Physical Sciences and Mathematics Commons^™

Geochemical And Climatic Controls On The Sulfur Cycle In Volcanic Settings: Implications For The Origin Of Sulfur-Rich Deposits Investigated By The Spirit And Opportunity Rovers On Mars, Rhianna D. Moore

Doctoral Dissertations

On Earth, volcanic activity with elevated sulfur (S) degassing in the presence of water leads to the formation of hydrothermal deposits enriched in S-bearing minerals. Similar processes may have been an important source of S on Mars. The landing sites of Gusev crater and Meridiani Planum investigated by the Spirit and Opportunity rovers, respectively, showed elevated SO₄^2- [sulfate] concentrations, suggesting high- and low-temperature aqueous processes. However, the SO₄^2- contribution from subsequent aqueous weathering of hydrothermal S deposits has been poorly constrained, thus its importance to regional S cycling in the landing sites is unclear. In this …

Natural, Experimental, And Educational Explorations Of The Interiors Of Terrestrial Planetary Bodies, Nadine L. Grambling

Doctoral Dissertations

Planetary interiors are enigmatic, inaccessible, and vital to the processes that have formed the rocks we see on the surface of bodies in the inner Solar System today. Based on geophysical explorations of the Moon and Earth, along with information gleaned from rocks at the surface today, there is understanding of the basic structure and processes at depth. Using a combination of natural samples and experimental studies, we attempt to learn more about the physical conditions beneath the surface, and their effect on material properties and tectonics processes in the mantle.

On Earth, mid-ocean ridge processes have long been debated, …

Experimental Approaches To Evaluating Silicate Melt Properties And Trace Element Fractionation During Crystallization At High Pressures And High Temperatures, Megan D. Mouser

Doctoral Dissertations

Current understanding of the evolution and behavior of silicate materials that form in planetary interiors at high-pressures and high-temperatures largely come from experimental work as natural samples are either rare, or physically inaccessible. Laboratory experiments provide a comprehensive way to constrain the crystallization history, elemental partitioning, and viscosity of different silicate materials at planetary mantle pressure and temperature conditions. This work utilizes two high-pressure experimental techniques, the Paris-Edinburgh apparatus, and the piston cylinder apparatus, to measure physical and chemical properties of silicate materials. The viscosity of reduced, Fe-free silicate liquids, with and without sulfur (S-free and S-bearing), were measured to …

Winter Wheat Cover Crop Increased Subsoil Organic Carbon In A Long-Term Cotton Cropping System In Tennessee, Rounak Patra, Debasish Saha, Sindhu Jagdamma

Biosystems Engineering and Soil Science Publications and Other Works

Long-term cover-cropping and no-tillage practices can facilitate soil organic carbon (SOC) accumulation in agroecosystems for soil health and climate mitigation benefits. However, the contribution of these conservation management practices to SOC gain from the subsoil layers is not been extensively studied. To understand this knowledge gap, it is essential to determine the distribution of total SOC and SOC fractions in response to management practices across the soil profile. Therefore, this study was conducted by leveraging a 40-year replicated field experiment in a continuous cotton (Gossypium hirsutum) system. The management treatments examined included three cover crop treatments: 1) hairy vetch, HV …

Fan And Fracture Formation: Morphologic And Sedimentologic Characteristics Of Alluvial Fans On Earth And Mars, And Fracture Population Distributions On Europa, Claire A. Mondro

Doctoral Dissertations

Planetary science is inherently limited by the resolution and coverage of the currently available data. What can be observed in person, measured precisely in high-resolution data, or sampled for lab analysis in terrestrial investigations ca only be inferred, modeled, or hypothesized on other planetary bodies. The Earth remains our best tool for understanding the geologic systems of the rest of the Solar System. By applying what is known or can be measured about terrestrial systems, it is possible to determine how large-scale controls and observable features relate to geologic complexity that is beyond the resolution of planetary data. This dissertation …

Precambrian Molar-Tooth Structure: Unraveling The Diagenesis Of Ancient Carbonates, Agustin Kriscautzky

Doctoral Dissertations

Molar-tooth structure (MTS) is an enigmatic carbonate fabric that occurs mainly within Proterozoic carbonate host rocks. It is composed of two distinct features: cracks of various morphologies and crack-filling calcite microspar. Although the origins of MTS remain unknown, most previous investigation has focused on the formation of the cracks and mechanisms involved in the void space generation, with less emphasis on the intriguing carbonate fill. In this study I have investigated molar-tooth bearing carbonates from regions that span both paleogeography and geologic time. Analysis at the microscopic scale, including traditional petrography, cathodoluminescence petrography, scanning electron microscopy, and micrometer-scale geochemical analyses …

Kinematic And Vorticity Analysis Of The Slide Lake And Homestake Shear Zones, Central Colorado, Carsen T. Adams

Masters Theses

Kinematic and quantitative vorticity analysis of the Homestake shear zone (HSZ) and the Slide Lake shear zone (SLSZ) in central Colorado provide further insight into crustal processes that controlled deformation within the Colorado Mineral Belt (CMB) shear zone system throughout the Proterozoic. Evaluating vorticity, that is, the relative contributions of pure to simple shear in sheared rocks, is crucial to understanding lithospheric tectonic evolution and allows for kinematic modeling of shear zone development at a variety of scales. Moreover, novel vorticity analyses involve determining the orientation of the vorticity vector and vorticity normal surface which can give insight into shear …

The Characterization Of Dynamic Soil Properties And Their Relation To Soil Organic Carbon In East Tennessee Soils, Shannon Marissa Newell

Masters Theses

Quantifying how dynamic soil properties (DSPs) are affected by different management regimes is essential for understanding how these vital resources can be better managed. The Dewey soil series is a critical soil series in East Tennessee. For this study, the University of Tennessee, Knoxville (UTK) worked alongside the National Cooperative Soil Survey (NCSS) in an effort to better understand the dynamics of the Dewey soil series through a wide range of DSP data. To accomplish this, Dewey soil was collected from five sites which are considered representative of five management regimes: well-managed cropland (WMC), poorly-managed cropland (PMC), well-managed pasture (WMP), …

Manganese Geochemistry And Plant Availability In Response To Agricultural Practices, Ashleigh R. Montgomery

Masters Theses

Manganese (Mn) is an essential micronutrient for all organisms. In soils, Mn forms determine availability to plants. Most Mn research has been conducted in forest ecosystems and Mn cycling in agricultural systems is understudied. Therefore, the objective of the experiment is to understand the effect of different agricultural management strategies on Mn cycling and plant availability. First, a greenhouse experiment was conducted to determine the effect of different application rates of two Mn fertilizers (MnSO₄ and MnEDTA) on soil geochemical properties and growth of corn (Zea mays) and soybean (Glycine max). The fertilizers were applied to …

Comparative Geochemical Analysis Of Recent Volcanic Flows On Barva Volcano, Costa Rica, Julie Coulombe

Masters Theses

ABSTRACT

Barva Volcano is a dormant stratovolcano in the Cordillera Central region of Costa Rica, rising above the capital city of San Jose with a population of 347,000. Barva’s recent inactivity and extensive forestation have resulted in fewer investigations of its composition, petrogenesis, and eruptive history. The objective of this research is to analyze the geochemical data from several of the most recent lava flows, evaluate variability between eruptive units, and ascertain physical conditions within the Barva magma storage region. The data collected in this study helps constrain the geochemistry of units seen in the quarry and provides information regarding …

Texture And Composition Of An Arid-Climate Weathering Profile And The Link Between Bedrock And Derived Sediment Composition, Kristan Leigh Watkins

Masters Theses

Multiple compositional aspects of Holocene, terrigenous-clastic sediment differ from its source, the underlying Cretaceous Stepladder granodiorite (Mojave Desert, California). Different processes can cause sediments to change in composition from source, including chemical weathering, hydrodynamic sorting during transport, and diagenesis. Sorting and physical processes have previously suggested. To assess the relative contributions of these processes to understand provenance reconstruction, the textures and compositions of an exposed Holocene saprolite weathering profile, grus, and granodiorite bedrock were studied. Fracture density in the weathering profile decreased from ~10% at the top to ~2% at the bottom of the profile in contact with the bedrock. …

Evaluation Of Microbiometer As A Tool To Estimate Soil Health In A West Tennessee Cotton Crop, Daniel T. Sain

Masters Theses

Healthy soils are critical for optimized yields and sustainability in agriculture. Soil health testing can provide valuable information on how management practices are affecting soil health. In west Tennessee, existing soil health tests were unable to discern between significant differences in management practices. A new soil health test called microBIOMETER® has been developed by Prolific Earth Sciences® (Montgomery, NY). MicroBIOMETER® utilizes a new methodology for estimating microbial biomass and uses that estimate as a soil health score. This test has not been validated for use in west Tennessee. This research was focused on the validation of microBIOMETER® in a continuous …

Challenges In Approaching The Detection Limits For Hillslope Erosion Using Terrestrial Laser Scanning, Gene Nathan Bailey Iii

Masters Theses

Accurately quantifying soil loss due to water erosion is a critical step in managing soils. Terrestrial LiDAR (Light Detection and Ranging) presents a potential alternative to traditional soil loss measurement by estimating soil erosion and deposition through detecting surface changes. Terrestrial LiDAR can also provide spatial distribution information without disturbing the observed surface. While erosion estimation through terrestrial LiDAR detects large magnitude erosion well, the finer temporal/spatial scale erosion experienced on the hillslope in sheet and rill erosion has remained a challenge to detect. This research addresses two of the challenges in using terrestrial LiDAR on fine scales in two …

Understanding Hydrogen Variations In Silicate Glasses As A Result Of Degassing: Fire-Fountaining On The Moon And Earth, Erin M. Recchuiti

Masters Theses

Volatiles, particularly hydrogen, play a key role in volcanic eruptions, especially explosive eruptions like fire-fountaining [e.g., Saal et al. 2002; Dixon 1997; Arndt & von Engelhardt 1987; Yoder 1976]. Discerning volatile abundance and behavior during ascent and eruption can aid in understanding the source melt and primary volatile content of planetary interiors. Volcanic glasses are samples closest to the primary melt, as they quench quickly enough to limit fractionation or crystallization. This is paramount for volatile studies, especially pertaining to water as its constituents are oxygen and hydrogen. Hydrogen is the most volatile element and one of the first to …