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- …}

A Comprehensive Evaluation Of C25 Highly Branched Isoprenoid Alkenes Of Marine Diatoms As Proxies For Sea Ice Extent In The Arctic Ocean, Tetiana Muniak

OES Theses and Dissertations

Sea Ice extent is one of the major factors regulating carbon cycling and ecosystem function in the modern Arctic Ocean. It is an essential component of climate models and is crucial for the evaluation of various oceanographic processes that influence a particular region. Yet it is also one of the most difficult attributes of the ocean with respect to our ability for its accurate reconstruction from paleo records. The lack of the detailed records prior to satellite information has encouraged the development of new proxy records for the reconstruction of past

sea ice conditions. In recent years, a new monounsaturated …

Correlating Late Pleistocene Deposits On The Coastal Plain Of Virginia With The Glacial-Eustatic Sea-Level Curve, Timothy Wullschleger Scott

OES Theses and Dissertations

Late Pleistocene sediments mapped along Virginia's southeastern coastal plain record deposition by high-frequency cycles during isotope stages 5 to 1. Correlations between several geologic units both south (S) and east (E) of the Chesapeake Bay have proven difficult due to insufficient dating methods. To improve these regional correlations, two members of the Tabb Formation on Virginia's southside and two formations on the southern Delmarva Peninsula were selected for stratigraphic analyses. Ground penetrating radar provided geologic details in areas where samples were collected for optically stimulated luminescence (OSL) dating. The stratigraphically older units, Sedgefield Member of the Tabb Formation (S) and …

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 …

40Ar/39 Ar Geochronology Of The Lowland Creek Volcanic Field And Its Temporal Relations With Other Eocene Volcanic Areas, Vladimir Olegovich Ispolatov

OES Theses and Dissertations

Exposures of the Eocene Lowland Creek Volcanics (LCV) cover an area of 2000 km² in southwestern Montana, and consist of basal elastic deposits, felsic tuffs, and felsic and intermediate lavas with an aggregate thickness of about 2 km. New ⁴⁰Ar/³⁹Ar dates show that volcanic activity lasted for at least 4.2 million years (52.7- 48.5 Ma), or even longer (4.5-4.7 million years: from 53.0-53.2 Ma to 48.5 Ma). During evolution of the volcanic field, early explosive volcanism was gradually replaced by extrusive activity. During the transition period (52.7-51.5 Ma), the two volcanic styles coexisted.

The evolution of …

Middle Shoreface Intervals: Evidence Of Barred Nearshore Systems In He Stratigraphic Record, James V. Gravette

OES Theses and Dissertations

An interpretation for middle shoreface (MSF) intervals was developed by comparing MSF intervals from the Upper Cretaceous (Campanian) Blackhawk Formation, east-central Utah, with conceptual models proposed for modern nearshore areas. Specifically, MSF intervals identified within the Sunnyside Member were compared with MSF intervals identified within the Spring Canyon (Kamola and Van Wagoner, 1995) and the Aberdeen (Kamola, unpublished data) members.

A comparison of MSF interval data revealed that MSF intervals occur stratigraphically between upper and lower shore face deposits, disrupting the standard vertical succession for nearshore marine deposits (consisting of offshore, lower shore face, upper shore face, and foreshore deposits). …

Late Cretaceous Foraminifera As Indicators Of Sequence Boundaries, Book Cliffs, Utah, U.S.A., Kimberly A. Smith

OES Theses and Dissertations

Foraminiferal assemblages were described from three different depositional settings within the Upper Cretaceous (Campanian) Blackhawk Formation of Utah (known marginal marine environments, known marine environments, and along a suspected sequence boundary). Assemblages from the known marginal marine setting (as defined by sedimentologic-stratigraphic criteria) consisted of entirely agglutinated taxa dominated by Textularia sp. A. Assemblages from the known marine environment consisted of a mix of calcareous and agglutinated species, dominated by calcareous species (e.g., Gavelinella talaria). The foraminiferal assemblages from these known environments provide independent evidence that these sampled areas are characterized by marginal marine and fully marine deposits.

The foraminiferal …

The Dinoflagellate Flora Of The Late Oligocene - Early Miocene Old Church Formation Mid-Atlantic Coastal Plain, Alan P. Hoffmeister

OES Theses and Dissertations

The Old Church Formation contains the only presently known exposed Oligocene sediments in the North American mid-Atlantic Coastal Plain. Some ambiguity concerning the exact age of the Old Church Formation exists because it may include both Oligocene and Miocene sediments. Two outcrops and four cores containing the Old Church Formation were examined for dinoflagellates to determine the composition of the dinoflagellate flora in the Old Church Formation, the age of the Old Church Formation as indicated by this flora, general depositional environment of the Old Church Formation and correlative relationships of the Old Church Formation with other Coastal Plain units. …

Lithofacies Of The Pliocene-Pleistocene Lucayan Limestone, Great Abaco Island, Little Bahama Bank, Mary K. Mullen

OES Theses and Dissertations

Petrographic and sedimentologic analyses of eleven shallow subsurface cores (3 to 19 meters in length) from the Lucayan Limestone where it occurs along northeastern Great Abaco Island (little Bahama Bank) are used to delineate five carbonate lithofacies. The most prevalent lithofacies is a mottled, nonskeletal, peloidal packstone to grainstone. Other lithofacies include a rudstone, a laminated nonskeletal grainstone, a crossbedded grainstone and a mudstone-wackestone.

Cementation varies from poor to very well cemented core intervals. Cements observed included equant granular, equant blocky, drusy, meniscus, and needle fiber "whisker" cements. These cements reflect a variety of diagenetic environments such as the vadose, …

Paleobathymetric Interpretation Of Pleistocene Sediments In The South Padre Island Area, Northwestern Gulf Of Mexico, Using Benthic Foraminiferal Morphology, Karen Ianthe Kruebbe-Belwood

OES Theses and Dissertations

This study tested the validity of using intraspecific variation in benthic foraminifera as a means for determining Pleistocene paleobathymetry. Canonical variate analysis was used as a means for determining visually undetectable but statistically significant differences in the morphology of selected species. Two species, Cassidulina subglobosa and Uvigerina peregrina, were collected from Pleistocene well cuttings from the northwest Gulf of Mexico. The canonical analysis involved comparing the intraspecific variation of these Pleistocene species to their counterparts occurring in the modern Gulf of Mexico, where intraspecific variation was previously analyzed and found to be sufficient to allow detection of bathymetric differences …

Paleocene To Miocene Foraminifera From A Well Near Gloucester, Virginia, Nelson Stanley Ford

OES Theses and Dissertations

Lithologic analysis of twenty-one core samples from a well near Gloucester, Virginia, when compared to published descriptions of formations occurring in the study area, indicates the presence of five formations. From oldest to youngest these units are the Aquia (late Paleocene), Nanjemoy (early Eocene), Chickahominy (late Eocene), Old Church (late Oligocene and early Miocene), and Eastover (late Miocene) formations. Comparison of the stratigraphic ranges of key planktic and benthic foraminifera from each of the core samples shows chronological agreement with previously published ages for each of these formations.

Paleoenvironmental analysis of each of the formations in the well is based …

Relation Of Groundwater Fluoride Concentrations To Sediment Mineralogy, Potomac Formation (Cretaceous), Southeastern Virginia, Paul Anthony Maciuika

OES Theses and Dissertations

Thirty-seven Early cretaceous sediment samples of the Potomac Formation were obtained from four cores to determine if fluoride bearing minerals are responsible for elevated fluoride concentrations in Potomac Formation groundwaters of southeastern Virginia. Investigative methods included total sediment fluoride and particle size analysis, semiquantitative mineralogical analysis (achieved by X-Ray Diffraction) and statistical methods (cluster, canonical and regression analysis). The sediments showed wide variation in textures, ranging from clean sands and gravels to silty clays. Sediment mineralogies were dependent on the prevailing size fraction, with quartz and feldspar dominating the sand and silt fractions, muscovite primarily being found in the silt …

A Paleoenvironmental Analysis Based On Ostracode Assemblages From The Late Pliocene Tuapaktushak And Middle Pleistocene Karmuk Members Of The Gubik Formation Of The Arctic Coastal Plain, Western Alaska, D. E. Loehrke

OES Theses and Dissertations

This study records and analyzes ostracode assemblages recovered from sediments assigned to the Late Pliocene Tuapaktushak and Middle Pleistocene Karmuk members of the Gubik Formation in the Skull Cliff area of the Arctic Coastal Plain in western Alaska. Forty-three species were identified from 47 samples (25 from the Tuapaktushak Member and 23 from the Karmuk Member). Samples were grouped by Q-mode cluster analysis and by member assignment for the purpose of analysis.

Paleoenvironmental analyses of ostracode assemblages representative of each cluster suggest all samples, regardless of cluster membership, were deposited in similar marine environments where water depths were in the …

Distribution Of Foraminifera And Pollen In Coastal Depositional Environments Of The Southern Delmarva Peninsula, Virginia, U.S.A., Han Jun Woo

OES Theses and Dissertations

The coastal zone of the southern Delmarva Peninsula exhibits a wide variety of barrier island system subenvironments. This study investigates whether 20 a priori subenvironments can be distinguished from each other on the basis of abiotic environmental variables, pollen assemblages, living foraminiferal populations, and total (living plus dead) foraminiferal assemblages.

The physical data collected from the coastal zone were subjected to canonical variate analysis which discriminated 83% of the stations in 19 groups. These groups were clustered into two internally overlapping sets which represented the inside and outside of the inlet.

Twenty-two pollen types were found in low-energy marsh and …

Middle Eocene Foraminifera From The Piney Point Formation Of The Virginia And Maryland Coastal Plain, Megan S. Jones

OES Theses and Dissertations

This study examines the foraminiferal fauna, both benthic and planktonic, of the outcropping (45 samples) and subsurface (31 samples) middle Eocene Piney Point Formation in Virginia and Maryland. The primary objective of this study is to further refine the depositional history of the Salisbury Embayment which is represented by the middle Eocene Piney Point Formation. Ninety-six species of benthic and planktonic foraminifera were identified in this study. Of these, several are characteristic of the middle Eocene: Asterigerina texana, Hanzawaia danvillensis, Ceratobulimina exima, Cibicides westi, Chiloguembelitria columbiana, C. stavensis, Testacarinata inconspicua and Pseudohastigerina wilcoxensislmicra. While these were relatively abundant, diagnostic middle …

Foraminiferal Biostratigraphy And Paleoenvironmental Analysis Of The Anahuac Formation (Late Oligocene-Early Miocene) From A Deep Well In Vermilion Parish, Louisiana, Audrey Lynne Orndorff

OES Theses and Dissertations

In the subsurface of Vermilion Parish, Louisiana, sediments from the Anahuac Formation in the #1 J. W. Steen well are assigned an Upper Oligocene-Lower Miocene age based on planktonic foraminifera. Previous age determinations for sediments from this formation elsewhere range from Middle to Late Oligocene based on the presence of larger foraminifera contained within these strata. Planktonic foraminifera in Anahuac formation sediments in the #1 J. W. Steen well permit their assignment to an established worldwide zonation scheme and indicate that the age ranges from the Globorotalia kugleri Interval Zone (Upper Oligocene) to the Catapsydrax dissimilis Zone (Lower Miocene). Benthic …

Benthic Foraminifera And Paleoenvironments Of The Arcola Limestone Member Mooreville Formation (Campanian) In Eastern Mississippi And Western Alabama, Julia K. Palmer

OES Theses and Dissertations

Eighty-one species of benthic foraminifera have been recovered from chalky marls of the upper Mooreville Formation including the Arcola Limestone Member, and the basal Demopolis Formation located in five sections in east-central Mississippi and west-central Alabama. These species have been described and seventy-nine illustrated. Analysis of the environmental or depth preferences of abundant species together with planktonic percentages and benthic species diversity, indicates that the chalky marls were deposited in a broad shallow shelf sea (subtidal conditions less than 100m) greatly influenced by open ocean conditions. The benthic assemblage is composed of a mixture of typically neritic and bathyal species …

Depositional Environments Of Late Precambrian Sediments From Liberia, Sierra Leone, And Senegal, West Africa, Alfred W. Magee Iii

OES Theses and Dissertations

Field and hand sample descriptions were supplemented with petrographic and textural analyses derived from thin sections, and scanning electron microscopy (SEM) to determine environments of deposition for the late Precambrian Gibi Mountain Formation, Liberia, Tabe

Formation, Sierra Leone, and the basal Mali Group, Senegal, West Africa.

The Gibi Mountain Formation consists of a glaciomarine tillite, marine laminites with dropgrains, and shallow water arkoses. A shale facies remains unresolved in origin.

The Tabe Formation is composed of three members: Tibai, Dodo, and Taban. The Tibai Member contains a glaciomarine tillite deposited in a shallow shelf marine environment, marine laminites, and shallow …

Foraminiferal Paleoenvironments Of The Eastover Formation (Upper Miocene Virginia), Joann H. Goshorn

OES Theses and Dissertations

Sixty-two taxa representing 29 genera from 39 foraminiferal sample pairs have been documented and analyzed in a paleoenvironmental study of the Eastover Formation in southeastern Virginia. The Eastover Formation consists of a lower Claremont Manor Member, a silt fine-grained sand and an upper Cobham Bay Member, a shelly fine grained sand. Planktonic specimens were rare and indicated a late Miocene to early Pliocene age for the Eastover Formation. Benthics were used to interpret paleoenvironments by comparison with data from the distribution of Recent foraminifera, species diversity, planktonic to benthic ratios, and sediment analyses. The foraminifera indicate that the Eastover Formation …

Stratigraphy And Textural Analyses Of A Beach Ridge Complex, Cape Henry, Virginia, Daniel Leland Oyler

OES Theses and Dissertations

Eight lithological units, documented from the analyses of 26 boreholes, comprise five laterally extensive horizons in the subsurface of Cape Henry, Virginia. Interpretations of the environments of deposition for those units are based upon textural and compositional features, fossils, thickness and distribution of strata, and previous reports about late Tertiary and Quaternary deposits in nearby areas. The incised, Pliocene Chowan River Formation (Unit H) underlies Pleistocene Units F and G which are concentrated in a buried river valley beneath Cape Henry. Estuarine Units D and E resulted from a marine transgression of the study area during the early Holocene. The …

Fourier Series Analysis Of The Relationship Of Morphologic Variations And Bathymetry In Recent Bolivina (Foraminiferida) From The Northwestern Gulf Of Mexico, Anthony Cavedo Gary

OES Theses and Dissertations

Automated video digitization and closed-form Fourier series analysis were used to investigate the applicability of benthic foraminiferal test morphology for paleo-bathymetric/paleoenvironmental reconstructions. Sample relationships and harmonics with the greatest power for discriminating between samples were determined using canonical discriminant analysis. Samples were eleven short cores obtained from the northwestern Gulf of Mexico. Three species of Bolivina were analyzed, B. albatrossi, B. lowmani, and B. subspinescens.

Results show populations of Bolivina albatrossi from the upper bathyal and upper-middle bathyal zones to have more triangular tests and lobulate chambers than lower-middle and lower bathyal zone populations. Specimens of Bolivina subspinescens …

Seismic Refraction Study Of Post-Pliocene Stratigraphy, Dismal Swamp, Virginia, William Brian Fraser

OES Theses and Dissertations

This study examines Pliocene-Pleistocene lithostratigraphy and the Yorktown unconformity within the Dismal Swamp by means of remote sensing analysis, Wyrobek-Gardner seismic refraction profiling and split-spoon coring. Pre-Sangamon fluvial/tidal channel deposits are not present and the Yorktown unconformity dips irregularly southeastward at 0.35 meters/kilometer (2 feet/mile) from a high at 4 meters above sea level to a low of -1 meter (+12 to -2 ft) below sea level. The marker velocity for the Yorktown Formation is 1600 mps (5250 fps) and regression of seismic depths of the Yorktown Formation with corresponding split-spoon depths yields a high correlation. Short line upper layer …