Earth Sciences Commons^™

Long-Term Effects Of Harvesting Disturbance And Site Preparation On Soil Properties And Tree Growth In A Loblolly Pine (Pinus Taeda) Forest, Kyle M. Caccamesi

LSU Master's Theses

Productivity decline between rotations has long been a concern in intensively managed forest plantations. Research done over the last century has provided greater clarity on why this phenomenon occurs. The objective of this research was to observe long-term soil and tree growth characteristics that are likely to be influenced by operational harvesting activities. The experiment was conducted in Washington Parish, Louisiana on a site dominated by Ruston soil series, a well-drained, fine loamy, siliceous and thermic typic Paleudult. A randomized complete block design with 2 x 2 x 2 factorial treatments was used. The treatment factors were harvesting method, fertilization, …

The Case For Ice Rises At Ross Bank Since The Middle Miocene, William Weber

LSU Master's Theses

Many tens of ice rises exist at the marine margins of the Antarctic Ice Sheet. Isle-type ice rises in particular are those where an ice shelf is pinned to an underlying submarine bank. Recent and ongoing studies show that Ross Bank, on the middle continental shelf of central Ross Sea, was the former site of an important Ross Ice Shelf ice rise during the advance and retreat of the West Antarctic Ice Sheet (WAIS) in the last glacial cycle. Ross Bank is a broad and anomalously shallow water platform whose crest rises to 170 m water depth. Despite their importance …

Evaluating Soil Health And Crop Yield In Louisiana Agricultural Systems: Impacts Of Best Management Practices And Prediction Models, Hector J. Mendoza Lagos

LSU Doctoral Dissertations

The adoption of conservation management practices is critical for improving soil health, enhancing nutrient use efficiency, and sustaining crop productivity in row crop systems in Louisiana. This study evaluated the role of conservation agronomic practices, soil biochemical indicators, and machine learning predictive models to improve soil nutrient dynamics, soil health indicators, microbial communities (MC), and crop productivity on a corn (Zea mays L.) research plot scale and in a commercial forty-hectare cotton (Gassypium hirsutum L.)-corn-soybean (Glycine max L.) rotation system in northeast Louisiana. The objectives of the study were to evaluate soil nutrient dynamics and MCs under …

Recent Wetland Elevation Dynamics In Coastal Louisiana, Usa, Elizabeth Harris

LSU Master's Theses

Coastal marshes globally are increasingly vulnerable to accelerating relative sea-level rise (RSLR), which threatens their capacity to maintain elevation through feedbacks among sediment supply, vegetation productivity, hydrology, and soil processes. Although many marshes can persist under moderate rates of sea-level rise through vertical accretion and belowground biomass production, this resilience is strongly constrained by sediment availability and subsurface processes such as autocompaction and organic matter decomposition. High accretion is often assumed to confer marsh resilience; however, subsurface processes, particularly autocompaction driven by surface loading, can substantially offset elevation gains. Coastal Louisiana experiences among the highest rates of RSLR worldwide due …

Machine Learning Based Models For Simulation And Analysis Of Bulk Earth Melt System, Abin Shakya

LSU Doctoral Dissertations

Understanding the segregation of bulk Earth melt systems into metallic (core) and silicate (mantle) phases under high-pressure and high-temperature conditions is central to modeling Earth’s interior, yet relevant experimental and computational studies remain limited. This work develops a machine learning–based simulation pipeline that iteratively couples first-principles (quantum mechanical) calculations with neural network training to generate high-fidelity force fields. Using major-element Fe–Mg–Si–O melt systems, with and without H and N, as testbeds, we demonstrate that this framework enables large-scale molecular dynamics simulations at near first-principles accuracy. We further introduce a sequence of phase identification methods, progressing from statistical binning of elemental …

Effect Of Light Elements On The Melting Behavior Of Liquid Iron Alloys Under Earth’S Inner Core Boundary Conditions, Olaniyi Anisere

LSU Master's Theses

The temperature at Earth’s inner core boundary (ICB) is set by the melting temperature of the iron-rich outer core at core pressures, yet this remains uncertain because melting depends strongly on composition and pressure. Light elements are required to explain the core’s density deficit, but the identity, abundance, and combined influence of these elements on melting under ICB conditions are still debated. This thesis quantifies how candidate light elements modify the melting behavior of iron alloys at ICB-relevant pressures and uses these composition-dependent melting relations to constrain ICB temperature.

Melting relations were determined using molecular dynamics simulations in VASP accelerated …

Biogeochemical Controls On Phosphorus Transport And Legacy Storage Across A Coastal Watershed, Lee Potter

LSU Doctoral Dissertations

Excess phosphorus (P) loading is a key driver of eutrophication and harmful algal blooms (HABs) in aquatic systems worldwide. This relationship is of increasing concern in coastal Louisiana, where climate variability, altered hydrology, and land-use change converge, resulting in increased hydrologic and nutrient loading into coastal systems. This dissertation examines controls on P cycling in the Lake Pontchartrain Basin through a multi-scale framework linking estuarine processes, watershed loading, climate and weather patterns, and sediment dynamics. The dissertation begins with an overview of the study region, P dynamics, and changes in hydrology and nutrient loading patterns. Chapter 2 presents a spatial …

Supplemental Bibliographic Details. From 2001 Mars Odyssey To Earth’S Climate Crisis: Integrating Gamma Spectroscopy, Martian Soil Simulants, And Plant Genomes For Agroecology, Anchored In Sri Lanka’S Mars-Context Serpentinites, Suniti Karunatillake, Maheshi Dassanayake, Carlos Gary Bicas

Planetary Science Lab

Bibliographic details follow to supplement hyperlinked citations in the multinational GANGOTRI-supporting project conceived by Karunatillake, Dassanayake, and Gary-Bicas

Quantifying Uncertainty In Landscape Evolution And Provenance Analysis: Insights From Statistical And Numerical Modelling, Vivian Carmello Grom

LSU Doctoral Dissertations

Landscape evolution models (LEMs) and detrital zircon provenance are widely used to investigate Earth surface processes, yet both face challenges related to quantifying model behavior and interpreting sedimentary signals under realistic, heterogeneous conditions. This thesis addresses these challenges through analysis and case studies that develop and apply new approaches for analyzing landscape dynamics and assessing uncertainties in sediment provenance.

Chapter 1 introduces a quantitative framework for evaluating LEM outputs using Shannon Entropy, Moran’s I, and Geary’s C. Applied to simulations with steady uplift, periodic uplift, spatially variable uplift, and a timeseries of DEMs, these metrics capture spatial organization and information …

Compound-Specific Isotope Records Of Dust Provenance And Hydroclimate In The North Pacific And Marginal Seas Of East Asia: Integrating N-Alkane Δ13c And Δd With Standardized Analytical Frameworks, Julian W. Traphagan

LSU Doctoral Dissertations

This dissertation presents advancements in compound-specific isotope analysis (CSIA) through methodological innovation and paleoclimate reconstruction in Central and East Asia. Utilizing plant wax n-alkanes from International Ocean Discovery Program (IODP) and Ocean Drilling Program (ODP) sediment cores, this research reconstructs atmospheric circulation shifts responding to tectonic evolution and climate transitions since the Late Miocene.

Chapter 1 investigates hydrogen isotope compositions (δD_wax) from IODP U1430 (Sea of Japan), ODP 886, and ODP 1208 (North Pacific) to trace dust provenance and hydroclimate changes since ~13 Ma. Results reveal persistently segmented source-to-sink systems: the Sea of Japan dominated by westerly …

Measuring The Impact On Landscape And Sediment Transport Of Climate And Anthropogenic Influence In The Mississippi River Since 2000 Bce, Bailey Wycoff

LSU Master's Theses

Understanding river dynamics is crucial to being able to interpret the geological history preserved in sediment deposited on continental margins, deltas, and alluvial plains. Sediment buffering can be a key control on the sediment flux to the ocean and involves sediment storage and recycling in flood plains. The efficiency of the transport varies depending on climatic and more recently anthropogenic influences. Sediment moving through meandering streams may be temporarily deposited in a point bar on the convex side of a meandering river. Meanders are sometimes cut off, creating an oxbow lake and filled in. The area of study, False River, …

Investigating The Relationships Among Suspended Sediment Concentration, And Marsh Edge Erosion In Barataria Bay, La, Lily Vowels

LSU Master's Theses

Barataria Bay, Louisiana, USA exhibits a unique microtidal, wind-driven hydrodynamic climate where extensive levee infrastructure throughout Louisiana has starved Barataria Bay and similar interdistributary bays of the historic levels of terrigenous sediment import. This has contributed to extreme coastal wetland loss in Louisiana. This project seeks to understand how hydrodynamic and meteorological conditions are linked to sediments’ fate after erosion from the marsh edge. Specifically, this project seeks to differentiate the roles of wave resuspension and marsh edge erosion (MEE) in sediment dynamics in Barataria Bay. An acoustic wave and current profiler (AWAC) was used to capture hydrodynamic conditions, and …

Decadal To Millennial-Scale Morphodynamic Evolution Of Microtidal Marshes, Samuel Mason Zapp

LSU Doctoral Dissertations

Tidal marshes are susceptible to rapidly converting to open water due to their low elevations within the tidal frame. A continuous supply of externally supplied mineral sediment and in situ organic material production is necessary to offset elevation losses from relative sea level rise and erosion. Complex feedbacks between hydrodynamics, the erosion, transport, and deposition of sediment, and physical modification of the landscape by the establishment of intertidal vegetation govern the spatial and temporal patterns of elevation response. This dissertation focuses on modeling how these dynamics drive marsh landscape evolution in the past, present, and into the future under changing …

Identifying Saharan Air Layer Events And Their Relationship To Instability And Rainfall Patterns In The Tropical North Atlantic Ocean, Charles H. Dolce

LSU Master's Theses

Every year, strong North African winds across the Sahara loft dust particles and advect them westward within the Saharan Air Layer (SAL). These plumes of dust often reach the Caribbean Sea and can heavily affect regional weather patterns by suppressing convection. When concentrations are high, decreased rainfall can yield negative societal and ecological impacts, potentially leading to drought. The Puerto Rican early rainfall season (ERS), spanning from 1 April through 31 July, overlaps with Saharan dust migration periods, and systematically detecting instances of SAL activity near the island is important for understanding longer-term drought-forcing trends in the region.

Corridors of …

Assessing Groundwater Availability And Land Subsidence Risk Associated With Anthropogenic Activities In A Complex Aquifer System, Aya Bakr Attya Mohamed

LSU Doctoral Dissertations

The Southern Hills aquifer system (SHAS) is the primary source of water in the Capital area of Louisiana. However, the overexploitation of freshwater-bearing aquifers and the presence of two active faults, the BR fault and the DSS fault, have resulted in groundwater depletion, saltwater intrusion, and increased the risk of land surface subsidence. Such critical issues pose substantial threats to groundwater availability and exert detrimental effects on the environment and urban infrastructures. This dissertation presents a comprehensive investigation of the SHAS for recognizing the consequences of groundwater depletion and its potential long-term impacts on groundwater availability and land stability. A …

Quaternary Subsurface Characterization Of The Mississippi River Valley Alluvial Aquifer: Insights From Interval Kriging And Airborne Em-Borehole Data Integration, Yuqi Song

LSU Doctoral Dissertations

The Pleistocene period significantly contributed to the formation of alluvial aquifer worldwide. These productive aquifers are crucial for domestic, industrial, and agricultural water supplies. The Mississippi River Valley alluvial aquifer (MRVA), a principal aquifer in the U.S., is crucial for national food security and global agricultural supply. This study aims to characterize the subsurface architecture of the MRVA, thereby enhancing fundamental understanding of sedimentological processes involved in the genesis of glacio-fluvial aquifers worldwide. The research objectives are threefold: (1) to provide a detailed characterization of the MRVA; (2) to develop 3D geostatistical methods for geological modeling; and (3) to develop …

Evaluating Biotic Effecrs Associated With The Paleocene-Eocene Thermal Maximum In Mississippi And Alabama: A Palynological And Biostratigraphic Study Of Amoco's Legacy Samples, Sarah Fortin Bancroft

LSU Master's Theses

The Paleocene-Eocene Thermal Maximum (PETM) was a ~200 ka period of rapid global warming in the earliest Eocene (~56 Ma) involving a roughly 7 °C rise in atmospheric and sea-surface temperatures. The Gulf of Mexico Wilcox Group contains very well-preserved terrestrial and deltaic sediments that contain exploitable hydrocarbons . The Wilcox Group’s Paleocene Tuscahoma and Eocene Hatchetigbee Formations have been roughly dated with calcareous and planktonic foraminiferal assemblages by AMOCO; however, the precise ages of these formations, their palynological assemblages, and their paleo-depositional geosystems are an area of active research.

Through a high-resolution palynological analysis, this study assesses the depositional …

Temporal Scales Of Sediment Accumulation, Mass Wasting, And Stratigraphy Across The Mississippi River Delta Front, Jeffrey E. Duxbury

LSU Doctoral Dissertations

The Mississippi River Delta Front (MRDF) is a subaqueous apron of rapidly deposited, weakly

consolidated sediment extending from the subaerial portions of the Mississippi River’s Birdsfoot Delta, historically known for sediment transport via mass wasting. To better understand the spatial and temporal dynamics of processes influencing the MRDF, 29 cores ranging from 5.8 to 8.71 meters in length were collected from the South Pass (SP) and Southwest Passes (SWP). These cores targeted specific depositional environments, including the undisturbed topset apron, medial mudflow gully, mudflow lobe, and prodelta. The cores were analyzed along their full lengths for gamma density, grain size, …

Effects Of Longitudinal Training Walls On Two-Dimensional Flow Structure, Sediment Transport, And Bed Aggredation Using Numerical Methods And Sediment Core Analyses In Grand River, Michigan, Sumaiya Tul Siddique

LSU Doctoral Dissertations

Longitudinal training walls (LTWs) are structures oriented parallelly with the main flow and separate the channel into two sub-channels. One channel acts as the main navigational channel and the other is considered a secondary side channel. The long-term effects of the LTWs on morphodynamics and deposition remain poorly understood. This study investigated the long-term effects of the LTWs on flow, sediment transport and long-term deposition of the Grand River using numerical approaches and sediment core analysis. The effects of LTWs on 2D flow dynamics and sediment transport were investigated by using numerical approaches. The long-term deposition under the influence of …

Modern Lakeshore Processes And Historic Lake And Glacial Changes In Taylor Valley, Antarctica, Michael Stanley Stone

LSU Doctoral Dissertations

Taylor Valley, which opens to the Ross Sea, is one of several ice-free valleys comprising the McMurdo Dry Valleys, Antarctica. The valley is home to several close-basin, perennially ice-covered lakes, whose lake levels largely reflect a balance between meltwater inputs and lake ice ablation; both being driven by climate. A dynamic environment exists where the lake ice covers meet the lakeshore, with the ice grounding to the substrate throughout the cold and dark of winter, and melting to form a perimeter of thin-to-no ice around the lake during the summer. These marginal freeze-thaw regions are known as moats. Here, physical, …

Coastal Sedimentary Records Of Extreme Events And Human Activity: Examples From Hurricanes And Microplastics, Nicholas T. Culligan

LSU Doctoral Dissertations

Coastal regions are uniquely vulnerable to a myriad of natural and anthropogenically caused stresses such as hurricane strikes and chronic microplastic pollution. Both hurricanes and microplastics have major negative effects on global coastlines and are forecast to become more damaging in the future. However, current model trends are based on limited modern data and may not provide an accurate or comprehensive view of the future. Therefore, this dissertation investigates coastal stratigraphic records to determine long-term past trends of these presses and pulses so that researchers, stakeholders, and policy makers can use them to enact strategies to mitigate damages from worsening …

The Hydrological Impacts Of Woody Plant Encroachment On Coastal Tallgrass Prairie Of Texas, Zhiwei Guo

LSU Master's Theses

Globally, woody plant encroachment into grassland and savanna ecosystems impacts the hydrological functions of grasslands and associated wetlands. In the coastal tallgrass prairie of Texas, encroachment of woody plants has altered vegetation structure, but the hydrological impacts are poorly understood. In this study, I evaluated and quantified how woody plant encroachment affects hydrological processes on the pimple mounds and inter-mound freshwater marsh, including precipitation partitioning, infiltration in the vadose zone, groundwater recharge, and water volume in the inter-mound marsh. I randomly selected three pimple mounds with woody plants and three pimple mounds with tallgrass w to quantify hydrologic processes. The …

Impacts Of Morphological Changes On Water Residence Times In River Deltas, Md. Muzahidul Islam

LSU Master's Theses

Coastal river deltas possess substantial socioeconomic and ecological importance and are expected to encounter increasing risks because of global climate change. The long-term sustainability of many deltaic systems is at risk due to a mix of natural and human-induced factors. Deltas are characterized by their continuous reconfiguration of channels and floodplains due to allogenic and autogenic processes. Sediment supply and composition, sea level rise, vegetation, river discharge, and human development may affect the morphological evolution of river deltas. The timescales and patterns of hydrological transport within a river delta are important indicators of ecological function. One such metric, the water …

Coordination Numbers And Grain Texture From Micro-Xray Tomography Of Angular Unconsolidated Sediments: Velocity Prediction Using Hertz-Mindlin Model., Kwabena Poku-Agyemang

LSU Master's Theses

Elastic properties of unconsolidated sediments depend on parameters such as porosity, grain texture (i.e., grain shape and sizes), sorting and coordination number. Coordination is the average number of grains each grain has with touching grains, is a critical parameter in rock physics models for estimating elastic moduli of materials. While previous works have focused on the influence of porosity and sorting on coordination numbers within well-rounded grains, natural sediments have a wide range of grain shapes and sizes, and it remains unclear how these parameters influence coordination numbers within angular unconsolidated sediments.

We investigate the impact of porosity, sorting and …

Estimating Crustal Thickness In Northwest Louisiana Using The Receiver Function Method, Delton Samuel

LSU Master's Theses

I aim to constrain the crustal thickness of the Sabine Block in the Sabine Uplift region of northwest Louisiana, using the frequency domain receiver function deconvolution technique followed by H-κ stacking. The passive margin on the southern edge of the North American continent experienced an active tectonic history, including the spreading events that led to the formation of the Gulf of Mexico. A previous study proposed the Sabine Block is a residual fragment of Proterozoic orogenic origin; however, its full extent and geometry are up for debate. It is now overlain by thick sedimentary sequences ranging from ~4-6 km deposited …

Quantification Of Belowground Biomass And Sediment Accretion In Mangroves Of Different Coastal Environmental Settings Of The Costa Rican Pacific Coast, Denise M. Poveda

LSU Master's Theses

The adaptation of intertidal ecosystems such as mangroves to anticipated accelerated relative sea level rise is dependent on net increase of sediment surface elevations and forest migration inland. Ecosystem models developed to simulate trajectories of ecosystem adaptations have determined that rates of soil formation are most sensitive to surface sediment (organic and inorganic) deposition and subsurface organic production by mangrove roots. Mangrove belowground biomass contributes to soil organic matter accumulation, while mangrove litter has minor contribution due to export and annual decay. In addition to belowground biomass production, inorganic sediment loading is also key contribution to soil formation and accretion. …

Applied Depositional Geosystems Of The Coos Bay Basin, Oregon: Organic Geochemistry, Maturation, Paleoenvironmental Reconstruction And Biostratigraphy Of The Coaledo Delta During The Middle Eocene Climatic Optimum (Meco), Allison K. Barbato

LSU Doctoral Dissertations

The Coos Bay Basin on the southwestern coast of Oregon is a forearc basin that contains exceptionally preserved Eocene to Miocene, tidal to wave-dominated, shallow deltaic to deep marine sediments of the Coaledo Delta. Coastal depositional environments are known to host source, reservoir, and seal rocks. Climate, topographic relief, and geographical position all play an important role in regional vegetation development and oceanic setting. This study assesses 84 outcrop and 12 core samples from Coos Bay for their organic geochemical characteristics and microfossil assemblage to provide source rock characterization information, organofacies descriptions, environmental reconstructions, and age control.

Results indicate the …

Investigation Of Gas Dynamics In Water And Oil-Based Muds Using Das, Dts, And Dss Measurements, Temitayo S. Adeyemi

LSU Master's Theses

Reliable prediction of gas migration velocity, void fraction, and length of gas-affected region in water and oil-based muds is essential for effective planning, control, and optimization of drilling operations. However, there is a gap in our understanding of gas behavior and dynamics in water and oil-based muds. This is a consequence of the use of experimental systems that are not representative of field-scale conditions. This study seeks to bridge the gap via the well-scale deployment of distributed fiber-optic sensors for real-time monitoring of gas behavior and dynamics in water and oil-based mud. The aforementioned parameters were estimated in real-time using …

The Impacts Of Nature-Based Sediment Restoration Practices On Coastal Wetland Soil Biogeochemistry, Jacob Z. Cheng

LSU Master's Theses

Coastal marshes provide many valuable ecosystem services. However, these wetlands are threatened worldwide, being subject to sea level rise, sediment starvation, subsidence, coastal edge erosion, etc. Many efforts are being made to counteract this wetland loss and preserve the ecosystem services. Two such methods are sediment diversion and the thin layer placement (TLP) of dredged sediment.

Sediment diversion involves reconnecting the main channel of a river body to disconnected wetlands, supplying much needed soil-building materials. However, this method affects the salinity of the waters, introducing large amounts of freshwater into the system. Salinity changes can affect marsh biogeochemistry. Most ecological …

Investigating Gulf Coast Aquifer System: Stratigraphy Reconstruction, Inverse Modeling, And Groundwater Stress Assessment, Shuo Yang

LSU Doctoral Dissertations

The Mississippi Embayment aquifer system (MEAS) and the Coastal Lowlands aquifer system (CLAS) provide substantial groundwater resources for human activities in the U.S. Gulf Coastal Plain. However, the overexploitation has led to groundwater depletion in the MEAS and the CLAS, threatening sustainable groundwater use. Such concern highlights the crucial need for an advanced understanding of stratigraphy and groundwater in these aquifer systems, which is essential for effective regional groundwater management. This dissertation presents a comprehensive investigation of MEAS and CLAS in the Louisiana and southwestern Mississippi region, encompassing three fundamental dimensions: stratigraphy reconstruction, groundwater modeling, and groundwater stress assessments. A …