Earth Sciences Commons^™

Grounding Line And Calving Front Retreat In Glomar Challenger Basin And Pennell Trough Of Ross Sea, Antarctica Reconstructed From Diatom Abundances And Assemblages, Jaren Bradford

LSU Master's Theses

Previous studies showed that West Antarctic Ice Sheet (WAIS) retreat from the Whales Deep Basin continental shelf edge in eastern Ross Sea was underway by 14.7 ± 0.4 cal kyr BP. Following an ice-shelf breakup at 12.3 ± 0.6 cal kyr BP, a calving cliff margin remained within 60 km of the shelf edge until 11.5 ± 0.3 cal kyr BP. McGlannan et al. (2017) inferred that an ice shelf reformed immediately during a subsequent rapid retreat. That interpretation of grounding-line retreat with an intact ice shelf is being reevaluated by Sivils (in prep.). Here, we conducted a similar synthesis …

Collapse Of The Bindschadler Ice Stream At 11.5 Cal Kyr Bp Via Marine Ice Cliff Instability, Anna Sivils

LSU Master's Theses

Previous studies of the Whales Deep Basin (WDB) outer continental shelf showed that the paleo-ice shelf fronting the Bindschadler Ice Stream broke up at 12.3 cal kyr BP. A calving cliff was subsequently maintained until at least 11.5 cal kyr BP. Slightly after that time, the grounding line rapidly retreated creating a 200 km embayment of grounded ice over the foredeepened middle continental shelf. The rapid opening of the embayment is recorded by a backstepping succession of small-scale morainal ridges on the middle continental shelf. The overlapping and end-to-end spacing of morainal ridges requires that the retreating grounding line experienced …

Sedimentary Processes And Instability On The Mississippi River Delta Front Near The Wreck Of The Ss Virginia, Nathan Figueredo

LSU Doctoral Dissertations

Multi-cores and piston cores were collected seaward of the Mississippi River Delta’s Southwest Pass at ~80 m water depth in 2017 to better understand sedimentary characteristics and processes on the Mississippi River Delta Front (MRDF) in the vicinity of the SS Virginia shipwreck, and to support marine archeological research. Core analyses were performed to inform our understanding of the dynamics of sediment motion in the study area through radionuclide activity (²¹⁰Pb and ¹³⁷Cs), volume frequency of grain size, bulk density, and fabric (X-Radiography). Sediment accumulation rates (SAR), calculated from multi-core ²¹⁰Pb activity are 0.22 - 0.29 …

A Stable Isotopic Profile Of Atmospheric River Precipitation Impacting Northern California, Erika Clarise Ornouski

LSU Master's Theses

Atmospheric river (AR) storms are an integral part of California’s hydrologic cycle, providing 30–50% of the state’s annual precipitation. However, “too much of a good thing” can swell

rivers beyond capacity leading to widespread flooding, erosion, and environmental damage. Northern California’s steep topography coupled with its seasonal Sierra Nevada snowpack puts this region at risk for floods and extreme weather hazards that can be triggered by strong ARs. Identifying AR contributions in the water cycle is crucial for informing water resource and emergency management decisions Stable isotope analysis provides a means to understand the movement of precipitation based on fractionation …

Seasonal Seepage Fluid Flow And Pressure Detection Beneath Flood Protection Levees In The Lower Mississippi River Valley Using Non-Invasive Geophysical Methods, Daniel Locci

LSU Doctoral Dissertations

This study explores the use of shear-wave seismic reflection and electrical resistivity techniques to complement our understanding of seepage pore pressure variations and soil type estimation beneath earthen levees in the Mississippi River floodplain. The seasonal variations of water level in the river create changes in pore pressure in the adjacent aquifer, which can be detected using time-lapse shear-wave velocity analysis. The seismic reflection patterns during these pressure variations show changes in velocity that can be translated into changes in effective pressure, allowing us to distinguish between confined and leaky aquifers.

In addition, the integration of geophysical methods such as …

Evaluating Fungal Population Response To The Miocene Climatic Optimum: High-Resolution Palynological Insights From The South China Sea And Mcmurdo Sound, Antarctica, Mallory Pilie

LSU Master's Theses

Fungi play key and specific roles in ecosystems, specifically as many have restricted geographic distributions, known host/substrate preferences, and are important local environmental indicators due to their short dispersal distances. This study of fossil fungi from a time interval of pronounced global warming, the Miocene Climatic Optimum (MCO), allows analysis of fungal response to an analogue for future climate change scenarios. The research presented herein is part of a larger project, Fungi in a Warmer World (FiaWW), which is using globally-distributed sediment samples to provide foundational information on fungal community distribution patterns and will provide the first fungi-based climatological reconstructions …

Quantifying Mud Settling Velocity As A Function Of Turbulence And Salinity In A Deltaic Estuary, Michael W. Mcdonell

LSU Master's Theses

Mud settling velocity is controlled by flocculation, which in turn strongly depends on turbulence and on the chemistry and biology of the water-sediment mixture. As a result, mud settling velocity can be poorly constrained in coastal areas and vary in space and time by orders of magnitude. Here we quantified mud settling velocity in Barataria Basin, a deltaic estuary in Louisiana (USA), using three independent methods: eddy covariance (one station for 200 days), floc cameras (4 stations at one time), and Rouse profile inversion (14 stations, replicated 10-30 times each). Eddy covariance indicates that settling velocity increases with turbulence, at …

Snow Distribution And Influence In Taylor Valley, Antarctica, Using Remote Sensing, Katherine Mcnulty, Peter Doran, Mark Salvatore, Suniti Karunatillake

LSU Master's Theses

The McMurdo Dry Valleys is the largest ice-free area in Antarctica, but seasonal snow covers the valley floors sporadically throughout the year. In this study, a model to estimate areal snow coverage from satellite imagery was created. An area-volume model was created to estimate the amount of snow water equivalent (SWE) from the snow area extracted from the imagery. Snow cover influences the total albedo, the hydrologic budget, and the soil moisture and soil temperature in Taylor Valley (TV). Quantifying snow precipitation in TV is challenging because snow redistributes with winds, sublimates, or melts within a short period. Previous estimates …

Geophysical Characterization Of Underground Storage In Salt Domes During The Clean Energy Transition, Joses B. Omojola

LSU Master's Theses

Safely transforming geological formations into cost-effective underground storage is critical for the US energy security and global energy transition. Seasonal energy demand requires relatively cheap, impermeable, non-reactive materials for storing vast amounts of natural gas and hydrogen. Due to their low risk of fracturing and leakage, salt formations are ideal for these purposes however, pressure variations during drawdown, differential salt creep, and reactivation of pre-existing fractures along boundary shear zone(s) (BSZ) can be detrimental to salt cavern safety and long-term cavern operations. Several environmental disasters at storage facilities in the US and Europe, have created a need to understand how …

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

LSU Doctoral Dissertations

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

First-Principles Molecular Dynamics Study Of Liquid Iron-Rich Alloys Under Conditions Of The Earth’S Core, Dipendra Banjara

LSU Doctoral Dissertations

In this dissertation, we report the results of the first-principles molecular dynamics (FPMD) simulations and data analysis on the thermodynamic, structural, and transport properties of iron-rich metallic liquids considering several light and heavy elements under wide ranges of pressure and temperature that are relevant to the earth’s core. Our simulations of pure liquid iron cover the pressure range from 0 GPa at 2000 K to 380 GPa at 7000 K perhaps representing the most extensive computational study to date. We studied four molten iron-rich alloys corresponding to 2.67 atom% of Ni, Co, Mo, and W at pressures up to 380 …

Visual Analytics And Modeling Of Materials Property Data, Diwas Bhattarai

LSU Doctoral Dissertations

Due to significant advancements in experimental and computational techniques, materials data are abundant. To facilitate data-driven research, it calls for a system for managing and sharing data and supporting a set of tools for effective data analysis and modeling. Generally, a given material property M can be considered as a multivariate data problem. The dimensions of M are the values of the property itself, the conditions (pressure P, temperature T, and multi-component composition X) that control the concerned property, and relevant metadata I (source, date).

Here we present a comprehensive database considering both experimental and computational sources …

Environmental Controls On Carbon Biogeochemistry In Aquatic Systems, Lee Potter

LSU Master's Theses

Carbon dioxide (CO₂) outgassing from inland waters is a small but critical component of the global carbon cycle that is currently not well constrained. This thesis is composed of three interrelated studies with an overarching goal to further determine environmental factors impacting carbon dynamics in rivers and lakes. These studies utilized water samples and in situ measurements of pCO₂ and ambient water parameters from the Lower Mississippi River at Baton Rouge and University Lake in Baton Rouge Louisiana, USA collected between January 2021 and August 2022. Additional Meteorological and hydrological data were download from public sources. Results …

Archean Metamorphosed Ultramafic Rocks And Chromitites From The Beartooth Mountains, Montana, Usa: Insights Into Mantle Geochemistry And Tectonics, Rachel M. Gnieski

LSU Master's Theses

Metamorphosed ultramafic rocks and associated chromitite pods in the eastern Beartooth Mountains, Montana (USA) provide a window into the tectonic evolution of the Archean northern Wyoming Province. Meta-ultramafic rocks occur with a variety of metasupracrustal rocks as xenoliths in an extensive 2.8 Ga suite of TTG (meta)plutonic rocks. The origin of the ultramafic rocks is obscured by an upper amphibolite-to-greenschist facies overprint. Major element analyses (XRF, wt. %) of meta-ultramafic host rocks show SiO₂ from 40.53-50.37, MgO from 15.33-45.25, TiO₂ from 0.07-0.62, Al₂O₃ from 1.25-10.62, and Fe₂O₃(t) from 8.06-14.54. Total alkali …

Snapshots Of Coastal Ecology During Glacial And Deglacial Intervals: A Multiproxy Assessment Of Northern Gulf Of Mexico Sediment Cores, Kendall Emilie Brome

LSU Master's Theses

Terrestrial ecosystems along exposed continental shelves during times of relatively low sea level and glaciation are rarely preserved due to the mechanically erosive nature of marine transgression and regression. In this study, I investigate the geochemical and palynological characteristics of two well-preserved sites in the northern Gulf of Mexico (NGOM) to determine the ecologic settings and subsequent mechanisms of preservation in this region. Both sites contain preserved terrigenous sediments of previously exposed coastal margins; the first is located at the Alabama Underwater Forest (~13 km south of Gulf Shores, AL, at ~15 mbsl), and optically stimulated luminescence dates to 72–56 …

Time-Varying Rates Of Organic And Inorganic Mass Accumulation In Louisiana Marshes And Relation To Sea-Level Change, Sophie Vincent

LSU Master's Theses

Louisiana wetlands are complex systems that require a continuous input of organic and inorganic material to keep pace with relative sea-level rise (RSLR). Marshes, specifically, rely on organic material to build soil volume and maintain surface elevation. Interannual-to-decadal sea-level anomalies induced by Earth's internal climate variability and atmospheric disturbances such as hurricanes can affect marsh accretion, mineral deposition, and plant productivity. Coastal restoration projects such as sediment diversions are in progress to mitigate land loss and increase availability of inorganic sediment to coastal wetlands. The goal of this project is to determine if organic mass accumulation rates in Louisiana marshes …

Hydrogeologic Investigation Of A Covered Karst Terrain, Joseph Peter Honings

LSU Doctoral Dissertations

Increasing demand for water for agricultural use within the Dougherty Plain of the Southeastern United States has depleted surface water bodies. In karstic landscapes, such as the Dougherty Plain in southwest Georgia where the linkages between surface and ground waters are close, there is a need to understand the physical characteristics of the subsurface that allow these close linkages. Having a better understanding of the subsurface characteristics will aid numerical modeling efforts that underpin policy decisions and economic analyses. Two common features on this karstic landscape are draws and geographically isolated wetlands. Using LiDAR, aerial imagery, and ground-penetrating radar, this …

Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot

LSU Master's Theses

Coastal wetlands provide an abundance of ecosystem services that benefit society, such as essential habitat for commercial species, storm protection, nutrient cycling, and carbon storage. Louisiana faces rapid rates of relative sea level rise (natural subsidence and eustatic sea levels) that threaten wetland survival, which are amplified by a reduction of riverine sediment input. An important determining factor of marsh survival is the formation of wetland platform elevation, known as vertical accretion, which is determined by several processes including sediment deposition & erosion, below ground biomass (BGB) productivity, decomposition of organic matter, shallow & deep subsidence, and soil compaction. Feldspar …

Spatial Variations In The Stress Field Near The Wilmington Blind-Thrust, An Earthquake Source Beneath Los Angeles, California, Justin Kain

LSU Master's Theses

A newly identified blind-thrust fault in the southern Los Angeles basin may have substantial implications for earthquakes in the region. A previous study suggests that the Wilmington blind-thrust may link up with nearby faults to produce a multisegment (M_w 6.6–7.4) earthquake rupture. These estimates are based on the joint rupturing of the Wilmington blind-thrust, Compton, Newport Inglewood, and the Huntington Beach fault segments (~85 km total length). However, stress heterogeneity near these faults may limit the size and intensity of earthquakes when incorporated into earthquake hazard modeling. This study presents a detailed model of the stress field in this …

Quantitative Analysis Of The Maximum Rate And Minimum Duration For A 200 Km Stepwise Retreat Of The Bindschadler Ice Stream At ~11.5 Cal Kyr Bp, Matthew E Kratochvil

LSU Master's Theses

Small-scale morainal ridges on the middle continental shelf of the Whales Deep Basin partly record the rapid opening of a 200-km grounding line embayment slightly after ~11.5 cal kyr BP. The overlapping pattern of backstepped moraines indicates that the grounding line oscillated back and forth during the retreat. Published sediment fluxes were combined with new sediment volume mapping of the moraines to infer the rates at which the grounding line retreated. The analyses indicate that the rates of grounding line retreat on the eastern flank of the embayment ranged from ~490 m a^-1 to 1,300 m a^-1. …

Connections Between Interglacial Variation And Lithological Variability Within Midland Basin Permian Shale Rocks In Martin County, Texas, Helen Rice Hammon

LSU Master's Theses

The Upper Pennsylvanian (323.2–289.9 Ma) and Lower Permian (289.9-251 Ma), (Wolfcamp and Spraberry formations) interval of the Midland Basin, West Texas, contains a mixed succession of shale, carbonate, and siltstone/sandstone lithofacies that accumulated in a deep-water marine environment under variable hydrographic restrictions. The heterogenous stratigraphy found in the Wolfcamp and Spraberry formation was formed in response to variations in sea level and a transition from a glacial to an interglacial climate during the Early Permian. These fluctuations left behind alternating beds of mudstone and carbonate, interwoven with thin sandstone beds. Because the Wolfcamp and Spraberry formations are highly heterolithic, it …

Connections Between Interglacial Variation And Lithological Variability Within Midland Basin Permian Shale Rocks In Martin County, Texas, Helen Rice Hammon

LSU Master's Theses

The Upper Pennsylvanian (323.2–289.9 Ma) and Lower Permian (289.9-251 Ma), (Wolfcamp and Spraberry formations) interval of the Midland Basin, West Texas, contains a mixed succession of shale, carbonate, and siltstone/sandstone lithofacies that accumulated in a deep-water marine environment under variable hydrographic restrictions. The heterogenous stratigraphy found in the Wolfcamp and Spraberry formation was formed in response to variations in sea level and a transition from a glacial to an interglacial climate during the Early Permian. These fluctuations left behind alternating beds of mudstone and carbonate, interwoven with thin sandstone beds. Because the Wolfcamp and Spraberry formations are highly heterolithic, it …

Seismic Inversion And Modeling For Improving Earthquake Hazard Assessment, Rasheed Ajala

LSU Doctoral Dissertations

The substantial research and the uncertain timeline to achieve deterministic earthquake prediction make the ground-shaking estimation of realistic earthquake scenarios a helpful approach in seismic hazard assessment. The accuracy of these computations depends on having structural subsurface models with good representations of sedimentary basins, fault zones, and crustal heterogeneity. We develop higher resolution seismic models for the Coachella Valley in Southern California and Indo-Burma. These areas have rising populations, expanding infrastructure, and highly anticipated disruptive earthquakes. We utilize data from recent seismic deployments and newly developed seismic imaging algorithms and the techniques of travel time tomography, wave propagation simulation, and …

Gps Observations Of Subsidence In South Louisiana Over Seasonal And Sub-Seasonal Timescales Associated With Hydrologic Loading, Nicholas Schuler

LSU Master's Theses

Louisiana’s primary environmental concern is arguably coastal wetland loss due to high subsidence rates, previously estimated to range from 1-14 mm/yr across much of the coast. Spatially and temporally varying strong short-term and seasonal components of deformation associated with changes in hydrologic loading throughout the year can give information about the elastic properties of the shallow crust, having implications for better understanding long-term subsidence trends across the region. Therefore, we quantify and characterize vertical deformation that occurs on annual to sub-annual timescales across southeast Louisiana. Vertical deformation is evaluated using publicly available daily GPS positions from 2016–2020 at 16 stations …

Sediment Buffering And Recycling On An Annual To Centennial Scale Along The Mississippi River, Nikki E. Neubeck

LSU Master's Theses

Although the Mississippi River and its tributaries have been investigated for many years, the alteration of the river through dams, levees, and diversions has affected how sediment is transported from source to sink (>10³ y). Previous provenance research using detrital zircon U-Pb dating indicates a slow transport time from source-to-sink, but recent anthropogenic alterations of the river may potentially diminish the transportation time of heavy minerals due to an increase in flow efficiency. The objective of this study is to analyze the degree of buffering and recycling of Mississippi River sediment over a range of short time scales, …

Competitive Sorption And Transport Of Heavy Metals In Soil And Mn Oxide-Coated Sand, Joshua Tyler Padilla

LSU Doctoral Dissertations

This study investigated the competitive sorption of Ni, Pb, and Zn as well as synergistic interactions between Ni and phosphate (P) in soils and Mn oxide-coated sand. During stirred-flow experiments, the sorption of heavy metal cations by Olivier soil was mutually reduced when applied simultaneously. When applied consecutively, the cation of higher affinity was able to displace the cation of lower affinity from the soil surface, however, no evidence for the reverse case was observed. A novel general exchange kinetics model was able to correctly describe such displacement. Competition between Ni and Zn mutually increased mobility in Olivier and Windsor …

A Numerical Investigation Of Flood And Sediment Dynamics Over The Coastal Watersheds During Hurricane Events, Dongxiao Yin

LSU Doctoral Dissertations

Landfalling tropical cyclones can cause catastrophic floods and sediment disturbance over the coastal watersheds. This study aims to unravel the contribution of different processes to hurricane-induced flooding, to assess the uncertainties in flood modelling and forecasting, and to advance the techniques in sediment simulation over coastal watersheds during hurricanes.

First, I examined the hydrometeorology and hydrology of Hurricane Florence (2018) induced inland flooding. My results suggest that the slow motion in combination with the “L-shaped” path was the most distinctive feature of the hurricane that incurred catastrophic and widespread rainfall and flooding over the Cape Fear River Basin (CFRB).

Second, …

Application Of Gravity Data For Hydrocarbon Exploration Using Machine Learning Assisted Workflow, Oluwafemi Temidayo Alaofin

LSU Master's Theses

Gravity survey has played an essential role in many geoscience fields ever since it was conducted, especially as an early screening tool for subsurface hydrocarbon exploration. With continued improvement in data processing techniques and gravity survey accuracy, in-depth gravity anomaly studies, such as characterization of Bouguer and isostatic residual anomalies, have the potential to delineate prolific regional structures and hydrocarbon basins. In this study, we focus on developing a cost-effective, quick, and computationally efficient screening tool for hydrocarbon exploration using gravity data employing machine learning techniques. Since land-based gravity surveys are often expensive and difficult to obtain in remote places, …

Testing Xrf Identification Of Marine Washover Sediment Beds In A Coastal Lake In Southeastern Texas, Usa, Harry F. L. Williams, Chelsea E. Beaubouef, Kam-Biu Liu, Nicholas Culligan, Lance Riedlinger

Faculty Publications

This study tests the ability of a novel approach to identifying washover beds in coastal lakes. Combined X-Ray Fluorescence (XRF) and cluster analysis was used to identify hurricane washover beds in sediment cores from Clam Lake on the McFaddin National Wildlife Refuge in southeastern Texas. The lake is known to contain washover beds from recent hurricanes, but the washover sediment has similar microfossil, loss-on-ignition and textural characteristics to non-washover sediment and is not readily distinguishable. Sediment cores taken from marshes surrounding the lake do contain visually-recognizable sandy washover beds of Hurricanes Ike, Rita, Carla and Audrey. XRF analysis of these …

Assessing Mangrove Wetland Structure And Function Regulated By Environmental Gradients Under Climate Change And Increasing Human Impacts: A Modeling Approach, Xiaochen Zhao

LSU Doctoral Dissertations

Mangroves are blue-carbon-rich wetlands that can potentially contribute to climate change mitigation policies. However, mangroves are increasingly impacted by both natural and human disturbances worldwide that require restoration and rehabilitation programs to advance their conservation. Yet, there are major knowledge gaps in our understanding of how local resources (nutrients), regulators (e.g., salinity) and hydroperiod gradients interact in controlling mangrove role as carbon sink or source at different spatiotemporal scales under increasing disturbance frequency and climate change.

Here, I developed a mass-balance-based hydrology model to estimate soil porewater salinity (PWS) in riverine mangroves along the Shark River estuary (SRE), South Florida; …