Physical Sciences and Mathematics Commons^™

Bacterial Diversity And Function Within An Epigenic Cave System And Implications For Other Limestone Cave Systems, Kathleen Merritt Brannen-Donnelly

Doctoral Dissertations

There are approximately 48,000 known cave systems in the United States of America, with caves formed in carbonate karst terrains being the most common. Epigenic systems develop from the downward flow of meteoric water through carbonate bedrock and the solutional enlargement of interconnected subsurface conduits. Despite carbonate karst aquifers being globally extensive and important drinking water sources, microbial diversity and function are poorly understood compared to other Earth environments. After several decades of research, studies have shown that microorganisms in caves affect water quality, rates of carbonate dissolution and precipitation, and ecosystem nutrition through organic matter cycling. However, limited prior …

Experimental Limestone Dissolution And Changes In Multiscale Structure Using Small- And Ultra Small- Angle Neutron Scattering, Chad Alan Novack

Masters Theses

Small angle neutron scattering (SANS), ultra-small angle neutron scattering (USANS), and backscatter electron (BSE) imaging, along with neutron computed tomography (NCT) were used in this study to experimentally quantify pore size, distribution, and connectivity of dissolved limestone geometries. Eight samples of Indiana limestone of two different initial permeabilities (2-4 mD and 70 mD ) [millidarcy] were reacted with HCl [hydrochloric acid] solutions at differing pH (2 and 4), and flow rates (0.1 and 10 cm³/min) [cubic centimeters per minute] to describe a broad range of parameters that affect limestone dissolution. NCT was first used to image the dissolution …

Late Tertiary Tectonic Uplift In The Southern And Central Appalachians, Mary Sheela Biswal

Masters Theses

The exposed Appalachian Mountains extend about 2500 km from Newfoundland to Alabama with the highest peaks >2000 m above sea level. The last orogeny that affected Appalachian crust was the 325-260 Ma Alleghanian. Even with minimal erosion rates, it is highly unlikely that the Appalachians could have sustained such elevations for over 200 m.y., suggesting that recent tectonic uplift has produced today’s mountainous topography. The multiple phases of Tertiary uplift are related to poorly understood processes, but a large amount of data from today’s mountain chain and the adjacent Coastal Plain indicate the present high topography is anomalous and clearly …

Examination Of Banded Iron Formation Through Petrographic, Geochemical And Iron Isotope Analyses, Melissa Margaret Hage

Doctoral Dissertations

Banded iron formation (BIF) has the potential to preserve geochemical signatures critical to interpretation of early Earth because: (1) it is found within the Precambrian when fundamental changes in Earth’s physical, biological and chemical evolution occurred, and (2) it may preserve a record of the depositional environment. Rare earth elements (REE) are useful for investigating BIF because they have characteristic features. One goal of this study was to evaluate the calculation of certain REE ratios to determine if the calculation affected the interpretation. It was concluded that the method for calculating certain ratios may affect the interpretation of redox conditions …

Insights Into Planetesimal Evolution: Petrological Investigations Of Regolithic Howardites And Carbonaceous Chondrite Impact Melts, Nicole Gabriel Lunning

Doctoral Dissertations

Asteroidal meteorites are the only available geologic samples from the early part of our solar system’s history. These meteorites contain evidence regarding how the earliest protoplanetary bodies formed and evolved. I use petrological and geochemical techniques to investigate the evolution of these early planetesimals, focusing on two meteorite types: Howardites, which are brecciated samples of a differentiated parent body (thought to be the asteroid 4 Vesta), and CV chondrites, which are primitive chondrites that have not undergone differentiation on their parent body.

Quantitative petrological analysis and characterization of paired regolithic (solar wind-rich) howardites indicate that this large sample of the …

Measurement Of Hysteretic Shale Capillary Pressure – Saturation Relationships Using A Water Activity Meter, Brendan Michael Donnelly

Masters Theses

Capillary pressure is the pressure difference across the interface of two immiscible fluids within a porous medium due to the interfacial tension between fluids and is related to both the properties of the fluids and the porous medium. Capillary pressure within a porous medium will change depending upon its degree of saturation. Understanding the relationship between capillary pressure and saturation for a rock allows for the modeling of multi-phase flow. Many traditional methods of measuring capillary pressure are unsuitable for the characterization of shale due to their inability to measure the high capillary pressures found within the small pores. Furthermore, …

Establishing A Chronology Of Late Quaternary Glacial Advances In The Cordillera De Talamanca, Costa Rica, Rebecca Susan Potter

Masters Theses

Little research has focused on glacial events in the tropics. Providing an absolute glacial chronology in Costa Rica will build a foundation for future glacial chronologies and paleoclimate reconstructions in the highlands of Central America. Evidence of past glaciation, including moraines and glacial lakes, is preserved within formerly glaciated valleys in the Cordillera de Talamanca. Orvis and Horn (2000) constrained deglaciation ages of the most recent glacial event in the Cordillera de Talamanca based on radiocarbon dates of glacial lake sediments. Radiocarbon ages indicated complete deglaciation after 12.4 ka cal BP but before 9.7 ka cal BP (Orvis and Horn, …

Europan Double Ridge Morphology As A Test For Hypothesized Models Of Formation, Ashley Caroline Dameron

Masters Theses

Double ridges on the Jovian satellite Europa consist of two ridges with a central trough. Several hypotheses exist describing their formation. Explosive cryovolcanism would result in granular ice depositing as two self-symmetric ridges flanking a central fracture, lying at or below the angle of repose (AOR). Cryo-sediments deposited by tidal squeezing and low-viscosity cryolavas emplaced by effusive cryovolcanism would likely have shallow slopes, although ridge symmetry is not expected. A second group of hypotheses involves brittle deformation of the crust, namely by diapirism, shear heating, and buckling of the lithosphere due to compression. Because these models involve uplifting vertical fractures, …

Survival And Growth Rate Of Translocated Freshwater Mussels Lampsilis Fasciola And Medionidus Conradicus, Laura L. Pullum

Masters Theses

Freshwater mussels (Family Unionidae and Margaritiferidae) are a widely threatened group of bivalve molluscs, particularly in the Southeastern United States. Translocation of freshwater mussels is an increasingly common conservation method. However, there are relatively few studies that quantitatively investigate the factors influencing translocation success or failure. In October 2013, hundreds of Medionidus conradicus and Lampsilis fasciola were translocated to the Pigeon and Nolichucky Rivers in Tennessee, with an interim partial survey (June 2014) and a full survey (October 2014). In this study, I analyze this field-collected data to determine the mechanism(s) that currently influence the outcomes of Tennessee mussel translocation. …

Geostatistical Analysis Of Point Soil Water Retention Parameters For Flint Sand, William Blake Roberts

Masters Theses

Geostatistics were employed to characterize sub-core scale heterogeneity and identify spatial structure in previously published water retention data (Kang et al., 2014) obtained using neutron radiography for Flint sand. The water retention data were parameterized using the Brooks and Corey (BC) model. The BC parameters investigated were: saturated water content (Ѳ_s), residual water content (Ѳ_r), air entry value (ψ_a), and pore size distribution index (λ). Spatial dependency in the BC parameters was identified using semivariograms. Of the four BC parameters analyzed, two were found to be spatially correlated, Ѳ …

Distinguishing Primary Versus Secondary Geochemical And Silicon Isotope Characteristics Of Precambrian Chert And Iron Formation, Latisha Ashley Brengman

Doctoral Dissertations

Precambrian chert and banded iron formation (BIF) are defined as chemical sediments precipitated directly from seawater. As such, their geochemistry, including trace elements, rare earth elements (REE), and isotopes (O, Si) may preserve Precambrian seawater conditions. However, the chemical signature of these rocks may not simply reflect seawater, because hydrothermal interactions and metasomatism may produce rocks that petrographically and chemically resemble chert and BIF, including seawater-like compositional characteristics acquired during mineral replacement. Interpreting the major-, trace-, and rare-earth element signatures of these rocks requires the identification of geochemical and isotopic fingerprints that differentiate rocks formed from chemical sedimentation from rocks …

Characterizing Groundwater Ch4 And 222rn In Relation To Hydraulic Fracturing And Other Environmental Processes In Letcher County, Ky, St. Thomas Majeau Ledoux

Masters Theses

Hydraulic fracturing of shale deposits has greatly increased the productivity of the natural gas industry by allowing it to exploit previously inaccessible reservoirs. However, previous research has demonstrated that this practice can contaminate shallow aquifers with CH₄ [methane] from deeper formations. This study compares concentrations and isotope compositions of CH₄ sampled from domestic groundwater wells in Letcher County, Kentucky in order to characterize its occurrence and origins in relation to neighboring hydraulically fractured natural gas wells. Additionally, this study tests the reliability of ²²²Rn [radon] as an alternative tracer to CH₄ in identifying processes of gas …