Geology Commons^™

Spatial Trends And Variability Of Marsh Accretion Rates In Barataria Basin, Louisiana, Usa Using 210pb And 137cs Radiochemistry, Samuel Bryant Shrull

LSU Master's Theses

Coastal Louisiana is presently experiencing large amounts of coastal land loss with estimated rates exceeding 50 km² lost per year. In an attempt to mitigate or reverse land loss, billions of dollars are earmarked for restoration projects that promote land reclamation, habitat stabilization, and defending against saline intrusion. This study was performed in an effort to better understand spatial trends of accretion rates in Barataria Basin in coastal Louisiana. Data for this project came from twenty-five shallow cores extracted over a broad span of the entire basin, from freshwater to saline environments. Cores were processed for ¹³⁷Cs and …

A Novel Multiproxy Approach To Reconstructing Sea Surface Temperature In The Southwestern Gulf Of Mexico, Marissa Anne Vara

LSU Master's Theses

Coral Sr/Ca is a widely-used proxy for sea surface temperature (SST); however, discrepancies in the coral Sr/Ca-SST relationship among colonies of the same species makes uncertainty in absolute temperature reconstructions larger than the climate signal yet climate variability studies are possible. Furthermore, the riverine input of terrestrial carbonate weathering products to the coastal waters can disrupt the coral Sr/Ca-SST signal by changing local seawater chemistry. This study evaluates the fidelity and reproducibly of coral SST proxies (Sr/Ca, Li/Ca, Mg/Li, Sr-U, Mg/Ca, and U/Ca) and a riverine-upwelling proxy (Ba/Ca) in four Orbicella faveolata colonies in two reefs offshore from Veracruz, Mexico …

Micropaleontological Record Of A Preserved, Late Pleistocene Bald Cypress Forest On The Northern Gulf Of Mexico Inner Shelf, Jonathan Thien Truong

LSU Master's Theses

A cluster of previously buried Taxodium distichum stumps are exposed and preserved in growth position at the bottom of a trough on the inner Gulf of Mexico (GOM) continental shelf in 18 m water depth and 13 km offshore Orange Beach, AL. Radiocarbon ages from wood and optically stimulated luminescence (OSL) dating of sediments suggest a Marine Isotope Stage (MIS) 3 age, or older. This study builds on the previous work of Gonzalez (2018) and Obeclz (2017). Five biofacies were identified in vibracore collected in 2015 and 2016: 1) the Holocene Mississippi-Alabama-Florida (MAFLA) sand sheet, 2) a Holocene interbedded sand …

Reconstruction Of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis Of Subglacial Lake And Ice Stream Sediments, Patrick Baudoin

LSU Master's Theses

The West Antarctic Ice Sheet (WAIS), with a large portion being grounded below sea level, is historically known for its instability. Timing and evaluating the magnitude of WAIS advance and retreat is essential to improve our understanding of control mechanisms. The scarcity of accessible subglacial geology in areas such as the Siple Coast in West Antarctica limits our understanding and ability to gauge WAIS response to environmental changes. To evaluate the ice-sheet history around the Siple Coast, i.e., when it was last covered by vegetation, access to sediment immediately below the ice-sheet is essential. In the absence of large-scale drilling, …

Investigating Trace Metal Sequestration Of Reducing Environments In Modern And Ancient Settings, Adam Charles Turner

LSU Doctoral Dissertations

The incorporation of trace metals into a variety of reducing sediments are important proxies for the oxic state of the water mass in which the sediments form. While much work has been done interpreting these proxies, questions remain on the exact processes and products in which trace metal proxies form. This work employs bulk geochemical techniques to investigate circulation in the Late Pennsylvanian North American Midcontinent Sea (NAMS), and then uses sequential extractions to further understand the chemical phases in which trace metals are incorporated. Sequential extractions are then used to further investigate how trace metals are sequestered in modern …

Stratigraphic Reconstruction Of A Late Pleistocene Bald Cypress Forest Discovered On The Northern Gulf Of Mexico Continental Shelf, Suyapa Michell Gonzalez Rodriguez

LSU Master's Theses

A previously buried bald cypress forest (Taxodium distichum) was discovered on the continental shelf, offshore of Orange Beach, Alabama, USA, in ~20 m water depth. The forest was exhumed by Hurricane Ivan in 2004, and is now exposed as stumps in life position in a trough located in the northern Gulf of Mexico continental shelf seafloor. We are investigating the local stratigraphy, paleo-landscape, and mode of forest preservation of this unique site. In August 2015 and July 2016, submersible vibracores (18 in total) were collected. Core analysis included: bulk density and imaging via Geotek multi sensor core logger, …

Investigating Uranium Incorporation In Modern Carbonates By Sequential Extraction: Applied To The Permian - Triassic Boundary In Lung Cam, Vietnam, Christopher Michael Wray

LSU Master's Theses

The Uranium (U) isotopic system can be used to model the extent of global-scale ocean anoxia by utilizing the 238U/235U ratios as a paleo-redox indicator (δ238U). While recent studies have shown promise with the use of this novel proxy, variability is seen in modern carbonate sediment samples suggesting that more work is needed in order to understand elemental U uptake during early marine diagenesis. This thesis utilizes a sequential extraction methodology in order to understand the distribution of authigenic U within carbonate sediments.

This thesis consists of four parts, (1) an evaluation and modification of a sequential extraction methodology for …

Sh-Wave Seismic Reflection Imaging And Inversion: An Analysis Of Architectural And Physical Properties Of A Near-Surface Point-Bar, Nathan William Benton

LSU Master's Theses

Both architecture and physical properties of near-surface point-bar sediment packages have not be imaged or analyzed via SH-wave seismic reflection surveying, respectively. Point-bar architecture within near-surface environments characterized by conductive, saturated, and/or unconsolidated sediments cannot be well-imaged with other remote sensing methods compared to the SH-wave seismic reflection surveying method. The physical properties that distinguish different point-bar sediment packages are variably altered during early-stage diagenetic processes such as compaction and dewatering, thereby changing SH-wave seismic velocities and subsequently shear impedance of different sediment packages. This study accomplishes two objectives by acquiring, processing, and inverting seismic reflection data from two surveys …

Vertical Sediment Accretion In Jamaica Bay Wetlands, New York, Ryan Christopher Clarke

LSU Master's Theses

Over the last century, ~60% of the saltmarsh wetlands in Jamaica Bay (in the Gateway National Recreation Area of the Greater New York City region) have been converted to intertidal or subtidal unvegetated mudflats and projections suggest that all of Jamaica Bay’s saltmarsh wetlands may disappear within the next two decades. After landfall of Hurricane Sandy in 2012 and to better understand environmental controls on the maintenance of the remaining Jamaica Bay wetlands, cores were collected from twelve saltmarsh locations in the bay to study the chronology of wetland vertical accretion and mineral sediment accumulation. In association with the United …

Topographic Control On Post-Lgm Groundings Of The West Antarctic Ice Sheet In The Whales Deep Basin, Eastern Ross Sea, Matthew Danielson

LSU Master's Theses

By the peak of the Last Glacial Maximum (LGM), the West Antarctic Ice Sheet (WAIS) had advanced to the outer continental shelf of eastern Ross Sea trough basins. During the post-LGM retreat, the WAIS paused several times within 75 km of the Whales Deep Basin (WDB) shelf edge. An overlapping stack of seven grounding zone wedges (GZWs) records the locations of these groundings. Here we used ~7500 km of seismic reflection data to map the subglacial unconformity that was eroded when WAIS was grounded at the shelf edge, i.e., prior to the deposition of the backstepping GZWs. With respect to …

Signal Propagation, Provenance, And Climate Records In The Indus Submarine Canyon Since The Last Deglacial, Yuting Li

LSU Doctoral Dissertations

The Monsoon is one of the most powerful climatic phenomena on Earth and controls environments in South Asia. Erosion and weathering patterns are influenced by monsoon variations and can be reconstructed through marine sediment records. However, such reconstruction is based on the assumption that such sediments are representative of the onshore basins from which they are sourced. Debate continues regarding the degree to which storage and recycling homogenize short-term variations in sediment compositions. The Indus Submarine Canyon links the river mouth and the deep-water fan of the Indus drainage system. Determining how sediment fluxes through this canyon is important if …

Natural And Anthropogenic Impacts On Sediment Dynamics And Preservation In Contrasting Mississippi Deltaic Coastal Environments, Jiaze Wang

LSU Doctoral Dissertations

Deltas worldwide share the same sinking problem in face of pressure from natural and anthropogenic activities. Many restoration strategies are being planned or have been implemented in the coasts around the world. However, many conventional hard structure constructions are energy-intensive. There are also associated uncertainties and limitations on the effectiveness and sustainability of these restoration plans. Soft or ecological engineering strategies normally take advantage of or mimic the coastal system self-response and feedbacks to natural and anthropogenic activities. The successful implementation of soft strategies relies on process-based studies on the change of complex coastal system. In addition, post-implementation monitoring work …

Evidence Of Subglacial Brine Inflow And Wind-Induced Mixing From High Resolution Temperature Measurements In Lake Bonney, Antarctica, Jade Lawrence

LSU Master's Theses

Hypersaline brine beneath Taylor Glacier enters proglacial West Lobe Lake Bonney (WLB) subglacially as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the water column of WLB. Because of the extremely high salinities below the chemocline in WLB, density is determined almost entirely by salinity and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude in to the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. This study …

Combining Downhole And Sediment Logging To Understand Spatial Variability In Grain-Size, Facies, And Reservoir Quality Of A Large-Scale Mississippi River Point Bar, False River, Louisiana, Elizabeth D. Olson

LSU Master's Theses

Although the general processes by which meandering river point bars are constructed have been known for some time, there is a lack of clarity regarding why small-scale heterogeneities develop. This is especially true in the largest meandering river systems, which are equivalent to some of the most important hydrocarbon reservoirs in the world. In this study, we evaluate the stratigraphic architecture of the 80 km² False River Point Bar System on the Lower Mississippi River and use the knowledge gained to better comprehend point bar construction at different phases. Previous studies of small to medium-scale systems have been unable …

How Dredge Pits Evolve Over Time: A Look At Their Geomorphologic Evolution And Infilling Processes, Patrick Robichaux

LSU Master's Theses

As coastal environments become more susceptible to land loss through accelerating sea level rise and subsidence, new restoration methods harnessing borrowed sediment are more valuable than ever. Mud-capped dredge pits (MCDPs) are a relatively new source of restoration-quality sediment that has only recently been utilized for beach and barrier island restorations in Louisiana. Because MCDPs have been in use for less than two decades in only a handful sites, little is understood about their evolution over decadal timescales. To improve our understanding of MCDPs after they are dredged, we have conducted a suite of geophysical surveys including bathymetry, sidescan sonar, …

Paleoenvironmental Variation And Provenance Records From Neogene Deep Sea Sediment Of The South China Sea, Chang Liu

LSU Doctoral Dissertations

I employed several paleoenvironmental proxies by utilizing deep sea sediment from the largest marginal basin in east Asia, namely the South China Sea (SCS), to reconstruct the long term paleoenvironmental variation in SE Asia since the Neogene. Sediments deposited within the SCS were mainly delivered by several major fluvial systems whose catchment basins cover several geological blocks in SE Asia. By analyzing the sediment’s geochemical and mineralogical characteristics, several indices which are affected by the source of the sedimentary influx, as well as the weathering state could be built and applied to constrain my paleoenvironmental reconstructions

Two deep sea drilling …

When, How, And Why Did The West Antarctic Ice Sheet Retreat In The Ross Sea Since The Last Glacial Maximum Using Foraminiferal And Porewater Geochemistry, Matthew Decesare

LSU Doctoral Dissertations

The Antarctic Ice Sheets (AIS) began to retreat from their Last Glacial Maximum (LGM) position sometime after 19,000 years ago. However, the corrosive waters circulating around Antarctica has prevented the recovery of radiocarbon-dateable material, hindering the development of deglacial chronologies. During Expedition NBP1502B to the eastern Ross Sea, an unprecedented quantity of fossil foraminifera and bivalves were recovered. Radiocarbon-dated specimens have been used to constrain the timing of West-AIS retreat from Whales Deep basin and Ross Bank. Whales Deep samples show that the WAIS retreated from its LGM position on the continental shelf edge by 14,700 ± 400 calibrated radiocarbon …

Overbank Deposition Of Sand And Mud Within Two Point Bars Bound By The Mississippi River Levee System: Implications For Coastal Restoration Sediment Budgets, Christopher Magliolo

LSU Master's Theses

As ongoing Mississippi River sediment diversion projects are being developed and planned, the availability of sand and mud for use in the lower Mississippi River Delta is being calculated and budgeted. This project attempts to quantify the amount of sand and mud being lost from the lower Mississippi River past the Old River Control Structure in the remaining unleveed floodplains, an area that encompasses 270 km². Two land masses were chosen along each bank of this reach of the Mississippi River: Raccourci Island (west bank) and the Cat Island National Wildlife Refuge (east bank). Seventeen sediment cores were …

Influences Of Hurricanes, Floods, And Organic Production On River-Delta Evolution Over Decadal To Centennial Time-Scales, Crawford M. White

LSU Doctoral Dissertations

Episodic overbank flooding and sediment resuspension events (such as cold front passages or tropical cyclones) are recognized as important natural components for wetlands maintaining vertical equilibrium with sea-level. However, the relative importance of these components to an anthropogenically unmodified delta complex remains unclear. This study uses sediment cores to describe the relative importance of these vertical accretion components the Lafourche and Balize Deltas of the Mississippi River. Existing wetlands of the abandoned lower Lafourche receive no direct fluvial sediment, but instead are supported by sediment resuspended by tropical cyclones and cold fronts that pass over them. Wetlands of the modern …

Investigating Core Shale Depositional Environments Of Late Pennsylvanian Cyclothems Utilizing Geochemical Proxies To Test The Superestuarine Model, Bryce A. Mathis

LSU Master's Theses

The Late Paleozoic Midcontinent Sea (LPMS) inundated vast areas of the North American interior during glacio-eustatic transgressions, depositing widespread black shales facies within the core shale intervals of major cyclothems. These black shale deposits are unique because no modern analogs can adequately explain the depositional environments and model for organic matter preservation across such vast ancient epicontinental settings. One possible explanation is that a superestuarine circulation system developed across the LPMS during humid interglacial phases, which promoted strong water column stratification and benthic anoxia.

The goal of this research was to test the validity of the superestuarine estuarine model and …

Facies Reconstruction And Stratigraphy Of A Late Pleistocene Bald Cypress Forest Discovered On The Northern Gulf Of Mexico Continental Shelf, Suyapa Gonzalez-Rodriguez

Honors Capstones

No abstract provided.

Facies Reconstruction And Stratigraphy Of A Late Pleistocene Bald Cypress Forest Discovered On The Northern Gulf Of Mexico Continental Shelf, Suyapa Gonzalez

Honors Capstones

No abstract provided.

Stratigraphic Analysis Of Florissant Fossil Beds National Monument Using Magnetic Susceptibility, Geochemical Comparison, And Gamma Ray Spectroscopy, Jennifer Kenyon

Honors Capstones

No abstract provided.

Using Foraminifera Shell Geochemistry To Test Proxies For Paleoenvironmental Reconstruction, Catherine Hudson

Honors Capstones

No abstract provided.

On The Amount Of Sediment Deposited In Floodplains From The Mississippi River: A Case Study In Cat Island National Wildlife Refuge, Louisiana, Matthew Smith

Honors Capstones

No abstract provided.

Consolidation And Suspension Of Mud From Lake Lery And Relevance To Wetland Restoration In Louisiana, Edward L. Lo

Honors Capstones

No abstract provided.

Microbially Mediated Carbonate Precipitation Within Microbial Mat In Hyper-Saline Lakes Of The Bahamas, Shane Cone

Honors Capstones

No abstract provided.

Reinterpreting The Stratigraphy Of The Florissant Fossil Beds National Monument Through Correlation By Magnetic Susceptibility And Geochemical Comparison, Lindsay Prothro

Honors Capstones

No abstract provided.

Eastern Mediterranean Pore Waters: Clues Into The Geochemical Pathways From Evaporated Seawater To Basinal Brines, Jessica A. Mumphrey

Honors Capstones

No abstract provided.

The Storm 2.0 Project Next Generation Hurricane Data Collection, Santhana Krishnan Balaji

Honors Capstones

No abstract provided.