Physical Sciences and Mathematics Commons^™

History Of Ice-Rafting In The Arctic Ocean During Glacial Maxima Through Marine Isotope Stage 6, Shannon M. Cofield

OES Theses and Dissertations

Numerous studies attempted to reconstruct Arctic paleoclimate, specifically ice mass timing and locations, during glacial maxima. While some regions, like the Barents-Svalbard Ice Sheet (BSIS) are well-studied, they may benefit from a high-resolution paleo proxy. Other regions are highly contested, such as the East Siberian Sea or the presence of a central Arctic Ocean ice mass.

This research uses an Fe-grain provenance method to (1) define how the BSIS behaved during Marine Isotope Stage (MIS) 2, 4, and 6, and when it retreated; (2) determine the presence and ages of Shelf Ice Masses (SIMs) in the Beaufort Sea and East …

Reconstructing Surface Water Carbonate Ion Concentration Changes In The Eastern Equatorial Pacific Across Glacial Transitions, Lenzie Gail Ward

OES Theses and Dissertations

Today, the eastern equatorial Pacific (EEP) plays a critical role in the global CO₂ budget as a major source of CO₂ to the atmosphere, but recent studies suggest the region may shift to a sink for atmospheric CO₂ under different climate states. Here, I focus on two transitional periods, the last deglaciation (25 kyr to present) and last glaciation (the Marine Isotope Stage (MIS) 5a-4 transition, 96 to 60 kyr), to investigate how the carbon system in the EEP responds to major climate changes. I measured B/Ca ratios in the planktic foraminifera Globigerina bulloides from core MV1014-17JC …

Constraining Respired Carbon Storage In The Eastern Tropical Pacific Over The Last 25 Thousand Years Using Benthic Foraminiferal Boron/Calcium Ratios, Brian James Close

OES Theses and Dissertations

The storage of inorganic carbon in the deep Pacific Ocean is thought to play an important role in regulating both glacial-interglacial and millennial-scale atmospheric CO₂ concentrations (Broecker and Barker 2007; Sigman et al., 2010). A recent study by Loveley et al. (2017) showed that sedimentary authigenic uranium (aU) concentrations, a proxy for suboxic bottom-water conditions, increased significantly in the Eastern Equatorial Pacific (EEP) during the Last Glacial Maximum (LGM, 18 kyr – 23 kyr). If this is correct, the low-oxygen, CO_2-rich waters would also have a lower pH and a lower carbonate ion concentration ([CO₃^{2- …}

Circum-Arctic Mineralogy & Pan-Arctic Chronostratigraphy Of Late Pleistocene Sediments: Developing A Comprehensive Age Model For The Western Arctic Ocean Using Unique Ice-Rafted Signals, Wesley Blake Myers

OES Theses and Dissertations

To improve understanding of geographic mineral distribution from the circum-Arctic Ocean, samples from the Arctic periphery were collected and analyzed for (semi-) quantitative mineral composition. Most samples were collected from the North American region of the Arctic Ocean, a region which has had limited mineral investigation. In addition, more than 1000 published clay mineral data points were gathered to provide the most comprehensive clay mineral distribution map to date. The identification of a smectite source within the Canadian Arctic may reduce the usefulness of this mineral as a unique provenance signal for the Eurasian region. Smectite speciation may be useful …

Sediment Resuspension In A Microtidal Estuary: Causative Forces And Links With Algal Blooms, Samantha C. Mcgill

OES Theses and Dissertations

After years of efforts to restore the Chesapeake Bay, bacterial levels are down and species diversity has increased, however, algal blooms (primarily dinoflagellates) persist, occurring nearly every summer. Dinoflagellates produce resting cysts that accumulate in the bottom sediments and are thought to provide seed populations for future algal blooms when they are resuspended. When estuarine sediments are advected from a bed, other materials, such as pollutants, nutrients, and organic matter are also released into the water column. Thus, resuspended sediments can contribute to the degradation of water quality, habitat, and aquatic life, and impart negative impacts on local ecosystems and …

Persistence Of Depositional Features In A Strongly Seasonal, Tide-Dominated Delta, Kallie Flaxington Brown

OES Theses and Dissertations

The Ganges-Brahmaputra-Meghna (GBM) Delta is one of the largest deltas in the world, covering more than 100,000 km². The GBM River system transports over one billion tons of sediment annually and delivers ~750 million tons to the Bay of Bengal, ~25% of which is advected by tides into the fluvially abandoned western delta plain. The Sundarbans National Forest (SNF) is located within the GBM Delta and, covering more than 10,000 km², is the world’s largest continuous mangrove stand. The present rate of sediment delivery allows the SNF platform elevation to keep pace with regional sea level …

The Effect Of Evapotranspiration On The Groundwater Dome And Past Drought Conditions At Cape Henry, Virginia, Bryce Omar Shoup

OES Theses and Dissertations

First Landing State Park, located in Virginia Beach, is a cuspate foreland developed from a succession of erosional and progradational events forming a series of dunes and interdunal swales. Low-lying swales dominate the southern portion of the park forming many wetlands, but the northern portion of the park has fewer wetlands. An asymmetric groundwater dome has been observed on Cape Henry, cresting north of the geographic center of the cuspate foreland. The purpose of this study was to determine if the wetlands that dominate the southern portion of the park are the major driver of the asymmetric groundwater dome and …

Precipitation And Sea Level Rise Impacts On Groundwater Levels In Virginia Beach, Virginia, Brett A. Buzzanga

OES Theses and Dissertations

Global sea level rise (SLR) is one of the most immediate impacts of climate change, and poses a significant threat to low-lying coastal communities worldwide. The metropolitan region of Hampton Roads in Southeastern Virginia is one such community, and one where knowledge surrounding SLR is rapidly accumulating. However, most of the research is focused exclusively on surface water processes despite the presence of a shallow groundwater table closely connected to them. SLR will continue to cause the groundwater table to increase in tidally influenced areas of Hampton Roads, and thereby decrease storage capacity of the unsaturated zone.

This study investigates …

Groundwater And Tidal Controls On Wetland Hydrology, Julie J. Metz Wetland Mitigation Bank, Woodbridge, Virginia, Benjamin Stuart Hiza

OES Theses and Dissertations

Julie J. Metz Wetlands Mitigation Bank, a 92-hectare freshwater wetland located in Woodbridge, Virginia, borders the tidally-influenced Neabsco Creek. Seven pods separated by earthen berms were built by Wetland Studies and Solutions Inc. (WSSI) in 1995 and 1997 by removing the toe of small sandy alluvial fans and covering the underlying coarse gravel bed with a low permeability cap. The basal Quaternary gravels were deposited in a creek valley incised into a thick sand-and-clay Cretaceous delta. The alluvial-fan apron developed at the base of steep slopes along the sides of the valley. Pressure transducer data from five monitoring wells along …

Hydrologic Response Caused By Wetland Expansion At Huntley Meadows Park In Hybla Valley, Virginia, Stephen Fraser Stone

OES Theses and Dissertations

The goal of this study was to understand the effects of wetland expansion across a watershed. The 2013 restoration and expansion of the wetlands at Huntley Meadows Park (Fairfax County, VA) performed by Wetland Studies and Solutions, Inc. provided the opportunity to study this process. The 630 ha park contains more than 364 ha of freshwater emergent and freshwater forested wetlands. The restoration and expansion project used a subsurface vinyl-piling dam that impedes groundwater flow leaving the wetland, thus expanding the existing pond and the surrounding wetland.

This study used a network of more than twenty monitoring instruments making observations …

Reevaluating The Geologic Formations Of The Upper Coastal Plain In Chesterfield County, South Carolina, Bradley Aaron Fitzwater

OES Theses and Dissertations

Data from a new geological map of the Patrick, S.C. 7.5 minute quadrangle (1:24,000) and detailed descriptions of two cores collected nearby (Middendorf and Cheraw, S.C.) permit improved interpretation of the geology of this portion of the Carolina Sandhills. Geologic mapping incorporated analyses of outcrops with LiDAR data, soil survey maps, ground-penetrating radar transects, and hand auger borings. Micro- and macrofossil identification and optically-stimulated luminescence (OSL) dating provided age control.

Four distinct mappable units occur throughout the Patrick quadrangle. Resting unconformably on schist of the Paleozoic Persimmons Fork Formation, the Cretaceous Middendorf Formation is more than 85.3 m thick and …

Crustal Accretion And Mantle Geodynamics At Microplates: Constraints From Gravity Analysis And Numerical Modeling, Katherine Ames

OES Theses and Dissertations

This study investigates crustal accretion and mantle geodynamics at microplates using mantle Bouguer anomaly (MBA) gravity calculations and exploratory numerical models. The Easter and Juan Fernandez microplates are located in the eastern Pacific Ocean along the Pacific, Nazca, and Antarctic plate boundaries. Both microplates formed 3-5 Ma and they are currently rotating clockwise at 15° myr^-1 and 9° myr^-1,respectively [ e.g., Searle et al., 1993]. The study area also encompasses the Easter /Salas y Gomez mantle plume located near the Easter microplate. Both microplates show a difference in average MBA between their west and east ridges, with …

Hydrogeologic Variations Across A Barrier Island That Influence Inter-Dune Wetlands False Cape State Park, Virginia, Matthew Collier Richardson

OES Theses and Dissertations

False Cape State Park in southeastern Virginia Beach, Virginia contains a transgressive barrier island complex. Inter-dune swales located on the eastern coast of the barrier island contain soils that experience hydric conditions. However, these swales lack the prolonged presence of hydric soil indicators that are necessary for a site to be officially recognized as a jurisdictional wetland. The appearance and subsequent disappearance of redoximorphic wetland soil features in the young, sandy soils of the inter-dune swales here may stem from changes in the patterns of groundwater recharge and discharge across the island. These soils are being monitored by the Mid …

Gravity Anomalies Along The East Scotia Ridge: Constraining The Relative Importance Of Magmatic And Tectonic Controls On Crustal Accretion, Briton Lee Nicholson

OES Theses and Dissertations

Similar to regions such as the Lau Basin and the Caribbean Sea, the eastern Scotia Sea is a geologically complex area that involves multiple plate boundary types. This study uses bathymetry and gravity data to infer upper mantle geodynamics in the eastern Scotia Sea region. Beneath this region is an intermediate-rate back-arc spreading center known as the East Scotia Ridge (ESR) that forms the boundary between the Scotia and Sandwich plates. To the east of the ESR are the South Sandwich island arc and the South Sandwich Trench. The ESR is a relatively young feature, with spreading estimated to have …

A New Phase Speciation Leaching Procedure For The Determination Of Metals In Oxic And Anoxic Sediments, Brandon R. Gipson

OES Theses and Dissertations

Toxic trace elements such as cadmium, lead, chromium, and arsenic released by human activities can accumulate in marine and estuarine sediments, where these metals are often sequestered until local environmental changes (e.g., redox, salinity, and/or pH) allow these elements to be reintroduced into the food web. In order to assess the extent of toxic trace element contamination in sediment, numerous leaching schemes have been developed that separate sediment-bound trace metals into operationally defined geochemical phases. These "phase speciation" leaching schemes are typically designed with the purpose of being used on either oxic or anoxic sediments. However, natural sediments often contain …

Microtextures Of Cyanobacterial Mats In Siliciclastic Sedimentary Environments (Modern & Ancient): Applications To The Search For Life On Mars, Dina M. Bower

OES Theses and Dissertations

The current Mars Exploration Rover Program (MER) is one of NASA's most successful missions. The aim of the MER is to explore for possible life on the surface of Mars. My thesis developed new methods of how to detect and to identify microbial mats in siliciclastic sediments (modern and ancient), and to make recommendations on the applicability of MISS as biosignatures. Predominantly, I employed instrumentation portable by future rovers. To search for life on other planets, we need to have information on how this life might look. Most astrobiological studies therefore focus on Earthly analogues of life and its habitats. …

Cave Development In Strata Of Ordovician-And Silurian-Devonian-Age In Highland County, Virginia, Carol Ann Peterson

OES Theses and Dissertations

Picturesque Highland County, Virginia, also known as "Virginia's Little Switzerland", is characterized by high mountains, tranquil rivers, and hundreds of caves. This study determines how geologic structures and processes control speleogenesis, or cave development, in the county. Solutional caves in Highland County are found in Ordovician limestones and dolostones and in Silurian- to Devonian-age limestones. Despite the lithologic and structural differences between the strata, caves in both sections tend to be similarly joint-controlled in directions of both regional strike (N40°E), dip (northwest or southeast), or in fractures intersecting at 60 and/or 120 degrees. Brittle failure, including fractures and faults induced …

Condensed And Expanded Sections In The Lower Mesaverde Clastic Wedge, Campanian Of Wyoming: Evidence For Tectonic Rectification Of Sea Level, Matthew W. Botzler

OES Theses and Dissertations

The stratigraphy of the Cretaceous Western Interior basin indicates that sea level oscillated during the late Cretaceous. The oscillations were polyharmonic, with periods ranging from millions of years to hundred thousands and ten thousands of years. However, there is disagreement over the extent to which sea level change was global in nature and the extent to which it was driven by local uplift or subsidence (tectonism). In orogenic regions where subsidence, sediment supply, and eustatic variation are all affecting sea level, comparisons of high and low frequency cycles can help to sort out forcing mechanisms. Low frequency eustatic sea level …

Investigation Of A Possible Lead-Lag Relationship Between The Innuitian And Laurentide Ice Sheets, Arctic Canada, Paula Zimmerman

OES Theses and Dissertations

Peaks of iron-rich grains in Arctic Ocean sediment cores matched to the Laurentide and Innuitian Ice Sheets appear to show a lead-lag relationship during the Late Pleistocene when grain abundances are plotted against time and depth below sea floor. Cores from across the Arctic have been analyzed to determine if this is the case. Of the six IRD events identified, the Innuitian leads 68% of the time with 26% of events in all cores occurring simultaneously. The Innuitian seems to lead 33.3% of the time when peaks from the Innuitian and Laurentide occur within close proximity (less than 1 cm), …

Correlation And Causes Of Fifth Order Cycles Within The Upper Cretaceous Eagle Formation, Bighorn Basin Of Wyoming, Kimberly Ann Johnson

OES Theses and Dissertations

Cyclic stratification was examined in the Upper Cretaceous (Santonian-Campanian) section (Eagle Formation) within the Bighorn Basin of Wyoming. Of particular concern was the 10³ to 10⁴ year band, which in marine settings has been attributed to orbital forcing (Milankovitch cyclicity). A series of 19 sections were measured through the Virgelle Member of the Eagle Formation. Most were measured on the “J”-shaped escarpment that constitutes the nose and north flank of the Thermopolis anticline. Several others were measured at sites up to 30 km to the northwest along paleo-shoreline. In the study, detailed thickness data of all sections and …

Hydrologic Variations Within Created And Natural Wetlands In Southeastern Virginia, Aaron Dyer Despres

OES Theses and Dissertations

The hydrology of wetlands, particularly how wetland soils collect, store, and redistribute water strongly affects how wetland systems function. In created wetlands, construction processes and materials influence the hydrology and consequently, the potential for successful reestablishment of target vegetation communities. During .2002- 2004, the Virginia Department of Transportation constructed large mitigation wetlands on two different Quaternary aged surfaces with very similar hydrogeomorphic conditions. The Sandy Bottom Nature Park site (SBNP) located in Hampton, VA and rests on the sandy loam Tabb Formation while the Charles City Wetland site (CCW) lies on the older and clay-rich Shirley Formation. This study documents …

Anthropogenic Lead Deposition And Four National Parks In Poland As Determined By Lead Isotope Ratios, Shannon Simcoe

OES Theses and Dissertations

Polluted soils are recognized by having high concentrations of heavy metals, including Pb. Partitioning of metals in geochemical fractions, by sequential chemical extractions, may indicate whether a metal has been recently deposited in the soil. While concentration levels alone cannot distinguish between natural and anthropogenic Pb, studies have demonstrated that anthropogenic pollution is accurately recorded by specific Pb isotope signatures, which differ from natural Pb isotopes. The objective of this project was to use ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁶Pb/²⁰⁴Pb isotope ratios to differentiate between the anthropogenic Pb input and the naturally occurring Pb in four national …

Dissolved Humic Substances: Characterization Of Their Sorption Onto Iron Hydroxide Aluminum Hydroxide Kaolinite And Smectite, Sarah E. Diebel

OES Theses and Dissertations

Humic (HA) and fulvic (FA) acids participate in many geochemical processes and the mechanisms of their sorption to colloidal surfaces are numerous, indicating these substances are complex and heterogeneous. The current study focuses on the interactions of the Fe hydroxide (FE), Al hydroxide, Kaolinite (KA) and Smectite (SM) and these naturally occurring organic acids using Fourier Transform Infrared Spectroscopy (FTIR) and DOC analysis at pH 4. FTIR was used for the initial functional group characterization, as well as the comparison of before and after adsorption spectra of the HA and FA. DOC examined the amounts of HA and FA adsorbed …

Dynamical Sedimentary Models Of Shallow Marine Environments, Yong Zhang

OES Theses and Dissertations

This treatise represents a contribution of quantitative, dynamical sedimentary modeling to the analytical understanding of sedimentary processes in shallow marine environments. The dynamical sedimentary models in this treatise numerically simulate the sedimentary processes from an event time scale, based on the fundamental physics of sediment dynamics in coastal and shelf depositional environments, to a longer, facies time scale. The simulated geologic processes serve to the illustrate shoreface equilibrium profile, shelf storm bed generation, and the shelf sedimentary facies system.

This treatise presents a nearshore profile evolution model for the abandoned Huanghe Delta, a two-dimensional storm deposition model, and a sedimentary …

Effects Of Organic Matter And Iron-Rich Clay On Mobility Of Trace Metals From Flue Dust Contaminated Soil, Scott Ephraim Lewis

OES Theses and Dissertations

The enhanced leaching of trace metals through soil becomes a concern for human health if dissolved trace metals reach groundwater and migrate into a public water system. A serial batch extraction procedure was implemented to determine the effects of Vitagrow © organic matter and Fe-Rich TM clay on the mobility of trace metals (Zn, Pb, and Cd) from a flue dust treated (0, 600, 1200, and 2400 μgig Zn) Appling soil.

The addition of an organic matter (OM) amendment to the Appling soil enhanced Pb mobility and reduced soluble Zn and Cd. In general, average solution concentrations of trace metals …

The Geomorphological History Of An Alluvial Fan Complex In Nelson County, Virginia, Melinda Ann Youngblood

OES Theses and Dissertations

An alluvial fan complex blankets a portion of the Rockfish Valley in Nelson County Virginia, located along the eastern slope of the Blue Ridge Mountains. The seven-km² field area contains three mappable relict alluvial surfaces (Qf1, Qf2, and Qf3) and one modern surface (Qa1), each of which is underlain by fluvial deposits dominated by greenstone and charnokite cobbles. The four surfaces were mapped according to topographic position and degree of stream dissection. Alluvial deposits underlying each surface were characterized using a 3-part clast weathering scale based on greenstone clast weathering rinds and using soil development criteria (clay content, Munsell …

A Paleoenvironmental Study Of A Middle Wisconsinan Biota Site, Russell County, Virginia, Thomas C. Wynn

OES Theses and Dissertations

The study area lies in a first-order valley on the northwestern slope of Clinch Mountain that drains into Moccasin Creek. The deposit is 50 m long, 25 m wide and approximately 10 m thick and overlies the Ordovician Moccasin Formation. Preserved within the deposit are mammoth and mastodon bones, logs, and plant macrofossils. Radiocarbon analyses indicate the age of the organic-rich sediments ranges from 29, I 00 BP to >44,000 BP, a time period with no fossil remains reported in this region of the Appalachians. Analyses of field observations, textural data, organic carbon content, and plant macrofossils indicate the organic-rich …

Biostratigraphic Analysis Of Southern Florida's Plio-Pleistocene Shell Beds, Dalton L. Rasmussen

OES Theses and Dissertations

Four molluscan assemblage zones in southern Florida corresponding to the Pinecrest Sand Member of the Tamiami Formation, and the Caloosahatchee, Bermont and Fort Thompson shell beds were identified following quantitative and qualitative analyses of the fossil molluscan fauna. Twenty-eight bulk sediment samples collected from 16 localities across southern Florida were processed for fossil material, and yielded nearly 60,000 specimens belonging to 311 species. A Q-mode cluster analysis compared sediment samples on the basis of 188 species whose abundances had been converted to binary presence-absence form. The cluster analysis was run four times using the Jaccard and Dice similarity coefficients as …

The Effects Of Organic Matter Rich Topsoil On The Germination Growth And Metal Uptake Of Corn (Zea Mays) Grown In Flue Dust Contaminated Soil, Christopher Allen Impellitteri

OES Theses and Dissertations

The large biomass of corn (Zea mays) and promising results from a previous experiment (Chlopecka and Adriano, 1995) concerning metal uptake by corn indicate that corn may be a good candidate for phytoremediation of trace metal contaminated soil. Appling soil (acid, thermic, typic paleudult) was treated with increasing levels of a metal rich flue dust based on Zn concentration (0, 150, 300, 600, 1200, and 2400 mg/kg). Four replicates at each Zn treatment level were either limed to pH 6.3-6.5 and covered with a two inch thick layer of organic matter rich topsoil (OM), unlimed and covered with …

Ice Transport In The Queen Elizabeth Islands, Canadian Arctic Using Detrital Fe Oxide Grain Composition, Duan Li

OES Theses and Dissertations

Nine Fe oxide mineral types (45pm-250pm) separated from 54 glacial and glaciomarine sediment samples from the Queen Elizabeth Islands (QEI) of Canada were analyzed for 12 elements by electron microprobe to determine the dispersal patterns of ice rafted debris in this area. Both cluster analysis and discriminant function analysis (DFA) on the chemical compositions were used to match each detrital Fe oxide grain to a source The entire QEI area can be subdivided into eight unique areas based on the elemental composition of the Fe oxide minerals. These subdivisions are similar to the source areas based on the assemblage of …