1.6 x 10-6/s to compare the differences in melt development depending on which hydrous phase is partially melting. The Nemo Amphibolite (d = 140 ± 85 μm) is composed of 62 vol% amphibole (Fe-hornblende), 27 vol% plagioclase (andesine; An30Ab69Or1), 8 vol% quartz, and 3 vol% titanite. The biotite-bearing gneiss (d = 80 +/- 40 microns) consists of quartz (43 vol%), plagioclase (andesine (An22Ab77Or1); 40 vol%), biotite (16 vol%), and ~1 vol% muscovite/Fe-Ti oxides. The muscovite-bearing quartzite is composed of 90 vol% q (open full item for complete abstract)

Master of Science (M.S.), University of Dayton, 2024, Materials Engineering

If gone undetected, volcanic ash in the atmosphere can have significant negative effects on the performance of air-breathing gas turbine engines. When ingested into the front of the engine, abrasion and erosion of key mechanical components can occur, accompanied by degradation of the materials located in the late-stages of the engine by ash that has become molten due to the high-temperature environment. These phenomena can lead to significant damage and premature failure in a fielded gas-turbine engine, thus the need to evaluate engine materials prior to their implementation arises. While volcanic ashes and turbine engine materials have been studied extensively in the literature, they have largely been studied independently, therefore no standardized volcanic ash media to be used in materials testing has been developed. In this work, a group of natural volcanic ash samples were evaluated using a variety of techniques to understand their chemical, physical, and thermal behavior. The information gathered in the characterization of the group of natural ash samples was then used to develop a synthetic volcanic ash media that has similar chemistry to and behaves like a natural ash when exposed to an environment like that in a late-stage gas turbine engine. The new synthetic ash media was compared to a natural ash, from Mt. Mazama in Oregon, USA. Specifically, its ability to melt and infiltrate the microstructural features of 7% yttria-stabilized zirconia thermal barrier coatings deposited on superalloy coupons was examined. It was shown via SEM analysis that when heated to 1200 °C, the synthetic ash melts and infiltrates the thermal barrier coating within a comparable time (<30 minutes) as Mt. Mazama ash, leading to the conclusion that it can be deemed an effective replacement for natural volcanic ash in materials testing. The development of this synthetic ash test media is meant to provide a solid starting point for future development of medias used (open full item for complete abstract)

Master of Science (M.S.), University of Dayton, 2024, Aerospace Engineering

This research introduces an Origami-inspired dynamic spacecraft radiator, capable of adjusting heat rejection in response to orbital variations and extreme temperature fluctuations in lunar environments. The research centers around the square twist origami tessellation, an adaptable geometric structure with significant potential for revolutionizing radiative heat control in space. The investigative involves simulations of square twist origami tessellation panels using vector math and algebra. This study examines both a two-dimensional (2- D), infinitely thin tessellation, and a three-dimensional (3-D), rigidly-foldable tessellation, each characterized by an adjustable closure or actuation angle “φ”. Meticulously analyzed the heat loss characteristics of both the 2D and 3D radiators over a 180-degree range of actuation. Utilizing Monte Carlo Ray Tracing and the concept of “view factors”, the study quantifies radiative heat loss, exploring the interplay of emitted, interrupted, and escaped rays as the geometry adapts to various positions. This method allowed for an in-depth understanding of the changing radiative heat loss behavior as the tessellation actuates from fully closed to fully deployed. The findings reveal a significant divergence between the 2D and 3D square twist origami radiators. With an emissivity of 1, the 3D model demonstrated a slower decrease in the ratio of escaped to emitted rays (Ψ) as the closure/actuation angle increased, while the 2D model exhibited a more linear decline. This divergence underscores the superior radiative heat loss control capabilities of the 2D square twist origami geometry, offering a promising turndown ratio of 4.42, validating the model's efficiency and practicality for radiative heat loss control. Further exploration involved both non-rigidly and rigidly foldable radiator models. The non-rigidly foldable geometry, initially a theoretical concept, is realized through 3D modeling and physica (open full item for complete abstract)

PHD, Kent State University, 2023, College of Arts and Sciences / Department of Biological Sciences

Climate change is exerting profound and far-reaching impacts on ecosystems worldwide, encompassing both aquatic and terrestrial environments. The evolving precipitation patterns and shifting temperature regimes impact fluctuations in hydrology, resulting in shifts in redox conditions which can impact the availability of nutrients like phosphorus (P). Phosphate, the bioavailable form of P, is only present in small amounts within soils, making the biological demand greater than soil phosphate availability. The majority of soil P is present in non-labile forms including organic P and phosphate sorbed to metal oxides like iron (Fe). Microorganisms must content with geochemical and other abiotic factors to access phosphate from these non-labile sources through the use of various strategies including the secretion of enzymes, the production of phosphate solubilizing acids, as well as indirect mechanisms associated with the reduction of Fe oxides. The primary goal of this dissertation was to advance our understanding of how microorganisms access both labile and non-labile forms of P in the presence of changing hydrologic and redox conditions which impact the speciation of Fe that is present, altering phosphate availability. Specifically, I investigated 1) how phosphate availability changes across a permafrost thaw gradient (palsa, bog, and fen) in the presence of iron oxides, 2) how microorganisms access and mobilize chemically diverse phosphorus sources under contrasting redox conditions, and 3) how changes in hydrology, redox, iron mineralogy, and phosphate availability drive shifts in microbial community composition, specifically iron oxidizers, reducers, and phosphate solubilizers. In our first study assessing microbial phosphate accessibility across a permafrost thaw gradient, we found that near surface redox conditions changed as a function of permafrost thaw which impacted phosphate availability. Reducing conditions in the bog promoted the dissolution of Fe oxides, (open full item for complete abstract)

Master of Science (MS), Bowling Green State University, 2023, Geology

Concrete production is the third largest energy consumer in the world and the calcination process used to produce Portland Cement is responsible for 7% of global CO2 emissions; hence, there is great interest in developing methods to decrease the amount of Portland Cement used in concrete. One such method is the use of supplementary cementitious materials (SCM). In a recent study, Bernard (2023) evaluated the use of dolomite aggregate of various sizes and replacement quantities on the compressive strength of mortar samples made without SCMs and with limestone SCM. The results showed that mortar made with dolomite SCM had a greater compressive strength after 1 day of curing than samples without SCM or with limestone SCM. Other researchers have also reported concretes with dolomite SCM have higher compressive strengths at shorter curing times and have suggested that the formation hydrotalcite may be the cause. The objective of this study is to determine if hydrotalcite formed in the dolomite SRM mortar samples in sufficient manner to cause the early strengthening. The mortar samples were analyzed using a Scanning Electron Microscope with an Energy Dispersive Spectrometer (SEM-EDS) and by powder x-ray diffraction (XRD). The results of the SEM-EDS analysis confirmed the presence of hydrotalcite grains within dolomite reaction rims. However, the amount of hydrotalcite in the mortar samples was too low for detection by XRD analysis. As such, the direct impact of hydrotalcite formation on early strengthening of the dolomite SCM mortar cubes is questionable. Prior studies that reported significant hydrotalcite formation in dolomite SCM concretes were cured at higher temperatures and for longer durations than the mortar samples analyzed in this study.

Master of Science (MS), Ohio University, 2023, Geological Sciences (Arts and Sciences)

The Rio San Juan (RSJC) and Samana Metamorphic Complexes (SMC) are paleosubduction complexes exposed on northern Hispaniola. The RSJC has previously been classified as an example of a “warm” paleosubduction zone, as it contains metamorphic rocks that record thermal gradients of ~18 °C/km. However, the SMC, which is located ~100 km to the east, preserves lawsonite eclogite, a type of metamorphic rock that only forms under lower geothermal gradients (~ 5 – 6 °C/km). Although the rocks in these complexes have been proposed to form in a common subduction zone, the geologic and tectonic relationships between the high-pressure/low-temperature (HP/LT) metamafic blocks that record different geothermal gradients in these two complexes are debated. To evaluate the temperature-time-composition relationships between the HP/LT rocks in these complexes, bulk-rock major and trace element geochemistry, zircon trace element and U-Pb geochronology, and single trace element geothermometry studies were conducted on blueschist- and eclogite-facies rocks from the RSJC and the SMC. Bulk-rock major and trace element compositional studies of RSJC and SMC metamafic rocks show that they have geochemical affinities to N-MORB and arc-related rocks, indicating that both upper plate and lower plate material was likely incorporated into the subduction zone as a result of subduction erosion processes. Most RSJC and SMC metamafic rocks also record variable enrichments in the LILE that may reflect periods of fluid-rock interaction. Zircons in RSJC and SMC metamafic rocks are scarce, and, when present, generally unzoned. Zircons from a RSJC epidote eclogite record metamorphic ages ranging from ~90 – 125 Ma, indicating subduction-related metamorphism was likely occurring for at least 35 million years. Rare zircon cores preserved in this sample record ages of ~130 Ma that are interpreted as reflecting the age of the protolith. Two zircons recovered from a RSJC retrogressed metama (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2023, Chemical Engineering (Engineering and Technology)

Sour hydrocarbon reservoirs, containing H2S gas, are receiving increasing attention due to the growing demand for energy. Although uniform corrosion is not a significant obstacle for oil and gas companies in sour environments, the major challenge in this field is prevention of localized corrosion that can cause failures in production infrastructure. Formation of different types of iron sulfides as corrosion products has been postulated to be a main culprit for localized attack, due to their wide-ranging physicochemical properties, such as their electrical conductivities. The galvanic coupling between iron sulfides layers and mild steel was shown to be the mechanism associated with the localized attacks in sour environments. However, the mechanism of galvanic coupling between mild steel and iron sulfides has not been understood due to the lack of systematic and parametric studies. The research described herein addresses the galvanic coupling between mild steel and iron sulfide polymorphs to investigate the involved mechanisms. For the first step, the uniform corrosion of mild steel in aqueous H2S solutions was critically reviewed, and the mechanism associated with this system including the involved chemical electrochemical reactions was fully described. Furthermore, the mathematical modeling of uniform corrosion rate of mild steel in H2S environments was also comprehensively reviewed. In addition, some new approaches for the modeling of electrochemical reactions as well as corrosion rate were proposed, and the validity of the proposed models were verified through comparing with experimental data. Next step of the current research focused on the galvanic corrosion between mild steel and iron sulfides using both experimental and modeling investigations. In the experimental section, a systematic study was performed in order to determine the contribution of the influential parameters on the galvanic corrosion between mild steel and iron sulfides. On that account, the (open full item for complete abstract)

Master of Science, Miami University, 2023, Geology and Environmental Earth Science

Goethite (α-FeOOH) is an iron-oxyhydroxide mineral that is commonly found in soils and is of importance within the context of industrial mineralogy and aqueous geochemistry. The structure of goethite is such that vacant rows of octahedral sites form “channels” or micropores within the structure. This study aims to investigate the role these “channels” have in distributing the force induced by dynamic shock compression. Shock compression of synthetic goethite powdered samples were achieved by using an inverted shock microscope and laser driven flyer plates. With this set-up a high-energy laser shoots small aluminum discs at high velocity towards the sample causing compression upon impact. In this experiment, 25 µm aluminum flyer plates with 3.5 km/s impact velocities were used. This resulted in the production of planar shock waves of 5 ns duration in the target goethite. Subsequent investigations of the experimental change via TEM documented that crystal morphology remained unchanged, and that goethite's “bird's nest” texture was maintained. Crystal lattices showed small zones of distortion shift in peaks and the formation of hematite. XRD interestingly identifies two blunt phases: goethite and magnetite. A thixotropic-like model for accompanying shock compression is proposed to account for goethites its shock resistant behavior.

Master of Science (MS), Ohio University, 2023, Geological Sciences (Arts and Sciences)

Syrtis Major Planum is a low-relief shield volcano on Mars with a minimal dust content and is considered the best example of a Surface Type 1 dominated volcanic region. While no longer volcanically active, lava flows that were generated from Syrtis may serve as a reflection of the processes that were occurring in its magmatic source from the Late Noachian to the Late Hesperian martian epochs. This study sought to identify compositional, mineralogical, and petrological variations between temporally and spatially distinct flows using thermal infrared (TIR) spectroscopy to determine the extent of any differentiation throughout the volcanic record of Syrtis Major. A total of 610 Thermal Emission Spectrometer (TES) emissivity spectra were selected from 30 thermophysical units (assumed to be individual lava flows) as delineated by Demchuk (2021). Averaged TES spectra for all 30 units were modeled using spectral endmembers over a defined spectral range which excluded the prominent martian atmospheric CO2 absorption centered at 667 cm-1. Modeled endmember percentages are reflective of mineral modes, which were used to calculate bulk chemistries and rock types for each unit. Lava flows are dominated by high-Ca pyroxene and plagioclase feldspar, and bulk chemistries are consistent with mafic igneous rocks. Units are predominantly characterized as tholeiitic basalt, with rock types ranging from picrite to basaltic andesite. Any apparent variations in minerals, major oxides, and rock types across much of Syrtis from the Late Noachian to the Late Hesperian, are within the detection limits of the technique, which implies limited or no melt evolution in the magmatic source of Syrtis. Comparisons to terrestrial volcanoes and volcanic regions suggest differences in tectonic regimes and crustal thicknesses could affect the manifestation of hot spot volcanism on Mars. Further research on smaller Syrtis lava flows is needed to determine if temporal and/or spatial compositiona (open full item for complete abstract)

Master of Science, University of Akron, 2023, Geology

Within the mid to lower continental crust distributed ductile thinning occurs, in orogens that form mountains like the Himalayas and Appalachia, due to a weak middle to lower crust that deforms laterally in response to loading of a thickened, cold upper crust. This thinning destabilizes large orogens and causes the exhumation of hot and weak rock from the mid to lower crust that begins to partially melt. This melting further weakens the rocks and may affect the deformation mechanisms operating in the crust. Melting has been seen to have impacts on the deformation mechanisms and resulting lattice preferred orientations (LPO) that form in olivine-basalt aggregates (Holtzman et al., 2003). To investigate the effects of partial melting on deformation mechanisms and LPO development in two common foliated felsic rocks, I performed general shear deformation experiments on a fine-grained quartzite and fine-grained gneiss at T = 800°C, 850°C, 900°C, 950°C, or 975°C, P = 1.5 GPa, and strain rate of 6*10-5/s. The quartzite (grain size ~30 microns) is composed of 90% quartz and 10% muscovite. The fine-grained gneiss (grain size ~50 microns) is composed of 43% quartz, 40% plagioclase, 16% biotite, and 1% accessory minerals. The foliation in the slices of each rock was oriented parallel to the shear plane between Al2O3 shear pistons with a cut made at 45° to the compression direction. Experiments were performed at a range of temperatures to change the melt fraction present in the rocks during deformation (Melt = ~0%, 0.25%, 0.5%, and 1%). The yield stress of Moine Thrust quartzite decreased as a function of increasing temperature from ~1000 to ~300 MPa. However, all the experiments with melt present (T equal to to greater than 850°C) significantly strain hardened after a shear strain (g) of 1. This hardening may be due to the presence of melt along grain boundaries which is absorbing water from the recrystallizing quartz grains which slows diffusive recovery in quartz. The Gne (open full item for complete abstract)

Doctor of Philosophy, Miami University, 2022, Geology and Environmental Earth Science

Volcanic rocks record the complex nature of magmatic systems. The mineralogical, petrological, and geochemical heterogeneity that exists within an eruptive unit at a single volcano is challenging to reconcile with a static magma chamber model. Current understanding, therefore, supports the presence of complex, dynamic trans crustal magmatic systems (TCMSs) that consist of interconnected regions of magma storage where liquid-poor, crystal-rich mushes exist and variably interact. This dissertation presents an investigation into the magmatic and crustal components of TCMSs through a study of andesitic-dacitic lavas, hornblendite cumulates, and crustal xenoliths from the Plio- Pleistocene Pampa Aullagas (PA) and Quillacas (QL) monogenetic centers on the Bolivian Altiplano, Central Andes. In Chapter 1, amphibole's role in continental arc petrogenesis is investigated through a textural and geochemical study of hornblendite cumulates entrained within QL lavas. Granular, idiomorphic textures, the absence of relict clinopyroxene, and mesocumulate textures defined by intercumulus feldspar, apatite, and Fe-Ti oxides all support the formation of the hornblendites as cumulates in the lower arc crust. Reaction rims associated with cumulus amphiboles record cumulate mobilization, ascent, and eruption through TCMSs over relatively short timescales (<30 days). In Chapter 2, the crustal components of the QL and PA TCMSs are investigated through a lithologically diverse crustal xenolith suite which provides insights into the tectonomagmatic history of the Central Andean continental crust. From U-Pb zircon geochronology, evidence for ~3 Ga of tectono-magmatic events is recorded within the Central Andean continental basement. Age population peaks correlate with global supercontinent cycles, including the establishment of Nuna, Rodinia, and Gondwana, and record a long history of terrane accretion and arc magmatism along the western margin of South America. In Chapter 3, the origin of num (open full item for complete abstract)

Master of Science, Miami University, 2022, Geology and Environmental Earth Science

Observations of Allan Hills 81005 via PLM and SEM-EDS are consistent with the classification of anorthositic regolith breccia. Clasts of anorthosite, basalt, granulite, and impact melt breccia are present. The brecciated matrix is dominated by plagioclase, minor (clino)pyroxene, and rarer olivine in addition to trace oxides and sulfides. Phosphates, spinels, glass spherules, and crystalline spherules are rare and not ubiquitous in studied sections. In section -92, a spinel-bearing dunite clast is present alongside several pink spinel-bearing troctolitic clasts. The composition of dunitic olivines is consistent with the lunar Mg-suite as exemplified by Mg#, CaO, Cr, and Mn systematics. Compositions also overlap with those from dunite sample 72417. Both are distinct from non Mg-suite dunites in 74275 and the modeled composition of early-formed LMO cumulates. Spinels within the dunite clast are also consistent with spinels within Mg-suite dunites (Mg# ~50, Cr# ~70) while troctolitic pink are consistent with Mg-suite spinel troctolites (Mg# ~70-80, Cr# <10). Collectively, the clast and mineral assemblages support an origin of ALHA81005 from the lunar highlands. The observation of a lunar dunite contributes to our understanding of Mg-suite magmatism during lunar differentiation.

Master of Science (MS), Ohio University, 2021, Geological Sciences

Syrtis Major is an important and somewhat under-studied shield volcano on Mars, being distinct from other martian volcanoes in terms of morphology and the amount of exposed autochthonous or parautochthonous low-albedo material available for spectral studies. Syrtis Major lava flows were distinguished and mapped based on thermophysical properties when using thermal infrared data such as Thermal Emission Spectrometer (TES) and Thermal Emission Imaging System (THEMIS) and visible imagery such as Context Camera (CTX), Mars Orbiter Camera (MOC), and High Resolution Imaging Science Experiment (HiRISE). Defined units were assigned relative ages through crater counting processes using crater density estimates. Unit ages ranged from Late Noachian to Late Hesperian. An analysis of thermal infrared emissivity data indicated that 12 of the units were geochemically similar which could suggest undifferentiated lavas. Further spectral analysis of the thermophysical units could give greater constraints on the mineralogy and geochemistry of Syrtis Major.

Master of Science (MS), Ohio University, 2020, Geological Sciences

This study evaluated the use of geophysical well logs to interpret igneous and metamorphic lithologies from the Precambrian basement in east-central Ohio.Geophysical well logs are a staple of the oil and gas industry, but are designed and calibrated for use in sedimentary rocks. Thin-section petrography and X-ray Fluorescence were used to analyze 13 and 16 basement sidewall core samples, respectively, from two wells in Noble and Coshocton counties. The samples were separated into two broad groups on a standard Quartz-Alkali-Plagioclase plot. The Noble county samples were predominantly syenogranites with minor monzogranite and quartz syenite. The Coshocton county samples were more mafic falling into the tonalite, quartz gabbro/anorthosite, and diorite/anorthosite fields. The responses of a suite of geophysical well logs from both wells were compared to the geochemical data in order to determine whether or not the tool response could identify the different crystalline rocks. Gammaray, bulk density, and photoelectric logs were used due to their distinctive responses in sedimentary rocks. Mann-Whitney nonparametric comparisons of well responses showed that the gamma-ray and bulk density responses could delineate lithologies whereas the photoelectric log values could not.

Master of Science, Miami University, 2020, Geology and Environmental Earth Science

Apatite group minerals are ubiquitous in crustal carbonatites and can accommodate many elements useful for assessing the chemical provenance of these rocks. Apatite from c. 65 crustal carbonatite occurrences in Ontario, Quebec and New York were analyzed using single crystal X-ray diffraction (SCXRD) to determine the column anion composition (via structure and site occupancy refinement) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to assess the trace element composition. Four trends of crustal carbonatites are apparent (Bancroft, Frontenac, Lowlands and Highlands). Most crustal carbonatite apatite is hydroxyl-rich fluorapatite of the approximate composition c. 60:40 F:OH, although chlorapatite and hydroxylapatite also occur. Apatite from the Bancroft and Highlands trends is generally less enriched in Mg and Cl but more enriched in Fe, Mn, As, U, Th and REE than apatite from the Frontenac and Lowlands trends, which commonly contains Cl to c. 10% column anion site occupancy. Plots of 1/δSr vs 1/δEu suggest evolution towards larger Sr/Eu anomalies and higher U/Th/REE concentrations possibly resulting from lower degrees of crust partial melting during the Ottawan-Rigolet transition, whereas no geographic trend in U/Th/REE concentrations and Sr/Eu anomalies is observed in Frontenac and Lowlands samples. No correlations to wall rock chemistry were observed.

Doctor of Philosophy, The Ohio State University, 2020, Earth Sciences

Upland catchments play an outsized role in the processing and export of water, sediments, nutrients, and organic matter, thus strongly influencing downstream water quality. In Chapter 1, an overview of biogeochemical cycling within upland fluvial sediments is presented, focusing on key regional biogeochemical cycling patterns and solute export processes. Additionally, anthropogenic influences on this environment, such as historical mining activities and climate change, are briefly reviewed in this chapter. Chapter 2 explores the relationship between spatial hydrologic heterogeneity and microbial community assembly and functional potential within the hyporheic zone. The region of groundwater and river water mixing, known as the hyporheic zone, is a hotspot of microbial activity that influences solute export and cycling in rivers. Hyporheic mixing patterns can vary over small spatial scales, leading to heterogeneity in fluid chemistry and microbial community composition and function. Here, we integrate new mass-spectrometry data, metagenomic insights, and ecological models with previous analyses of microbial community composition and dissolved organic matter (DOM) quality to understand spatial relationships between hyporheic flow and microbial community assembly, metabolism, and DOM processing at high-resolution (100 locations) along a 200 m meander of East River, Colorado (USA). Ecological modeling revealed a strong linkage between community assembly patterns and underlying hydrologic and geochemical drivers, including the impact of physical heterogeneity (riverbed grain size) on microbial community structure. Geochemical profiles associated with upwelling groundwater suggest the influence of underlying geology, specifically Mancos-derived solutes, in driving community assembly. Distinct microbial community profiles and functional potential in zones of upwelling groundwater suggest that groundwater chemistry may have a greater influence on biogeochemical cycling wi (open full item for complete abstract)

Master of Science, Miami University, 2020, Geology and Environmental Earth Science

The uranium boom in the United States from the 1940's to the 1980's was a period of extensive uranium mining on Native American lands. However, detailed environmental investigations of the resulting uranium pollution are sparse. The Midnite Mine is an abandoned open pit uranium mine located on the Spokane Indian Reservation, where approximately 35 million tons of ore and waste rock were left behind in stock piles. Although investigations of water and soil contamination have been conducted, there have been no investigations of associated airborne particulate matter. Bulk elemental analyses of tree bark from 31 Pinus ponderosa trees throughout the study area show that significant levels of U, moderate levels of Th, and low levels of Pb and As contamination are present in particulate matter on the reservation. SEM investigations confirm that U and Th particulate matter exist in the inhalable size range while geospatial analyses indicate that U, Th, and As contamination are centralized along the Midnite Mine access road and at the nearby Dawn Mill. These findings indicate that airborne particulate matter from the Midnite Mine and Dawn Mill may be a cause for concern to local health and provides context for future health and environmental studies.