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Articles 31 - 60 of 3555

Full-Text Articles in Physical Sciences and Mathematics

Stoichiometric Determination Of Hydride Materials At Extreme Conditions, Gregory Alexander Smith May 2023

Stoichiometric Determination Of Hydride Materials At Extreme Conditions, Gregory Alexander Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen was predicted to be a high-temperature superconductor at near-megabar conditions in 1968,[1] but only recently was been experimentally observed.[2] This is due to the extraneous metrological constraint of requiring 5 megabars of pressure to stabilize. A more practical approach for synthesis of high-temperature superconductors has been pro-posed through the use of hydride compounds. Recently, a surge of rare earth hydrides have achieved critical superconducting transition temperatures (T_C ) close to room temperature.[3, 4, 5, 6] However, due to limitations of the necessary instrumentation to achieve megabar pressures, many techniques traditionally used to measure stoichiometry are unavailable.Three works presented in …

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The Effects Of Habitat Isolation On Fine-Scale Genetic And Geographic Structure Of Populations Of Two Threatened Endemic Insects In Southern Nevada, Pseudocotalpa Giulianii And Icaricia Shasta Charlestonensis, Kristen Tovar May 2023

The Effects Of Habitat Isolation On Fine-Scale Genetic And Geographic Structure Of Populations Of Two Threatened Endemic Insects In Southern Nevada, Pseudocotalpa Giulianii And Icaricia Shasta Charlestonensis, Kristen Tovar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Assessing the role geographic isolation and ecological specialization have on phylogeographic patterns contributes to our understanding of the evolutionary history of a species and the processes that erode genetic diversity. I used mitochondrial and nuclear genomic sequences to assess whether habitat isolation has shaped the fine-scale patterns of present-day genetic structure and diversity in two threatened insect species endemic to southern Nevada. Pseudocotalpa giulianii (Coleoptera; Scarabaeidae) is a dune obligate scarab beetle endemic to only two small, isolated sand dunes in Nye County, Nevada, with a usable habitat of less than 4.2 km sq that is impacted by on-going degradation. …

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High Clearance Collision-Free Paths, Barun Thapa May 2023

High Clearance Collision-Free Paths, Barun Thapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

Path Planning is one of the widely investigated research areas in computational geometry and robotics. Given a set of polygonal obstacles inside a rectangular box, and start & goal points, the path planning problem is to construct a collision-free path connecting the start point to the goal point. We review existing well known algorithms for solving the path planning problem. We propose new approaches for constructing a collision-free path with high clearance from obstacles. The main idea of the proposed algorithm is the appropriate generation free-region nodes which can be processed to construct high clearance paths. Neighbors of free-region nodes …

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Dea2uth: A Decentralized Authentication And Authorization Scheme For Secure Private Data Transfer, Phillipe Austria May 2023

Dea2uth: A Decentralized Authentication And Authorization Scheme For Secure Private Data Transfer, Phillipe Austria

UNLV Theses, Dissertations, Professional Papers, and Capstones

The sharing of private information is a daunting, multifaceted, and expensive undertaking. Furthermore, identity management is an additional challenge that poses significant technological, operational, and legal obstacles. Present solutions and their accompanying infrastructures rely on centralized models that are susceptible to hacking and can hinder data control by the rightful owner. Consequently, blockchain technology has generated interest in the fields of identity and access control. This technology is viewed as a potential solution due to its ability to offer decentralization, transparency, provenance, security, and privacy benefits. Nevertheless, a completely decentralized and private solution that enables data owners to control their …

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Information-Theoretic Model Diagnostics (Infomod), Armin Esmaeilzadeh May 2023

Information-Theoretic Model Diagnostics (Infomod), Armin Esmaeilzadeh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Model validation is a critical step in the development, deployment, and governance of machine learning models. During the validation process, the predictive power of a model is measured on unseen datasets with a variety of metrics such as Accuracy and F1-Scores for classification tasks. Although the most used metrics are easy to implement and understand, they are aggregate measures over all the segments of heterogeneous datasets, and therefore, they do not identify the performance variation of a model among different data segments. The lack of insight into how the model performs over segments of unseen datasets has raised significant challenges …

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Desert Spring Prokaryotes And Benthic Macroinvertebrates: Geological And Ecological Controls, Ariel D. Friel May 2023

Desert Spring Prokaryotes And Benthic Macroinvertebrates: Geological And Ecological Controls, Ariel D. Friel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Desert springs are aquatic oases, being considered among the most diverse and imperiled ecosystems on Earth. Despite the ecological significance and threatened status of desert springs, few studies have surveyed the microorganisms in these systems or their interactions with other community members. The primary goal of this dissertation was to describe the major controls influencing the community ecology of prokaryotic and BMI communities in cold- and moderate-temperature desert springs of the southern hydrographic Great Basin. Chapter 1 provides a broad overview of spring ecosystems and of each chapter included in this dissertation. Chapter 2 documents the first-ever, regional-scale survey of …

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Solving Boundary Value And Initial Boundary Value Problems Of Partial Differential Equations Using Meshless Methods, Adam Johnson May 2023

Solving Boundary Value And Initial Boundary Value Problems Of Partial Differential Equations Using Meshless Methods, Adam Johnson

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this dissertation, the methods of fundamental solutions (MFS) and the methods of particular solutions (MPS) are used to solve the boundary value problems of the Poisson and Helmholtz equations, where the particular solutions of the Poisson and Helmholtz equations in [13, 14] are used. Then the initial boundary value problems of the diffusion and wave equations are discretized into a sequence of boundary value problems of the Helmholtz equation by using either the Laplace transform or time difference methods along the lines of [8]. The Helmholtz problems are solved consequently in an iterative manner which leads to the solution …

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Joint Constraints On Kepler-36 From Kepler And New Keck-Hires Data, Nicholas Juliano May 2023

Joint Constraints On Kepler-36 From Kepler And New Keck-Hires Data, Nicholas Juliano

UNLV Theses, Dissertations, Professional Papers, and Capstones

I analyze new HIRES Radial Velocity (RV) data in conjunction with transit mid-times and uncertainties from the full 17 quarters of Kepler data to reassess the orbital parameters of the Kepler-36 system. Six additional RV measurements were taken by the Keck-HIRES spectrograph from September 21, 2021 to October 11, 2021. I carry out a differential evolution Markov Chain Monte Carlo-based (DEMCMC) analysis to infer improved orbital elements for the two known planets in the system. Leveraging additional information provided by the new RV measurements, I extend this DEMCMC analysis to a possible three-planet configuration. I explore the likelihood of a …

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Critical Metals: From Granitic Pegmatites To The Anthropogenic Cycle, Dalton Mccaffrey May 2023

Critical Metals: From Granitic Pegmatites To The Anthropogenic Cycle, Dalton Mccaffrey

UNLV Theses, Dissertations, Professional Papers, and Capstones

Critical metals are vital to the functionality of the modern world. The increased diversity and usage intensity of these commodities in defense-related and strategic technologies (e.g., jet engines, rocket assemblies), modern infrastructure and products (e.g., high-strength steel, cellular phones, laptop computers), and energy-related, low-emissions technologies (e.g., nuclear reactors, solar panels, wind turbines, hybrid and electric vehicles) has drastically increased our reliance on critical metals and, thus, the United States (and global) exposure to supply restrictions. Granitic pegmatites are unique mineral deposits that represent a past, present and future resource for many (approximately half) of these critical resources. Even with the …

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Metastability And Degradation In Cu(In,Ga)Se2 Thin-Film Solar Cells, Mohsen Jahandardoost May 2023

Metastability And Degradation In Cu(In,Ga)Se2 Thin-Film Solar Cells, Mohsen Jahandardoost

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cu(In,Ga)(S,Se)2 or CIGS is a thin-film semiconductor that has shown a device efficiency of 23.35% and 24.2% for single-junction and perovskite/CIGS tandem solar cells, respectively. CIGS offers promising properties such as tunable bandgap and ease of processing making them great candidates for thin-film tandem devices. However, knowledge of the effect of material defects, buffer materials, and post-deposition treatment (PDT) on degradation and metastability behavior in these devices is not well understood.In this dissertation, metastability and long-term degradation of CIGS thin-film solar cells have been investigated under combinatorial stress factors of heat, light, and voltage bias to systematically understand the effect …

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A Generalized Family Of Exponentiated Composite Distributions With Applications To Insurance And Survival Data, Bowen Liu May 2023

A Generalized Family Of Exponentiated Composite Distributions With Applications To Insurance And Survival Data, Bowen Liu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The concept of composite distributions was proposed in the early 2000s as a good parametric solution to model the data with heavy tails. Since the concept was proposed, it has been widely used in different areas, such as modeling insurance claim size data, predicting the risk measures in insurance data analysis, fitting survival time data, and modeling precipitation data. While a lot of the composite distributions demonstrated great performances in real applications, many commonly used composite distributions such as the inverse gamma-Pareto (IGP) or exponential-Pareto (EP), did not demonstrate great performances when fitting to several particular data sets. In order …

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Investigating Haloacetonitrile (Han) Formation Potential From Nitrogenous Antibiotics And Agrochemicals, Kazi Shafayet Haider May 2023

Investigating Haloacetonitrile (Han) Formation Potential From Nitrogenous Antibiotics And Agrochemicals, Kazi Shafayet Haider

UNLV Theses, Dissertations, Professional Papers, and Capstones

Disinfection can promote safe drinking water. Chlorine and chloramines are the two most used disinfectants. While these disinfectants are effective in inactivating disease-causing pathogens, they also produce hazardous byproducts when they react with organic compounds (precursors). Nitrogenous disinfection byproducts (N-DBPs) are more toxic than their counterparts. The increased use of nitrogen-based agrochemicals and antibitics has led to their detection in different water sources. The presence of secondary amine and aniline in these compounds can act as a source of reactive nitrogen to form N-DBPs. In addition, the increased concentration of bromide in water systems due to anthropogenic activities can enhance …

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The Climate Change Hope Scale: Does The Three-Factor Model Fit An Adult Sample?, Yuhan Bi, Victoria Angulo, Michal Newhouse-Van Vlerin, Orei Z. Odents, Kimberly A. Barchard Apr 2023

The Climate Change Hope Scale: Does The Three-Factor Model Fit An Adult Sample?, Yuhan Bi, Victoria Angulo, Michal Newhouse-Van Vlerin, Orei Z. Odents, Kimberly A. Barchard

Psychology Faculty Presentations

The Climate Change Hope Scale (CCHS; Li & Monroe, 2017) adapted Synder et al.'s (1991) Hope Scale to focus specifically on climate change. In an adolescent sample, the CCHS has three factors: Personal-sphere willpower and waypower, Collective-sphere willpower and waypower, and Lack of willpower and waypower. Our research tests if Li and Monroe's (2017) three-factor model fits the data from an adult sample.

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Electric Utility Performance In The Mountain West, Hira Ahmed, Miguel Soriano Ralston, Caitlin J. Saladino, William E. Brown Jr. Mar 2023

Electric Utility Performance In The Mountain West, Hira Ahmed, Miguel Soriano Ralston, Caitlin J. Saladino, William E. Brown Jr.

Environment

This fact sheet examines select data from the Citizens Utility Board (CUB) report, “Electric Utility Performance: A State-By-State Review,” which provides information on the affordability, reliability, and environmental responsibility of electric utility energy consumption. The original report provides a comprehensive state-by-state profile of utility performance in the United States. These data were originally reported by the Energy Information Administration (EIA) of the U.S. Department of Energy. This federal entity is responsible for the aggregation and dissemination of information about the American energy industry. This fact sheet highlights energy sources, affordability, reliability, and environmental impact of energy consumption in the Mountain …

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Recycling In The Mountain West, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr. Mar 2023

Recycling In The Mountain West, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr.

Environment

This fact sheet synthesizes data on rates of recycling from the March 2021 report "50 States of Recycling," sponsored by the Ball Corporation.The information presented in this document focuses on the effectiveness of recycling in total and by recyclable item, as well as the quantity of product recycled specifically within the Mountain West states of Arizona, Colorado, Nevada, New Mexico, and Utah.

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Resident Scientists-In-Schools: Harnessing Altruism In Stem, Alison Sloat Jan 2023

Resident Scientists-In-Schools: Harnessing Altruism In Stem, Alison Sloat

UNLV Best Teaching Practices Expo

The Resident Scientists-in-Schools and the STEM Teacher Development Academy program helps to diversify and expand the STEM pipeline in CCSD schools.

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A Literature Review On Developments In Timber Design And Its Impact On Carbon Emissions, Raquel Jackson Dec 2022

A Literature Review On Developments In Timber Design And Its Impact On Carbon Emissions, Raquel Jackson

Undergraduate Research Symposium Posters

Carbon dioxide emissions are a growing issue worldwide as urbanization and industrialization continues to increase (ie. Steel and concrete). Non-renewable resources limit steel and concrete production. Despite current methods to reduce greenhouse gasses, carbon emissions remain difficult to reduce from steel and concrete industries.

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An Exploratory Factor Analysis Of Climate Friendly Purchasing Choices, Susan E. Gutierrez, Fred Vincent Y. Margallo, Zihan Gong Dec 2022

An Exploratory Factor Analysis Of Climate Friendly Purchasing Choices, Susan E. Gutierrez, Fred Vincent Y. Margallo, Zihan Gong

Undergraduate Research Symposium Posters

Climate change is negatively affecting the environment and all its inhabitants. People's increased awareness have made them more willing to adopt more climate friendly purchasing choices. The Climate Change Action Inventory measures how often individuals take actions that can reduce climate change. We focused on the Climate Friendly Purchasing Choices Domain. We conducted an exploratory factor analysis of the Climate Friendly Purchasing Domain to help us examine the factor structure.

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Development Of A Novel Ionic Liquid-Coated Adsorbent For Treating Emerging Contaminants In Recycled Water On The International Space Station, Madeline Carroll, Gabson Baguma, Savanna Vacek Dec 2022

Development Of A Novel Ionic Liquid-Coated Adsorbent For Treating Emerging Contaminants In Recycled Water On The International Space Station, Madeline Carroll, Gabson Baguma, Savanna Vacek

Undergraduate Research Symposium Posters

Synthesize at least 3 biobased ionic liquids. Optimize method for conducting liquid-liquid extractions. Analyze and quantify how much DMSO2 is removed by the ionic liquids. Coat biochar with the most effective biobased ionic liquids.

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Groundwater Remediation Using Modified Biochar, Kers Ung-Watson, Ismail Abdulraheem, Nikki Tibayan, Suraj Pochampally Dec 2022

Groundwater Remediation Using Modified Biochar, Kers Ung-Watson, Ismail Abdulraheem, Nikki Tibayan, Suraj Pochampally

Undergraduate Research Symposium Posters

Biochar, a lightweight black residue made of carbon, has proved to be an effective adsorbent to remove TCE from groundwater. Not only is it an economical substitute for conventional adsorbents but it can be created by using a variety of organic materials. For this project, it will rely on walnut shell feedstock to create biochar as this had the best ability to adsorb TCE.

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Nuclear Power Plant In Las Vegas, Ryan W. Murray Dec 2022

Nuclear Power Plant In Las Vegas, Ryan W. Murray

Undergraduate Research Symposium Posters

This research focuses on the impact of a “Nuclear Power Plant in Las Vegas” or ‘NPP in LV’ for short. Nuclear power is clean, has no greenhouse gas emissions, and has a moderate cost of kilowatt hours. Las Vegas, or more specifically Clark County uses Gas power plants to produce a majority of their electricity. My project will show what a nuclear plant could do if built in the city of Las Vegas. What is a Nuclear power plant? The EIA’s definition is “A nuclear power plant uses the heat that a nuclear reactor produces to turn water into steam, …

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Poliovirus Detection In Las Vegas Wastewater, Sage Boss, Hayley Baker, Ching-Lan Chang Dec 2022

Poliovirus Detection In Las Vegas Wastewater, Sage Boss, Hayley Baker, Ching-Lan Chang

Undergraduate Research Symposium Posters

Wastewater surveillance for poliovirus is a useful tool for spatial surveillance and evaluation of immunization efficacy. Polio testing in wastewater has been conducted since the 1980s in Finland and Israel, and the virus was recently discovered in New York. With increasing concern regarding the vaccination of children against the virus, there has been worry that polio cases could once again present themselves in the Las Vegas Valley. By testing for the virus in wastewater, we can monitor any new cases or outbreaks that occur and inform authorities as to the location and viral count. The wastewater samples were collected at …

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The Analysis Of Radio And X-Ray Energetics Of Fast Radio Bursts, Emily Huerta Dec 2022

The Analysis Of Radio And X-Ray Energetics Of Fast Radio Bursts, Emily Huerta

Undergraduate Research Symposium Posters

Here, we analyze the graphs and figures presented in Laha et al. (2022) and compare their slopes to our figures. Laha et al. (2022) includes two graphs, one that shows a comparison between radio fluence vs. x-ray fluence and radio energy vs. x-ray energy. In these graphs, the slopes are anywhere from 3.3e-14 to 2e-5, which are much less than unity. Our figures are consistent with these values, also providing slopes anywhere between the same range. Strong limits on this ratio between radio and x-ray energetics can either support the magnetar progenitor model, or completely dismiss it. Since we found …

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The Global Effects Of Climate Change: Detrimental Impacts On The Environment, Ecosystem, Coral Reefs, Human Health/Well-Being, And Global Economy, Lucky Heng Dec 2022

The Global Effects Of Climate Change: Detrimental Impacts On The Environment, Ecosystem, Coral Reefs, Human Health/Well-Being, And Global Economy, Lucky Heng

Undergraduate Research Symposium Posters

Despite criticism, scientists have been continuing to find more evidence to prove that the threats on the coral reefs around the world are real. The impact of rising climate temperature, pollution, ocean acidification, etc. has been leading to increasing amounts of mass bleaching and a massive decline in coral reefs in past decades. This research study utilizes a systematic literature review and secondary research to collect, analyze and provide evidence that climate change impacts the ecosystem, and marine life (coral reefs) species on the planet. By addressing the impact of climate change and its significance on the ecosystem and global …

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Trapping And Cooling Of Ca+ For Cold Ion-Radical Collisions, Bernardo Gutierrez Dec 2022

Trapping And Cooling Of Ca+ For Cold Ion-Radical Collisions, Bernardo Gutierrez

Undergraduate Research Symposium Posters

Free radicals are molecules that contain an unpaired valence electron which induces high reactivity. Ion radical reactions are typically exothermic and have low (or zero) activation energy. It is for these reasons that ion-radical reactions are believed to dominate in interstellar clouds where temperatures hover around 3-10K. State-to-state measurements require precision control of both reactants.

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3-D Visualizations Of Terrestial Exoplanet Interiors Generated With Magrathea In Blender, Tristan Benally, David Rice Dec 2022

3-D Visualizations Of Terrestial Exoplanet Interiors Generated With Magrathea In Blender, Tristan Benally, David Rice

Undergraduate Research Symposium Posters

There has been significant progress in simulating exoplanet interiors in the past decade. With the discovery of the TRAPPIST-1 system in the last few years, there have been many publications presenting models to best characterize specific aspects of exoplanets in study. However, with more parameters and considerations for different characteristics of an exoplanet there will be a need to represent many findings into a comprehensive model in the future. We extend the capabilities of MAGRATHEA from a planet interior solver to start incorporating multi-faceted functions starting with generating 3-D terrestrial planetary visualizations using a 3-D open-source computer graphic software called …

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Why Are My Rates Going Up? An Examination Behind Nv Energy's Recent Electric Rate Increase, Grace Zielinski Dec 2022

Why Are My Rates Going Up? An Examination Behind Nv Energy's Recent Electric Rate Increase, Grace Zielinski

Undergraduate Research Symposium Lightning Talks

96% of Nevadans live in NV Energy's service territory. Rate increase directly connected to natural gas consumption rate increase. Recent Californian heatwave raised demand for Natural Gas, straining supply and increasing prices. NV Energy does not make profit over recent increase. Electric rate increase implemented to cover the Natural Gas price increase.

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Drought Levels In Nevada Counties, 2022, Julianna Jovillar, Caitlin J. Saladino, William E. Brown Jr. Dec 2022

Drought Levels In Nevada Counties, 2022, Julianna Jovillar, Caitlin J. Saladino, William E. Brown Jr.

Environment

This fact sheet synthesizes data on drought levels within Nevada counties from the National Integrated Drought Information System (NIDIS) in 2022. The information presented in this document focuses on the breakdown of the number of Nevada residents affected by the droughts within each county and the drought experience in each county.

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Identification Of Factors Contributing To Traffic Crashes By Analysis Of Text Narratives, Cristian D. Arteaga-Sanchez Dec 2022

Identification Of Factors Contributing To Traffic Crashes By Analysis Of Text Narratives, Cristian D. Arteaga-Sanchez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The fatalities, injuries, and property damage that result from traffic crashes impose a significant burden on society. Current research and practice in traffic safety rely on analysis of quantitative data from crash reports to understand crash severity contributors and develop countermeasures. Despite advances from this effort, quantitative crash data suffers from drawbacks, such as the limited ability to capture all the information relevant to the crashes and the potential errors introduced during data collection. Crash narratives can help address these limitations, as they contain detailed descriptions of the context and sequence of events of the crash. However, the unstructured nature …

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Age And Genesis Of W-Mo-Cu Mineralization, Gold Hill, Utah, Nathan J. Carey Dec 2022

Age And Genesis Of W-Mo-Cu Mineralization, Gold Hill, Utah, Nathan J. Carey

UNLV Theses, Dissertations, Professional Papers, and Capstones

Utah's Gold Hill mining district hosts a Jurassic felsic pluton (~80 km^2) that was emplaced into a Mississippian to Pennsylvanian carbonate-dominated sedimentary sequence and is spatially associated with numerous polymetallic mineral deposits. This study focuses on W-Mo-Cu mineralization at the Lucy L., Doctor, Yellow Hammer, Reaper, and Rustler deposits within the district. The new, detailed petrographic observations, mineral chemistry (on scheelite, molybdenite, chalcopyrite, magnetite, garnet, and pyroxene), and Re-Os molybdenite geochronological data presented here allows for the determination of key mineral associations and paragenesis, the characterization of deposit types and their evolution, and the constraining of the relative and absolute …

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