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Earth Sciences

University of Kentucky

Theses/Dissertations

2021

Articles 1 - 12 of 12

Full-Text Articles in Physical Sciences and Mathematics

Analyzing Slab Holes In Subduction Zones And Their Impacts Through Numerical Simulations, Taylor M. Arrowood Jan 2021

Analyzing Slab Holes In Subduction Zones And Their Impacts Through Numerical Simulations, Taylor M. Arrowood

Theses and Dissertations--Earth and Environmental Sciences

Subduction zones form as higher density oceanic lithosphere is forced beneath an over-riding, lower density, continental or oceanic plate; a process driven by contrasts in buoyancy throughout this system. We seek to explore subduction zones in which the subducting lithosphere is discontinuous after passing through the trench, forming a slab gap. The main research objective is to determine the effect of slab gaps on surface topography in a subduction-related orogen and asthenospheric flow into the mantle wedge using two and three-dimensional numerical mechanical models. We obtain results from 24+ models that suggest a connection between slab gaps/holes and the magnitude …

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Timing Of Regional Metamorphism In The Inner Piedmont And Blue Ridge Of North Carolina: Evidence From Monazite U-Pb Geochronology, Nicholas Edwin Powell Jan 2021

Timing Of Regional Metamorphism In The Inner Piedmont And Blue Ridge Of North Carolina: Evidence From Monazite U-Pb Geochronology, Nicholas Edwin Powell

Theses and Dissertations--Earth and Environmental Sciences

Channel and escape flow, or lower crustal ductile flow and redirection from orogen-normal to orogen-parallel flow, are among the most impactful concepts introduced to explain shortening accommodation in large, hot orogens. In the Inner Piedmont (IP), southern Appalachians, channel and escape flow were proposed to have occurred during the Neo-Acadian (376–340 Ma) orogeny. However, the polymetamorphic history of the southern Appalachians makes it difficult to isolate thermal and deformational events for process-focused studies necessary to test these ideas in the IP. To address this, we used in situ laser ablation split stream (LASS) monazite U-Pb geochronology alongside new garnet chemical …

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Admittance Modeling For Elastic Thickness Across The Mars Crustal Dichotomy Boundary, Aspen Davis Jan 2021

Admittance Modeling For Elastic Thickness Across The Mars Crustal Dichotomy Boundary, Aspen Davis

Theses and Dissertations--Earth and Environmental Sciences

We use a Bouguer mass-sheet approximation for spectral admittance and correlation modeling to estimate elastic thickness, crustal thickness, crustal density, and load density across the Mars crustal dichotomy boundary near the landing site of NASA’s InSight Lander. We derive and constrain the parameter ranges using RMS misfit between the observed and theoretical admittance and their error bars. Spherical cap windows of 15° (900 km) radius are used to study 15 locations in the Northern Lowlands, the Southern Highlands and near and on the boundary which suggest distinct, but not sharp, difference in lithospheric properties. Elastic thickness estimates range generally between …

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Residual Spatial Autocorrelation In Macroecological And Biogeographical Modeling: A Review, Guetchine Gaspard Jan 2021

Residual Spatial Autocorrelation In Macroecological And Biogeographical Modeling: A Review, Guetchine Gaspard

Theses and Dissertations--Geography

Macroecological and biogeographical modelers have predicted the distribution of species across space relying on the relationship between biotic processes and environmental variables. Such a method employs data associated, for instance, with species abundance or presence/absence, climate, geomorphology, and soils. Statistical analyses found in previous studies have highlighted the importance of accounting for the effects of spatial autocorrelation (SAC), which indicates a level of dependence between pairs of nearby observations. A consensus has existed that residual spatial autocorrelation (rSAC) can substantially impact modeling processes and inferences. However, more emphasis should be put on identifying the sources of rSAC and the degree …

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What's In The Pan: An Evaluation Of Fragipan Evolution In Western Kentucky, Hannah Leigh Somerville Jan 2021

What's In The Pan: An Evaluation Of Fragipan Evolution In Western Kentucky, Hannah Leigh Somerville

Theses and Dissertations--Plant and Soil Sciences

The fragipan is a common diagnostic soil feature that does not follow a clear development path. Fragipans are found commonly throughout the southeastern US and cover 2.7 million acres in Kentucky alone. However prevalent, there is no currently accepted genesis theory for fragipans. In this study, we sought to better understand the formation of fragic features in Kentucky’s soils by evaluating fragipan characteristics across a sequence of pedons featuring varying degrees of fragipan development. We found that [Si/Al]Dithionite, [Si/(Si + Al)]Dithionite and SiDithionite concentration were all higher in well-developed fragipans, suggesting the involvement of an aluminosilicate …

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Integrated Geophysical Investigation Of Near-Surface Faults - Sassafras Ridge, New Madrid Seismic Zone, Usa, Cooper Cearley Jan 2021

Integrated Geophysical Investigation Of Near-Surface Faults - Sassafras Ridge, New Madrid Seismic Zone, Usa, Cooper Cearley

Theses and Dissertations--Earth and Environmental Sciences

The New Madrid Seismic Zone (NMSZ) is a large source of seismic hazard within the central and eastern United States. Seismogenic source parameters such as active fault location, slip rate, total displacement, and strain accommodation is poorly constrained due to the masking effect of the Mississippi Embayment sediment and agricultural practices on structures and surface expressions. Consequently, noninvasive geologic and geophysical investigation of the subsurface is needed to characterize seismogenic sources. Recent investigation of the Reelfoot Fault found that there is a strain accommodation enigma between the dextral offset at seismogenic depth versus the surface expression, Reelfoot Scarp. This strain …

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Geophysical Techniques Used For The Analysis And Prediction Of Soil Strength And Mechanical Behavior, Matthew A. Hurley Jan 2021

Geophysical Techniques Used For The Analysis And Prediction Of Soil Strength And Mechanical Behavior, Matthew A. Hurley

Theses and Dissertations--Civil Engineering

Determining soil properties involves extensive laboratory testing of samples at discrete timing and location. Non-destructive analysis methods, such as electrical and seismic, presents alternatives to means of gathering soil properties accompanied with increased flexibility due to spatial and temporal applications. This research examined the ability of seismic wave data to predict soil behavior such as stress-strain and pore pressures using a modified version of Duncan and Chang (1970). Friction angle predictions were also analyzed using shear wave velocity and a modified form of the Santos and Gomez-Correria (2001) equation. This research also analyzed the use of electrical data to predict …

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Landslide Site Assessment And Characterization Using Remote Sensing Techniques, Batmyagmar Dashbold Jan 2021

Landslide Site Assessment And Characterization Using Remote Sensing Techniques, Batmyagmar Dashbold

Theses and Dissertations--Civil Engineering

Landslides are common and dangerous natural hazards that occur worldwide, often causing severe direct impacts on human lives, public and private properties. It is imperative to identify the landslide susceptible areas to avoid or mitigate the possible damage. Landslide prediction can be presented in a slope failure in spatial and/ or temporal terms. If it is presented in spatial term, it is considered a landslide susceptibility map (LSM) defined as the probability of spatial occurrence of slope failures. If it is presented in a combination of spatial and temporal distribution of the landslide susceptibility, it is commonly referred to as …

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Understanding The Effects Of Complex Topography On Cover Crop Dynamics And Maize Production In Kentucky Agroecosystems, Samuel John Leuthold Jan 2021

Understanding The Effects Of Complex Topography On Cover Crop Dynamics And Maize Production In Kentucky Agroecosystems, Samuel John Leuthold

Theses and Dissertations--Plant and Soil Sciences

In Central Kentucky, rolling hill cropland presents a number of challenges related to soil sustainability. Increased topographic complexity can lead to increased erosion, inefficient crop nutrient use and increased nutrient loss. Further, grain crop yields can be variable across both space and time in rolling hill fields and are less resilient to changes in weather conditions than flatter, more homogeneous areas. More than 30% of cropland in Kentucky has a slope greater than 3⁰, which means a large swath of the row crop production land in the state is at increased risk of contribution to soil and water resource degradation. …

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Selenium Removal And Pollution Swapping Potentials Of Passive Anaerobic Bioreactors Receiving Coal Slurry Impoundment Wastes, Md Anik Mahmud Jan 2021

Selenium Removal And Pollution Swapping Potentials Of Passive Anaerobic Bioreactors Receiving Coal Slurry Impoundment Wastes, Md Anik Mahmud

Theses and Dissertations--Plant and Soil Sciences

Worldwide, selenium is a major contaminant of concern for coal and metal ore mining industries. In coal mining regions of the eastern USA, for example, billions of liters of wastewaters with elevated Se oxyanion concentrations (primarily SeO42- and SeO32-) are generated during coal washing which is often stored in > 700 man-made impoundments built into remote mountain valleys. Because impoundments are unlined systems, they tend to leak contents into nearby streams, which has detrimental effects on sensitive biota, particularly fish. The primary goal of this project was to evaluate the capacity of passive anaerobic bioreactors (PAB) …

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Topographic Gradients In Bulk Soil Properties In Central Kentucky Karst Sinkholes, Anne Kathryn Mcgraw Jan 2021

Topographic Gradients In Bulk Soil Properties In Central Kentucky Karst Sinkholes, Anne Kathryn Mcgraw

Theses and Dissertations--Plant and Soil Sciences

The Bluegrass physiographic region of Kentucky is underlain by the late Ordovician Lexington Limestone formation. This area has many identifiable karst features, including sinkholes. Karst sinkholes and associated soils coevolve, which may influence the distribution of bulk soil properties and storage of carbon across karst landscapes. Two sinkholes on the University of Kentucky’s C. Oran Little Animal Research Center in Woodford County, central Kentucky, were selected for analysis. We described and sampled nine pedons at the dominant landscape positions (e.g., summit, shoulder, backslope, footslope, and toeslope) within the two sinkholes; we characterized the physical, chemical, and mineralogical soil properties across …

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Enhancing Agroecosystem Phosphorus Management: Root Phenotyping And Decomposition For Improved Phosphorus Cycling, Rebecca Kay Mcgrail Jan 2021

Enhancing Agroecosystem Phosphorus Management: Root Phenotyping And Decomposition For Improved Phosphorus Cycling, Rebecca Kay Mcgrail

Theses and Dissertations--Plant and Soil Sciences

Plant roots are often overlooked when making nutrient management decisions. Evaluating differences in P acquisition strategies and cycling resulting from years of shoot-specific plant breeding will aid in reducing fertilizer inputs, with the ultimate goal of improving economic sustainability of crop production and preservation of ecosystem services. To achieve this goal, this research screened a diverse panel of winter wheat cultivars that included old and modern, dwarfed and wild type varieties for physical and chemical root phenotypes related to P acquisition. Old cultivars had larger root systems with more roots that grew two times faster than intermediate/modern cultivars. Wild type …

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