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Full-Text Articles in Physical Sciences and Mathematics

Deformation And Evolution Of Achondrite Parent Bodies, Yaozhu Li Oct 2023

Deformation And Evolution Of Achondrite Parent Bodies, Yaozhu Li

Electronic Thesis and Dissertation Repository

Minerals in planetary bodies record accumulated strain from deformation events such as hypervelocity impacts but potentially also parent body processes such as gravitational compaction. This work investigates olivine microstructural features that may distinguish between different impact levels versus parent body plastic deformation regimes. Achondritic meteorites from the ureilite parent body, the Moon, Mars as well as terrestrial basalt and mantle xenolith have been investigated using micro-XRD, EBSD, micro-XRF and other methods to study their parent body deformation history. A Matlab® method, unit segment length (USL), is herein developed to visualize the crystal boundary geometry and quantify the apparent subboundary density …


Hydrochemistry Of An Alpine Karst System, Northern New Mexico: Las Huertas, Kambray A. Townsend Oct 2023

Hydrochemistry Of An Alpine Karst System, Northern New Mexico: Las Huertas, Kambray A. Townsend

Earth and Planetary Sciences ETDs

Las Huertas in the Sandia Mountains relies on snowmelt, monsoonal recharge, and groundwater inputs. Our hypothesis, the proportion of groundwater contribution varied spatially and temporally, was assessed by observing travertine and multiple geochemical tracers to differentiate water balance components. We report 26 samples from 13 locations (sampled between 2021-2023). Major ion and isotopic analysis indicated Las Huertas headsprings vary spatially. Capulin Spring has higher salinity; major ions suggest recharged waters are a mix of CaCO3-rich and sulfate-chloride-containing water. The proportion of groundwater to spring discharge is a mix of winter and summer precipitation. Travertine supersaturation is seasonal, with variations downstream, …


Seabed Reflection Coefficient Variability In The Mono Lake Using Seismic Reflection Sparker Data, Francis Nnamdi Okeifufe Oct 2023

Seabed Reflection Coefficient Variability In The Mono Lake Using Seismic Reflection Sparker Data, Francis Nnamdi Okeifufe

Earth Sciences Theses and Dissertations

Acoustic reflections from a lakebed provide valuable information about the dynamic boundary between water and the lakebed, where sediments and biota in the water column eventually settle. In this study, we present a comprehensive analysis of reflected sound wave amplitudes to gain insights into the physical properties of a water-sediment boundary. We decided to carry out this analysis within the unique ecosystem of the Mono Lake basin due to the fact that the Mono Lake, a meromictic and hypersaline waterbody is situated within one of the most active yet understudied volcanic regions in the United States. The fact that the …


Terrestrial Craters As Analogues For Degraded Craters On Titan, Taylor M. Duncan Aug 2023

Terrestrial Craters As Analogues For Degraded Craters On Titan, Taylor M. Duncan

Electronic Thesis and Dissertation Repository

Besides Earth, Titan is the only planetary body in our Solar System to currently have flowing liquid on its surface. Previous works note that dendritic and rectangular stream networks are present on a global scale on Titan, but do not map networks in the vicinity of Titan’s impact craters: Selk and Sinlap. The objective of this work is to understand how stream networks form adjacent to Titan’s impact craters. This information will inform future missions to Titan (i.e., Dragonfly) about the fluvial morphology of streams near their landing site. I conduct an analogue study with the stream networks at three …


Investigating Mercer's Paradox: A 10be Chronology Of Moraines Deposited During The Last Glaciation At Soda Lake, Wind River Range, Wyoming, U.S.A., Lauren M. Woods Aug 2023

Investigating Mercer's Paradox: A 10be Chronology Of Moraines Deposited During The Last Glaciation At Soda Lake, Wind River Range, Wyoming, U.S.A., Lauren M. Woods

Electronic Theses and Dissertations

Here I use geomorphic mapping and 10Be surface-exposure dating to address the paradox that lies within the general understanding of the mechanisms driving ice-age climate and glacial cycles. The long-standing and widely accepted Murphy-Milankovitch hypothesis suggests glacial cycles are controlled by the local intensity of summer-time insolation. By this hypothesis, glacier maxima should be achieved at times of low insolation intensity and asynchronously between the polar hemispheres, a pattern which is inconsistent with the glacial geomorphic record. The 10Be chronology I have constructed of moraines at Soda Lake, Wind River Range, Wyoming, U.S.A. shows nine glacial advances to …


Applications Of Observational Seismology: Insights Into Volcanic And Near Surface Processes, Justin T. Wilgus Aug 2023

Applications Of Observational Seismology: Insights Into Volcanic And Near Surface Processes, Justin T. Wilgus

Earth and Planetary Sciences ETDs

The field of observational seismology has made tremendous progress in the past two decades. This progress has been multi-faceted in form, but significant contributions emanated from 1) increases in both the quality and the quantity of seismic data 2) advances in computational power 3) advances in algorithmic capability, including machine learning. In this dissertation I report on three distinctly different seismic applications made possible by the aforementioned progress and discuss the insights these applications have provided in understanding volcanic and near surface processes of the Earth.

In the first chapter titled, “Shear Velocity Evidence of Upper Crustal Magma Storage Beneath …


Towards Automated Mineral Identification In Martian Rocks From X-Ray Diffraction Patterns, Luke Tambakis Aug 2023

Towards Automated Mineral Identification In Martian Rocks From X-Ray Diffraction Patterns, Luke Tambakis

Electronic Thesis and Dissertation Repository

The CheMin (Chemistry and Mineralogy) instrument on the Curiosity rover has provided a rich set of X-ray diffraction (XRD) patterns from Martian rocks and regolith. These XRD patterns have allowed geologists to make exciting new discoveries about the mineralogy and the geological history of Mars. These discoveries pave the way for further Martian exploration and provide a deeper understanding of Martian geology. The Curiosity rover is very slow by design, travelling at about 4 cm/s. New, faster rovers are being developed to increase scientific throughput and exploration. XRD is valuable for future missions as it can produce new discov- eries …


Architecture Of Extraction: Imagining New Modes Of Inhabitation And Reclamation In The Mining Lifecyle, Erica Dewitt Aug 2023

Architecture Of Extraction: Imagining New Modes Of Inhabitation And Reclamation In The Mining Lifecyle, Erica Dewitt

Masters Theses

Mining is the primary method through which modern society obtains the minerals needed to fuel the global economy, provide for modern energy requirements, and support the built environment. Presently, mining accounts for nearly 1% of the global ice-free land surface, with a dramatic increase anticipated in the coming decades. Mining permanently changes and often destroys the pre-existing topography, hydrology, and ecology of the ground, and efforts to reclaim mining landscapes—with the aim of encouraging reforestation and soil replenishment—are often unsuccessful, rendering the land of abandoned mines both unusable and uninhabitable.

This thesis addresses the current state of mining in the …


Seismic Shadow Zone Investigation In The Upper Magma Reservoir Of The Yellowstone Caldera, Sarah Nolt-Caraway Aug 2023

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 …


Seismic Analysis Of The Upper & Lower Falls Of The Yellowstone River, Loring Schaible Aug 2023

Seismic Analysis Of The Upper & Lower Falls Of The Yellowstone River, Loring Schaible

Earth and Planetary Sciences ETDs

Twelve years of concurrent hydrologic and continuous seismic data along with temporary seismic data demonstrate that the Upper and Lower Falls of the Grand Canyon of the Yellowstone River comprise a highly localized source of 0.5-5 Hz seismic energy that overwhelms anthropogenic contributions. In aggregate, seismic amplitude from 2008-2019 is linearly related to discharge with a correlation coefficient of 0.96. Repeated deviations from this linear relationship persist for 1-2 weeks prior to the date that Yellowstone Lake becomes clear of winter ice coverage. Seismic efficiency increases by ~50-250% during this period of ice-breakup, during which lake ice flows into the …


Growth Of Purple Sulfur Bacteria Allochromatium Vinosum On Solid Phase Metal Sulfides As Sulfur And Electron Sources, Hugo Alarcon Aug 2023

Growth Of Purple Sulfur Bacteria Allochromatium Vinosum On Solid Phase Metal Sulfides As Sulfur And Electron Sources, Hugo Alarcon

Open Access Theses & Dissertations

Purple sulfur bacteria (PSB) are photosynthetic microorganisms known for their vital roles in geochemical cycles, especially the sulfur cycle, within anoxic photic environments. PSB are also key contributors to the nitrogen, carbon, and oxygen cycles. This study focuses on the autotrophic growth of Allochromatium vinosum, a model strain of PSB, that utilize solid-phase metal sulfides (MS) as both sulfur and electron donors. Through characterizing the growth profiles of A. vinosum on pyrite (FeS2), nickel sulfide (NiS), and iron monosulfide (FeS) nanoparticles, respectively, and investigating the bacteria-MS interaction mechanisms, this work expands our current knowledge of the metabolic capabilities and flexibility …


High-Energy Storm Events And Their Impacts On Carbon Storage In Tidal Wetlands Of South Carolina, Gavin Gleasman Aug 2023

High-Energy Storm Events And Their Impacts On Carbon Storage In Tidal Wetlands Of South Carolina, Gavin Gleasman

All Dissertations

Atmospheric carbon dioxide (CO2) concentrations have been increasing at an accelerating rate for the past two centuries, profoundly impacting global climate change. Atmospheric CO2 concentrations are influenced by the global carbon cycle through physical and biogeochemical pathways. Tidal wetland environments play a vital role in the global carbon cycle by offsetting atmospheric CO2 concentrations through their natural physiochemical processes of high autotrophic productivity, allochthonous organic matter deposition, anoxic soils, and continuous accretion which promotes carbon sequestration with long-term storage at the land-ocean margin. The Intergovernmental Panel on Climate Change (IPCC) and United States Global Change Research …


Quantifying The Contribution Of Atmospheric And Land Surface Characteristics To The Prediction Of Sub-Pixel Scale Surface Soil Moisture In The Jornada Experimental Range Through Interpretable Machine Learning, Stephanie Nicole Marquez Aug 2023

Quantifying The Contribution Of Atmospheric And Land Surface Characteristics To The Prediction Of Sub-Pixel Scale Surface Soil Moisture In The Jornada Experimental Range Through Interpretable Machine Learning, Stephanie Nicole Marquez

Open Access Theses & Dissertations

This study presents machine learning-based approaches for understanding and predicting plot-scale soil moisture's spatial variability using hydrometeorological and biogeophysical data from in-situ, multi-sensor and remote sensing sources. The high-resolution input features include numerical and categorical data such as land surface temperature, ground albedo, 1-day, 1-week and 2-week antecedent precipitation, soil type, land cover type, distance to nearest vegetation individual, terrain slope and elevation, and normalized differenced vegetation index (NDVI). Soil moisture measurements are collected within a 3 km x 3 km desert grid with Campbell Scientific Hydrosense II-12 soil moisture sensors and validated with a gravimetric method of measuring volumetric …


Paradox Diapir Inclusions As A Window Into Diapiric Processes In Proximity To The Uncompahgre Uplift And The Early History Of The Paradox Basin, Utah And Colorado, Madison Clare Woelfel Aug 2023

Paradox Diapir Inclusions As A Window Into Diapiric Processes In Proximity To The Uncompahgre Uplift And The Early History Of The Paradox Basin, Utah And Colorado, Madison Clare Woelfel

Open Access Theses & Dissertations

Layered evaporite sequences, cyclic, kilometer-thick deposits of salt, are among the most unusual and fascinating lithologies that geologists encounter. There is no recent analogue to their formation, and their ability to flow when subject to differential pressure makes them unique. Salt structures serve as sources for halite, bittern salts, metals, and hydrocarbons and can be used for storage of materials, including hydrocarbons, carbon dioxide, hydrogen, and nuclear waste. Basins in which layered evaporite sequences are deposited receive detrital input sporadically from adjacent areas, depositing inclusions of non-evaporite lithologies that are entrained when salt flows. These inclusions are exposed in a …


Evaluating The Feasibility Of Using Strain Measured During Sinusoidal Rate Pumping Tests To Characterize An Aquifer, Riley Blais Aug 2023

Evaluating The Feasibility Of Using Strain Measured During Sinusoidal Rate Pumping Tests To Characterize An Aquifer, Riley Blais

All Theses

Pumping tests with sinusoidal variation in pumping rate have been proposed as a method for improving aquifer characterization. These tests can interrogate a larger aquifer volume than slug tests and they can be more sensitive to small variations in drawdown. Current methods of using sinusoidal variations of rate are based on measuring pressure signals from the reservoir or aquifer, which requires access to monitoring wells. An alternative approach has been developed that measures the strain in the vadose zone instead of pressure in the reservoir. An instrument has been developed at Clemson University that can measure small strains using optical …


Origin Of The Mega-Streamlined Morphology In Ne Africa And Arabia: Remote Sensing And Field-Based Investigations, Mohamed Samy Mohamed Elhebery Aug 2023

Origin Of The Mega-Streamlined Morphology In Ne Africa And Arabia: Remote Sensing And Field-Based Investigations, Mohamed Samy Mohamed Elhebery

Dissertations

Mega-streamlined landforms on Earth and Mars have been attributed to aeolian, glaciogenic, fluvial, and tectonic processes. Identifying the forces that shaped these landforms is paramount for understanding landscape evolution and constraining paleo-climate models and ice sheet reconstructions. Exhumed Late Ordovician glacial deposits and landscape of the North Gondwana are reported here for the first time from SE Egypt. Using field and remote sensing (Advanced Land Observing Satellite [ALOS], Phased Array L-band Synthetic Aperture Radar (PALSAR) radar, multispectral Landsat TM datasets, and digital elevation models (DEMs) I mapped the distribution of the Late Ordovician glacial features (i.e. deposits and landforms) in …


Reservoir Characterization Of The Utica Shale Play Using Well Log Data In Columbiana, Ohio, Tyler L. West Aug 2023

Reservoir Characterization Of The Utica Shale Play Using Well Log Data In Columbiana, Ohio, Tyler L. West

Electronic Theses and Dissertations

The Ordovician Utica shale play is rapidly developing throughout the Appalachian Basin. The play is a mixed carbonate-siliciclastic system that grades from primarily carbonates at its base in the Lexington/Trenton limestones into primarily shale within the Utica shale. As of January 2021, it is the third highest-producing dry shale gas play in the contiguous U.S., although it is known to produce wet gas and oil in various parts of the basin. In addition to being an unconventional reservoir, the Utica shale, an informal unit in Ohio where the main fairway is located, is a known source rock for much of …


Measurement Of Microplastics In A Freshwater Micro-Watershed, Cole Bowman Aug 2023

Measurement Of Microplastics In A Freshwater Micro-Watershed, Cole Bowman

All Theses

The role of microplastics as an emerging contaminant can be complex to study because of the lack of standardization in the collection and analysis of microplastic particles. The purpose of this manuscript is to detail an iterative process of different collection methods in trying to understand microplastic deposition and transport in a freshwater micro-watershed through lab-based and field-based studies. A flume experiment was conducted to test the trapping efficiency of a sediment trap design at two different velocities (1.12 m/s and 2.24 m/s). Eight types of microplastics varying in morphology and density were introduced to the flume in order to …


Structural And Kinematic Investigation Of The Dadeville Complex-Brevard Zone Contact (Southern Appalachians): Polyphase Emplacement Of An Allochthonous Terrane On The Laurentian Margin, Andrew Williams Aug 2023

Structural And Kinematic Investigation Of The Dadeville Complex-Brevard Zone Contact (Southern Appalachians): Polyphase Emplacement Of An Allochthonous Terrane On The Laurentian Margin, Andrew Williams

Master's Theses

The Dadeville Complex (DC) lies in the Inner Piedmont of eastern Alabama and western Georgia. The DC formed as a volcanic island arc during the Taconic orogeny (Ordovician Period) and was accreted onto Laurentia during the Acadian orogeny (Devonian-Mississippian Periods); however, the mechanism and role of accretion during the Acadian orogeny is not well constrained. Three proposed emplacement mechanisms for the DC include: (1) orogen-perpendicular translation; (2) orogen-parallel translation; (3) orogenic channel flow.

Today, the DC is a major (over 100 kilometers long) allochthonous terrane composed mostly of meta-igneous rocks. This study investigated structural fabrics and kinematic indicators in the …


Volatile Cycling And Metasomatism In Flat-Slab Subduction Zones Of The Central Andes, Coleman Hiett Aug 2023

Volatile Cycling And Metasomatism In Flat-Slab Subduction Zones Of The Central Andes, Coleman Hiett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Flat-slab subduction, where an oceanic plate subducts horizontally below a continental margin for hundreds of kilometers, is an enigmatic but prevalent tectonic configuration in which chemical cycling and alteration of the continental plate is poorly constrained. Geochemical investigations in regions of modern and ancient flat-slab subduction in the Central Andes afford an opportunity to study this process. Certain elements naturally occur with varying number of neutrons in their nuclei (isotopes), and measurements of isotope ratios within geologic materials inform on chemical sources and geologic processes. This research leverages stable isotope analyses and other geochemical tools to investigate volatiles and other …


Constraining High Temperature Deformation And Metamorphism In The Southern Wet Mountains, Colorado, Usa: Implications For The Regional Extent Of The Picuris Orogeny, Sarah Morse Aug 2023

Constraining High Temperature Deformation And Metamorphism In The Southern Wet Mountains, Colorado, Usa: Implications For The Regional Extent Of The Picuris Orogeny, Sarah Morse

Graduate Theses and Dissertations

The Wet Mountains of Colorado are underlain by exhumed Proterozoic metamorphic rock that lies north of the recently identified 1.46 to 1.40 Ga Picuris orogen in northern New Mexico. The Picuris orogen is inferred to have formed in response to a Mesoproterozoic (ca. 1.49-1.40 Ga) contractional to transpressional event extrapolated to be regional in extent. It has been proposed that the Picuris orogen composes the westernmost tectonic segment of the Pinware-Baraboo-Picuris orogen that formed along an evolving convergent margin that becomes younger from northeast to southwest. This study is focused on the record of high temperature deformation, metamorphism, and plutonism …


Numerical And Experimental Constraints On Trace Element Fractionation During Lunar Magma Ocean Solidification, Dian Ji Aug 2023

Numerical And Experimental Constraints On Trace Element Fractionation During Lunar Magma Ocean Solidification, Dian Ji

Masters Theses

Traditional lunar magma ocean (LMO) theory suggests the anorthositic lunar crust formed by floating of buoyant plagioclase, one of the major products of LMO solidification, on the surface of LMO. To test this model, after applying experimentally determined LMO solidification sequences, we compared calculated Rare Earth Element (REE) concentrations of lunar plagioclase to plagioclase in Apollo ferroan anorthosites and lunar anorthositic meteorites. Several initial LMO compositions, and lunar-relevant mineral-melt partition coefficient predictive models were tested (where the partition coefficient is the concentration ratio of a specific element between two phases). Compared with plagioclase in the natural samples, modeled plagioclase directly …


Chemostratigraphic And Paleoclimatic Studies Of Cloverly Formation, Northern Wyoming, U.S.A, Queen Amarachi Kalu Aug 2023

Chemostratigraphic And Paleoclimatic Studies Of Cloverly Formation, Northern Wyoming, U.S.A, Queen Amarachi Kalu

Graduate Theses and Dissertations

The Early – Late Cretaceous transition in Western North America recorded a period of rapid climatic and tectonic change in Earth’s history. Major climate events associated with large igneous province eruptions caused several instances of ocean anoxic events (OAE) and perturbations to the global carbon (C) – cycle. These perturbations to the global C-cycle are observed in the bulk organic C record of both marine and terrestrial deposits and can be used to correlate units across major depositional basins. Major efforts are being made to generate time-constrained palaeontologic and paleoclimate information from the North American Cordilleran foreland basin and C-isotope …


Lidar Monitoring Of Annual And Storm-Driven Episodic Erosion At Rainsford Island, Alan H. Bartels Aug 2023

Lidar Monitoring Of Annual And Storm-Driven Episodic Erosion At Rainsford Island, Alan H. Bartels

Graduate Masters Theses

Boston Harbor and its thirty-four islands are subject to erosion, driven by rain, winds, and waves. Climate change threatens to increase erosion over time as sea levels rise and the frequency and intensity of storms increase. Understanding the dynamics of coastal erosion is key to guiding the design of coastal shoreline protections, the research of which a goal of Stone Living Laboratory at the University of Massachusetts Boston. To better understand the impact of both annual weather and episodic severe storms, the high-resolution Riegl VZ400i LiDAR was deployed four times over 14 months from July 22, 2021 to October 19, …


A Hybrid Lateral Flow Sand Filter Wastewater Treatment System: An Evaluation On The Treatment And Disposal Capabilities Of A Modified Sand Filter, Harry Mccaskill Iv Aug 2023

A Hybrid Lateral Flow Sand Filter Wastewater Treatment System: An Evaluation On The Treatment And Disposal Capabilities Of A Modified Sand Filter, Harry Mccaskill Iv

<strong> Theses and Dissertations </strong>

Decentralized wastewater treatment exists primarily in suburban and rural areas where centralized treatment is not an option. Traditional on-site treatment systems usually include the use of a septic tank and a drain field. This orthodox method works well when implemented into environments that are accommodating for the infiltration of effluents, and thus allowing for soil treatment. Unfortunately, there are some circumstances that prevent traditional systems from working such as impermeable soil conditions. The Wastewater Treatment System analyzed in this thesis was created to overcome such inhospitable environments. More specifically, this system is catered towards the rural residences of The Alabama …


History Of Ice-Rafting In The Arctic Ocean During Glacial Maxima Through Marine Isotope Stage 6, Shannon M. Cofield Aug 2023

History Of Ice-Rafting In The Arctic Ocean During Glacial Maxima Through Marine Isotope Stage 6, Shannon M. Cofield

OES Theses and Dissertations

Numerous studies attempted to reconstruct Arctic paleoclimate, specifically ice mass timing and locations, during glacial maxima. While some regions, like the Barents-Svalbard Ice Sheet (BSIS) are well-studied, they may benefit from a high-resolution paleo proxy. Other regions are highly contested, such as the East Siberian Sea or the presence of a central Arctic Ocean ice mass.

This research uses an Fe-grain provenance method to (1) define how the BSIS behaved during Marine Isotope Stage (MIS) 2, 4, and 6, and when it retreated; (2) determine the presence and ages of Shelf Ice Masses (SIMs) in the Beaufort Sea and East …


Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen Jul 2023

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen

Dissertations and Theses

Volcanic glass has been used extensively as a paleoclimate proxy. Deuterium (2H) concentrations in glass have been found to be stable over geologic timescales, making δD a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in ash. Here, I analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ashflow tuff, and create an isoscape to assess variations in δD across Oregon during that time. Additionally, I examine compositional data from glass shards to explore the relationship between δD and shard composition. The RST exhibits well defined …


Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar Jul 2023

Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar

Earth and Planetary Sciences ETDs

The complex vertebrate ecosystem of the Late Triassic has not yet been fully understood, largely due to oversimplification of hypothesized trophic hierarchies and limited preservation of direct evidence of faunal interaction. Paleocommunity reconstruction attempts can also fall victim to taphonomic biases, time-averaging inaccuracies, and non-analogue paleoecologies. Utilizing a combination of PAIRS analysis and NMDS ordination, we highlight vertebrate faunal relationships within the Adamanian and Revueltian faunachrons of Petrified Forest National Park, assess the likelihood that these patterns have ecological rather than preservational drivers, and examine how these potential interactions may have been impacted by the Adamanian-Revueltian turnover event. We are …


Polygonal Faults In The Austin Chalk: Invariance Of Scale From Mud Cracks To Polygons With Implications Of Structural, Geomorphic And Isotopic Data On Polygonal Fault Geometry And Origin., Kun Shang Jul 2023

Polygonal Faults In The Austin Chalk: Invariance Of Scale From Mud Cracks To Polygons With Implications Of Structural, Geomorphic And Isotopic Data On Polygonal Fault Geometry And Origin., Kun Shang

Earth Sciences Theses and Dissertations

The Cretaceous Austin Chalk contains large numbers of fractures and normal faults whose orientations have been attributed to either regional stresses (e.g., the Balcones fault trend) or, by analogy with the mudrocks, to polygonal faulting resulting from compaction. In this study, we present geomorphic data, field study, and stable isotope data to support that the majority of these faults in North Texas are polygonal. Field-measured fault orientations suggest randomly distributed fault strikes, indicating a polygonal fault structure. Using geomorphologic data (topographic and DEM data) on stream orientations suggests that the polygonal fault patterns are best reflected in the headwater (1st …


Hf Radar: Shining A Light On Ocean Currents, Douglas Cahl Jul 2023

Hf Radar: Shining A Light On Ocean Currents, Douglas Cahl

Theses and Dissertations

High Frequency (HF) radar systems are commonly used to estimate surface ocean currents over the coastal ocean. Their range depends on their operational frequency and low frequency systems (≤ 10 MHz) can reach distances up to 200 km from the coastline. These systems are used to estimate surface currents by measuring the phase speed of wind-driven waves and comparing the measured speed with that expected theoretically; deviations from the theoretical still-water phase speed are attributed to ocean surface currents. Although HF radar systems are considered a mature technology and the accuracy of the radar-derived surface current estimates is well studied, …