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Articles 151 - 180 of 1536

Full-Text Articles in Geochemistry

Utilizing Isotope Tracing To Assess Land Use Implications To Tap And Stream Water Chemistry, Katrina Alexis Mcfadden Jan 2024

Utilizing Isotope Tracing To Assess Land Use Implications To Tap And Stream Water Chemistry, Katrina Alexis Mcfadden

Theses and Dissertations--Biosystems and Agricultural Engineering

Water quality is an issue that continues to be worsened by extreme flooding, specifically in Eastern Kentucky. The most recent 2022 flooding event in Eastern Kentucky resulted in loss of human life, over $23.3 billion in damaged infrastructure, and impaired human health. Infrastructure failures, such as leaky pipes, are a growing challenge in these regions as rebuilding has occurred. Therefore, the goal of this project was to evaluate water quality in two of the counties most impacted by the 2022 flood in Kentucky, Breathitt and Perry Counties, using sulfur isotopes as a novel tracer to identify potentially failures in distribution …


Water Column Controls On Magnetic Mineral Formation And Preservation, Josephine Benson Jan 2024

Water Column Controls On Magnetic Mineral Formation And Preservation, Josephine Benson

Dartmouth College Master’s Theses

Iron-bearing minerals in the sedimentary record are frequently used to reconstruct past depositional environments. This is accomplished through geochemical, magnetic, and mineralogical analyses placed in geological context. These interpretations, however, depend on our understanding of how iron minerals form in nature. To better understand the formation of magnetic iron minerals in redox-stratified depositional settings, the study of modern analogs is crucial to unraveling environmental context no longer available from geological deposits. In this study, I utilized four anoxic and sulfidic stratified lakes within a 100-mile radius to examine the effects of small variations in lake properties on magnetic mineral formation …


An Experiment To Determine Mineral-Associated Organic Matter Turnover In A Sandy Clay Loam, Samantha Abel Jan 2024

An Experiment To Determine Mineral-Associated Organic Matter Turnover In A Sandy Clay Loam, Samantha Abel

All Master's Theses

Soil is an important terrestrial carbon sink. Through regenerative land management, which includes minimizing soil disturbance, the carbon content of soil can be raised towards preindustrial levels. This feat requires effectively storing carbon in a natural system that is inclined to cyclicity. The most stable form of soil organic matter is mineral-associated organic matter (MAOM). This carbon labelling experiment was designed to identify short-term CO2 fluxes within the soil-plant-atmosphere system, particularly those related to MAOM turnover in the rhizosphere. Basil (Ocimum basilicum) was planted on a plot at the campus farm at Central Washington University. Another plot …


Eruption Initiation Mechanisms And Timescales At A Very-High-Threat Washington Volcano: Clues From Crystal Cargo In Lavas From Mount Baker (Koma Kulshan), Emily Yoder Jan 2024

Eruption Initiation Mechanisms And Timescales At A Very-High-Threat Washington Volcano: Clues From Crystal Cargo In Lavas From Mount Baker (Koma Kulshan), Emily Yoder

All Master's Theses

Understanding the timescales of pre-eruptive processes is key for improving forecast models of future eruptions. Mount Baker (Koma Kulshan), WA, is part of the northern Cascade volcanic arc and classified as a very high threat volcano. However, we lack an understanding of the duration of time between the final magmatic process before eruption (potentially the process that initiated the eruption) and the eruption itself. This study focuses on (1) estimating eruption initiation timescales via diffusion chronometry and (2) determining eruption initiation mechanisms for three andesitic lava flows from Mount Baker: Dobbs Creek (~119 ka), Dobbs Cleaver (~105 ka), and Swift …


Constraining Magma Oxidation State Through Zircon Trace Elements: Estimating Tungsten Mineralization Potential In Northeastern Washington, Robin Gaudette Jan 2024

Constraining Magma Oxidation State Through Zircon Trace Elements: Estimating Tungsten Mineralization Potential In Northeastern Washington, Robin Gaudette

All Master's Theses

The oxidation state of a magma (measured by oxygen fugacity, fO2) controls what reactions are favored during crystallization and what elements are concentrated and potentially precipitated into minerals, making it a key factor in ore-forming processes as some commodity elements are best concentrated under specific redox conditions. Tungsten (W) is best concentrated under reducing magmatic conditions, a characteristic that makes constraining magma oxidation state, done through analysis of zircon trace elements, an essential tool in plutonic tungsten deposit exploration.

This research analyzes the zircon trace elements of several Cretaceous-age intrusions in the region surrounding the now-inactive Germania tungsten …


Timescales Of Magma Storage And The Pre-Eruptive History For The Most Recent Lava Flow At Mount Baker (Koma Kulshan), Wa, Desiree Cunningham Jan 2024

Timescales Of Magma Storage And The Pre-Eruptive History For The Most Recent Lava Flow At Mount Baker (Koma Kulshan), Wa, Desiree Cunningham

All Master's Theses

Mount Baker, ranked as a very-high threat volcano in the United States, is in a well-populated area in northern WA, putting many at risk in the event of a future eruption. Previous work on Mount Baker focused on understanding the magmatic architecture beneath the volcano and has identified multiple magmatic components that contributed to different eruptions throughout its history. The youngest lava flow in the Mount Baker Volcanic Field is the 9.8 ka Sulphur Creek lava flow. The last study conducted on this flow by Garvey (2022) determined the most recent magma mush configuration that was tapped for this eruption. …


Coal As A Resource For Rare Earth Elements In West Virginia, Rachel Elizabeth Yesenchak Jan 2024

Coal As A Resource For Rare Earth Elements In West Virginia, Rachel Elizabeth Yesenchak

Graduate Theses, Dissertations, and Problem Reports (ETD)

Although rare earth elements and yttrium (REY) are essential for manufacturing technologies vital to economic and national security, the U.S. is heavily reliant on foreign imports of these critical metals. There is significant interest in identifying and developing unconventional REY resources including coal and coal-byproducts to help secure domestic supplies of these elements. Appalachian Basin coals and byproducts are particularly enriched in REY. Coal-producing states within the basin, including West Virginia, can utilize existing infrastructure and legacy coal mining wastes to transition into the production of REY. However, in order to develop these resources, it is critical to understand the …


Potentially Massive And Global Non-Pyrogenic Production Of Condensed "Black" Carbon Through Biomass Oxidation, Aleksandar I. Goranov, Hongmei Chen, Jianshu Duan, Satish C. B. Myneni, Patrick G. Hatcher Jan 2024

Potentially Massive And Global Non-Pyrogenic Production Of Condensed "Black" Carbon Through Biomass Oxidation, Aleksandar I. Goranov, Hongmei Chen, Jianshu Duan, Satish C. B. Myneni, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

With the increased occurrences of wildfires worldwide, there has been an increase in scientific interest surrounding the chemistry of fire-derived "black" carbon (BC). Traditionally, wildfire research has assumed that condensed aromatic carbon (ConAC) is exclusively produced via combustion, and thus, ConAC is equated to BC. However, the lack of correlations between ConAC in soils or rivers and wildfire history suggests that ConAC may be produced non-pyrogenically. Here, we show quantitative evidence that this occurs during the oxidation of biomass with environmentally ubiquitous hydroxyl radicals. Pine wood boards exposed to iron nails and natural weather conditions for 12 years yielded a …


A Petrographic And Geochemical Study Of The Rangataua Lava Flows, Mount Ruapehu, Aotearoa New Zealand, Lucy Smith Jan 2024

A Petrographic And Geochemical Study Of The Rangataua Lava Flows, Mount Ruapehu, Aotearoa New Zealand, Lucy Smith

Scripps Senior Theses

Mount Ruapehu is a large stratovolcano on the North Island of Aotearoa New Zealand. The Rangataua lava flow is situated on the southern flanks of Ruapehu, and extends for 15-16 km. The flow is of andesite composition and comprised of three units: proximal, medial and distal. Mount Ruapehu is both scientifically and culturally significant.

Geochemical analyses of 13 whole rock samples, Electron Microprobe analyses of three polished thin sections, and geothermobarometry calculations were conducted to obtain data on pre-eruptive intensive parameters. Petrographic observations were used to investigate disequilibrium textures and shed light on magma chamber processes.

Results of this study …


Interconnectivity Of Melt During Partial Melting And Deformation Of A Peridotite, Jordan Collins Jan 2024

Interconnectivity Of Melt During Partial Melting And Deformation Of A Peridotite, Jordan Collins

Williams Honors College, Honors Research Projects

The mechanisms that allow basaltic magma to be transported to the surface are well understood, but not much is known about how the transport channels form as the basalt melt forms at the source. I performed experiments to determine these mechanisms during general shear deformation of a natural olivine aggregate (dunite) from Anita Bay, New Zealand as it partially melts using a high pressure/temperature rock deformation apparatus. Samples were analyzed using the scanning electron microscope and I observed that melt pockets started to form at the grain scale (1-2 vol% melt) prior to becoming interconnected at the sample scale (3 …


Supporting Dataset For The Influence Of Tile-Water On Groundwater Nitrate Concentrations Within A Saturated Riparian Buffer Zone, Aminat Tosin Abdulsalam, Eric Wade Peterson Jan 2024

Supporting Dataset For The Influence Of Tile-Water On Groundwater Nitrate Concentrations Within A Saturated Riparian Buffer Zone, Aminat Tosin Abdulsalam, Eric Wade Peterson

Faculty Publications - Geography, Geology, and the Environment

In the U.S. Midwest, where fertile soils with high water retention are prevalent, the installation of tile drainage networks have become a common practice to drain excess soil water, which enhances plant growth and increases crop productivity. However, tile drainage networks coupled with the use of inorganic fertilizers have significant implications on water quality, contributing to eutrophication, leading to harmful algal blooms, and resulting in hypoxic conditions in surface water bodies. To mitigate excess nutrient exports to surface water bodies, edge-of-field practices have been introduced. One such practice is the saturated riparian buffer (SRB), which utilizes a diversion system to …


Million-Year Melt-Presence In Mogollon-Datil Volcanic Field Rhyolites: Constraining The Histories Of The Bursum Caldera Resurgent Domes, Ethan Wagner Jan 2024

Million-Year Melt-Presence In Mogollon-Datil Volcanic Field Rhyolites: Constraining The Histories Of The Bursum Caldera Resurgent Domes, Ethan Wagner

Graduate Theses/Dissertations

The Mogollon-Datil volcanic field which is located in southwestern New Mexico, is the result of punctuated volcanism and the transition between arc and rift magmatism. The resurgent domes within the 28 Ma Bursum caldera records the transition from rhyolitic to basaltic andesite volcanism that occurred between 27-26 Ma. Using a combination of new zircon U-Pb ages using chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) with zircon U-Pb geochronology and trace element contents by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and whole rock and mineral trace element contents and isotope geochemistry this study investigates the temporal and …


Water Quality Of A Karstic Shallow Aquifer In Greene And Lawrence Counties, Missouri, Claudia Patricia Colmenero Chacon Jan 2024

Water Quality Of A Karstic Shallow Aquifer In Greene And Lawrence Counties, Missouri, Claudia Patricia Colmenero Chacon

Graduate Theses/Dissertations

A water quality investigation in the Springfield Plateau aquifer of Greene and Lawrence counties, Missouri, was conducted. Water samples from eleven springs were collected at regular intervals during 2023 to determine major water quality parameters: total dissolved solids (TDS), alkalinity, calcium (Ca), magnesium (Mg), sodium (Na), sulfate (SO4), chloride (Cl) and nitrate-nitrogen (NO3-N), along with per- and poly-fluorinated alkali substances (PFAS) from spring sediments. Nitrate-nitrogen was analyzed because of the importance for environmental health (e.g. to avoid eutrophication). Springs samples were separated by land use into urban and rural samples. In addition, Springfield Plateau water quality …


10be Dating Of Last Glacial Maximum Moraines And Subsequent Glacial Retreat In Chirripó National Park, Costa Rica, Caleb Emeka Okpala Jan 2024

10be Dating Of Last Glacial Maximum Moraines And Subsequent Glacial Retreat In Chirripó National Park, Costa Rica, Caleb Emeka Okpala

Dartmouth College Master’s Theses

During the Last Glacial Maximum (LGM; ~26-19 ka) and Termination 1 (~19-12 ka), the expansion and retreat of glaciers across the Southern and Northern Hemispheres, as well as other paleoclimate proxies, document a complex pattern of global climate change. While the timing and magnitude of LGM cooling and subsequent warming is relatively well constrained in mid- and high-latitude regions across both hemispheres, less information is available about climate changes in the tropics. To provide more information about tropical climate conditions during the LGM and Termination 1, I mapped and dated the extents of past glaciers in two valleys in Chirripó …


Geoelectrical And Hydrochemical Characterization Of Submarine Groundwater Discharge In Florida Bay, Ifeanyi Emmanuel Eze Jan 2024

Geoelectrical And Hydrochemical Characterization Of Submarine Groundwater Discharge In Florida Bay, Ifeanyi Emmanuel Eze

College of Graduate Studies: Theses & Dissertations

Florida Bay, situated at the southern tip of Everglades National Park and underlain by the Miami Limestone formation, is an ecosystem of global significance. Over the past century, the bay has faced threats such as droughts, seagrass mortality, and hypersalinity. Despite various studies and management efforts, the dynamics of submarine groundwater discharge (SGD) in the region remain underexplored. Given that SGD plays a significant role in the chemical dynamics of coastal ecosystems, it warrants thorough investigation. This study aims to characterize the spatial and temporal patterns of SGD in Florida Bay by surveying three basins – Rankin, Whipray, and Rabbit …


Diatom Productivity And Nutrient Dynamics In The Ross Sea, Antarctica During Warm Events In The Neogene, Marialena Christopoulou Jan 2024

Diatom Productivity And Nutrient Dynamics In The Ross Sea, Antarctica During Warm Events In The Neogene, Marialena Christopoulou

Graduate Research Theses & Dissertations

Increased melting of the Antarctic Ice Sheet (AIS) in recent decades, has had a significant impact on many aspects of the global ocean. Models indicate that by the end of the 21st century atmospheric carbon dioxide (CO2) concentrations may exceed 500 ppm, and the average global temperature will likely warm by more than 2°C. However, data that provide model constraints on potential feedbacks in ice-ocean-atmosphere system are limited by short-timescales (e.g., decadal- to centennial-scale) and incomplete spatial coverage. In particular, little is known about the impacts of future warming and widespread melting of AIS on marine biological productivity, silicate weathering …


Re-Evaluating Missouri’S Strategic Element Potential: A Geochemical Study Of The Mesoproterozoic Fe-Cu-Co-Ree Deposits In Southeast Missouri, Usa, Brandon James Sullivan Jan 2024

Re-Evaluating Missouri’S Strategic Element Potential: A Geochemical Study Of The Mesoproterozoic Fe-Cu-Co-Ree Deposits In Southeast Missouri, Usa, Brandon James Sullivan

Doctoral Dissertations

"Iron-oxide-copper-gold (IOCG) deposits are poorly understood mineral systems. For example, we do not know why Cu- and Co-rich IOCG deposits typically occur proximal to Fe ore deposits that are notably Cu and Co-poor, such as Iron Oxide Apatite (IOA) deposits. To better understand the formation of IOA and IOCG deposits in Missouri, USA, this PhD thesis examines the genesis of the Kratz Spring IOA and the Boss Central Dome IOCG deposits. This study presents the first constraints on formation conditions and fluid sources in the studied deposits using integrated petrographic, mineral composition, and Fe isotope analyses of oxide minerals. Observations …


Modeling Apparent Pb Loss In Zircon U-Pb Geochronology, Glenn R. Sharman, Matthew A. Malkowski Jan 2024

Modeling Apparent Pb Loss In Zircon U-Pb Geochronology, Glenn R. Sharman, Matthew A. Malkowski

Geosciences Faculty Publications and Presentations

The loss of radiogenic Pb from zircon is known to be a major factor that can cause inaccuracy in the U–Pb geochronological system; hence, there is a need to better characterize the distribution of Pb loss in natural samples. Treatment of zircon by chemical abrasion (CA) has become standard practice in isotope dilution–thermal ionization mass spectrometry (ID-TIMS), but CA is much less commonly employed prior to in situ analysis via laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) or secondary ionization mass spectrometry (SIMS). Differentiating the effects of low levels of Pb loss in Phanerozoic zircon with relatively low-precision in situ U–Pb …


Quantifying Chemical Erosion In The Lithologically-Heterogenous Appalachian Valley And Ridge, Amelia Jayne Zanoni Jan 2024

Quantifying Chemical Erosion In The Lithologically-Heterogenous Appalachian Valley And Ridge, Amelia Jayne Zanoni

Graduate Theses, Dissertations, and Problem Reports (ETD)

Quantifying chemical erosion in the lithologically-heterogenous Appalachian Valley and Ridge

Amelia J. Zanoni

The interplay between physical and chemical erosion is well understood in landscapes underlain by a uniform rock type, but many regions are underlain by a mixture of rock types with varying erosion resistance and solubility. We used measurements of stream-water chemistry to estimate chemical erosion rates in the Appalachian Valley and Ridge, a region where the mechanisms of lithologic control over topography are poorly understood. Newly acquired stream water samples were collected from 51 locations across the research area during the Fall of 2023. The sampled waters …


Estimating Inorganic Carbon Flux From Coal Mining Discharge Portals In The Bituminous Coal Field Region Of Pennsylvania, Lauren J. Rockwell Jan 2024

Estimating Inorganic Carbon Flux From Coal Mining Discharge Portals In The Bituminous Coal Field Region Of Pennsylvania, Lauren J. Rockwell

Graduate Theses, Dissertations, and Problem Reports (ETD)

A fundamental driver of the adverse effects associated with coal mining is the interplay of water and oxygen within mined sites, leading to the creation of coal mine drainage (CMD). One often overlooked consequence of CMD is the release of geologically-bound carbon as carbon dioxide (CO2). The interaction of CMD with carbonate rocks, specifically the presence of sulfuric acid driving the dissolution of these rocks, leads to the release of dissolved inorganic carbon (DIC). This study examined 25 CMD locations in an approximately 2,370 km2 area within the bituminous coal field region of Pennsylvania (PA), specifically in …


Fluid-Rock And Fluid-Steel Interaction In Geothermal Energy Development In The Appalachain Basin, Samuel H. Bowman Jan 2024

Fluid-Rock And Fluid-Steel Interaction In Geothermal Energy Development In The Appalachain Basin, Samuel H. Bowman

Graduate Theses, Dissertations, and Problem Reports (ETD)

The ever-increasing demand for clean energy requires creative solutions. In the United States, unconventional energy sources such as geothermal are conventionally limited to the western half of the country. The Appalachian Basin in the Eastern United States is one such possible creative solution, although the comparatively low temperature gradient presents a significant challenge to delivering economically feasible geothermal energy. An emerging technology is enhanced geothermal systems, these are engineered reservoirs where a working fluid (typically water) is cycled between the subsurface energy source and the energy collection facility at the surface. The liquid water interacts with the geothermal reservoir rock …


Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia Dec 2023

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …


Reverse Pseudo-Gours: A New Sub-Type Of Folia Observed In The Nerja Cave (Se Spain), Cristina Liñán Baena, Concepción Jiménez De Cisneros, Yolanda Del Rosal, Paolo Forti Dec 2023

Reverse Pseudo-Gours: A New Sub-Type Of Folia Observed In The Nerja Cave (Se Spain), Cristina Liñán Baena, Concepción Jiménez De Cisneros, Yolanda Del Rosal, Paolo Forti

International Journal of Speleology

A new sub-type of folia named “reverse pseudo-gour” has been observed and described in the Nerja Cave, southern Spain. It consists of fairly vertical, thin barriers (about 5 mm high and 2 mm thick) that develop on the underside of a sub-horizontal surface (shelfstone) and grow in the opposite direction to normal gours (rimstone dams), generating sinuous shapes. Their mineral composition is essentially calcium carbonate, although globular aggregates composed of clay and phosphate minerals have also been identified. The genesis and evolution of these reverse pseudo-gours occur just at the air-water interface and are controlled by (1) the sub-horizontality of …


Environmental Fate Of Sulfur In Sulphur Creek, Valles Caldera, Nm: Implications For Metal Transport And Water Quality, Daniel Lavery Dec 2023

Environmental Fate Of Sulfur In Sulphur Creek, Valles Caldera, Nm: Implications For Metal Transport And Water Quality, Daniel Lavery

Earth and Planetary Sciences ETDs

The 1.2 Ma Valles Caldera in north-central New Mexico hosts a young igneous volcanic hydrothermal system after the model proposed in Goff and Janik (2000). The Sulphur Springs area within Valles Caldera is an acid-sulfate area typical of this model, discharging acidic waters (pH 1.5-3) formed by oxidation of magmatic H2S at the surface. We report on samples obtained from springs and streams collected between October 2021 and May 2023 in the Sulphur Creek and Alamo watersheds. Sulphur Creek receives input from Sulphur Springs and exhibits low pH (2-4) and high concentrations of Al (≤110 mg/L), Fe (≤60 …


Landscape/Atmosphere Interactions And Carbon-Dioxide Dynamics In The Great Onyx Groundwater Basin, Mammoth Cave National Park, Kentucky, Meghan Raines Dec 2023

Landscape/Atmosphere Interactions And Carbon-Dioxide Dynamics In The Great Onyx Groundwater Basin, Mammoth Cave National Park, Kentucky, Meghan Raines

Masters Theses & Specialist Projects

An increase in atmospheric CO2 since the Industrial Revolution has altered rates of global climate change and has motivated a need to better quantify the flux of carbon between Earth’s reservoirs. Attempts to quantify the exchange of atmospheric carbon between sources and sinks have led to an increasing interest in the terrestrial landscape, including the continental carbon sink associated with carbonate-mineral dissolution. This research sought to better inform an understanding of karst landscapes and their relationship with global climate change through carbon cycling. The study utilized high-resolution data collection of pH, temperature, and specific conductance of waters in the Cascade …


Wonderstone And Its Connection To Liesegang, Microbes, And Beyond, Haden S. Mandery Dec 2023

Wonderstone And Its Connection To Liesegang, Microbes, And Beyond, Haden S. Mandery

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

In the western and southwestern United States, the term wonderstone is used to describe volcanic, volcaniclastic, and sedimentary rocks with variegated banding produced by iron oxide mineralization or staining. This iron oxide mineralization is typically described as Liesegang banding. In this paper I will (1) test if the banding in wonderstone follows the spacing and width laws characteristic of Liesegang, (2) identify the source of iron that ultimately precipitated in the bands, and (3) examine the role that microbes played in the formation of the mineralization in these rocks. I conclude that the iron oxide mineralization is not Liesegang banding. …


Preliminary Assessment For Critical Minerals In The Terlingua Quicksilver District, Texas And Tres Marias Mine, Chihuahua, Mexico, Eduardo Lee Zuniga Dec 2023

Preliminary Assessment For Critical Minerals In The Terlingua Quicksilver District, Texas And Tres Marias Mine, Chihuahua, Mexico, Eduardo Lee Zuniga

Open Access Theses & Dissertations

The Terlingua Quicksilver district was discovered around the 1880s and was a mercury producing district from 1900 through 1946. The most productive years were during World War one and two. From 1900-1946 the Terlingua Quicksilver District (TQD) produced 150,000 flasks; 80% came from three mines: the Rainbow-Chisos, Mariposa, and Study Butte mines. The structural controls of the Mercury mineralization within these mines are breccia pipes and fractures, often located near igneous intrusions. This study will assess the potential for Critical Minerals and Rare Earth Elements in the Terlingua Quicksilver District. Fifty-five samples have been collected and analyzed for forty-four different …


Enhancing Our Understanding Of Ancient Oceans Through The Investigation Of Molybdenum Behavior Under Sulfidic Conditions, Rachel Faye Phillips Dec 2023

Enhancing Our Understanding Of Ancient Oceans Through The Investigation Of Molybdenum Behavior Under Sulfidic Conditions, Rachel Faye Phillips

Open Access Theses & Dissertations

The most abundant trace metal in the ocean today, molybdenum (Mo), exhibits distinct behavior in oxygenated water, where it remains predominantly dissolved, compared to euxinic (i.e., oxygen-free and sulfidic) water, in which it is sequestered into the sediment. This dissimilar behavior allows us to use Mo concentrations and isotopic compositions in sediment to reconstruct marine oxygenation conditions throughout geologic history. However, Mo sequestration mechanisms under euxinic conditions remain unresolved, which limits the accuracy and precision of reconstructions made using Mo signatures in the rock record. For my doctoral research, I experimentally investigated abiotic and biotic Mo sequestration mechanisms under various …


Geochemistry Of Metal-Rich Black Shales And Their Genetic Relationship To Mississippi Valley-Type Pb-Zn Ore Deposits, Midcontinent U.S., Noah S. Morris Dec 2023

Geochemistry Of Metal-Rich Black Shales And Their Genetic Relationship To Mississippi Valley-Type Pb-Zn Ore Deposits, Midcontinent U.S., Noah S. Morris

Graduate Theses and Dissertations

The formation of Mississippi Valley-type (MVT) lead-zinc (Pb-Zn) ores is complex, involving an interaction of tectonic compression, hydrothermal fluid migration, and geochemical processes within the subsurface. Fundamental questions regarding this interaction remain unclear, including the source(s) of the Pb and Zn ions that make up the ores. A genetic link between black shales and MVT ores has been thought to exist because of (1) the presence of mature hydrocarbon and brine fluid inclusions within many MVT ores, (2) the association of the hydrothermal fluids that are linked to MVT ore formation with organic compounds and oil-like droplets, and (3) the …


Geospatial Analysis Of Weathering And Recession On Architectural Limestone At The 1891 Powerhouse/Icehouse In Eureka Springs, Arkansas, Stuart Bruce Wright Dec 2023

Geospatial Analysis Of Weathering And Recession On Architectural Limestone At The 1891 Powerhouse/Icehouse In Eureka Springs, Arkansas, Stuart Bruce Wright

Graduate Theses and Dissertations

The objective of this study of the architectural limestone of the 1891 Powerhouse/Icehouse in Eureka Springs, Arkansas was to analyze the environmental factors that influenced the deterioration and surface recession of this historical stone structure. The focus of this research was to examine and establish a baseline study that may assist in future monitoring and documentation of this historic limestone structure on stone weathering. A replicable methodology was specifically created toward this baseline research in hopes that it represented a solid baseline study. Observations and data analyses revealed the relationship between the architectural limestone building structure and the dominating recession …