Physical Sciences and Mathematics Commons^™

Experimental Investigation Of High-Temperature Brine-Shale Interactions, Anna Atasha Hoffmann

Doctoral Dissertations

"Hydrofracturing (fracking), a common practice in the Petroleum Industry to induce or improve fluid flow in tight formations, creates chemical disequilibrium that further alters the porosity and permeability of host rocks and results in the production of saline and contaminated produced waters (PW). The PW of the Tuscaloosa Marine Shale (TMS) are Na-Ca-Mg-K-Cl brines with mean concentrations of approximately 16% Total Dissolved Solids (TDS) and circumneutral pH. Analysis of composition suggests the PW result from a 20 to 80% dilution of formation waters (relict brines of the Louann Salt) by fracking fluid. Trace element concentrations generally show moderate to strong …

Characterizing Silicate Materials Via Raman Spectroscopy And Machine Learning: Implications For Novel Approaches To Studying Melt Dynamics, Blake O. Ladouceur

Doctoral Dissertations

Silicate melt characteristics impose dramatic influence over igneous processes that operate, or have operated on, differentiated bodies: such as the Earth and Mars. Current understanding of these melt properties, such as composition, primarily comes from investigations on their volcanic byproducts. Therefore, it is imperative to innovate on modalities capable of constraining melt information in environments where a reliance on laboratory methods is severed. Recent investigations have turned to Raman Spectroscopy and amorphous volcanics as a suitable pairing for exploring these ideas. Silicate glasses are a proxy for igneous melts; and Raman spectroscopy is a robust analytical technique capable of operating …

Migmatite Formation, Geochronometer Petrogeneisis, And Rare Earth Element Mineralization In The Adirondack Mountains, Ny, Kaitlyn Suarez

Doctoral Dissertations

The Adirondack Mountains in upstate New York contain exposures of complex partially melted rocks, in addition to iron oxide-apatite (IOA) deposits with variable rare earth element (REE) concentrations. Previous workers have suggested that melting occurred during the ca. 1150 Ma Shawinigan and the ca. 1050 Ma Ottawan orogenies. However, there are challenges in determining the timing of melting and the number of partial melt events. Further, tectonic models must be developed to describe the petrogenesis of IOA and REE mineralization. Migmatites are present along Rt. 4/22 near Whitehall, NY. In chapter two, all layers of a single migmatitic rock were …

Large-Scale Volcanism On The Terrestrial Planets, Keenan Ben Golder

Doctoral Dissertations

Evidence for mafic volcanism has been found on each planet in the inner Solar System. Lava flows on these planets range in size from 10s to 1000s of kilometers in extent. I investigated large-scale lava flows on Mercury, Earth, and Mars throughout the chapters in this dissertation. Each of these lava flows provides an avenue to study the emplacement and evolution of lava on various planets and under differing conditions, the factors that affect their overall extent, and potential source areas.

Chapter One investigates large-scale lava flows in the Cerberus region on Mars, specifically to understand their emplacement history, material …

Geomorphology Of Tidal Wetlands: Impacts Of Extreme And Annual Flood Events To Salt Marsh And Mangrove Systems, Frances R. Griswold

Doctoral Dissertations

Tidal wetlands are vital for buffering coastal settings from the threats of accelerated sea level rise and storms. Understanding the factors that are most influential for the maintenance and recovery of tidal wetlands after extreme events compounded by future accelerated sea level rise is of the utmost importance, yet this knowledge is not well established. Two tidal wetland schemas investigated in this dissertation are mangrove systems in Vieques, Puerto Rico (including robust lagoonal-mangrove forest systems and fringing mangrove forests), and salt marshes in New England. While the climatic forcings, vegetation type, and locations are vastly different for these two tidal …

Applied Geochemistry, Geochronology And Biostratigraphy: Case Studies From The 38th Parallel Structures In Missouri And Orange Basin, Offshore Western South Africa, Marissa Kay Spencer

Doctoral Dissertations

"The unique alignment of the Decaturville, Crooked Creek, and Weaubleau geological structures in central Missouri, three of nine known such structures along the 38th parallel in Illinois, Missouri, and Kansas, has puzzled geoscientists for decades. Research using palynology (palynomorphs and particulate organic matter) and radiometric dating of impact spherules were used to constrain age and a relationship between these enigmatic structures and infer their paleoenvironmental conditions. Novel melting damages, unique to impact, were documented in the palynomorphs in all the three structures. Early Ordovician acritarchs with melted processes correlate with ⁴⁰Ar-³⁹Ar stepwise heating age of impact spherules …

Natural, Experimental, And Educational Explorations Of The Interiors Of Terrestrial Planetary Bodies, Nadine L. Grambling

Doctoral Dissertations

Planetary interiors are enigmatic, inaccessible, and vital to the processes that have formed the rocks we see on the surface of bodies in the inner Solar System today. Based on geophysical explorations of the Moon and Earth, along with information gleaned from rocks at the surface today, there is understanding of the basic structure and processes at depth. Using a combination of natural samples and experimental studies, we attempt to learn more about the physical conditions beneath the surface, and their effect on material properties and tectonics processes in the mantle.

On Earth, mid-ocean ridge processes have long been debated, …

Geochemical And Climatic Controls On The Sulfur Cycle In Volcanic Settings: Implications For The Origin Of Sulfur-Rich Deposits Investigated By The Spirit And Opportunity Rovers On Mars, Rhianna D. Moore

Doctoral Dissertations

On Earth, volcanic activity with elevated sulfur (S) degassing in the presence of water leads to the formation of hydrothermal deposits enriched in S-bearing minerals. Similar processes may have been an important source of S on Mars. The landing sites of Gusev crater and Meridiani Planum investigated by the Spirit and Opportunity rovers, respectively, showed elevated SO₄^2- [sulfate] concentrations, suggesting high- and low-temperature aqueous processes. However, the SO₄^2- contribution from subsequent aqueous weathering of hydrothermal S deposits has been poorly constrained, thus its importance to regional S cycling in the landing sites is unclear. In this …

Experimental Approaches To Evaluating Silicate Melt Properties And Trace Element Fractionation During Crystallization At High Pressures And High Temperatures, Megan D. Mouser

Doctoral Dissertations

Current understanding of the evolution and behavior of silicate materials that form in planetary interiors at high-pressures and high-temperatures largely come from experimental work as natural samples are either rare, or physically inaccessible. Laboratory experiments provide a comprehensive way to constrain the crystallization history, elemental partitioning, and viscosity of different silicate materials at planetary mantle pressure and temperature conditions. This work utilizes two high-pressure experimental techniques, the Paris-Edinburgh apparatus, and the piston cylinder apparatus, to measure physical and chemical properties of silicate materials. The viscosity of reduced, Fe-free silicate liquids, with and without sulfur (S-free and S-bearing), were measured to …

Size, Timing, And Landscape Impacts Of Glacial Lake Outburst Floods In The Channeled Scabland Of Eastern Washington, Usa, Karin E. Lehnigk

Doctoral Dissertations

Extreme floods have dramatically altered landscapes on Earth and Mars through bedrock erosion, sediment deposition, and canyon formation. The Channeled Scabland of the Columbia Plateau in eastern Washington, USA, is perhaps the most striking example of such a landscape, where outburst floods from an ice-dammed glacial Lake Missoula eroded immense canyons and transported large volumes of sediment during the late Pleistocene. Despite advances in numerical modeling and geochemical exposure dating methods, it has remained a challenge to untangle the complex interactions between floodwater, bedrock, and glacial ice to link the size of a flood with its impact on the landscape. …

Fan And Fracture Formation: Morphologic And Sedimentologic Characteristics Of Alluvial Fans On Earth And Mars, And Fracture Population Distributions On Europa, Claire A. Mondro

Doctoral Dissertations

Planetary science is inherently limited by the resolution and coverage of the currently available data. What can be observed in person, measured precisely in high-resolution data, or sampled for lab analysis in terrestrial investigations ca only be inferred, modeled, or hypothesized on other planetary bodies. The Earth remains our best tool for understanding the geologic systems of the rest of the Solar System. By applying what is known or can be measured about terrestrial systems, it is possible to determine how large-scale controls and observable features relate to geologic complexity that is beyond the resolution of planetary data. This dissertation …

Precambrian Molar-Tooth Structure: Unraveling The Diagenesis Of Ancient Carbonates, Agustin Kriscautzky

Doctoral Dissertations

Molar-tooth structure (MTS) is an enigmatic carbonate fabric that occurs mainly within Proterozoic carbonate host rocks. It is composed of two distinct features: cracks of various morphologies and crack-filling calcite microspar. Although the origins of MTS remain unknown, most previous investigation has focused on the formation of the cracks and mechanisms involved in the void space generation, with less emphasis on the intriguing carbonate fill. In this study I have investigated molar-tooth bearing carbonates from regions that span both paleogeography and geologic time. Analysis at the microscopic scale, including traditional petrography, cathodoluminescence petrography, scanning electron microscopy, and micrometer-scale geochemical analyses …

Hydroclimate Variability In Central America During The Holocene Inferred From Lacustrine Sediments In Lake Izabal, Eastern Guatemala, Edward Fernando Duarte

Doctoral Dissertations

"Holocene hydroclimate reconstructions have contributed to our understanding of the mechanisms controlling precipitation in Central America. Recent hydroclimate proxy records from the region, however, have revealed considerable spatiotemporal complexity in precipitation variability. This complexity is hypothesized to result from the interaction between multiple oceanic-atmospheric processes that converge in the region. This project analyzed three sediment cores from Lake Izabal, eastern lowland Guatemala, with the goal of understanding changes in precipitation, lake productivity, and lake water chemistry during the Holocene. Our proxy results indicate that precipitation in the region increased from the early to the middle Holocene, when Lake Izabal became …

Antarctic Ice Sheet Stability During Warm Periods: Integrating Numerical Modeling With Geologic Data, Anna Ruth W. Halberstadt

Doctoral Dissertations

Sea level rise is one of the major social and environmental challenges that threatens modern civilization, yet the response of polar ice sheets to future warming is deeply uncertain. Mass loss from the Antarctic Ice Sheet is projected to dominate global sea level rise in the near future, but how much, and when, remains a key unknown. The challenges associated with projecting Antarctica’s future sea level contribution are derived from a knowledge gap of physical ice sheet processes in a world warmer than today, and a lack of understanding of climatic thresholds that drive potentially irreversible retreat. Future and even …

Improving The Hydrological Analysis Of Groundwater Flow Paths By Integrating Geochemical And Physical Characteristics Of A Highly Fractured Aquifer System To Create Sustainable Use Of Groundwater In A Climate With Projected Drying Trends., Marsha K. Allen

Doctoral Dissertations

Improving the hydrological analysis of groundwater flow paths by integrating geochemical and physical characteristics of a highly fractured aquifer system to create sustainable use of groundwater in a climate with projected drying trends. Precipitation over Caribbean islands has decreased steadily since the 1950's, which has led to severe drought conditions. The most recent Pan-Caribbean Drought occurred from 2013 to 2016. Climate models predict that drying trends are expected to continue and become more severe over time as precipitation decreases and temperatures rise. In addition, evaporation rates on these islands are expected to increase by ~15-17%, contributing to the drought. Though …

Fundamental Controls On The Water Cycle In Arid Environments: A Mechanistic Framework For Spatiotemporal Connectivity Between Hydroclimate And Groundwaters In The Dry Andes, Brendan J. Moran

Doctoral Dissertations

There remain many persistent uncertainties regarding fundamental aspects of natural water cycles in arid mountainous regions, the Dry Andes of South America represents one of the most extreme examples of these environments on the Planet. Deep water tables (>100 meters), long groundwater transit times and distances (>100 years, 10-100 kilometers), limited and infrequent rainfall, remote and difficult to access terrain, and complex salar/evaporite hydrogeology common in these environments make reliable monitoring of these hydrological systems particularly difficult. As a result, major gaps remain in our understanding of critical aspects of the water cycle such as recharge and evaporation …

Mantle Flow And Transition Zone Discontinuities Beneath The Carribean Plate: Constraints From Shear Wave Splitting And Receiver Function Analyses, Tu Xue

Doctoral Dissertations

"Azimuthal anisotropy quantified by teleseismic SKS, SKKS, PKS (“XKS”) and local S wave splitting parameters is used to investigate lithospheric deformation and asthenospheric flow beneath the boundary zone of the North American and Caribbean plates and adjacent areas. A total of 4915 XKS and 1202 pairs of local S wave splitting parameters were obtained at 24 broad band seismic stations. The XKS observations can be divided into two groups based on the spatial distribution of the resulting fast polarization orientations. Those observed on the Caribbean Plate are mostly WNW-ESE which are roughly trench-parallel. In contrast, the fast orientations observed on …

The Kanarra Fold-Thrust System -- The Leading Edge Of The Sevier Fold-Thrust Belt, Southwest Utah, William Joseph Michael Chandonia

Doctoral Dissertations

“The Jurassic to Eocene Sevier fold-thrust belt is the subject of continued scientific curiosity in tectonics, stratigraphy, and industry. Understanding its development in southwest Utah is hindered in part due to the multiple origins proposed for the Kanarra anticline, a major leading edge structure -- a drag fold along the Hurricane fault, Laramide monocline, Sevier fault propagation fold, or a combination of these -- which have confused its tectonic significance and regional context. This confusion results from the structural complexity of its exposed eastern limb, as well as displacement and burial of its crest and western limb beneath Neogene sediments …

Application Of Machine Learning In Geophysics: Ranking Teleseismic Shear Wave Splitting Measurements And Classifying Different Types Of Earthquakes, Yanwei Zhang

Doctoral Dissertations

"During the past decades, applications of Machine Learning have been explosively developed to solve various academic and industrial problems, and over-human performance has been shown in diverse areas. In geophysical research, Machine Learning, especially Convolutional Neural Network (CNN), has been applied in numerous studies and demonstrated considerable potential. In this study, we applied CNN to solve two geophysical problems, ranking teleseismic shear splitting (SWS) measurements and classifying different types of earthquakes.

For ranking teleseismic SWS measurements, we utilized a CNN-based method to automatically select reliable SWS measurements. The CNN was trained by human-verified teleseismic SWS measurements and tested using synthetic …

Depositional Conditions, Stratigraphic Evolution, And Allo- And Autogenic Controls Of Lower Permian Non-Marine Carbonate Rocks, Lucaogou Low-Order Cycle, Bogda Mountains, Nw China, Yiran Lu

Doctoral Dissertations

"The overall objective of this study is to interpret the depositional conditions of lacustrine carbonate deposits of the lower Permian Lucaogou low-order cycle in the greater Turpan-Junggar continental rift basin, NW China. The depositional environments of ten carbonate lithofacies in the Tarlong-Taodonggou half graben and the Zhaobishan section were interpreted. Allo- and autogenic factors were identified. They controlled characteristics and distribution pattern of carbonate deposits in regional and local scale, respectively. Allogenic factors include the amount and direction of regional siliciclastic input, basin geometry, cyclic humidity/aridity oscillation, temperature, and regional tectonics. Autogenic factors include local siliciclastic input, local topography, local …

Laterally Heterogeneous Seismic Anisotropy Investigated By Shear Wave Splitting Analyses, Yan Jia

Doctoral Dissertations

"Numerous geophysical studies suggest that seismic anisotropy is a nearly ubiquitous property of the Earth’s crust and upper mantle. In this study, we utilize the shear wave splitting technique to investigate the piercing-point-dependent azimuthal anisotropy beneath the northeastern edge of the Sichuan Basin in central China, and the spatial and temporal variations of anisotropy near the 2019 M7.1 Ridgecrest earthquake in California, respectively. A clear back azimuthal dependence of the splitting parameters and the lack of a 90° or 180° periodicity of azimuthal variation in the observed fast orientations provide strong evidence for the existence of piercing-point-dependent anisotropy beneath the …

Planetary Processes Active And Ancient: Hollowing On Mercury, Ancient Crust Formation On Mars, And Identifying Mars-Analog Habitats., Michael Steven Phillips

Doctoral Dissertations

This dissertation comprises a thermophysical model that shows elemental sulfur may be involved in the potentially active processes that form enigmatic features called hollows on the Mercurian surface, a suite of remote sensing techniques that unveil anorthositic rocks in ancient martian crust, and deep learning to discover the spatial resolutions necessary to identify astrobiology targets in images of Mars analog landscapes.

On Mercury, hollows are high-reflectance, flat-floored depressions observed nearly globally. Hollows are thought to form via sublimation, or a “sublimation-like” process, but the identity of the sublimating phase is poorly constrained. To better understand which phase might be responsible …

Architectural-Element Analysis And Depositional Models For Pre-Vegetation Braidplain And Braid-Delta Environments, With Modern Analogues, Jason Gerhard Muhlbauer

Doctoral Dissertations

Pre-vegetation landscapes that blanketed the continents before the emergence vascular plants in the late-Silurian are proposed habitats for the earliest terrestrial biota and are analogous to martian setting thought to have potentially hosted life. Analysis of the middle member of the Wood Canyon Formation, a Cambrian age sandstone, reveal new details about terrestrial pre-vegetation environments. In fluvial middle-member stratigraphy, units are defined by stacking patterns of three facies associations (FA1-3). In FA1, stacked cosets, interpreted as braidplain barforms and channel fills, preserve vertical- and downstream-accretion elements under unimodal paleoflow. Floodplains, represented by FA2, include red-orange intervals of fine- to medium-grained …

The Pilot Knob Magnetite, Pilot Knob Hematite, And Shepherd Mountain Iron Oxide Deposits In Southeast Missouri -- Local Expressions Of A Magmatic-Hydrothermal Plumbing System?, Bolorchimeg N. Tunnell

Doctoral Dissertations

“The Southeast Missouri Iron Metallogenic Province in the Midwestern USA contains seven major and several minor IOA/IOCG-type deposits, all of which are spatially associated with the early Mesoproterozoic (1.50-1.44 Ga) magmatism in the St. Francois Mountains terrane. This Ph.D. project focuses on the Pilot Knob deposits, i.e., the deeper largely massive Pilot Knob Magnetite (PKM) and the shallower Pilot Knob Hematite (PKH) deposits, and the Shepherd Mountain deposit that are located less than 2.1 km distance from one another. The first precise age for the formation of the PKM ore is constrained at 1438±5.8 Ma using apatite U-Pb method. Petrographic …

Neogene Dinoflagellate Cysts From The Tropical Americas, Damian Cardenas

Doctoral Dissertations

"Marine palynomorphs, mainly dinoflagellate cysts and acritarchs, constitute excellent proxies for biostratigraphic and paleoceanographic studies in neritic sequences. Neogene marine palynological studies have mostly focused on the Northern Hemisphere, resulting in the scarcity of dinoflagellate cysts and acritarchs from tropical latitudes. Forty samples encompassing the late Chattian-late Burgidalian time interval (~24.1- 17.3 Ma) in the Southern Caribbean were analyzed for their marine palynological contents. A biostratigraphic scheme for the region is proposed and includes the upper Chattian-lower Aquitanian Minisphaeridium latirictum Interval Zone (~23.9-22.0 Ma), the upper Aquitanian Achomosphaera alcicornu Interval Zone (~22.0-20.3 Ma), and the Burdigalian Cribroperidinium tenuitabulatum Interval Zone …

Implications And Significance Of Partial Melting On The Tectonic History Of The Eastern Adirondack Mountains, Claire Rose Pless

Doctoral Dissertations

The eastern Adirondack Mountains contain abundant exposures of high-grade metamorphic rocks. These exposures are interpreted to be a window into the mid/deep crust of an ancient, large, hot, long-duration orogen, allowing the Adirondack Mountains to be used as an analogue to the deep processes of modern orogens. Currently interpreted thermo-tectonic events in the eastern Adirondack Mountains include the ca. 1245-1220 Ma Elzevirian orogeny, the ca. 1190-1150 Ma Shawinigan orogeny, emplacement of the ca. 1150 Ma AMCG igneous suite, the ca. 1090-1050 Ma Ottawan orogeny, and a ca. 1050-1020 Ma extensional collapse phase. This dissertation focuses on six migmatite domains within …

Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH₄ that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH₄ in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO₂, which energetically takes place of the …

Exploration Of Mid To Late Paleozoic Tectonics Along The Cincinnati Arch Using Gis And Python To Automate Geologic Data Extraction From Disparate Sources, Kenneth Steven Boling

Doctoral Dissertations

Structure contour maps are one of the most common methods of visualizing geologic horizons as three-dimensional surfaces. In addition to their practical applications in the oil and gas and mining industries, these maps can be used to evaluate the relationships of different geologic units in order to unravel the tectonic history of an area. The construction of high-resolution regional structure contour maps of a particular geologic horizon requires a significant volume of data that must be compiled from all available surface and subsurface sources. Processing these data using conventional methods and even basic GIS tools can be tedious and very …

Fire-Vegetation-Climate Interactions Across The Holocene On The U.S. Southeastern Coastal Plain, Mathew S. Boehm

Doctoral Dissertations

This dissertation research examined multiple proxy indicators in sediment cores from one lake and one wetland to reconstruct long-term relationships between fire, vegetation, and climate in the southeastern U.S.

At Lake Balboa (30.6992 N, 83.2031 W; 48 m elevation), a sinkhole pond located in southern Georgia, Bølling-Allerød conditions were sufficiently wet to maintain a shallow wetland at the site. Evidence for fire was minimal. Between 12,600 and 9200 cal yr BP, water availability declined, leading to a potential hiatus in sedimentation. During the early Holocene moisture availability increased, leading to greater primary productivity within and outside the lake, triggering an …

3-D Shear Wave Velocity Structures Of The Crust And Upper Mantle Beneath Cascadia And New Zealand From Full-Wave Ambient Noise Tomography, Sampath Rathnayaka Mudiyanselage

Doctoral Dissertations

The (de)hydration process and the amount of hydrated sediment carried by the downgoing oceanic plate play a key role in the subduction dynamics. The deformation and (de)hydration of the downgoing tectonic plates, as well as the seismic, tsunami, volcanic hazards, in Cascadia and the New Zealand regions are not fully understood, partly due to a lack of combined studies of onshore and offshore data. In order to address these questions, we developed a 3-D high-resolution shear wave velocity model beneath Cascadia, the North and the South Islands of New Zealand, extending from offshore to onshore, with the use of full-wave …