Geochemistry Commons^™

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

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 …

Regulation Of Dissolved Arsenic Using Zero-Valent Iron With Gypsum And Sulfate Reducing Bacteria: Laboratory Microcosm And Column Studies, Ying Liu

Dissertations, Theses, and Capstone Projects

Bench scale microcosm incubation was first conducted in two stages to examine the removal of arsenic (As) by zero-valent iron (ZVI) in the presence of sulfate reducing bacteria, gypsum as well as organic substrates under anaerobic condition. About 98% of dissolved As was removed from solution within 20 days with concurrent decrease of dissolved sulfate and growth of bacterial population. Mineralogy analysis using SEM-EDS found the formation of iron sulfide and Fourier-transformed infrared (FTIR) spectroscopy analysis indicates that some As is associated with pyrite. The main iron corrosion product was found as ferrihydrite with traces of lepidocrocite. Sequential leaching shows …

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

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

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 …

Spatial And Temporal Trends Of Mining-Related Lead-Zinc Sediment Contamination, Galena River Watershed, Sw Wisconsin-Nw Illinois, Dylan Alexander King

Graduate Theses/Dissertations

Alluvial sediments within the Galena River Watershed were severely contaminated with heavy metals by historical zinc (Zn) and lead (Pb) mining operations during the early 1800s until 1979. Since the mines closed, there have been efforts to remediate on-site mine waste. However, the effectiveness of these efforts to reduce metal concentrations in stream sediments is unknown. This study compares present-day (2017) contamination trends in the Galena River Watershed to trends reported 25 years ago. A total of 415 sediment/soil samples were collected and analyzed using X-ray florescence spectrometry to determine sediment metal concentrations. The highest concentrations of zinc measured were …

The Transition From Sevier To Laramide Orogeny Captured In Upper-Plate Magmatic Structures, Eastern Transverse Ranges, Ca, Brody Friesenhahn

Earth Sciences Theses and Dissertations

The onset of the Laramide orogeny is of great tectonic significance to the geologic history of the US, but the timing and nature of the shift between Sevier and Laramide tectonics remains enigmatic. The eastern Transverse Ranges of southern California provide the opportunity to observe the effects of Laramide tectonics on the mid-crust. Wide Canyon is a north/south-trending canyon in the northern Little San Bernardino Mountains of the eastern Transverse Ranges. Al-in-hornblende thermobarometry of Needy et al. (2009) yields a projected paleodepth depth of ~20 km for Wide Canyon where Cretaceous granitoids intrude metamorphic country rock of Proterozoic age in …

Geotraces And Beyond: Studies Of Trace Elements In Coastal And Open Ocean Waters With An Emphasis On The Effects Of Oxygen Depletion And Hydrothermal Plumes, Peng Ho

Dissertations

We investigated various dissolved trace element (dTE) distributions in two distinct areas: the coastal northern Gulf of Mexico and the eastern tropical Pacific Ocean.

A multi-year (2007‒2011) chemical time series of eight stations in the western Mississippi Sound (MS) and northwestern Mississippi Bight (MB) was undertaken to examine the factors affecting chemical distributions in this dynamic region. Key findings include the frequent development of bottom water hypoxia in MB during late spring-summer, the likely contribution of submarine groundwater discharge (SGD) to the material flows, and observation of effects of episodic events including tropical storms and the opening of the Bonnet …

The Geotraces Intermediate Data Product 2017, Reiner Schlitzer, Robert F. Anderson, Elena Masferrer Dodas, Maeve Lohan, Walter Geibert, Alessandro Tagliabue, Andrew Bowie, Gregory A. Cutter, Peter N. Sedwick, Bettina Sohst

OES Faculty Publications

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and …

Dissolution Rates Of Allophane, Fe-Allophane, And Hisingerite And Implications For Aqueous Alteration On Mars And In Potential Returned Martian Samples, S. J. Ralston

UNLV Theses, Dissertations, Professional Papers, and Capstones

Recent measurements from Mars document X-ray amorphous/nano-crystalline materials in multiple locations across the planet. However, despite their prevalence, little is known about these materials or what their presence implies for the history of Mars. The amorphous component of the martian soil in Gale Crater has an X-ray diffraction pattern that can be partially fit with allophane (approximately Al2O3•(SiO2)1.3-2•(H2O)2.5-3), as well as low-temperature water release consistent with allophane. The chemical data from Gale Crater suggest that other silicate phases similar to allophane, such as Fe-substituted allophane (here, approximately (Fe2O3)0.01(Al2O3)0.99(SiO2)2•3H2O) and hisingerite (approximately Fe3+2Si2O5(OH)4•(H2O)), may also be present. In order to investigate …

Seismic Facies Mapping For Source Rock Distribution Of The Rakopi Formation In Deep-Water Taranaki Basin, New Zealand, Sidney W. Mahanay

Graduate Theses and Dissertations

The Taranaki Basin is located off the coast of the north island of New Zealand and is currently the only producing basin in New Zealand. Hydrocarbon accumulation in the Tui, Maari, and Maui fields is sourced to the Late Cretaceous and Paleogene units. Exploration of these units has extended from the continental shelf of the Taranaki Basin into the deep-water to the northwest. The Romney 3D survey and Romney–1 well are some the first public exploration projects to supply data from this area. The objective of this study is to estimate source rock quality and distribution of the Rakopi Formation …

Hardbottom Characterization And Relationship To The Geologic Framework In Long Bay, South Carolina, Cathryn J. Wheaton

Electronic Theses and Dissertations

Hardbottom seafloor is a common element among sediment-starved portions of the inner continental shelf along the U.S. Atlantic margin. These areas are characterized by indurated sediment surfaces that are heavily altered by biological and physical processes. Long Bay, in northeastern South Carolina, offers ideal environmental conditions for hardbottom exposure with only patchy Holocene sand deposits, interspersed with extensive hardbottom areas. Here we use high-resolution multibeam bathymetry, CHIRP subbottom profiling and electrical resistivity data, along with surficial sediment samples, hardbottom thin sections, and water column radioisotope (radon-222) analysis to investigate the origin and geologic framework of a region of hardbottom seafloor …

Review Of Curbing Catastrophe: Natural Hazards And Risk Reduction In The Modern World, Kira H. Hamman

Numeracy

Timothy H. Dixon. 2017. Curbing Catastrophe: Natural Hazards and Risk Reduction in the Modern World. (New York, NY: Cambridge University Press) 300 pp. ISBN 978-1108113663.

In Curbing Catastrophe, Timothy H. Dixon explores commonalities among natural disasters like Hurricane Katrina, the 2010 earthquake in Haiti, and the meltdown at Fukushima. He identifies communication failure between scientists and policy makers as a major culprit in the devastation that results from such events and offers strategies for improving that communication. He includes optional in-depth scientific and quantitative examinations of the events and the resulting devastation, making the book appropriate for use …

Volcanic Glass As A Paleoenvironmental Proxy: Comparing Preparation Methods On Ashes From The Lee Of The Cascade Range In Oregon, Usa, Tessa Boe Carlson

Dissertations and Theses

Deuterium ratios (δD) of hydrated volcanic glass have been used to reconstruct paleoenvironments, although the reliability and proper sample preparation protocol have been debated. In this study, hydrated volcanic ash samples from the lee of the Cascades were prepared using two separate methods. Method 1 involves sonicating and rinsing samples with hydrochloric acid (HCl) followed by hand-selection of glass shards (125-212µm). Method 2 requires hydrochloric acid (HCl) and hydrofluoric acid (HF) abrasion as well as heavy liquid separation of shards (70-150µm). Method 2 produced more consistent results with decreased intra-replicate variability in both water content (-0.92 wt. %) and deuterium …

Hydrothermal Water-Rock Reaction Modeling With Microbial Considerations: Rabbit Creek Area, Yellowstone National Park, Wy, Shanna Law

Graduate Theses & Non-Theses

Water-rock reactions at depth are the main control on aqueous hydrothermal chemistries of hot springs and other thermal features. Thermophilic microbes living in the hydrothermal system are a secondary control on aqueous hydrothermal chemistries and are expected to have increasing influence as spring temperatures decrease. The Rabbit Creek area of Yellowstone National Park (YNP) is an ideal case study for investigating the geologic and biologic controls on aqueous hydrothermal chemistries due to the proximity of the drill core Y-5 to geochemically diverse hydrothermal features (17.3⁰C to 92.2⁰C ± 0.1⁰C; field pH values 6.50 to 9.60 ± 0.05).

The modeling program …

Advances In Amino Acid Analysis For Marine Related Matrices And Its Application To Coastal Shelf Settings In The Canadian Arctic, Rachel M. Mcmahon

OES Theses and Dissertations

Amino acids comprise up to 50% of organic matter in cellular material and are a major fraction of oceanic organic carbon. Amino acids are also considered highly labile during organic matter recycling, making them useful proxies for organic carbon cycling. Nevertheless, analysis of individual amino acids has been burdened by lengthy derivatization and complex analysis since the 1950s. In this thesis, I describe the modification of advanced analytical techniques, developed in the biomedical field, for analysis of marine matrices which allow the determination of at least 40 amino acids without the need for lengthy sample preparation and derivatization, twice the …

Extremely High Diversity Of Sulfate Minerals In Caves Of The Irazú Volcano (Costa Rica) Related To Crater Lake And Fumarolic Activity, Andrés Ulloa, Fernando Gázquez, Aurelio Sanz-Arranz, Jesús Medina, Fernando Rull, José María Calaforra, Guillermo E. Alvarado, María Martínez, Geoffroy Avard, J. Maarten De Moor, Jo De Waele

International Journal of Speleology

The caves of the Irazú volcano (Costa Rica), became accessible after the partial collapse of the NW sector of the Irazú volcano in 1994, offering the opportunity to investigate active minerogenetic processes in volcanic cave environments. We performed a detailed mineralogical and geochemical study of speleothems in the caves Cueva los Minerales and Cueva Los Mucolitos, both located in the northwest foothills of the main crater. Mineralogical analyses included X-ray diffraction (XRD) and Raman spectroscopy, while geochemical characterization used Energy Dispersive X-ray spectroscopy (EDX) coupled to Scanning Electron Microscopy (SEM). In addition, measurements of environmental parameters in the caves, …

Drip Water Measurements From Carlsbad Cavern: Implications Towards Paleoclimate Records Yielded From Evaporative-Zone Stalagmites, Victor J. Polyak, Jessica B.T. Rasmussen, Yemane Asmerom

International Journal of Speleology

Stalagmites can host numerous potential climate proxies (stable and radiogenic isotopes, trace elements, annual and non-annual banding, grayscale, growth hiatuses, mineral assemblage). Reproducibility and/or integration of proxy results between one or more stalagmites will become increasingly important, and ideally, climate records generated by multiple stalagmites from the same cave or cave room are expected to be near-identical. The reality is that stalagmites from the same cave room can yield differing results to some degree, especially in cave environment zones that are evaporative. Our drip water study in an evaporative shallow-depth cave environment in Carlsbad Cavern shows that adjacent drip sites …

Shergottite Northwest Africa 6963: A Pyroxene‐Cumulate Martian Gabbro, Justin Filiberto, Juliane Gross, Arya Udry, Jarek Trela, Axel Wittmann, Kevin M. Cannon, Sarah Penniston-Dorland, Richard Ash, Victoria E. Hamilton, Andrea L. Meado, Paul Carpenter, Brad Jolliff, Eric C. Ferré

Geoscience Faculty Research

Northwest Africa (NWA) 6963 was found in Guelmim‐Es‐Semara, Morocco, and based on its bulk chemistry and oxygen isotopes, it was classified as a Martian meteorite. On the basis of a preliminary study of the textures and crystal sizes, it was resubclassified as a gabbroic shergottite because of the similarity with terrestrial and lunar gabbros. However, the previous work was not a quantitative investigation of NWA 6963; to supplement the original resubclassification and enable full comparison between this and other Martian samples; here we investigate the mineralogy, petrology, geochemistry, quantitative textural analyses, and spectral properties of gabbroic shergottite NWA 6963 to …