Polygonal Faults In The Austin Chalk: Invariance Of Scale From Mud Cracks To Polygons With Implications Of Structural, Geomorphic And Isotopic Data On Polygonal Fault Geometry And Origin.,
2023
Southern Methodist University
Polygonal Faults In The Austin Chalk: Invariance Of Scale From Mud Cracks To Polygons With Implications Of Structural, Geomorphic And Isotopic Data On Polygonal Fault Geometry And Origin., Kun Shang
Earth Sciences Theses and Dissertations
The Cretaceous Austin Chalk contains large numbers of fractures and normal faults whose orientations have been attributed to either regional stresses (e.g., the Balcones fault trend) or, by analogy with the mudrocks, to polygonal faulting resulting from compaction. In this study, we present geomorphic data, field study, and stable isotope data to support that the majority of these faults in North Texas are polygonal. Field-measured fault orientations suggest randomly distributed fault strikes, indicating a polygonal fault structure. Using geomorphologic data (topographic and DEM data) on stream orientations suggests that the polygonal fault patterns are best reflected in the headwater (1st …
Investigation Of The Sheep Creek Carbonatites, Ravalli County, Montana,
2023
Montana Tech
Investigation Of The Sheep Creek Carbonatites, Ravalli County, Montana, Sarah Risedorf
Graduate Theses & Non-Theses
Carbonatite-related REE-Nb mineralization in southern Ravalli County, Montana was first discovered in the late 1950s and early 1960s. Over 30 discontinuous carbonatite bodies occur in a ~ 10 km2 area centered on Sheep Creek, a tributary to the headwaters of the West Fork of the Bitterroot River (WFBR). The deposits are contained in a belt that extends to the southeast into the Mineral Hill district of Lemhi County, Idaho. Country rocks include a deformed and metamorphosed bimodal igneous suite of diabase and A-type granite, both dated to 1.37 Ga by previous workers. These rocks are locally metamorphosed to amphibolite …
Geochemical Analysis And Numerical Modeling Of Central And East Tennessee Mississippi Valley-Type Ore Districts: Constraints On Ore Genesis,
2023
University of Arkansas, Fayetteville
Geochemical Analysis And Numerical Modeling Of Central And East Tennessee Mississippi Valley-Type Ore Districts: Constraints On Ore Genesis, Jackson Price Copeland
Geosciences Undergraduate Honors Theses
A simple two-way stochastic mixing model is presented for analysis of the lead (Pb) isotope compositions of the North American Mississippi Valley-Type (MVT) districts of East Tennessee, Central Tennessee, and Central Kentucky. Four distinct mixing scenarios were run to critically evaluate the stochastic model and examine different hypotheses regarding the genesis of Central Tennessee and Central Kentucky MVT deposits. Additionally, Pb isotope analysis was conducted on sphalerite samples from the Central and East Tennessee MVT districts. Model and sampling results suggest that Central Tennessee and Central Kentucky ores likely formed by mixing of three fluids. In contrast to conclusions from …
Comparing Igneous Geochemical Data From Hawaii And Southern California Via Machine Learning,
2023
Southern Adventist University
Comparing Igneous Geochemical Data From Hawaii And Southern California Via Machine Learning, Miro Manestar
MS in Computer Science Project Reports
Bi-plots are commonly used in geochemical analyses. However, their use can become cumbersome in the case of multi-variate analyses. Therefore, this thesis explores the application of unsupervised machine learning techniques, specifically PCA and K-Means, to analyze large geochemical data sets from two distinct regions, Hawaii and the \acrfull{prb} in Southern California. The IBM Foundational Methodology for Data Science was utilized to ensure proper data preparation and analysis. PCA provided dimensionality reduction, revealing which features correlated most strongly with variances within the data. K-Means clustering allowed for deeper interpretation of the data. The analysis yielded valuable insights into the composition and …
The Phosphorus Puzzle: Why Metal Phosphites Could Be The Missing Piece,
2023
Kennesaw State University
The Phosphorus Puzzle: Why Metal Phosphites Could Be The Missing Piece, Eleanor Boyle, Thomas J. Leyden Iii
Symposium of Student Scholars
It is well understood that phosphorylation of organic molecules is a keystone mechanism toward developing early cell function. However, the source of phosphorous in prebiotic chemistry is under debate. Phosphate minerals were abundant on the early Earth, but they are highly insoluble. In comparison, metal phosphites are significantly more soluble. While they may not have been preserved in the geological record, there are several plausible pathways for their formation under prebiotic conditions. We hypothesize that metal phosphites were a major source of phosphorus. To test our hypothesis, we synthesized and characterized metal phosphites, containing the most abundant cations on the …
The Fate Of Carbonate Rocks During Hypervelocity Impacts: Case Studies From Three Impact Structures On Earth,
2023
The University of Western Ontario
The Fate Of Carbonate Rocks During Hypervelocity Impacts: Case Studies From Three Impact Structures On Earth, Nicolas D. Garroni
Electronic Thesis and Dissertation Repository
Approximately 28% of all hypervelocity impact structures discovered on Earth exist in a carbonate-dominated target sequence. Despite decades of research, how carbonate rocks and minerals react to shock metamorphism is still poorly understood. In this contribution, three impact structures on Earth were studied to determine the effects of shock metamorphism on carbonate minerals: Chicxulub, Crooked Creek and Jebel Waqf as Suwwan.
At Chicxulub, carbonates from the impact-melt bearing breccia of drill core, M0077A were characterized petrographically and geochemically. Calcite was the only carbonate mineral present and is abundant throughout the impact breccia in five distinct varieties: limestone clasts …
Assessing Ecosystem Health Through Contaminants In The Tijuana River National Estuarine Research Reserve,
2023
University of San Diego
Assessing Ecosystem Health Through Contaminants In The Tijuana River National Estuarine Research Reserve, Nancy Torres
Theses
Although the Tijuana River Estuary (TRE) remains the largest, most-intact coastal wetland in Southern California, it has a history of major changes, much of this related to its location immediately north of the US / Mexico Border. One of the primary challenges is cross-border flows from the rapidly growing city of Tijuana, Baja California, Mexico, and the delivery of wastewater, debris, and sediment to sensitive coastal wetland ecosystems. There is a need to more fully investigate these environmental changes to assess the ecosystem health of the Tijuana River Estuary over time, especially related to pollution impacts. This can inform an …
Cementation And Groundwater Chemistry In Pleistocene Paleodune Deposits Of The Central Oregon Coast,
2023
Portland State University
Cementation And Groundwater Chemistry In Pleistocene Paleodune Deposits Of The Central Oregon Coast, Adrienne Lynn Stephens
Dissertations and Theses
Pleistocene paleodune deposits occur along the Oregon coast, underlying coastal towns, roadways, and associated power and water infrastructure(s). Secondary cementation within these deposits provides some stability, allowing for near-vertical sea cliffs and roadcut outcrops. Yet, slope instability is a prevalent hazard observed within the paleodune deposits. Weakening of cementing agents via changes to groundwater conditions due to altered vegetation, climate change, or contamination, for example, could promote slope instability, threatening lives and infrastructure. This study aims to investigate the variability in the type and degree of cementation and to determine how they are affected by changes in groundwater conditions.
To …
Cryogenic Ridges: A New Speleothem Type,
2023
University of South Florida, USA
Cryogenic Ridges: A New Speleothem Type, Bogdan P. Onac, Daniel M. Cleary, Oana A. Dumitru, Victor J. Polyak, Ioan Povara, Jonathan G. Wynn, Yemane Asmerom
International Journal of Speleology
Cryogenic cave carbonates have been described from several formerly or presently glaciated karst caves. In most of these occurrences, they precipitated as loose grains or aggregates with various morphologies and sizes. Here, we report on a new speleothem type (cryogenic ridges) identified in Sohodoalele Mici Cave (SW Romania) within a large chamber near the entrance shaft. This study was motivated by the presence of a network of calcite ridges over the stalactites’ surface and by the observation that during winter, these speleothems are covered by a thin ice layer. The higher δ18O (−3.5 to –1‰) and …
Dust Deposition To The Bermuda Region: A Comparison Of Estimates Using Seasonally-Resolved Measurements Of Aluminum In Water-Column, Aerosol, And Rain Samples,
2023
Old Dominion University
Dust Deposition To The Bermuda Region: A Comparison Of Estimates Using Seasonally-Resolved Measurements Of Aluminum In Water-Column, Aerosol, And Rain Samples, Tara Williams, Peter Sedwick, Bettina Sohst, Joe Resing, Kristen Buck, Salvatore Caprara, Rod Johnson, Dan Ohnemus, Ben Twining, Alessandro Tagliabue
College of Sciences Posters
Dust deposition is a major source of bioactive trace elements to the surface ocean, yet this flux remains difficult to constrain. Previously, time-averaged dust flux has been estimated using surface ocean dissolved aluminum (DAl) concentrations, assumed values for aerosol aluminum solubility (%AlS), and the residence time of DAl in the surface mixed layer (SML). We apply this method to estimate dust deposition in the Bermuda Atlantic Time-series Study (BATS) region using water-column DAl data from cruises in 2019, which is compared with direct flux estimates from contemporaneous measurements of aluminum in aerosols and rain collected on Bermuda. Seasonal …
Organic Matter Content And Grain Size Analysis In Seagrass Sediments,
2023
Old Dominion University
Organic Matter Content And Grain Size Analysis In Seagrass Sediments, Adriana Amrhein, Rip Hale
College of Sciences Posters
Anthropogenic stresses including increased water temperatures, decreased water quality, sea level rise, ocean acidification and sediment biogeochemical processes have caused a significant loss in seagrass meadow acreage. Seagrass meadows provide coastal protection from storms and recently have been emphasized for their importance in sequestering and storing “Blue Carbon” from the atmosphere and ocean. Seagrass meadows can trap this blue carbon in their sediment as organic carbon, and it can be stored for hundreds to thousands of years. Restoration efforts of seagrass meadows in the Virginia coast started in the 1990s and effects of increasing seagrass density can be observed in …
Natural Fracture Evolution: Investigations Into The Middle Devonian Marcellus Shale, Appalachian Basin, Usa,
2023
West Virginia University
Natural Fracture Evolution: Investigations Into The Middle Devonian Marcellus Shale, Appalachian Basin, Usa, Natalie Abigail Mitchell
Graduate Theses, Dissertations, and Problem Reports
Optimizing recovery from unconventional shale reservoirs has generated considerable research into optimal recovery methods through hydraulic fracturing design and shale reservoir characterization in the development of long-term hydrocarbon producers. Permeability at multiple scales from nanometer-scale pore sizes and nano-darcy permeability to completion-induced fractures defining a 100’s of meter stimulated reservoir volume plays a significant role in hydrocarbon flow during production in shale reservoirs. Preexisting cemented fractures in unconventional shale reservoirs are abundant and preferentially reactivate during induced hydraulic fracturing treatment to create necessary large-scale permeability. While previous investigations have significantly improved our knowledge of shale reservoirs, it has also highlighted …
Changes Of Water Chemistry From Rainfall To Stream Flow In Obagbile Catchment, Southwest Nigeria,
2022
Department of Geography, Obafemi Awolowo University, Ile Ife, 220101, Nigeria
Changes Of Water Chemistry From Rainfall To Stream Flow In Obagbile Catchment, Southwest Nigeria, Mojisola Hannah Omogbehin, Isaac Ayo Oluwatimilehin
Regional Sustainability
Water chemistry changes when it flows through different pathways. This study aims to characterize the differences of water (including rainwater, overland flow, soil water, groundwater, and stream water) chemistry of five kinds of water in Obagbile Catchment in Southwest Nigeria, determine the changes in water chemistry that occur as the water moves from one pathway to another, and identify the factors responsible for the water chemistry changes. To do these, we collected 50 water samples from 10 heavy storms that received equal to or more than 10 mm of rain within an hour to test the changes of water chemical …
Silting Dynamics And Metal Contaminants In The Georgetown Inner Harbor,
2022
Coastal Carolina University
Silting Dynamics And Metal Contaminants In The Georgetown Inner Harbor, Ezekiel Wil Meyers
Electronic Theses and Dissertations
The Georgetown inner harbor is an abandoned oxbow-like river loop and a vital historic site with a wealth of traditional businesses and heavy local industry located within Winyah Bay. Since the modification of the Sampit River in 1949, chronic rapid silting has plagued the inner harbor. With these substantial amounts of fine-grained material accumulating inside the inner harbor, business operations along the waterfront, navigational and maritime operations, and contamination within the harbor are of major concern. The goals of this study were to (a) understand the silting dynamics inside the inner harbor, (b) identify heavy metals which might be of …
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,
2022
University of Tennessee, Knoxville
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 SO42- [sulfate] concentrations, suggesting high- and low-temperature aqueous processes. However, the SO42- 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 …
Experimental Approaches To Evaluating Silicate Melt Properties And Trace Element Fractionation During Crystallization At High Pressures And High Temperatures,
2022
University of Tennessee, Knoxville
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 …
Phosphate Mineralogy And Paragenesis Of The Fletcher Pegmatite, North Groton, New Hampshire,
2022
University of New Orleans
Phosphate Mineralogy And Paragenesis Of The Fletcher Pegmatite, North Groton, New Hampshire, Susanna T. Kreinik
University of New Orleans Theses and Dissertations
Investigation of phosphate assemblages selectively collected at the Fletcher Mine pegmatite, North Groton, New Hampshire, yielded eighteen discrete secondary phosphate species. Secondary phases were formed via metasomatic (high temperature) and hydrothermal (low temperature) alteration of primary triphylite and fluorapatite. Mineral associations bear proximal phases known to occur under contrasting conditions, both oxidizing and reducing, suggesting the formation of microenvironments during concomitant mineral generation. Late-stage hydrothermal fluids provide ions taken up in low temperature secondary phases with calcium and magnesium most prevalent in these suites. High iron to manganese ratios in analyzed specimens establish the relative evolution of the pegmatite host. …
Ligand-Promoted Dissolution Of Uranyl Phosphate Across Scales,
2022
Clemson University
Ligand-Promoted Dissolution Of Uranyl Phosphate Across Scales, Brennan Ferguson
All Dissertations
The formation of uranyl phosphate precipitate is a remediation strategy because the low solubility of uranyl phosphate minerals, like chernikovite, limits the mobility of uranium in contaminated soils. However, organic ligands can complex with aqueous metal cations to form more soluble species. For example, citrate is a commonly occurring organic ligand produced by plants and microbes that increases the solubility of uranium and therefore the dissolution of uranyl phosphate minerals in the uranyl phosphate-citrate system. This effect is an important control on the mobility of uranium in organic-rich, and near-surface vegetated environments. Nevertheless, key aspects of the citrate-uranyl phosphate system …
Natural, Experimental, And Educational Explorations Of The Interiors Of Terrestrial Planetary Bodies,
2022
University of Tennessee, Knoxville
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, …
Computational And Experimental Investigations Of Alkali Cation Interactions At The Rutile – Water Interface,
2022
Clemson University
Computational And Experimental Investigations Of Alkali Cation Interactions At The Rutile – Water Interface, Isaac Johnston
All Dissertations
Overall, the objective of this dissertation was to investigate the degree of sorption for the alkali cations on rutile to ascertain the impact of different cation properties, such as ion size and charge density, on sorption mechanics as well as probe how the ion may alter the surface – aqueous interface. Initial molecular dynamic simulations and batch experiments showed minimal surface sorption for any alkali cation at relatively low concentrations while simultaneously suggesting the enthalpy of deprotonation shifts slightly in the presence of the alkali cations at different ionic strengths. The cations are likely causing small reorientations of the near-surface …
