Geology Commons^™

Modeling The Greenland-Iceland-Faroe Ridge Using Integrated Geophysical Analysis, Zachary Clowdus

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

The Greenland-Iceland-Faroe Ridge (GIFR) is an area of significant geologic interest with anomalously thick crust related to enhanced melt generation from the interaction between the Mid-Atlantic Ridge and the Iceland hotspot. To the northeast of Iceland lies the Jan Mayen Microcontinent (JMMC), which is a continental fragment separated from Greenland during the opening of the Northern Atlantic. The overall extent of the JMMC, especially its southern boundary, remains poorly constrained. The crust beneath the GIFR is believed to be primarily of oceanic affinity. However, a recent discovery of felsic lavas in Iceland led to an alternative hypothesis that implies the …

An Integrated Lithospheric Geotherm Model From Seismic Data And Plate Ages, Amanda R. Leaman

All Graduate Theses and Dissertations, Fall 2023 to Present

This research aims to develop advanced methods to accurately depict temperature profiles within the lithosphere, the Earth’s rigid outer layer. These temperature profiles extend from Earth’s surface to the asthenosphere, the ductile layer below the lithosphere. Constraining the poorly-known temperature distribution within the upper Earth is important for modeling the deformation of Earth’s crust over varying timescales and is essential for advancing realistic simulations of Earth dynamics. Here, I utilize enhanced global seismic data, coupled with recent advances in our understanding of mineral systems, to create several global lithospheric models in which I estimate temperature profiles from seismically observable features …

Survey Of A Paired Gravity Anomaly Within The Benton Uplift Of The Ouachita Mountains, Isaac B. Prud'homme

Physics Undergraduate Honors Theses

The Benton Uplift west of Hot Springs, AR is underlain by a paired gravity anomaly on the order of 80 mGal. Nicholas & Rozendal (1975) have theorized that the gravitational low is caused by a “downwarp of the crust into the mantle”1 however the cause of the gravitational high is still debated. This paired gravity anomaly within the Benton Uplift follows the Ouachita orogenic belt southwest for 500 miles where it meets the Marathon uplift in southwest Texas. We conducted a gravity survey along a 108-km-long transect east of two previous gravity surveys.2,3 We corrected the data from this transect …

Integrated Geophysical Modeling Of Newly Identified Pseudofaults Within Southern Cascadia Subduction Zone, Morgan R. Madsen

Honors Program: Senior Projects (Public)

The Cascadia Subduction Zone, located off the western coast of North America, has a long history of seismic activity, causing various geohazards such as megathrust earthquakes and tsunamis for the coastal population (Goldfinger et al., 2000; Tréhu et al., 2022). It is necessary to identify areas of greater risk, as seismic hazards will continue to affect the area due to ongoing subduction of the oceanic Juan de Fuca plate beneath the North American continent. Heavily fractured, weakened zones of oceanic crust, known as propagator wakes and pseudofaults, have been shown to correlate with greater seismicity (Ashraf and Filina, 2023a). Propagator …

Gravity And Magnetic Analysis Of The Amu Darya Basin Of Turkmenistan And Uzbekistan, Logan R. Rogers

Graduate Theses/Dissertations

The Jurassic-Tertiary Amu Darya Basin is mainly located within Turkmenistan and Uzbekistan with a small portion extending into Afghanistan and Iran. The basin is one of the largest petroleum systems in central Asia. The basin is located in the southeast corner of the Turan platform, where both the Middle Paleozoic Turkestan and Early Mesozoic Tethys oceans were closed during different orogenies. The southern boundary of the basin is along the Bande Turkestan fold belt, the Afghan-Tajik basin to the east, Paleozoic metamorphic terranes to the north, and the Karakum high (Paleozoic basement rocks) to the west. Several blocks and terranes …

Critical Mineral Exploration In The Superior Province Of Northwestern Minnesota - A Geophysical Data Analysis, Michell L. Waterman

Graduate Theses/Dissertations

The Archean basement geology of northwest Minnesota, a region covered by glacial deposits and historically underexplored for minerals, was analyzed using gravity, magnetic, radiometric, and geochemical data. These datasets were integrated to aid in identifying subsurface structures and evaluating the area's potential for economic mineralization within the Wabigoon, Quetico, and Wawa Subprovinces of the Superior Province. Gravity and magnetic datasets, analyzed through upward continuation, derivative maps, and two-dimensional modeling, revealed distinct northeast-to-southwest-trending maxima corresponding to fault-bounded, high-density, and magnetically susceptible bodies. These features were interpreted as mafic to ultramafic intrusions and dikes, several of which align with known Proterozoic fault …

Investigating Crystalline Rock Weathering In Distinct Climate And Ecological Settings: Insights From Shallow Seismic Refraction, Rachel Uecker

All Dissertations

Despite decades of research, understanding the subsurface of the critical zone (CZ) remains a challenge, constrained by limited access to information at depth. Traditionally, boreholes, outcrops, soil pits, and near-surface (<1 meter) geochemical measurements provided access to and quantified CZ structure. These methods, though valuable in their detail, are spatially limited, and many landscape-scale weathering hypotheses are based on these observations. In recent years, geophysical techniques have been applied to characterize large-scale CZ structure and test the validity of existing hypotheses. This dissertation harnesses nearly 10 kilometers of seismic refraction data from diverse ecoregions across the United States to challenge prevailing assumptions about weathering patterns and CZ evolution. The objective of this work is to characterize the interpreted range of weathered materials in each ecoregion and connect them to remotely-sensed information like canopy height, elevation, slope, and aspect. To do this, this work first investigates differences in weathering at depth in a north and south-facing slope system in the Laramie Range, Wyoming. The motivation for this work came from nearly a century of soil and geochemical studies from the western United States that show a greater degree and depth of weathering on north-facing slopes when compared to south-facing slopes. Our seismic refraction data were used to show that there is not a significant difference in weathering thickness at depth between north and south-facing aspects at the study site, thus conflicting with the hypothesis that there would be. Next, the hypothesis that the depth of weathering is affected by elevation was tested in the San Jacinto Mountains in southern California. The motivation for this work came from several geochemical studies in the Sierra Nevada Mountains that show ecologically prosperous mid-elevations possess an ideal combination of temperature and precipitation to produce a greater degree and depth of weathering. Again, the seismic results from the San Jacinto Mountains provided observations that conflict with the existing hypothesis that climate conditions dominate the thickness of weathering seen in rocks. Lastly, I used seismic refraction data and topographic curvature to build a groundwater model of a watershed in the Carolina Piedmont. The results of this model reveal that seismic refraction as an application for including more realistic geometry in groundwater models can improve model calibration fits. This model is the first of its kind, and, therefore, is an important step forward in merging geophysical data with the hydrogeologic and modeling field and, with further development, can be used to explore the role of topographic and regional groundwater flow as a driver of CZ evolution.

New Constraints On The Stratigraphic Architecture And Evolution Of Mississippi River Delta Lobe Activity: Barataria Basin, Southeastern La, Wilke Coleman

LSU New Orleans Theses and Dissertations

Barataria Basin is a shallow water, interdistributary estuary that has evolved in response to dynamic depositional regimes governed by distributary avulsion and reworking of sediments by coastal processes. In the Mississippi River delta plain, the migratory nature of the River has produced an evolving landscape constructed through episodes of regressive and transgressive sedimentation. These processes produce unique depositional signatures in the stratigraphic record, however the transgressive component of the delta cycle often results in obliteration of the regressive phase. This study uses a modern suite of geophysical and sediment core data to construct a revised geologic framework in Barataria Basin, …

A Python Pipeline For Rapid Inversion Of Gravity Data Aimed At Early Career Researchers: Application To The Lost River Fault, Idaho, Bradford C. Mack

USF Tampa Graduate Theses and Dissertations

Gravity data and modeling can be used to create a 3D view of basin and fault geometries, a valuable tool for seismic hazard assessment. Additionally, access to a high-speed, easy-to-use modeling workflow will enable more researchers to supplement their work with a new method and allow students to be exposed to modeling earlier in their academic careers. The primary goals of this work are to create a widely usable 3D gravity and basin model, to create an introduction to modeling teaching module for undergraduate geology students, and to apply the model to the northernmost two segments of the Lost River …

Utilizing Electrical Geophysical Methods To Map Mycorrhizal Mycelium Networks Non-Invasively, Donald Pesonen

Graduate Dissertations and Theses

Mycorrhizal mycelium networks are a key component to forest health. These networks act as a transportation system for nutrients, are major players in carbon and nitrogen cycling, and can provide some level of drought resistance to the surrounding flora. Due to the location and size of these network’s filaments, studying mycelium non-invasively has been difficult. The alternative method of laboratory grown samples, lacks the important environmental factors that play into the growth and development of mycelium. Mycelium’s inherent conductivity and moisture retention allows for these networks to be a viable target for electrical geophysical equipment. CMD-Tiny, a small shallow depth …

Groundwater System Characterisation: Fortescue Alluvial Fan, Michael J. Donn, Olga V. Barron, Axel Suckow, Chris Turnadge, John A. Simons, Robert J. Paul, Christopher Schelfhout Dr

Natural resources commissioned reports

This report focuses on groundwater system characterisation in the region north of Newman, based on analysis of pre-existing data and data newly acquired during project activities. Groundwater system characterisation was an important research component supporting the assessment of managed aquifer recharge opportunities, using mine dewatering surplus generated (due to mining below the watertable) at large BHP Billiton Iron Ore operations in the eastern Pilbara mining zone, and aiming to support irrigated agriculture. The assessment area is located north of Ethel Gorge and covers the Upper Fortescue River floodplain and surroundings. The project added much knowledge to this largely ‘data-poor’ region, …

Geophysical Survey In Central North Dakota, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet about a 2023–2024 Energy & Environmental Research Center (EERC) geophysical survey in central North Dakota to evaluate the feasibility of developing safe and permanent CO₂ storage in the project area. Describes the purpose of the survey and potential impact on local landowners.

Seismic Shadow Zone Investigation In The Upper Magma Reservoir Of The Yellowstone Caldera, Sarah Nolt-Caraway

Earth and Planetary Sciences ETDs

This study investigates whether the Yellowstone Caldera has enough melt to mute S-waves, creating a seismic shadow zone. Using a dense nodal deployment of ~650 stations, 7-9 earthquakes during the nodal deployment, and 21 broadband stations with 3,000-4,000 events per station; amplitude and noise maps, seismograms, and automatic phase picks probabilities from a deep learning model were analyzed to assess the potential role of melt, crustal attenuation, and noise in affecting body waves, particularly S-phases. The results are inconclusive, with unclear evidence whether observed amplitude decay is normal signal decay due to distance, noise-related, melt, or from scattering and intrinsic …

Quantifying Heterogeneity Along A Hillslope Using Seismic Refraction, Structure From Motion, And X-Ray Fluorescence In The Piedmont, South Carolina, Leah Topping

All Theses

The critical zone (CZ) is the life sustaining outer layer of the earth that spans from the top of unweathered bedrock to the tops of the trees. This dynamic zone is always evolving because a variety of chemical, physical, and biological processes transform bedrock into regolith, creating a spatially heterogeneous CZ architecture. This study aims to investigate the relationships between regolith thickness, seismic velocities, and chemical profiles as a function of slope position and it is hypothesized bedrock composition, fracture density, and foliation are the key factors controlling the physical heterogeneity in the top 1-2 meters of the CZ. To …

Sediment Transport And Geomorphological Evolution In The Northern Gulf Of Mexico, Kelli Moran

LSU Doctoral Dissertations

This dissertation explores the mechanisms driving sediment transport and deposition on the continental shelf and within the bays of the northern Gulf of Mexico via a suite of geophysical methods and sediment cores on a variety of timescales. This dissertation is comprised of three main chapters, each focusing on a different location, environment, and process but tied together using geophysical survey, a thematic focus on geomorphic change and sediment transport within the deltaic cycle and deltaic plain environments, and the implications this change poses for both past and future sediment transport and environmental change in response to sea level change. …

Investigating Elastic Deformation Induced By Surface Loads On Planetary Bodies, Ashlesha Khatiwada, Hilary Martens, Donald F. Argus

Graduate Student Theses, Dissertations, & Professional Papers

Planetary bodies, including the Earth, deform when there is a redistribution of surface load. In this thesis, I conduct three independent projects related to surface loading, two of which investigate methods related to the modeling of surface loading and one which seeks to catalog the displacement responses of other planetary bodies to a surface load.

The first project aims to compare four methods for modeling the elastic loading response of the Earth: a homogeneous, non-gravitating, half-space method; a homogeneous, gravitating, spherical method; a homogeneous, non-gravitating spherical method; and a radially stratified gravitating spherical method. Many studies have focused on computing …

Structural Interpretation Of An Alkaline-Carbonatite Complex Using Gravity And Magnetic Methods At Magnet Cove, Arkansas, Chelsea Morgan Amaral

Graduate Theses and Dissertations

The Magnet Cove alkaline-carbonatite complex in the Ouachita Mountains of south-central Arkansas could be a valuable resource for rare earth elements, though it has not yet been thoroughly studied using geophysical methods, and existing geophysical models simplify its diverse nature. Prior to this study, the subsurface structure and extent of the Magnet Cove complex was poorly understood and, in general, the process of emplacement of alkaline carbonatite complexes worldwide is also not fully understood. The Magnet Cove complex hosts an extensive variety of rare rock types and mineral resources that contrast significantly to the sedimentary rocks into which they have …

Water And Soil Gas Sampling Near Richardton, North Dakota, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet on a 2019 Energy & Environmental Research Center project to collect water and soil gas samples near Richardton, North Dakota, as part of the Red Trail Energy carbon capture and storage (CCS) research effort. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]

Using Geologic Principles And Data To Create A Symphony For Wind Ensemble, Thomas J. Davis

2022 Symposium

Geology and geologic processes have featured in many pieces of classical music such as Alan Hovhaness’ symphonic works after Mt. St. Helens and Glacier Peak but these pieces are impressionistic and only take general inspiration from the geology of their subjects. This paper describes the creation of Tectonics (2021) a piece which incorporates and describes many geologic principles and processes, such as mantle convection, through the musical form of cannon, the formation of fold and thrust belts whose cross sections are directly visually recreated in the score, and the physical dynamics of earthquake waves demonstrated through variations of pitch and …

Processing Seismic, Gravity And Magnetic Data Over Diebold Knoll On Juan De Fuca Plate, Md Ariful Islam, Irina Filina

UNL Student Research Days Posters, Graduate

The Juan de Fuca plate is subducting beneath the North American plate along the Cascadia Subduction Zone. The CSZ is associated with multiple earthquakes, although compared to other subduction zones, it is less active. Many studies suggest that subduction will cause major mega thrust earthquake in near future, while others oppose this view. This project is focused on the Diebold Knoll on the JdF plate Various geophysical methods will be integrated to determine its origin and tectonic history.

Toward The Understanding Of The 2018 Arnold, Ne Earthquake Cluster: Relocation Of Hypocenters And Establishment Of New Gravity Base Stations, Kris Guthrie

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

In 2018, 27 unexpected earthquakes occurred in central Nebraska near Arnold. These earthquakes have no readily apparent cause and no evidence of the responsible fault system is seen at the surface. A joint analysis of vintage, regional gravity and magnetic datasets before the first earthquake revealed a lineament that could represent a pre-existing fault system. New high resolution potential fields data are needed to confidently map the subsurface features around the cluster. To design a survey and collect the data, the following tasks need to be addressed: [1] The earthquakes’ hypocenters need to be improved (relocated) to increase the efficiency …

Investigation Into Karst Of Southwest Missouri Using Electrical Resistivity, Donald Zachary Wormington

Graduate Theses/Dissertations

Nixa, Missouri is located on the southwestern edge of the Ozark Dome which has a karst geomorphological environment. Near surface geophysical methods can be used in determining the location and nature of karst features such as caves and sinkholes. Electrical resistivity methods have been shown to be among the most useful methods in deciphering sinkholes and caves. To investigate a known cave and related sinkholes and faults within Mississippian carbonates south of Nixa, Missouri, a series of two-dimensional electrical resistivity profiles were collected using the dipole-dipole and Schlumberger arrays. Terrain data was collected to include in modeling. The data were …

Detailed Structural And Stratigraphic Analysis Of The Salt-Sediment Interactions On Top Of The Wheeler Dome Salt Tongue, Mississippi Canyon Area, Gulf Of Mexico, Ryan Jaska

Electronic Theses and Dissertations

The Mississippi Canyon is in the northeastern part of the Gulf of Mexico, south of the state of Mississippi. In this area, there are many different salt structures present including salt canopies, diapirs, and salt pillows. The Callovian aged Louann Salt covers this area and is the cause of many of the salt structures and structures of the overlying formations seen in Gulf of Mexico today. Salt is mobile when subjected to stress from overlying sediment and gravity. Stress will force the salt to not only move upward, but to also move down slope deeper into adjacent basins through the …

Three-Dimensional Intrusion Geometries In The Monogenetic San Rafael (Utah) Sub-Volcanic Field Revealed By Nonlinear Inversion Of Magnetic Anomaly Data, Troy A. Berkey

USF Tampa Graduate Theses and Dissertations

Distributed volcanic fields are common on Earth and nearby planetary bodies. Unlike their central-vent counterparts, these volcanic centers are comprised of many individual basaltic magmatic dikes, which are often only expressed at the surface in the form of vents, domes, and lava flows. In situ imaging of the shallow (<1 km) subsurface can reveal important details about the 3D geometry of fissure systems that feed distributed eruptive centers, with implications for the nature of these eruptions: their mass flow rates, explosivity, durations, and volcanotectonic interaction. Luckily, dikes, sills, conduits and related near-surface structures tend to carry high remnant magnetizations, creating magnetic anomalies at the surface where sufficient magnetic contrast exists with the host rocks they intrude. In the San Rafael Sub-volcanic field (SRSVF), basaltic dikes intrude fractured and horizontally bedded Jurassic sandstones, now eroded to a depth of about 800 m beneath the paleo-surface. Detailed mapping and profiles with a Cs-vapor magnetometer reveal far more complex anomalies than can be attributed to simple planar dikes, including: sills, buds, and domes. We image these geometries using MagCube-parallel, an open-source nonlinear inversion code we developed that models complex geometry with multiple (<= 1,000) vertical-sided prisms. I show one normally polarized fissure system to include along strike: An ~3-14 m thick, ~50 m wide dome-like feature or laccolith at depths of ~9-20 m, a roughly vertical conduit ~15 m thick, ~36-50 m wide, at ~1-16 m depth near the center of the mapped fissure-like system, and a ~8-48 m. wide dike at ~2-17 m depth that is <1-6 m thick, with reducing magnitude northward. While model depth and thickness vary with magnetization contrast, the main geometric relationships do not. Magnetic mapping of a nearby fissure reveals the same types of structures. The implication of these structures is that the small-volume fissure eruptions were likely pulsatory, with episodes of horizontal intrusion of sills, and sufficient time to develop gravitational instabilities.

Geology Study – Drilling Down At Red Trail Energy, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet about a 2019–2020 geophysical survey near Richardton, North Dakota. The survey investigated the area’s feasibility as a CO₂ storage site, as part of the Red Trail Energy carbon capture and storage (CCS) research effort. Summarizes survey process and results. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]

Application Of 3d Seismic Signal And Geomechanical Attributes For Subsurface Fracture Characterization: A Case Study In Clearfield County, Central Pennsylvania, Iman F. Zulkapeli

Graduate Theses, Dissertations, and Problem Reports (ETD)

Hydrocarbon exploration in unconventional reservoirs is highly risky due to the nature of the reservoirs and the variability in fractures and reservoir geomechanical properties in the subsurface. The reservoir needs to be fully characterized to avoid any complication such as frac hit, wellbore failure, blowout, or even a dry hole. The Clearfield reservoir produces an exceptionally low amount of gas, compared to the neighboring region in the proximity, which has been poorly understood. This raises the question as to what causes the reservoir to have low productivity.

This study focuses on the natural fracture characterization using high-quality 3D seismic signal …

North Dakota Carbonsafe – Permanent Co2 Storage In Central North Dakota, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet on North Dakota CarbonSAFE project. An Environmental & Energy Research Center-led project, under the U.S. Department of Energy’s CarbonSAFE Initiative, it seeks to safely deploy safe and permanent CO₂ storage in North Dakota. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]

Quaternary Shelf-Slope Development In The Northern Gulf Of Alaska From Combined Geophysical And Geomorphologic Analysis, Wesley A. Clary

Earth and Planetary Sciences ETDs

This dissertation follows the hybrid format as defined by the Office of Graduate Studies at the University of New Mexico. The three chapters defined herein were prepared as manuscripts to be submitted for publication in peer reviewed journals in the field of Earth sciences. A version of chapter 1 was published in Proceedings of the Integrated Ocean Drilling Program, 2017, Volume 41. Chapter 2 was submitted to Marine Geology in Feb 2020, and is under revision as of this date. A version of chapter 3 will be submitted to the Journal of Geophysical Research. In chapter 1, I …

Core And Geophysical Analysis Of Biogenic Tufa Deposits In The Spring River In Northern Arkansas, Tyler W. Engelbart

Graduate Theses/Dissertations

The Spring River is fed by Mammoth Spring, a large spring on the Missouri-Arkansas border which produces roughly 240 million gallons of water per day (MGD). In this area there are deposits that appear as dams which cause water to pool upstream. Aerial analysis of the dams shows that there are approximately 100 of these features present in the first 45 miles downstream of Mammoth Spring. These deposits, known as tufa, are not uncommon in a karstic area of a spring fed river, but these are more frequent farther downriver than near the mouth of the spring. Preliminary mapping data …

Testing A Drone-Based Magnetic Field Surveying System, Erik Jacobson, Irina Filina

UCARE: Research Products

Aeromagnetic surveys are conducted by geoscientists to study subsurface geologic structures, such as faults. This type of survey uses a magnetometer mounted upon an airborne vehicle to collect magnetic field data. Magnetic anomalies are caused by variations in subsurface geology, namely in magnetic properties of subsurface rocks. Jacobson and Filina (2019) reported on the development of a new low cost drone, based magnetic field surveying system by the UNL Geophysics Team. This drone-based magnetic system is capable of collecting high resolution data at low speeds and low altitudes. The current study focuses on testing this system by conducting two flights …