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Articles 1 - 12 of 12
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Identifying Biogeochemical Factors Responsible For The Cyclical Precipitation Of Sphalerite And Galena In Low Temperature Mississippi Valley Type Ore Deposits, Daniel John Makowsky
Identifying Biogeochemical Factors Responsible For The Cyclical Precipitation Of Sphalerite And Galena In Low Temperature Mississippi Valley Type Ore Deposits, Daniel John Makowsky
Theses and Dissertations
Mississippi Valley Type (MVT) lead and zinc deposits provide a significant source of sedimentary galena and sphalerite. However, geochemical characteristics and genesis including the source and production of hydrogen sulfide required for galena and sphalerite ore formation and the reasoning for quick, episodic mineralization is not fully understood. By simulating regional MVT brines, the input and effect of biological by-products during the development of these ores as well as the cause of cyclicity within MVT deposits have been observed. Experiments using compositions from MVT fluid inclusions were conducted over two-week periods. Variables during the experiments included temperature, CO2, hydrogen sulfide …
Chemical And Physical Weathering Rates Of Basaltic Volcanic Regions: Utilizing Space In Place Of Time In The Hawaiian Archipelago, Benjamin Clyde Barton
Chemical And Physical Weathering Rates Of Basaltic Volcanic Regions: Utilizing Space In Place Of Time In The Hawaiian Archipelago, Benjamin Clyde Barton
Theses and Dissertations
With large populations living in tropical regions of the world with volcanic substrates, understanding basalt weathering processes is vital. The Hawaiian Islands are an excellent natural analogue to study chemical weathering rates due to a uniform bedrock (basalt), large variations in rainfall, and varying ages across the islands. Laterite weathering profiles (LWP) develop over time through chemical weathering, where LWP thickness is influenced by many factors, including precipitation and time. Using the rapid, non-invasive horizontal-to-vertical spectral ratio (HVSR) method, LWP thicknesses can be estimated to constrain chemical weathering rates. Studying the laterite weathering profiles developed from basaltic bedrock of varying …
Analyzing Weathering Patterns In Modern And Paleolake Deposits Of Tecopa, California: Implications For The Detection Of Paleolakes On Mars, Jason Benjamin Carman
Analyzing Weathering Patterns In Modern And Paleolake Deposits Of Tecopa, California: Implications For The Detection Of Paleolakes On Mars, Jason Benjamin Carman
Theses and Dissertations
This study focuses on two stratigraphic sections from the Tecopa paleolake and samples from the modern Tecopa and Amargosa River basins as a terrestrial analogue to Martian paleolakes. Previous work shows that the later stages of Pleistocene Lake Tecopa were highly alkaline and saline due to evaporation, which led to the formation of authigenic lacustrine minerals such as zeolites, clays, and precipitates that are potentially similar to Martian paleolakes. Paleolakes can provide information on past aqueous processes, such as the changes in the hydrologic cycle that a particular area experienced over the lifespan of a lake on Earth or Mars. …
A South Polar View Of Late Paleozoic Glaciation: Physical Sedimentology And Provenance Of Glacial Successions In The Tasmanian And Transantarctic Basins, Elizabeth Rosa Woodford Ives
A South Polar View Of Late Paleozoic Glaciation: Physical Sedimentology And Provenance Of Glacial Successions In The Tasmanian And Transantarctic Basins, Elizabeth Rosa Woodford Ives
Theses and Dissertations
The Late Paleozoic Ice Age (LPIA; ~ 374 – 256 Ma) is the longest Phanerozoic icehouse interval. this interval in Earth’s history was largely defined by extensive glaciation of the southern hemisphere at both polar and temperate latitudes. Glaciers are powerful climatic and geologic actors, especially during icehouse periods, and widespread glaciation can have a significant influence on both regional and global climate and geology. Therefore, constraining the characteristics of LPIA glaciers is essential to developing a global-scale understanding of this key climatic event in Earth’s history. The manuscripts in this dissertation examine the sedimentology, transport directions, stratigraphy, and detrital …
Carbon Storage Via Mineral Bonding In Subsoils A Review Of Soil Processes, Kiele Goins
Carbon Storage Via Mineral Bonding In Subsoils A Review Of Soil Processes, Kiele Goins
Theses and Dissertations
Soil is an important but often poorly understood portion of the carbon cycle. Soil can store more carbon than twice today’s atmosphere, but the factors that control carbon storage are often unclear. Carbon enters the soil through input of organic matter, erosion, and aerosol deposition and is lost mostly via microbial decomposition. Carbon loss in soil is impacted by the chemical composition of organic compounds, environmental factors, and human activities. Furthermore, as climate changes soil, carbon storage may be vulnerable. Although carbon can be stored throughout soil, carbon storage varies with depth. In topsoil, carbon is stored for short periods …
Groundwater Flow And Transport At The Forest-Marsh Boundary: A Modeling Study, Sophia Chason Sanders
Groundwater Flow And Transport At The Forest-Marsh Boundary: A Modeling Study, Sophia Chason Sanders
Theses and Dissertations
The forest-marsh boundary, where tidally influenced salt marshes meet a forested upland, is hydrologically complex due to its multiple water inputs. Groundwater flow and salinity transport at this boundary are not well understood. In order to make predictions about salinity at this boundary as it responds to climatic factors, a two-dimensional model was built to simulate groundwater flow and solute transport at a salt marsh on Sapelo Island, Georgia. After calibration based on observed data from wells at the study site, the model can be used to identify patterns in groundwater movement and solute transport that may influence the vegetation …
Groundwater Discharge From Passive Continental Margins: Rethinking Marine Chemical Budgets, Andrew William Osborne
Groundwater Discharge From Passive Continental Margins: Rethinking Marine Chemical Budgets, Andrew William Osborne
Theses and Dissertations
Geothermal convection and sediment compaction drive large-scale flow in continental shelves. We suggest that this flow is an overlooked control on the major ion chemistry of the ocean. Conventional ocean chemical budgets are constructed using river discharge, axial mid-ocean ridge (MOR) convection and CaCO3 production, but these budgets are still poorly quantified. We synthesized data from 17 passive continental margin basins to calculate a range of estimated groundwater and chemical fluxes from continental shelves, considering five major ions (Ca2+, Na+, K+, Mg2+, and Cl-). When extrapolated globally, volumetric groundwater flux estimates were comparable to those for MOR axial circulation, and …
Fluid Flow And Deformation: Exploring The Relationships Between Fluid Flow, Deformation Mechanisms, Quartz Crystallographic Preferred Orientation Fabric Development, And Kinematics In The Willard Thrust Fault, Utah, Falyn Strey
Theses and Dissertations
Thirty-four quartz-rich samples were collected across the Willard thrust fault in Utah to explore the effects that fluid has on faulting. In particular, the relationships between fluid, deformation mechanisms, crystallographic preferred orientation (CPO) fabric development, and kinematic vorticity were investigated. A petrographic analysis of all 34 samples determined the relative contributions of brittle fracturing, crystal plasticity, and diffusional processes along with their possible relation to fluid interaction. Crystal plasticity dominates throughout most of the field area except where significant contributions from diffusive deformation occurs in rocks with significant mica concentrations and fine grain sizes, especially those located near the fault. …
Fluvial And Sequence Stratigraphy Analysis Of The Hell Creek And Fort Union Formations To Test Models For Sedimentation Across The Cretaceous-Paleogene Boundary In Makoshika State Park, Glendive, Montana, Quintin Bendixen
Theses and Dissertations
The Cretaceous-Paleogene Boundary outcrops extensively throughout Makoshika State Park in Glendive, Montana. A distinct change in sedimentation style occurs across the Cretaceous- Paleogene in the Williston Basin deposits found in eastern Montana and western North Dakota. The well documented Hell Creek Formation of the Upper Cretaceous period consists of fresh and brackish water influenced deposits on the western low-lying coast of the Western Interior Seaway. The overlying Fort Union Formation consists of coals and fluvial sandstone deposits. Geologic explanations for the depositional shift include tectonic forces of the Sevier/Laramide Orogeny to the west, The Cretaceous-Paleogene Extinction Event, and the advancement …
Monitoring Of Carbon Dioxide Injection In The Southeastern United States, Adil Murad Awad Alshammari
Monitoring Of Carbon Dioxide Injection In The Southeastern United States, Adil Murad Awad Alshammari
Theses and Dissertations
Over the past few decades, measured levels of atmospheric carbon dioxide have substantially increased. One way to limit the adverse impacts of increased carbon dioxide concentrations is to capture and store it inside Earth's subsurface, a process known as CO2 sequestration. This method's success is critically dependent on the ability to confine injected CO2 for up to thousands of years. Establishing effective maintenance of sealing systems of reservoirs is of importance to prevent CO2 leakage. Understanding the nature and rate of potential CO2 leakage related to this injection process is essential to evaluating seal effectiveness and ultimately mitigating global warming. …
Carbonatite Metasomatism And Water Systematics Of Peridotite Xenoliths From Lanzarote, Canaries, Sierra N. Patterson
Carbonatite Metasomatism And Water Systematics Of Peridotite Xenoliths From Lanzarote, Canaries, Sierra N. Patterson
Theses and Dissertations
Water in Earth’s mantle, present as structurally bound hydrogen in minerals, influences large scale processes like mantle deformation, plate tectonics, and melting. To better understand the processes controlling water concentrations in the Earth’s upper mantle, we analyzed hydrogen (calculated as ppm wt. H2O), major, and trace element concentrations in minerals from peridotite mantle xenoliths of Lanzarote, Canaries. The Canaries Islands are thought to be the surface expression of a deep-seated mantle plume erupting through the Atlantic Ocean lithosphere. Carbonatite magmas have erupted in the Canaries and previous studies have shown evidence for carbonatite metasomatism in Lanzarote peridotites. Thus, …
Radium At The Lost City And Mid-Cayman Rise Hydrothermal Fields, Jessica D. Frankle
Radium At The Lost City And Mid-Cayman Rise Hydrothermal Fields, Jessica D. Frankle
Theses and Dissertations
Fluid residence times of deep-sea hydrothermal circulation influence chemical cycling in the ocean. While fluid residence time estimates exist for many basalt-hosted systems, no estimates exist for serpentinite hosted systems that emit fluids with inherently different chemistry. We measured short- and long-lived radium (Ra) nuclides in fluids from two hydrothermal systems on the Mid-Cayman Rise to constrain their residence times: the Von Damm Vent Field, a mixed ultramafic-mafic system, and the Piccard Vent Field, a mafic, neovolcanic system. Von Damm fluids contain remarkably elevated 223Ra activities (half-life = 11.4 days), surpassing those from basalt-hosted hydrothermal systems by one to two …