Physical Sciences and Mathematics Commons^™

Timing And Characterization Of The Change In The Redox State Of Uranium In Precambrian Surface Environments: A Proxy For The Oxidation State Of The Atmosphere, Gerald D. Pollack

Geosciences Dissertations

The redox-sensitive geochemical behavior of uranium permits the use of Th/U ratios as a geochemical proxy for the oxidation state of the atmosphere and oceans during sedimentary processes. Due to the effects of post-depositional uranium mobility on Th/U ratios during events involving oxygenated fluids, direct measurements of Th/U ratios are often misleading, but the whole rock Pb isotope composition may be used to determine a sample¡¦s apparent time-integrated Th/U ratio (ƒÛa) and the timing associated with the onset of the U-Th-Pb geochemistry. Rare earth element (REE) concentrations were determined by isotope dilution mass spectrometry to evaluate the influence of multiple …

Using Geoscience Education Graduate Students To Help Faculty Transform Teaching Practice, Teagan L. Tomlin

Theses and Dissertations

Universities make claims about student learning that graduates don't often achieve and are under pressure to show improvement in teaching and learning in their undergraduate programs. This has been the constant focus of university-level professional development programs, but most teachers are still not using the most effective teaching methods. Individual departments need to find ways to help their instructors overcome three main challenges associated with adopting more effective student-centered teaching methods. No matter what strategy is adopted, instructors need considerable support to 1) change their beliefs about what constitutes effective teaching and learning, 2) learn to effectively implement new strategies, …

Assessing The Tree-Ring Oxygen Isotope Hurricane Proxy Along The Atlantic And Gulf Coastal Seaboards, Usa, Whitney L. Nelson

Doctoral Dissertations

A recent increase in hurricane activity has put coastal populations at risk. To better understand hurricane activity, it is necessary to look beyond the modern instrumental record, using proxy records to establish modes of past variability. The utility of a newly developed tree-ring oxygen isotope proxy is further assessed. I present oxygen isotope time series from three sites: Francis Marion and Sandy Island, South Carolina and Eglin Air Force Base, Florida. Proxy results are verified against the instrumental record of hurricane occurrence. The sites record similar percentages (45% for Francis Marion and Sandy Island, 63% for Eglin Air Force Base) …

Insights Into Biogeophysical Signatures Using Polarization Force Microscopy, Elizabeth Bartosik

All Theses

The success of bioremediation strategies is dependent upon effective monitoring of microorganisms in the subsurface. Induced polarization (IP) may represent a cost-effective, complementary technique to existing borehole-based microbe detection schemes. Recent studies show a significant, yet poorly understood IP effect associated with the presence of bacteria in aqueous and porous media. This effect is believed to be rooted in the physicochemical surface interactions between cells and minerals which we probe using polarization force microscopy. Polarization force experiments were conducted on a hydrated mica surface using the gram positive bacterium Bacillus subtilis and the gram negative bacterium Escherichia coli. On all …

Sedimentology, Stratigraphy, And Organic Geochemistry Of The Red Pine Shale, Uinta Mountains, Utah: A Prograding Deltaic System In A Mid-Neoproterozoic Interior Seaway, Caroline Amelia Myer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Red Pine Shale (RPS; ~1120m thick), uppermost formation of the Neoproterozoic Uinta Mountain Group, Utah, is an organic-rich sedimentary succession interpreted as a marine deltaic system that delivered immature sediment from the north that mixed with mature sediment from the east. Multiple data sets suggest regional climate and sea-level changes associated with changing organic-carbon burial rates.

Six facies were identified and represent wave-, tidal-, and river-influenced parts of the distal prodelta to delta front in a marine system. These include the shale facies and associated concretion facies (distal prodelta), the shale-sandstone facies (proximal prodelta to delta front), the slump …

Decadal-Scale Changes On Coral Reefs In Quintana Roo, Mexico, Thaddeus Allen Nicholls

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In 1988 data on coral reef community composition were collected from two areas, Akumal and Chemuyil, Quintana Roo, Mexico, ranging from 5-35m depth. These areas were revisited in 2005 and data were collected by the same methods and at the same depths as in 1988. Data from 1988 and 2005 were compared to determine if the coral reefs had undergone significant changes, and what specific changes had occurred. Chi-square analysis determined that community composition data collected in 1988 are significantly different from data collected in 2005 at all sites and depths within the categories of corals, gorgonians, sponges, and macroalgae. …

Investigating The Margins Of Pleistocene Lake Deposits With High-Resolution Seismic Reflection In Pilot Valley, Utah, John V. South

Theses and Dissertations

A vast area of the northeastern Great Basin of the western USA was inundated by a succession of Plio-Pleistocene lakes, including Lake Bonneville (28 ka to 12 ka). The Pilot Valley playa, located just east of the Utah-Nevada border near Wendover, Utah, within the eastern Basin and Range Province, represents an 8 to 16 km wide and ~50 km long remnant of these lakes. The playa corresponds to the upper surface of a closed basin that is delimited by two mountain ranges, which are mantled by recent alluvial fans over which the playa sediments have prograded. In order to investigate …

Wolfcampian Development Of The Nose Of The Eastern Shelf Of The Midland Basin, Glasscock, Sterling, And Reagan Counties, Texas, Douglas S. Flamm

Theses and Dissertations

The nose of the Eastern shelf of the Midland Basin is a prominent structural and depositional feature present in Glasscock, Sterling, and Howard counties, Texas. This feature has been expressed in many regional maps and mentioned in some literature, but has not otherwise been studied significantly. This study looks at the viability of using an acoustic impedance seismic inversion to interpret the 2nd and 3rd order sequence stratigraphy of the southern portion of the nose of the Eastern shelf along with its shelf to basin transition in Glasscock, Sterling, and Reagan counties during the Wolfcampian (Asselian-Sakmarian) time (Early Permian). The …

A Microanalytical Approach To Understanding The Origin Of Cumulate Xenoliths From Mauna Kea, Hawaii, Megan Pickard

Theses and Dissertations

Cumulate xenoliths erupted with alkalic hawaiite lavas from a postshield cinder cone on Mauna Kea, Hawaii include a variety of mafic and ultramafic rock types. Previous studies of major and trace element compositions of minerals in the xenoliths are interpreted to show transitional to alkalic magma parentages from the postshield stage, although any orthopyroxene-bearing xenoliths are considered to have tholeiitic parents. Major element compositions minerals were analyzed using the electron microprobe and trace element compositions of clinopyroxene grains were analyzed by laser ablation inductively coupled plasma mass spectrometry. In this study, major element compositions of clinopyroxene, olivine and plagioclase grains …

Magmatic Sulfur And Chlorine Abundances At Stromboli, Italy And Their Role In The Formation Of Vesicle-Hosted Metal Alloys, Nichelle Lynn Baxter

Theses and Dissertations

Strand et al. (2002) discovered small metal alloy grains rich in Cu, Co, and Sn (maximum size 150 µm) in vesicles of lava from Kilauea Volcano. These alloys are also found in basaltic rocks of several Italian volcanoes. To better understand the origin of these metal-rich grains, bombs from Stromboli Volcano were examined. Two bomb types were collected from Stromboli: pumiceous bombs and scoriaceous bombs. Bulk rock trace element geochemistry indicates that there are no significant differences in Cu, Co, or Sn (the three major components of the metal alloys) between the pumiceous and scoriaceous bombs. Comparison of olivine melt …

Pre-Eruptive Conditions Of The Oligocene Wah Wah Springs Tuff, Southeastern Great Basin Ignimbrite Province, Kurtus Steven Woolf

Theses and Dissertations

The Wah Wah Springs Tuff (30.0 Ma) is one of several very large volume ash-flow tuffs (>3200 km³ of erupted magma) that were emplaced near the peak of the flare-up of activity in the Great Basin ignimbrite province of western North America. It can be characterized as a "monotonous intermediate" ignimbrite because of its intermediate concentrations of silica (~63 to ~70 wt. %), apparent uniform chemical and mineralogical characteristics, and crystal-rich nature (32 ± 10 % phenocrysts on a dense rock basis). The major phase assemblage found throughout deposit is similar to other monotonous intermediates with a few exceptions …

The Mayan Ice Cap: Glacial Geology And Paleoclimate Of The Northern Guatemalan Highlands, Alex Joseph Roy

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Sierra de los Cuchumatanes region of the northern Guatemalan highlands supported a large plateau ice cap with an area of -40 km2 along with a group of 5 cirque glaciers -1 to 2 km2 during the local last glacial maximum (LLGM). A comprehensive mapping reconstruction of the northern Guatemalan highlands is presented here, including glacial geology and an estimate of maximum ice limits from physical evidence and computer modeling. The glacial geologic map was produced via field mapping with global positioning system (GPS) surveying combined with aerial stereo photographic and topographic map analysis. This new field work on moraine …

Remote Sensing Studies For The Assessment Of Geohazards: Toxic Algal Blooms In The Lower Great Lakes, And The Land Subsidence In The Nile Delta, Richard H. Becker

Dissertations

Remote sensing techniques provide valuable tools for assessing a wide variety of environmental phenomena. They have been used for monitoring and assessment of various types of geologic and environmental hazards occurring on land, in the air, or in oceans. I present results from two studies, the first of which examines the spatial and temporal distribution of algal blooms in the Great Lakes; the second measures subsidence in the Nile Delta.

In the first study, methodologies to investigate the extent and distribution (temporally and spatially) of algal blooms in Lake Erie and Lake Ontario are studied. Millions of people in the …

Relationship Between Slug-Test And Effective Hydraulic Conductivities For 2-Dimensional Heterogeneous Aquifers, Richard Walker Donat

Masters Theses

Slug tests are one of the most common field tests used by hydrogeologists to evaluate the hydraulic conductivity of an aquifer system. Steady-state and transient (slug test) numerical simulations were run in 37, 2-dimensional randomized multifractal hydraulic conductivity fields. Each field consisted of 59,049 individual saturated hydraulic conductivity (K) values with varying numbers of hydrofacies and different degrees of spatial heterogeneity. The K_eff values were determined by examining the flux in and out of the steady-state numerical model. The K_slug values were determined by adding a slug of water to the center node of the field and evaluating …

Origin Of Tunnel Valley And Esker Assemblages In The Saginaw Lobe, Barry County, Michigan, Caleb J. Woolever

Masters Theses

Surficial mapping, borehole analysis, and ground penetrating radar surveys are used to reconstruct conditions leading to the formation of tunnel valley and esker networks within the Dowling 7 .5 minute quadrangle. The relationship between tunnel valleys and eskers has important implications on the subglacial hydrology beneath the Saginaw Lobe of the Laurentide Ice Sheet.

Surficial mapping reveals northeast-southwest trending tunnel valleys, some containing eskers of the same orientation, in hummocky topography mapped as the Saginaw Kalamazoo Moraine. A borehole hole drilled through one such tunnel valley and esker pair reveals sand and gravel fining upwards to fine sand. Stratigraphy suggests …

Influence Of Bioirrigation On Metal Distribution Within Burrows, Terri Shattuck

Masters Theses

Bioirrigation is the increase of solute transport resulting from introduction of oxygenated water from the surface into the more reduced environment deep within the burrow. Fe and Mn hydr-(oxides) accumulate on burrow margins in response to the oxygen flux into suboxic porewaters. This has been shown to trap trace metals (Harding and Risk, 1986; Tessier and Campbell, 1988; Tessier et al., 1979, 1982). The diagenesis, mobility, and transport of metals contribute to the bioavailability of metals in the environment possibly to the extent of harming ecosystems; especially in coastal areas with buried waste. This study assesses Fe and trace metal …

Kinematics And Timing Of Orogen-Parallel Flow, Grouse Creek Mountains, Utah, Tonia Gail Arriola

UNLV Theses, Dissertations, Professional Papers, and Capstones

Alternating contractional and extensional events in orogenic belts play a significant role in dynamically adjusting crustal thickness during regional contraction. Distinguishing between these two contrasting kinematic regimes is not only important for understanding the tectonic setting but also provides insights into the dynamics of evolving orogenic wedges. The earliest pervasive fabric, D ₁ , in the Grouse Creek Mountains of northwest Utah is interpreted to have played an integral role in accommodating such a dynamic adjustment. It is interpreted that focused crustal thickening led to differences in gravitational potential energy along strike, facilitating an episode of mid-Cretaceous synconvergent orogen-parallel extension. …

Improving Summer Drought Prediction In The Apalachicola-Chattahoochee- Flint River Basin With Empirical Downscaling, John Robert Dean

Geosciences Theses

The Georgia General Assembly, like many states, has enacted pre-defined, comprehensive, drought-mitigation apparatus, but they need rainfall outlooks. Global circulation models (GCMs) provide rainfall outlooks, but they are too spatially course for jurisdictional impact assessment. To wed these efforts, spatially averaged, time-smoothed, daily precipitation observations from the National Weather Service cooperative network are fitted to eight points of 700 mbar atmospheric data from the NCEP/NCAR Reanalysis Project for climate downscaling and drought prediction in the Apalachicola-Chattahoochee-Flint (ACF) river basin. The domain is regionalized with a factor analysis to create specialized models. All models complied well with mathematical assumptions, though the …

Microtextures Of Cyanobacterial Mats In Siliciclastic Sedimentary Environments (Modern & Ancient): Applications To The Search For Life On Mars, Dina M. Bower

OES Theses and Dissertations

The current Mars Exploration Rover Program (MER) is one of NASA's most successful missions. The aim of the MER is to explore for possible life on the surface of Mars. My thesis developed new methods of how to detect and to identify microbial mats in siliciclastic sediments (modern and ancient), and to make recommendations on the applicability of MISS as biosignatures. Predominantly, I employed instrumentation portable by future rovers. To search for life on other planets, we need to have information on how this life might look. Most astrobiological studies therefore focus on Earthly analogues of life and its habitats. …

Geochemistry, Structure, And Tectonic Evolution Of The Eldivan Ophiolite, Ankara Melange, Central Turkey, Anne Dangerfield

Theses and Dissertations

The Eldivan ophiolite, in the Ankara Mélange, represents the remnant of an ocean basin that developed in the İzmir-Ankara-Erzincan Ocean and collapsed the form the İzmir -Ankara-Erzincan suture zone (İAESZ) through continental block collision. Whole-rock and mineral geochemical evidence show supra-subduction zone tectonomagmatic affinity for the ophiolite, revealing this basin formed in the upper plate of an intra-oceanic subduction zone. Detrital zircon from the ophiolitic mélange sandstone and the overlying Karadağ Formation suggest the ophiolites maximum age is 143.2 (±2) Ma, and the overlying Karadağ Formation is 105.2 (±5) Ma. The angular unconformity between the ophiolite and Karadağ formation reveal …

Remote Sensing Solutions For Estimating Runoff And Recharge In Arid Environments, Adam M. Milewski

Dissertations

Efforts to understand and to quantify the interplay between precipitation, runoff, and recharge are often hampered by the paucity of appropriate monitoring systems. We developed methodologies for rainfall-runoff and groundwater recharge computations that heavily rely on observations extracted from a wide-range of global remote sensing data sets (TRMM, SSM/I, AVHRR, and AMSR-E,) using the arid Sinai Peninsula (SP; area: 61,000 km²) and the Eastern Desert (ED; area: 220,000 km²) of Egypt as our test sites. A two-fold exercise was conducted. Temporal remote sensing data (TRMM, AVHRR and AMSR-E) were extracted from global data sets over the …

Geotechnical Investigation Of The New Site Of The American University In Cairo, Yehia Abdel Maksoud Abdallah Eissa

Archived Theses and Dissertations

No abstract provided.

Analysis Of Pore Architecture And Correlation To Sonic Velocity Values In Silurian (Niagaran) Reefs Of The Michigan Basin, Amy Kathryn Noack

Masters Theses

Recent work has shown that there is a complex relationship among porosity, permeability, and rock fabric in carbonate rocks. Porosity/permeability transforms are of limited value when evaluating carbonate reservoirs because permeability is controlled by pore type. Vuggy, moldic, or fenestral pore types have high porosity but poor permeability; in contrast, intergranular and intercrystalline pore networks have high porosity and high permeability. Visible pore types of key facies in five Middle Silurian (Niagaran) Reef reservoirs of the Michigan Basin were evaluated to better understand related permeability. Image analysis was performed on key facies to understand pore geometries and pore connectivity. Facies …

Evaluation Of A Pilot-Scale Constructed Wetland Treatment System For Ash Basin Water, Lane Dorman

All Theses

This investigation examined the feasibility of using surface-flow constructed wetland treatment systems (CWTSs) to decrease the concentration and bioavailability of targeted constituents of concern (COC) in ash basin water. Ash basin water results from hydraulic transport (sluicing) of coal ash produced during thermoelectric power production. During the sluicing process, potentially toxic trace elements contained within coal ash may be transferred to the aqueous phase and subsequently introduced to aquatic receiving systems. COC in ash basin water were identified by a risk quotient method in order to determine biogeochemical conditions needed within wetland reactors for reducing the aqueous concentration and bioavailability …

Refining Models Of Crustal Growth And Evolution In Southwestern Laurentia With Paired U-Pb And Lu-Hf Analyses Of Igneous And Detrital Zircon, Mark E. Holland

Earth and Planetary Sciences ETDs

The origin and evolution of continental crust is a fundamental and debated topic in geoscience. For over thirty years, Proterozoic crust of the southwestern United States has been a field laboratory for studying orogenic processes in the middle crust, and the growth of continental lithosphere via accretionary orogenesis. Three distinct crustal provinces are delineated based on differences in isotopic, structural, and geochronologic characteristics. To address questions about the origin of each province, this dissertation is composed of three chapters that present new U-Pb and Lu-Hf isotope analysis of plutonic, volcanic, and detrital zircon from the oldest known rocks in each …

Investigating The Petrogenesis Of The Basaltic Crust Of Asteroid 4 Vesta: A Combined Petrologic-Spectral Study Of The Unbrecciated Eucrites, Rhiannon Gwenllian Mayne

Doctoral Dissertations

The Dawn mission, which launched in September 2007, will orbit and analyze two of the largest asteroids, 4 Vesta and 1 Ceres. These small, proto-planetary bodies retain a record of the conditions and processes that occurred in the early history of the Solar System, and, as such, provide us with a tool to understand its formation and evolution. Additional information can also be gleaned from the meteorite samples derived from such objects. This dissertation aims to increase understanding of the formation of the basaltic crust of the asteroid Vesta, and the lithologic variety that exists within it, by studying the …

Determination Of Mineral Abundances In Ordinary Chondrites Using Powder X-Ray Diffraction: Applications To Parent Body Processes And Asteroid Spectroscopy, Tasha L. Dunn

Doctoral Dissertations

The ordinary chondrites, the most abundant group of meteorites, are divided into three chemical groups (H, L, and LL), which are distinguished based on variations in bulk composition and iron content. Although ordinary chondrites are relatively abundant, our understanding of their formation has been hampered by an inability to accurately measure the abundances of minerals that they contain. Here I use power x-ray diffraction (XRD) to quantify the modal abundances of 48 unbrecciated ordinary chondrite falls, which represent the complete petrologic range of equilibrated ordinary chondrites (types 4-6).

Although the degree of metamorphism varies within each ordinary chondrite group, many …

Ground Penetrating Radar Investigations On The Relationship Between Horizontal Sub-Wavelength ‘Thin-Layer’ Bedrock Fractures And Reflection Amplitudes, Kevin E. Burns

Masters Theses

Several theoretical equations that predict sub-wavelength ‘thin-layer’ reflection amplitudes are compared to the results of a series of controlled ground penetrating radar surveys using 1 GHz transducers over a physical model of a horizontal bedrock fracture. Two large plastic (UHMW-PE) blocks, separated by one or more stacked inserts (polyethylene; ~0.1 mm thick) for a total of 101 surveys, generate a modeled fracture with an aperture ranging from 0-300 mm. All existing theoretical reflection coefficient equations fail to predict observed reflection amplitude oscillations in the data when the fracture aperture is less than 1/48 of a wavelength. The only theoretical formulation …

Assessing The Impact Of Water Harvesting On Water Resources, Jennifer Oblinger

All Theses

Clean water supplies, like all natural resources, are becoming scarce all over the world, but especially in developing countries where special interest groups (such as city governments, commercial farmers, other villages downstream, etc.) fight over water rights. The Foundation for Ecological Security (FES) is a non-government organization in India whose mission is to restore degraded lands through cooperation with rural villages. In order to increase the water supply to the ecosystem, FES constructs water harvesting structures (WHS) which impound rainfall, water that would have otherwise runoff and contributed to erosion, in surface storage. This study was conducted to assess the …

A Post-Project Assessment Of The Provo River Restoration Project: Channel Design, Reconfiguration, And The Re-Establishment Of Critical Physical Processes, Randy Ray Goetz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A physical assessment of the Provo River Restoration Project was undertaken in order to determine how alterations to the channel were designed, the nature of as-built channel morphology, and the performance of the reconfigured channel in terms of achieving frequent (2-year recurrence) bankfull discharge and increasing transient storage. Measures of channelized and reconfigured channel morphology were obtained using total station survey, digital aerial photography, and pebble counts. Results of geomorphic analysis were compared with similar measurements made by a regional consulting company, and stream channel design data, in order to determine that intended mitigation included reducing channel capacity, increasing sinuosity, …