Open Access. Powered by Scholars. Published by Universities.®

Geology Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 1861 - 1890 of 29999

Full-Text Articles in Geology

Wetlands In The Nebraska Sandhills, Nawaraj Shrestha Jan 2024

Wetlands In The Nebraska Sandhills, Nawaraj Shrestha

Conservation and Survey Division: Faculty and Staff Publications

Infographic titled “Status of Wetlands in the Nebraska Sandhills” showing multiple maps and charts. The top left features a color-coded wetland persistence map where blue indicates more consistent wetlands and red indicates intermittent wetlands. Additional inset maps show a regional zoom and a U.S. location map highlighting Nebraska. A large scatter plot displays wetland occurrence percentages over time using MODIS (green points) and Sentinel (blue points) satellite data from 2000 to 2024. Text explains how wetlands vary seasonally and annually and how satellite imagery tracks these changes. A smaller bottom chart shows long-term wetland trends, noting increasing occurrence since 1984. …

Go to article

Integration Of 3d Structural Modelling And Well Logging Analysis In The Evaluation Of October Oil Field, Gulf Of Suez, Egypt, Lamiaa Yahia, Mostafa Toni, Farouk I. Metwalli, M. H. Mansour, Amir Ismail Jan 2024

Integration Of 3d Structural Modelling And Well Logging Analysis In The Evaluation Of October Oil Field, Gulf Of Suez, Egypt, Lamiaa Yahia, Mostafa Toni, Farouk I. Metwalli, M. H. Mansour, Amir Ismail

Trends in advanced sciences and technology

An extensive study of the NUBIA and MAT reservoirs, incorporating numerous data sources, enhances the accuracy of production forecasts for hydrocarbon exploration and development. This study aims to integrate seismic and well data for re-assessment and to delineate the geological and petrophysical characteristics of the October oil field which is one of the most productive in the central Gulf of Suez, but it has recently witnessed a drop in output in some regions, and some wells have begun to depletion. While facies modeling enabled the spatial distribution of lithologic facies inside the constructed 3D structural model, which reflected two types …

Go to article

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

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

Williams Honors College, Honors Research Projects

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

Go to article

Coupling-Informed Data-Driven Scheme For Joint Angle And Frequency Estimation In Uniform Linear Array With Mutual Coupling Present, Yanming Zhang, Wenchao Xu, A. Long Jin, Min Li, Peifeng Ma, Lijun Jiang, Steven Gao Jan 2024

Coupling-Informed Data-Driven Scheme For Joint Angle And Frequency Estimation In Uniform Linear Array With Mutual Coupling Present, Yanming Zhang, Wenchao Xu, A. Long Jin, Min Li, Peifeng Ma, Lijun Jiang, Steven Gao

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel coupling-informed data-driven algorithm tailored for the concurrent estimation of frequency and angle within a uniform linear array (ULA), while addressing the complicating influence of mutual coupling. Leveraging the hybrid dynamic mode decomposition (DMD) methodology, termed as averaged DMD, we incorporate moving average techniques to achieve effective denoising. The averaged DMD further decomposes the received signal into eigenvalues and corresponding eigenvectors. The frequency information is derived from the eigenvalues and the corresponding eigenvectors represent the steering vectors of sources. Subsequently, mutual coupling is informed into the calibration of the steering vector for each source. Specifically, the …

Go to article

A Tensor-Based Data-Driven Approach For Multidimensional Harmonic Retrieval And Its Application For Mimo Channel Sounding., Yanming Zhang, Wenchao Xu, A. Long Jin, Min Li, Ping Yuan, Lijun Jiang, Steven Gao Jan 2024

A Tensor-Based Data-Driven Approach For Multidimensional Harmonic Retrieval And Its Application For Mimo Channel Sounding., Yanming Zhang, Wenchao Xu, A. Long Jin, Min Li, Ping Yuan, Lijun Jiang, Steven Gao

Electrical and Computer Engineering Faculty Research & Creative Works

In wireless channel sounding, accurately estimating multiple parameters within a multipath signal, such as azimuth, elevation, Doppler shift, and delay, necessitates addressing the challenges posed by the multidimensional harmonic retrieval (MHR) problem. To overcome these complexities, we propose a framework based on high-order dynamic mode decomposition (HODMD) that designed for robustly estimating frequencies of interest from high-dimensional sinusoidal signals, particularly in additive white Gaussian noise conditions. The HODMD approach, a hybrid algorithm amalgamating high-order singular value decomposition (HOSVD) and dynamic mode decomposition (DMD), operates by initially decomposing observed tensorial data into a core tensor and R mode matrices through HOSVD. …

Go to article

Experimental Investigation Of High-Temperature Brine-Shale Interactions, Anna Atasha Hoffmann Jan 2024

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 …

Go to article

Storm-Generated Molluscan Thanatocoenosis Along A Carbonate Paleoshoreline: Southern Eleuthera Island, The Bahamas, Ilya Val Buynevich, Michael Savarese, H. Allen Curran, Tara Ingalsbe Jan 2024

Storm-Generated Molluscan Thanatocoenosis Along A Carbonate Paleoshoreline: Southern Eleuthera Island, The Bahamas, Ilya Val Buynevich, Michael Savarese, H. Allen Curran, Tara Ingalsbe

Geosciences: Faculty Publications

Concentrations of large mollusc shells in coastal deposits provide important information about the local malacofauna and potential transport agents, including extreme events [1-4]. Such accumulations are common in the rock record [5,6], with Quaternary examples serving as good time-averaged examples by combining aspects of both the modern biocoenoses and the fossil record. Death assemblages of local organisms (thanatocoenosis) and their preserved record (taphocoenosis) in carbonate settings, where granulometric spectrum may be very limited (e.g., ooilitic sand), can serve as important paleo-environmental indicators, especially when considered in combination with primary sedimentary structures (in outcrops or geophysical images) and in situ biogenic …

Go to article

A New Method To Invert For Interseismic Deep Slip Along Closely Spaced Faults Using Surface Velocities And Subsurface Stressing-Rate Tensors, Hanna Elston, Michele Cooke, John Loveless, Scott Marshall Jan 2024

A New Method To Invert For Interseismic Deep Slip Along Closely Spaced Faults Using Surface Velocities And Subsurface Stressing-Rate Tensors, Hanna Elston, Michele Cooke, John Loveless, Scott Marshall

Geosciences: Faculty Publications

Inversions of interseismic geodetic surface velocities often cannot uniquely resolve the three-dimensional slip-rate distribution along closely spaced faults. Microseismic focal mechanisms reveal stress information at depth and may provide additional constraints for inversions that estimate slip rates. Here, we present a new inverse approach that utilizes both surface velocities and subsurface stressing-rate tensors to constrain interseismic slip rates and activity of closely spaced faults. We assess the ability of the inverse approach to recover slip rate distributions from stressing-rate tensors and surface velocities generated by two forward models: (a) a single strike-slip fault model and (b) a complex southern San …

Go to article

Diagenesis And Quartz Grain Provenance Of The Turner Sandstone, Carson Lee Broaddus Jan 2024

Diagenesis And Quartz Grain Provenance Of The Turner Sandstone, Carson Lee Broaddus

Graduate Student Theses, Dissertations, & Professional Papers

Provenance analysis of sedimentary rocks is an essential tool for basin analysis and paleogeographic reconstructions. Numerous tools and analytical methods have been developed over the years to investigate the source of detrital constituents in sedimentary rocks. The Late Cretaceous (Turonian) Turner Sandstone in the eastern Powder River Basin (PRB), WY, and the time equivalent Frontier Formation in the western PRB are commonly described as the remnants of a marginal marine depositional system. However, contradictory evidence exists about the source of those deposits. Here, I present results from a comprehensive scanning electron microscope panchromatic cathodoluminescence (SEM-PCL) analysis of >1200 individual sand-sized …

Go to article

Paragenesis Of The Austin Chalk Formation In Southwest Texas, Mitchell C. Sherry Jan 2024

Paragenesis Of The Austin Chalk Formation In Southwest Texas, Mitchell C. Sherry

Graduate Student Theses, Dissertations, & Professional Papers

Presented in this study is a detailed investigation of the paragenesis and diagenetic processes of the Austin Chalk Formation in southwest Texas, utilizing a combination of core-based, petrographic, mineralogic, SEM, and geochemical based analyses. This study is conducted on a single whole rock core from an oil and gas producing well in Webb County, Texas. At this distal shelf location within the Maverick Basin, the Austin Chalk Formation consists of foraminiferal wackestones, siliceous wackestones, foraminiferal mudstones, bentonites, and foraminiferal packstone facies. These facies were deposited below wave base through pelagic, hemipelagic, and gravity driven processes. Petrographic and SEM analyses reveal …

Go to article

Investigating The Relationship Between Inherited Geologic Framework And Saltwater Intrusion On St. Catherines Island, Georgia, Juliet Talaber, Jacque Kelly, Robert Vance Jan 2024

Investigating The Relationship Between Inherited Geologic Framework And Saltwater Intrusion On St. Catherines Island, Georgia, Juliet Talaber, Jacque Kelly, Robert Vance

Honors College Theses

Since the late 1800s, the oldest cities on the Georgia coast have been withdrawing water from the confined Floridan Aquifer System. As the population has grown, a cone of depression has formed extending from Savannah, GA to St. Catherines Island, GA, a barrier island 50 km southeast of Savannah. On St. Catherines Island, the cone of depression has reversed the lateral and horizontal groundwater flow gradients causing saltwater intrusion into the Upper Floridan Aquifer from the Lower Floridan Aquifer through joints, faults, or solution collapse features. Previous studies from the southern and central areas of the island have found evidence …

Go to article

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

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

Geosciences Faculty Publications and Presentations

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

Go to article

(Non-) Recovery Of An Agricultural Stream From Straightening And Dredging, Aras Anderson Mann Jan 2024

(Non-) Recovery Of An Agricultural Stream From Straightening And Dredging, Aras Anderson Mann

Graduate Theses, Dissertations, and Problem Reports (ETD)

In recent history, natural, meandering streams have been straightened and dredged to reduce flooding. While this practice can be effective in reducing flooding locally, it often results in the degradation of stream water quality and aquatic ecosystems. A straighter channel inherently increases the stream gradient, which could increase flow velocity, shear stress, and potentially downstream sediment yield. Studies have shown that straightened, channelized streams often begin to return to a meandering pattern 35-50 years post-channelization. Yet cross-sectional surveys and air photo analysis of the stream reach in this study, Deckers Creek, indicate little to no observable trend of the stream …

Go to article

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

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

Graduate Theses, Dissertations, and Problem Reports (ETD)

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

Go to article

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

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

Graduate Theses/Dissertations

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

Go to article

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

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

Graduate Theses/Dissertations

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

Go to article

Thermochronology And Exhumation Dynamics Of Metamorphic Units In The Salmon River Suture Zone, Jonathan J. Cone Jan 2024

Thermochronology And Exhumation Dynamics Of Metamorphic Units In The Salmon River Suture Zone, Jonathan J. Cone

Graduate Theses/Dissertations

The Salmon River suture zone in western Idaho records the Jurassic-Cretaceous (160-90 Ma) accretion of amalgamated volcanic arc terranes onto the North American continent. Rocks exposed at the surface record burial to depths of more than 20 kilometers, with unclear drivers for uplift and exhumation. Two competing hypotheses have been proposed to explain the transport of deep crustal rocks to the surface: (1) delamination of a dense lithospheric root resulted in rapid isostatic uplift of the crust and (2) exhumation of crustal blocks along thrust faults. To test these models, I present temperature-time (T-t) paths for mid-crustal metamorphic rocks constructed …

Go to article

Geology Of The Bishop 7.5-Minute Quadrangle And Geophysical Modeling To Constrain Syndepositional Deformation Of The Black Warrior Foreland Basin, Joseph Edward Lane Jan 2024

Geology Of The Bishop 7.5-Minute Quadrangle And Geophysical Modeling To Constrain Syndepositional Deformation Of The Black Warrior Foreland Basin, Joseph Edward Lane

Graduate Theses/Dissertations

The Black Warrior basin is a foreland basin formed by the Ouachita–Appalachian orogeny during the late Paleozoic Era. Mississippian strata record the transition from the carbonate platform within the Tuscumbia Limestone to the clastic-rich units within the overlying Pride Mountain Formation and Hartselle Sandstone. The western and southern-most fringes of the Black Warrior basin are covered by thin, post orogenic Cretaceous sediments of the East Gulf Coastal Plain. Geological mapping of the Bishop 7.5-Minute quadrangle revealed subtle deformation in Mississippian strata in the form of gentle folds (

Go to article

Beach Erosion And Recovery Since Hurricane Ivan In 2004 Along A Headland-Bay Coast In Treasure Beach, Jamaica, Elandé Engelbrecht Jan 2024

Beach Erosion And Recovery Since Hurricane Ivan In 2004 Along A Headland-Bay Coast In Treasure Beach, Jamaica, Elandé Engelbrecht

Graduate Theses/Dissertations

Anthropogenic climate change is causing sea-level rise and shoreline changes that threaten the environment and economy of coastal communities in Caribbean Island nations. To assess this risk, this study quantifies shoreline changes at Treasure Beach in St. Elizabeth Parish on the south coast of Jamaica from 2001 to 2023. The effects of storm events on erosion were also assessed. Over 10 km of shoreline are assessed with about half being sandy pocket beaches ranging from 300 to 900 m in length, separated by rocky headlands and beach rock outcrops. Sand beach erosion trends since 2001 are assessed for seven sandy …

Go to article

Origin Of Carbonate Mud Mounds In Southwestern Missouri, Jared Mcavoy Jan 2024

Origin Of Carbonate Mud Mounds In Southwestern Missouri, Jared Mcavoy

Graduate Theses/Dissertations

Small carbonate mud mounds are found in Lower Mississippian strata of southwestern Missouri. These compare favorably with larger mounds, known as Waulsortian mounds, located in the Meuse River valley of southern Belgium. The origin of Waulsortian and similar mounds is unknown, but they commonly are interpreted as accumulations of mud, where the presence of biological organisms responsible for supposed bio-construction remains uncertain. Alternative hypotheses are that these may have been non-cohesive slump or cohesive slide masses. Multiple techniques, including δ13C and δ18O isotopic analyses and unmanned aerial vehicle photography, were used to determine the most feasible working hypothesis. Determining the …

Go to article

The Magmatic Origin Of The Columbia River Gorge, Usa, Nathaniel Klema, Leif Karlstrom, Charles Cannon, Chengxin Jiang, Jim O'Connor, Ray E. Wells, Brandon Schmandt Dec 2023

The Magmatic Origin Of The Columbia River Gorge, Usa, Nathaniel Klema, Leif Karlstrom, Charles Cannon, Chengxin Jiang, Jim O'Connor, Ray E. Wells, Brandon Schmandt

Geology Faculty Publications and Presentations

Along subduction zones, high-relief topography is associated with sustained volcanism parallel to the plate margin. However, the relationship between magmatism and mountain building in arcs is poorly understood. Here, we study patterns of surface deformation and correlated fluvial knickpoints in the Columbia River Gorge to link long-term magmatism to the uplift and ensuing topographic development of the Cascade Range. An upwarped paleochannel exposed in the walls of the Gorge constrains unsteady deep magma flux, the ratio of intrusive to extrusive magmatic contributions to topography, and the impact of magmatism on Columbia River incision since 3.5 million years ago. Geophysical data …

Go to article

Zagamiite, Caal2si3.5o11, The Hexagonal High-Pressure Cas Phase With Dominant Si, As A Mineral From Mars, Chi Ma, Oliver Tschauner, John R. Beckett, Eran Greenberg, Vitali B. Prakapenka Dec 2023

Zagamiite, Caal2si3.5o11, The Hexagonal High-Pressure Cas Phase With Dominant Si, As A Mineral From Mars, Chi Ma, Oliver Tschauner, John R. Beckett, Eran Greenberg, Vitali B. Prakapenka

Geoscience Faculty Research

Within the Ca-Al-silicate system, dense, layered hexagonal phases occur at high temperatures and pressures between 20 and 23 GPa. They have been observed both in nature and in experiments. In this study, we describe the endmember with a dominant sixfold coordinated Si as a mineral zagamiite (IMA 2015-022a). This new mineral identified in Martian meteorites has a general formula of (Ca,Na)(Al,Fe,Mg)2(Si,Al,□)4O11, thus defining CaAl2Si3.5O11 as a previously unknown endmember of the hexagonal CAS phases. Zagamiite assumes space group P63/mmc with a unit cell of a = 5.403(2) Å, c = 12.77(3) Å, V = 322.9(11) Å3, and Z = 2. …

Go to article

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

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

International Journal of Speleology

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

Go to article

Studi Alimentari Italiani E Geologia: Vino E Vulcani Da Diverse Prospettive, Maria Varriale Gomez Dec 2023

Studi Alimentari Italiani E Geologia: Vino E Vulcani Da Diverse Prospettive, Maria Varriale Gomez

Italian Renaissance Foodways

Nel mio progetto di integrazione avanzata, mi impegnerò in un'esplorazione interdisciplinare del vino. Analizzerò il vino utilizzando gli studi alimentari italiani e la geologia, concentrandomi in particolare sugli effetti che i vulcani hanno avuto sul vino in Italia sin dal Medioevo e dal Rinascimento. Nel corso della storia, il vino è stato una parte cruciale della cultura italiana e i vulcani del paese hanno influenzato la produzione della bevanda in modi diversi come la varietà delle uve coltivate e il suo sapore basato sulla composizione del terreno vulcanico. Le numerose regioni in Italia producono vino diverso in gran parte a …

Go to article

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

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

Earth and Planetary Sciences ETDs

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

Go to article

Comparative Lineament And Geomorphic Analysis Of Chaotic Terrains And Noctis Labyrinthus, Mars, Sarah A. Walton Dec 2023

Comparative Lineament And Geomorphic Analysis Of Chaotic Terrains And Noctis Labyrinthus, Mars, Sarah A. Walton

Electronic Theses and Dissertations

Noctis Labyrinthus (NL) is an extensional trough network connecting the Tharsis rise and Valles Marineris on Mars. Chaotic terrains are a group of polygonally-fractured surface features commonly associated with subsidence due to rapid fluid loss within the subsurface. Polygonal surface patterns are seen at both sites, where geometric topographic highs are bounded by low troughs. Lineaments, topography, and geomorphology of NL and chaotic terrains were analyzed to determine tectonics and fluid influence in the formation and evolution of both sites. NL shows preferential fracture patterns associated with regional extension. Lineaments within chaotic terrains do not show cumulative preferential trends but …

Go to article

Analyzing The Shark Paleoecology Of Coastal Georgia From The Miocene And Pliocene Epochs, Joshua Lee Clark, Benjamin Angalet Dec 2023

Analyzing The Shark Paleoecology Of Coastal Georgia From The Miocene And Pliocene Epochs, Joshua Lee Clark, Benjamin Angalet

Georgia Journal of Science

The field of shark paleoecology often yields indecisive conclusions based on the limited fossilization of their anatomical structures, with the exception of their teeth. The majority of the Atlantic coast has been studied regarding the presence of certain prehistoric shark species from the Miocene, Pliocene, and Pleistocene epochs. However, information pertaining to the Georgia coast and understanding its potential community structure is relatively understudied. This study was conducted in which thousands of fossil shark specimens and subsequent marine fauna were collected from dredge spoils created by the US Army Corps of Engineers (USACE): Savannah District. A total of 5,127 fossil …

Go to article

Morphological And Structural Characterization Of Shortening Landforms On Mars, Leta Mccullough Dec 2023

Morphological And Structural Characterization Of Shortening Landforms On Mars, Leta Mccullough

Theses and Dissertations

The lithosphere of Mars accommodates shortening through folding and faulting, producing landforms qualitatively categorized as wrinkle ridges or lobate scarps. However, we lack a deep understanding of the morphological differences between these landforms. This study aimed to develop a quantitative model for shortening landform classification based on surface morphology and subsurface architecture. We developed this model by mapping 100 landforms in a GIS, recording parameters for each landform. We conducted a Discriminant Function Analysis (DFA) using these morphometrics. This DFA produced a predictive linear function for categorizing wrinkle ridges and lobate scarps. We then modeled the subsurface structural geology of …

Go to article

The Broadwater Formation (Pliocene) Of Nebraska And Southeastern Wyoming, Robert F. Diffendal Jr., James B. Swinehart Dec 2023

The Broadwater Formation (Pliocene) Of Nebraska And Southeastern Wyoming, Robert F. Diffendal Jr., James B. Swinehart

Robert F. Diffendal, Jr., Publications

The Broadwater Formation, initially defined in 1945, is a Pliocene-aged coarse-grained alluvial deposit in Nebraska and southeastern Wyoming. It is characterized by a complex stratigraphic history and debated geologic interpretations. The formation is a rich resource of groundwater for the citizens of Nebraska and the Central Great Plains. We aim to synthesize and redefine the Broadwater Formation, shedding light on its distribution, geological characteristics, and paleoenvironmental significance. While historical hypotheses on Broadwater Formation paleovalley trajectories suggested northwest-southeast trending valleys, later investigations proposed wind-driven erosional patterns to explain the unique topographic features observed. The Broadwater is divided into an unnamed Upper …

Go to article

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

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

Masters Theses & Specialist Projects

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

Go to article

First Prev Next Last