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Articles 331 - 360 of 850
Full-Text Articles in Geology
Variability In Groundwater Flow And Chemistry In The Houzhai Karst Basin, Guizhou Province, China, Joshua M. Barna
Variability In Groundwater Flow And Chemistry In The Houzhai Karst Basin, Guizhou Province, China, Joshua M. Barna
Theses and Dissertations--Earth and Environmental Sciences
Understanding how karst aquifers store and transmit water and contaminants is an ongoing problem in hydrogeology. Flowpath and recharge heterogeneity contribute to the complexity of these systems. This thesis explores karst-conduit connectivity and water chemistry variability in the Houzhai catchment in Guizhou province, China. Artificial tracer tests were conducted during both the monsoon and dry seasons to understand temporal variability in connectivity and water velocity between karst features. Multiple flowpaths through the catchment are activated during the monsoon season and partially abandoned during the dry season. Additionally, gradient reversals during monsoonal high-flow events and as a result of pumping can …
A Joint Xrf-Δ13CCarb Chemostratigraphic Approach For Characterizing Paleo-Environmental Processes In The Mudstone-Dominated Wolfcamp Formation Of West Texas, Frank Tamakloe
Theses and Dissertations--Earth and Environmental Sciences
The Late Paleozoic Ice Age represents a dynamic period in Earth system history recording a shift from icehouse to greenhouse conditions. Concomitant with this change was a series high-frequency, high-amplitude sea level fluctuations leading to the deposition of “Kansas type” cyclothems in the Mid-Continent, and a similar rhythmic expression of interbedded shales and carbonates in the Midland Basin. Stable isotope geochemistry is a particularly powerful tool when examining these mud-rich successions because changes in organic matter partitioning may be recorded first in δ13CDIC of sea-water and consequently in δ13Ccarb of marine rocks. The δ …
The Forestry Reclamation Approach: Measuring Sediment Mass Accumulation Rates In Reclaimed Mine Lands And Naturally Regenerated Logged Forests Of Eastern Kentucky, William E. Bond
Theses and Dissertations--Earth and Environmental Sciences
The spread of surface coal mining has resulted in loss of forests in the Appalachian region. The Forestry Reclamation Approach (FRA) was developed to provide guidance for restoring forests on reclaimed mined land. This study hypothesizes that the FRA will result in larger magnitude of sediment accumulation rates in reclaimed mine sites compared to those reclaimed using grassland reclamation. Three sediment cores and six trenches were sampled within four reclaimed mined and three previously logged sites in eastern Kentucky. Samples were processed for radionuclides, grain-size, stable isotopes (δ13C), and POC. LIDAR data were used to identify valley …
The Isotopic Composition Of Meteoric Water Along Altitudinal Transects In The Tian Shan Of Central Asia, John Bershaw, Alex R. Lechler
The Isotopic Composition Of Meteoric Water Along Altitudinal Transects In The Tian Shan Of Central Asia, John Bershaw, Alex R. Lechler
Geology Faculty Publications and Presentations
The Tian Shan in Central Asia are a unique mountain range in that they are in the world's most continental location. Seasonal precipitation in the northern Tian Shan is segregated into distinct elevation bands where high elevations receive precipitation primarily during summer and low elevations to the north receive precipitation primarily during the late winter and spring. In this study, we sampled stream water along multiple altitudinal transects to determine the effect unique seasonal patterns of precipitation have on the isotopic composition of surface water. Our results suggest that the northern Tian Shan exhibits an isotopic lapse rate for waters …
Late Devonian Sedimentary Record Of Appalachian Tectonics And Erosion: Geochronology And Geochemistry Of Detrital Muscovite And Zircon From Central Pennsylvania Strata, Cole T. Gardner
Honors Theses
Foreland basin sediment deposition in North-Central Pennsylvania during Late Devonian time records erosion of hinterland source terranes exhumed during regional plate convergence, including the collisional Acadian orogeny. The Catskill clastic wedge preserves a coarsening-upwards stratigraphic succession from marine to fluvial environments associated with sediment progradation and sea-level regression, yet depositional timescales and quantitative provenance data are largely unconstrained.
Detailed facies analysis of eight outcrops spanning >2 km of stratigraphy in Lycoming Co., Pennsylvania documents distinct upsection changes, interpreted to reflect changes in depositional environments consistent with previous sedimentology of the Catskill clastic wedge. Stratigraphy displays a transition from nearshore marine …
Exploration For Alteration Halos Around The Ag-W Deposits In Southeastern Missouri, Usa, Daniel Joseph Warbritton
Exploration For Alteration Halos Around The Ag-W Deposits In Southeastern Missouri, Usa, Daniel Joseph Warbritton
Masters Theses
"The St. Francois Mountains in SE Missouri are an extensive terrane of granitic ring complexes and associated rhyolites. They were an important source of Ag, W, and Sn and mined intermittently from the 1800s until the 1950s. The Ag-W ores occur in the Silvermine Granite and rhyolite roof rocks. The deposits are classified as a xenothermal ore system with mineralization occurring in quartz veins and surrounding greisen (up to 2.5 m). Exploration for hydrothermal ore deposits often focuses on the identification of alteration halos in the surrounding host rocks. In the vast majority of xenothermal ore deposits, such as in …
The Medicine Hat Block And The Assembly Of Laurentia: New Interpretations From Single-Grain Zircon Analyses, Blake Oswell Ladouceur
The Medicine Hat Block And The Assembly Of Laurentia: New Interpretations From Single-Grain Zircon Analyses, Blake Oswell Ladouceur
Electronic Theses and Dissertations
The Medicine Hat Block (MHB) is one of the core cratonic elements that amalgamated in the Paleoproterozoic to form Laurentia. However the role of the MHB in the formation of Laurentia is poorly constrained due to virtually all of the MHB being concealed by Proterozoic and younger supracrustal sequences limiting availability of data. The primary sources of samples from the MHB are 1) xenoliths of variable metamorphic grade including gneisses amphibolites and meta-plutonic rocks collected from Eocene volcanic rock; and 2) similar lithologies recovered from boreholes that penetrate to the MHB basement. Previous work on samples from the MHB yielded …
Precipitation And Transformation Of Iron-Sulfide Nanoparticles In Low-Temperature Aqueous Environment: Effects Of Reactant Iron And Sulfide Sources, Ezequiel A. Moreno Flores
Precipitation And Transformation Of Iron-Sulfide Nanoparticles In Low-Temperature Aqueous Environment: Effects Of Reactant Iron And Sulfide Sources, Ezequiel A. Moreno Flores
Open Access Theses & Dissertations
Iron sulfide nanoparticles assume an important role within a wide range of geological settings as indicators of redox environmental conditions and elemental cycling mechanisms. Initial precipitates of iron sulfide are exclusively nanoscale sized in low temperature aqueous conditions and have been reported to go through diverse morphological and phase transformations, possibly leading to the ultimate deposits of pyrite in geologic records of various times. A systematic understanding of how the early-stage nanoparticles of iron sulfide may develop into more crystalline iron sulfide forms is still lacking however. The major goal for this study was to illuminate the effects of the …
Ductile Deformation In The Central Panamint Mountains - A Multi-Disciplinary Approach To A Multi-Dimensional Problem., Tai Antonia Subia
Ductile Deformation In The Central Panamint Mountains - A Multi-Disciplinary Approach To A Multi-Dimensional Problem., Tai Antonia Subia
Open Access Theses & Dissertations
This study provides new insights into the geometry and timing of ductile, syn-metamorphic structures in the central Panamint Mountains of eastern California. The study focused on Surprise Canyon, where exposures of Meso- to Neoproterozoic miogeocline rocks, reworked crystalline basement, and syn-metamorphic granitoids record fabric overprints indicative of at least two distinct dynamo-thermal metamorphic events. Prograde metamorphism at greenschist and amphibolite metamorphic facies conditions occurred during Early Jurassic plutonism based on deformation of a dioritic pluton with a U-Pb date reported here of 175.6 ± 3.2 Ma. Mid Jurassic deformation (D1) generated the main continuous cleavage in the rocks (S1) as …
Utilizing Lipid Biomarkers To Understand The Microbial Community Structure Of Deep Subsurface Black Shale Formations, Rawlings Akondi
Utilizing Lipid Biomarkers To Understand The Microbial Community Structure Of Deep Subsurface Black Shale Formations, Rawlings Akondi
Graduate Theses, Dissertations, and Problem Reports (ETD)
The deep subsurface environment has been known to host microbes as early as 1926 and has also been suggested to potentially account for as much as 50% of the Earth`s biomass. Researchers have shown that microbes alter their membrane lipid components in response to physiological stress, producing stress indicative lipid biomarkers. However, little effort has been made to understand the subsurface microbial community of the shale ecosystem which is increasingly being exploited and altered by addition of drilling and hydraulic fluids to meet our growing energy needs. Phospholipid fatty acids (PLFAs) are microbial lipid biomarkers and are found in all …
The Petrogenesis Of The No Agua High-Silica Rhyolite In The Taos Plateau Volcanic Field, Northern New Mexico, Kevin M. Voelz
The Petrogenesis Of The No Agua High-Silica Rhyolite In The Taos Plateau Volcanic Field, Northern New Mexico, Kevin M. Voelz
Graduate Research Theses & Dissertations
The Taos Plateau volcanic field (TPVF) is located in Northern New Mexico between the eastern flanks of the Tusas Mountains and west of the Sangre de Cristo range. The TPVF is dominantly composed of basaltic lava flows, olivine andesites, and two-pyroxene dacites which erupted from 5.88 to 1.03 Ma. The variety of compositions within the field owes its origin to processes such as magma mixing, fractional crystallization, and crustal assimilation based on chemical modeling. Curiously placed within this spectrum of mafic to intermediate lavas exists the singular high-silica rhyolite of the No Agua Peaks. XRF and ICP-MS analyses from this …
Sediment Provenance Study Of The Lower Hamilton Group: An Analysis Of The Organic-Rich Facies And Its Depositional History, Luke Patrick Fritz
Sediment Provenance Study Of The Lower Hamilton Group: An Analysis Of The Organic-Rich Facies And Its Depositional History, Luke Patrick Fritz
Graduate Theses, Dissertations, and Problem Reports (ETD)
Currently, insufficient geological models exist to explain the variability and distribution of TOC in the Marcellus Shale, within the Hamilton Group. TOC is one of the several limiting factors for natural gas production within the Marcellus Shale basin. One possible explanation for the low TOC regions is that detrital dilution was variable across the basin, with different sediment sources contributing detritus to low TOC areas, compared to surrounding regions with higher TOC. This hypothesis is tested by analyzing the source composition of inorganic detritus, using elemental and mineralogical proxies, with two cores in the Hamilton Group. The Armstrong #1 core …
Provenance, Redox Conditions, And Diagenesis Of Shales In Chang 7 Member Of Upper Triassic Yanchang Formation, Ordos Basin, China, Bin Sun
Doctoral Dissertations
“This study aims to decipher provenance, redox conditions, and burial history of shales in Chang 7 Member of Upper Triassic Yanchang Formation, Ordos Basin, China. The first paper discusses the origins of single-channeled, vertical, sinuous, and calcite-bitumen-filled cracks in the shales. Results show that in early diagenesis, unconsolidated mud was expanded open by escaping gases produced during organic matter maturation under hydrothermal influences. Calcite initially filled the cracks; bitumen and pyrite came in later and occupied the cracks in various ways. Compaction occurred next and folded the calcite- and bitumen-filled cracks into sinuous shapes. The second paper uses geochemical and …
Volatiles And Trace Element Contents In Melt Inclusions From The Zoned Green Tuff Ignimbrite (Pantelleria, Sicily): Petrological Inferences., Pierangelo Romano, John C. White, Alessandro Ciulla, Ida Di Carlo, Claudia D'Oriano, Patrizia Landi, Silvio G. Rotolo
Volatiles And Trace Element Contents In Melt Inclusions From The Zoned Green Tuff Ignimbrite (Pantelleria, Sicily): Petrological Inferences., Pierangelo Romano, John C. White, Alessandro Ciulla, Ida Di Carlo, Claudia D'Oriano, Patrizia Landi, Silvio G. Rotolo
EKU Faculty and Staff Scholarship
The island of Pantelleria is one of the best known localities of bimodal mafic-felsic magmatism (alkali basalt and trachyte-pantellerite). Among the felsic rocks, the coexistence in a single eruption of products of both trachyte and pantellerite compositions is limited to few occurrences, the Green Tuff (GT) ignimbrite being one of these. The GT is compositionally zoned from pantellerite (70.1 wt% SiO2, mol Na+K/Al = 1.86, 1871 ppm Zr) at the base to crystal-rich (>30 vol%) comenditic trachyte (63.4 wt% SiO2, mol Na+K/Al = 1.10, 265 ppm Zr) at the top, although the pantellertic compositions dominate the erupted volume. We …
Mercury In Big Cypress Bayou And Caddo Lake Watersheds In Marion And Harrison Counties Texas, Joseph Watkins
Mercury In Big Cypress Bayou And Caddo Lake Watersheds In Marion And Harrison Counties Texas, Joseph Watkins
Electronic Theses and Dissertations
Caddo Lake has been included on the Texas Commission on Environmental Quality 303(d) list for impairment due to mercury (Hg) content since 1996. One of the primary tributaries, Big Cypress Bayou, flows across Eocene-aged rocks and sediments associated with the Wilcox Group; the Wilcox is of interest because it contains lignite coal, which has a direct link to mercury. Previous research has focused on dry deposition from fossil fuel combustion as the primary source of mercury but has not addressed the potential watershed contribution to mercury concentrations in Caddo Lake.
Big Cypress Bayou flows through Harrison and Marion counties in …
Diamond Intracrystalline Stable Isotope Chemical Image Analysis By Time-Of-Flight Secondary Ionization Mass Spectrometery, Tyler J. Sundell
Diamond Intracrystalline Stable Isotope Chemical Image Analysis By Time-Of-Flight Secondary Ionization Mass Spectrometery, Tyler J. Sundell
Graduate Theses/Dissertations
The chemical resistance of diamond allows in-situ study of the diamond source regions. For a majority of gem quality diamonds, this source region is the sublithospheric mantle keel of a cratonic nuclei. Through analysis of stable isotopes, radiogenic isotopes and trace elements, diamond geochemical analyses can define chemical fluxes in the mantle keel. However, such studies require multiple methodologies for each chemical suite, high spatial resolution and analytical precision. Here, I evaluate Time-of-Flight Secondary Ionization Mass Spectrometer (ToF-SIMS) as an alternative method for diamond geochemical analyses. ToF-SIMS analysis can perform in cation and anion mode to measure the entire periodic …
Evaluating Stable Isotope And Geochronologic Techniques For Paleoclimate Reconstruction: Case Study Of The Santa Cruz Formation, Argentina, Robin B. Trayler
Evaluating Stable Isotope And Geochronologic Techniques For Paleoclimate Reconstruction: Case Study Of The Santa Cruz Formation, Argentina, Robin B. Trayler
Boise State University Theses and Dissertations
Stable isotope analysis has become the method of choice for many studies investigating the paleoecology and paleoclimate of fossil mammal faunas. While organic tissues (collagen, keratins, proteins) persist for < 105 years highly mineralized tooth enamel is resistant to alteration and degradation and faithfully preserves its isotopic composition for millions (> 106) years. Reconstructing past climates from these records relies on both understanding both micro-scale mechanisms of isotope incorporation into individual teeth, and macro-scale changes in isotope compositions over hundreds of thousands or millions of years. In this dissertation I address three questions.
First, how does the geometry and …
Compositional And Thermodynamic Variability In A Stratified Magma Chamber: Evidence From The Green Tuff Ignimbrite (Pantelleria, Italy)., Katarzyna M. Liszewska, John C. White, Ray Macdonald, Bogusław Bagiński
Compositional And Thermodynamic Variability In A Stratified Magma Chamber: Evidence From The Green Tuff Ignimbrite (Pantelleria, Italy)., Katarzyna M. Liszewska, John C. White, Ray Macdonald, Bogusław Bagiński
EKU Faculty and Staff Scholarship
The Green Tuff Ignimbrite, Pantelleria, is compositionally zoned from pantellerite at the base to comenditic trachyte at the top, the variation apparently representing an inverted vertical zonation in the pre-eruptive reservoir. The main phenocryst assemblages are alkali feldspar + olivine + clinopyroxene + ilmenite + apatite in the trachytes and alkali feldspar + aenigmatite + clinopyroxene + quartz in the rhyolites. Thermodynamic modelling indicates that the temperature range was ~900–700°C, fO2 FMQ –1.5 to FMQ –0.5 (where FMQ is fayalite–magnetite–quartz buffer) and aSiO2 (relative to quartz saturation) 0.74–1.00. Melt water contents ranged from ~1wt % in the trachytes to ~4wt …
Interpreting The Origin And Evolution Of ‘Karst’ Features From A Siliceous Hydrothermal Terrane: A Case Study From The Upper Geyser Basin In Yellowstone National Park, Usa, Kevin W. Blackwood, Lainee A. Sanders, Stacy I. Gantt-Blackwood
Interpreting The Origin And Evolution Of ‘Karst’ Features From A Siliceous Hydrothermal Terrane: A Case Study From The Upper Geyser Basin In Yellowstone National Park, Usa, Kevin W. Blackwood, Lainee A. Sanders, Stacy I. Gantt-Blackwood
International Journal of Speleology
The Upper Geyser Basin in Yellowstone National Park occurs over a siliceous hydrothermal terrane containing numerous hot springs and geysers. The pool and vent-conduit geometries of these hydrothermal features share a resemblance to conventional karst features known from other rock types, suggesting karst processes could be responsible for their origin and/or evolution. Hypogene speleogenesis is a cave-forming process in which the formation of caves is decoupled from and occurs independently of surface recharge. The geologic setting for hypogene speleogenesis typically occurs at the distal end of regional groundwater systems wherein the hydrogeology is manifested by ascending fluids and/or by geochemical …
Mantle-To-Surface Neotectonic Connections In The San Juan Mountains Documented By 3he/4he, Co2 Flux Meaurements, And Hydrochemical Analysis Of The Geothermal System Near Rico, Colorado, Benjamin D. Holt
Earth and Planetary Sciences ETDs
This project investigates the controls on geothermal fluids and their conduit systems which may account for high mantle helium components of geothermal fluids in intracratonic continental regions. The field laboratory is the western San Juan Mountains of southwestern Colorado where the structural setting and hydrochemistry of carbonic springs suggest potential connections among surface hot springs, fault networks, CO2 degassing, significant geothermal potential, young volcanic and plutonic rocks (< 7 Ma), and low-velocity upper mantle. The Rico Hot Springs have the highest mantle volatile component of any spring in Colorado with air-corrected values of 3He/4He = 5.88 RA indicating 73% mantle helium component. This near-MORB mantle helium value at Rico indicates that volatiles degassing from the mantle must be rapidly transmitted into the groundwater system along deep-seated faults such that accumulation of 4He from radiogenic crust has not swamped mantle-derived primordial 3He. Geologic features that are important for volatile transport and spring chemistry controls include a complex conduit system and fault network involving the Precambrian-cored Rico Dome, ~4 Ma intrusive rocks at Calico Peak and Priest Gulch, and a low-velocity upper mantle. Therefore, Rico and the surrounding region is a natural laboratory for studying geothermal fluid and mantle volatile pathways. Additional noble gas analyses and hydrochemistry data were gathered from regional springs and modeled via chemical geothermometers. New noble gas measurements from this study, paired with literature values, reveal highest air corrected 3He/4He at Rico (4.09-5.88 RA), Dunton (3.11-4.54 RA), Geyser Warm Spring (3.39 RA), and Paradise Warm Spring (2.72 RA). Water volume is dominated by meteoric fluids as shown by stable isotope data but hydrochemistry indicates high TDS, high CO2, and high He come from a geothermal fluid endmember. Variable mixing and water-rock interactions are processes that can explain chemistry variations between spatially proximal springs. CO2 flux measurements (up to 36.2 g/m2/hr) vary across structural features and demonstrate that the faults act as pathways for CO2 flux suggesting ongoing degassing. Overall, we find that local high mantle helium signature is localized directly above regions of lowest upper mantle velocity in the San Juan mantle anomaly and is derived from neotectonic mantle melts in those regions.
Natural Trace Element Salinization Of The Jemez River, New Mexico By Geothermal Springs And Major Tributaries, Jon K. Golla, Laura J. Crossey, Abdul-Mehdi S. Ali, Karl E. Karlstrom
Natural Trace Element Salinization Of The Jemez River, New Mexico By Geothermal Springs And Major Tributaries, Jon K. Golla, Laura J. Crossey, Abdul-Mehdi S. Ali, Karl E. Karlstrom
Shared Knowledge Conference
The Jemez River (JR), a tributary of the Rio Grande, is in north-central New Mexico within the Jemez Mountains, which houses the active, high-temperature (≤ 300 oC), liquid-dominated Valles Caldera geothermal system (VC). This work focuses on the northern portion of the JR, spanning a reach from the East Fork JR to the town of San Ysidro. Previous decadal work during low-flow or baseflow conditions (~10-20 cfs) has identified and characterized significant major-solute contributions from two outflow expressions of the VC, Soda Dam Springs and Jemez Hot Springs, and two major tributaries, Rio San Antonio and Rio Guadalupe. There is …
Groundwater Contamination At Coal Ash Deposit Sites In Kentucky, Brandon Rose
Groundwater Contamination At Coal Ash Deposit Sites In Kentucky, Brandon Rose
Scholars Week
No abstract provided.
Ice And Guano Deposits In El Malpais Lava Tubes: Potential Paleoclimate Archives For The Southwest United States, Dylan S. Parmenter
Ice And Guano Deposits In El Malpais Lava Tubes: Potential Paleoclimate Archives For The Southwest United States, Dylan S. Parmenter
USF Tampa Graduate Theses and Dissertations
Three ice cores and one guano core were obtained from lava tubes in El Malpais National Monument, New Mexico, in the Southwest United States. A large hiatus in the Bat Cave guano record, resulting from mining activities in the early 1900's, left us with only ~50 years of data (from AD 1955-2006) to use in analysis. 13C values in guano (-18 to -11.6‰) primarily fall within the range of C4 plants, and likely indicate a tendency of Tadarida brasiliensis to feed on insects over grasslands to the North or South of the park. Variations in 13C values for this period …
Crustal Seismic Anisotropy Of The Ruby Mountains Core Complex And Surrounding Northern Basin And Range, Justin T. Wilgus
Crustal Seismic Anisotropy Of The Ruby Mountains Core Complex And Surrounding Northern Basin And Range, Justin T. Wilgus
Earth and Planetary Sciences ETDs
Metamorphic core complexes (MCC) are distinctive uplifts that expose deeply exhumed and deformed crustal rocks due to localized extensional deformation. Consequently, their detailed structure provide a window into deep crustal mechanics. The North American Cordillera contains numerous MCC, one of which is the Ruby Mountains core complex (RMCC) located in the highly extended northern Basin and Range. To constrain the extent to which anisotropy below the RMCC deviates from the regional Basin and Range average and test the depth dependence of crustal anisotropy we conduct a radial anisotropy investigation below the RMCC and surrounding northern Basin and Range. Data from …
The Sedimentology And Origins Of A Giant Mass Transport Complex: The Nataraja Slide, Arabian Sea, Sarah Dailey
The Sedimentology And Origins Of A Giant Mass Transport Complex: The Nataraja Slide, Arabian Sea, Sarah Dailey
LSU Master's Theses
A giant mass transport complex (MTC) was recently discovered in the eastern Arabian Sea exceeding in volume all but one other known complex on passive margins worldwide. The complex, named the Nataraja Slide, was drilled by IODP Expedition 355 in two locations where it is ~300 m (Site U1456) and ~200 m thick (Site U1457). The top is defined by the presence of both reworked microfossil assemblages and deformation structures, such as folding and faulting. The deposit consists of two main phases of mass wasting, each which consists of smaller pulses, with generally fining upward cycles, all emplaced just prior …
Unroofing History Of The Northwestern Ethiopian Plateau: Insights From Low-Temperature Apatite Thermochronology, Shelby Bowden
Unroofing History Of The Northwestern Ethiopian Plateau: Insights From Low-Temperature Apatite Thermochronology, Shelby Bowden
Masters Theses & Specialist Projects
The geology of Ethiopia is dominated by the Ethiopian Plateau that is similar in elevation to, but aerially larger than, the Colorado Plateau. Several rivers have incised through the plateau, creating gorges that reach up to 1.5 km in depth. The plateau uplifted to its current elevation and was subsequently incised sometime after the Oligocene flood basalt event that signaled the arrival of the African Superplume below Kenya and Ethiopia. Due to its size and extent, published climate modeling has indicated that Late Cenozoic plateau formation could have been a driving force in the East African Cenozoic climate changes. Although …
Indirect Greenhouse Gas Dynamics In Karst Groundwater Systems Under Agricultural Land Use, Stacy Wayne Antle
Indirect Greenhouse Gas Dynamics In Karst Groundwater Systems Under Agricultural Land Use, Stacy Wayne Antle
Masters Theses & Specialist Projects
Greenhouse gases (GHGs) are a major global environmental concern, because their concentrations have continuously increased over the past few centuries, due to global population growth, fossil fuel dependency, and the Industrial Revolution. Since these gases are naturally occurring phenomena, they will never be completely eliminated. Efforts to reduce them span numerous scientific attempts, with minimal improvements in reducing their atmospheric concentrations. In agricultural land practices, greenhouse gases are common byproducts that affect the atmosphere and, potentially, the groundwater where livestock and fertilizers are key contributors. Little is known about the fate of such greenhouse gases in dissolved form, known as …
Stylolites Cathodoluminescence Under Cross Polarized Light, Katherine Dvorak
Stylolites Cathodoluminescence Under Cross Polarized Light, Katherine Dvorak
The Hilltop Review
Devil's Gate limestone under cathodoluminescence. Bright yellow and orange areas are calcite and the bright blue indicates trace minerals along the solution seam. Trace minerals left in the seam are heavy metals and other silicate minerals.
High-Dimensional Isotope Relationships, Yuyang He
High-Dimensional Isotope Relationships, Yuyang He
LSU Doctoral Dissertations
High-dimensional isotope relationships describes the relationships of two or more element or position-specific (PS) elements in the same molecule or ion. It provides us more powerful tools to study reaction mechanisms and dynamics. Chapter 1 is about dual or multiple stable isotope relationship on δ-δ (or δ'-δ') space. While temporal data sampled from a closed-system can be treated by a Rayleigh Distillation Model (RDM), spatial data should be treated by a Reaction-Transport Model (RTM). Here we compare the results of a closed-system RDM to a RTM for systems with diffusional mass transfer by simulating the trajectories on nitrate's δ'18 …
Be-10/Be-9 Ratios Reflect Antarctic Ice Sheet Freshwater Discharge During Pliocene Warming, Rachel D. Valletta, Jane K. Willenbring, Sandra Passchier, Chiara Elmi
Be-10/Be-9 Ratios Reflect Antarctic Ice Sheet Freshwater Discharge During Pliocene Warming, Rachel D. Valletta, Jane K. Willenbring, Sandra Passchier, Chiara Elmi
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Along glaciated margins, ratios of meteoric cosmogenic beryllium‐10, 10Be, normalized to its stable isotope, 9Be, reflect an environmental signal, driven ultimately by climatic change. We explore the application of this isotopic pair as a proxy for East Antarctic Ice Sheet dynamics. We analyze 10Be/9Be in middle Pliocene glaciomarine sediments offshore the Wilkes Land Region (Integrated Ocean Drilling Program (IODP) Site U1361A) and examine our new record alongside existing biochemical/geochemical records (Ba/Al, opal %wt, εNd, and 87Sr/86Sr). 10Be/9Be ratios reach local maxima during pulsed, mild warming events and …