Physical Sciences and Mathematics Commons^™

Geochemistry And Geochronology Of The Steens And Monument Dike Swarm: Implications And Relationships To Magmatic Storage And To Lava Flows Of The Picture Gorge And Steens Basalt, Rachel Anne Sweeten

Dissertations and Theses

The Columbia River Basalt Group (CRBG) is the youngest and best-preserved example of a continental flood basalt province. Vents and dikes for the four main eruptive units (Steens, Imnaha, Grande Ronde, and Picture Gorge Basalt) are the Monument, Steens and Chief Joseph Dike Swarms located in eastern Oregon, southeastern Washington, and northern Nevada.

Here we report on the compositions and timing of the dikes and sills of the Monument Dike Swarm (MDS), as well as their relationship to the subaerial lava flows of the Picture Gorge Basalt (PGB) with implications for crustal storage of these magmas. We evaluate data from …

Tidal Bed Stress Asymmetry And Sediment Transport In Estuaries, Austin Scott Hudson

Dissertations and Theses

Rivers and estuaries provide numerous ecological, economic, and cultural resources. The value of these resources is greatly influenced by sediment transport processes, which can be affected by human activities and climate variability. A key driver of sediment transport in tidal rivers and estuaries is tidal asymmetry of velocity and bed stress, which can manifest from both non-linear tidal interactions and linear interactions among astronomical tidal constituents.

In this study, an analytical framework is developed to examine and describe the dynamics of bed stress asymmetry in semidiurnal, diurnal, and mixed-tide estuaries (Chapter 1). While tidal velocity asymmetry has been previously analyzed, …

Forest Fire Effects On Snow Storage And Melt Across Scales Of Forest Recovery In The Western Oregon Cascades, Megan Nicole Guinn

Dissertations and Theses

Snow is the largest component of water storage in the western United States, it serves as a key moisture source for forested ecosystems and is fundamentally linked to streamflow and nutrient cycling. Snow is vulnerable to climatic warming, and a key consequence of declining mountain snowpack is the escalation in wildfire frequency, extent, intensity, and duration across the seasonal snow zone. Fire modifies the spatial extent of snow in watersheds, reducing snow water storage and timing of melt across burned forests. Forested mountain ecosystems and water supplies are facing shifts in their structure, function, and succession. Previous research has focused …

Structure-From-Motion Derived Snow Cover In Burned Forests Of The Western Oregon Cascades, Siobhan Ciafone

Dissertations and Theses

Forest fire occurrence in the western US has increased rapidly since the 1980s, and most western US fires occur in the seasonal snow zone. Burned forests influence snow accumulation and melt patterns for years following fire, and understanding drivers of variability in snow cover across a burned landscape at the basin-scale is necessary for accurate hazard prediction and water resource forecasting. Basin-scale surveys of snowpack are possible with remote sensing, but accurate sensing methods such as Light Detection and Ranging (LiDAR) are often cost-prohibitive. In the last decade, structure-from-motion (SfM), an optical remote sensing technique, has emerged as an affordable …

Disentangling Groundwater Dynamics At Oregon's Mckenzie River Headwaters, Taylor Nicole Salazar

Dissertations and Theses

Widespread mountain snowpack declines have been occurring across the western United States over the last century, and are increasing in duration and severity, with several record-breaking low-snowpack years in the last decade. In the Pacific Northwest, summer streamflow is largely a result of melting snow and groundwater discharge, as summers are typically dry and warm in this Mediterranean bioclimate, thus making spring-fed rivers critical for regional water resources. However, current trends and predictions in hydroclimate modeling indicate spring-fed rivers will experience reduced summer discharge driven by the increasingly larger impact of anthropogenic climate change (warming) on (decreased) mountain snowpack. A …

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen

Dissertations and Theses

Volcanic glass has been used extensively as a paleoclimate proxy. Deuterium (²H) concentrations in glass have been found to be stable over geologic timescales, making δD a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in ash. Here, I analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ashflow tuff, and create an isoscape to assess variations in δD across Oregon during that time. Additionally, I examine compositional data from glass shards to explore the relationship between δD and shard composition. The RST exhibits …

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 …

Understanding The Impacts Of Freshwater Fluxes On The Biogeochemistry Of The Coastal Arctic: A Case Study Of Prudhoe Bay, Francesca Lingo

Dissertations and Theses

The Arctic region, undergoing significant environmental changes due to rapid warming, faces alterations in air temperatures, melting permafrost, declining sea ice, and changes in riverine inputs. These shifts have profound implications for Arctic coastal ecology and biogeochemical cycles. This study, focusing on Alaska's North Slope, explores the influence of freshwater fluxes on water optical properties, vital for accurate satellite remote sensing interpretations. Our approach combined field measurements, existing data, and satellite remote sensing retrievals to identify biogeochemical gradients and their seasonal and interannual variations. A novel finding was the unique CDOM composition in Prudhoe Bay, characterized by a lower molecular …

Shallow Water Coral Distribution And Its Response To Climate Change, Amaury De Jesus

Dissertations and Theses

Shallow water corals are one of the main reef-building organisms that secrete carbonates as their skeletons, and therefore, are one of the major sinks of CO2 in the ocean. These reef builders are also very crucial to marine environments and human society. As the global energy demand continues rising, fossil fuel burning increases at a faster pace despite the increase in energy supply using clean and renewable energy. The increase of CO2 in the atmosphere has been shown to exacerbate global warming and may cause ocean acidification, threatening the habitat of shallow-water corals. Many recent observations show alarming signs of …

Fine Characterization Of Leafing Phenology In The Brazilian Atlantic Forest By Optical And Microwave Remote Sensing, James B. Bell

Dissertations and Theses

Tropical forests provide important ecosystem functions in the global biosphere, but they remain among the most poorly understood elements of land surface models, especially with regard to their seasonal dynamics. For instance, in seasonally dry forests, the pattern of the annual green-up in their canopies closely follows annual patterns of rainfall. The same, however, does not occur in wet forest canopies which are dominated by evergreen trees. In the latter, water is not scarce enough to limit leaf photosynthetic function. Canopy leafing phenology in these forests is therefore poorly characterized by optical remote sensing methods which are not sensitive to …

Analysis Of Chemical Elements In Basalts Using Mislabeled Data, A Machine Learning Approach, Jenifer Vivar

Dissertations and Theses

Scientists use basalt chemistry to discriminate among different tectonic settings. There are well-known chemical elements used to classify tectonic settings. An exploration of new features is done using Logistic Regression and Random Forest to discover any new elements of interest. The models were used with other tools, such as recursive feature elimination and permutations, to increase reliability. Among the scarcely explored chemical elements are Terbium (Tb), Holmium (Ho), Samarium (Sm), and Erbium (Er). The data used for the exploration contained many outliers. Therefore, an ensemble model was created to explore the location and composition of such outliers. The ensemble was …

Most Recent Rupture On The Boulder Creek Fault Triggered Bedrock Landsliding In The Nooksack Watershed, Whatcom County, Washington, Abigail Catherine Underwood

Dissertations and Theses

Catastrophic bedrock landslides with volumes ranging from 10⁶ to 10⁸ m³ contribute to rapid landscape evolution, often resulting in erosion rates that exceed the long-term average rates caused by tectonic uplift. Understanding the spatiotemporal trends of large bedrock landslides helps us understand previous drivers of landscape evolution as well as predict how the landscape will respond in the future. The Nooksack Watershed, Whatcom County, Washington, is particularly susceptible to large slope failures because of its high relief, seismic activity, local geology, and relatively abundant precipitation. Specifically, folded and faulted bedrock structures conducive to landsliding in addition to …

Spatial Analysis Of Burn Severity And Streamflow Response In The Western Conus, Will Brendan Long

Dissertations and Theses

Wildfire increases the magnitude of runoff in catchments, which can lead to the degradation of ecosystems, risk to infrastructure, and loss of life. The Labor Day Fires of 2020 provided an opportunity to compare multiple large and severe wildfires with the objective of determining potential changes to hydrologic processes in Oregon Cascades watersheds. Geographic information systems (GIS) were implemented to determine the total percentage burned and percentage of high burn severity class of six watersheds on the west-slope of the Oregon Cascade Range. In addition, two control watersheds were included to contrast the influence of climatic effects. Spatial arrangement of …

Investigation Of Basal Imnaha Basalt Flows And Their Relationship To The Picture Gorge Basalt Of The Columbia River Basalt Group, Luke James Fredenberg

Dissertations and Theses

The lower American Bar flows (AB 1 and 2) of the Imnaha Basalt have previously been observed as being chemically similar to those of the Picture Gorge Basalt (PGB). Previous age data separate eruption of the Imnaha and Picture Gorge Basalts by approximately 1.5 Ma, precluding the possibility of a genetic link between the two basalt units. New age data for the Picture Gorge Basalt has expanded the eruptive timeframe and the earliest flows coincide with the eruption of the Imnaha Basalt, making it possible that the lower American Bar flows of the Imnaha Basalt and the Picture Gorge Basalt …

Post-Fire Erosional And Hydrological Processes Promoting Debris Flow Initiation In A Douglas Fir And Western Hemlock Forest In The Riverside Burn Area, Oregon, Morena Nicole Hammer

Dissertations and Theses

Post-fire debris flows initiated by overland flow in the Pacific Northwest (PNW) are largely undocumented. Instead, debris flows are typically initiated by shallow landslides that result in a mud slurry of water and sediments traveling downhill under the force of gravity. However, because of the Fall 2020 fires in Oregon, the typical initiation style and erosional patterns in burned catchments may have changed because of unusually high burn severity. Due to the intensity of these fires, we set out to determine how hydrologic processes and erosion occurred, when they occurred, and what process was primarily responsible for the erosion that …

Learning From Machines: Insights In Forest Transpiration Using Machine Learning Methods, Morgan Tholl

Dissertations and Theses

Machine learning has been used as a tool to model transpiration for individual sites, but few models are capable of generalizing to new locations without calibration to site data. Using the global SAPFLUXNET database, 95 tree sap flow data sites were grouped using three clustering strategies: by biome, by tree functional type, and through use of a k-means unsupervised clustering algorithm. Two supervised machine learning algorithms, a random forest algorithm and a neural network algorithm, were used to build machine learning models that predicted transpiration for each cluster. The performance and feature importance in each model were analyzed and compared …

Electron Backscatter Diffraction Analysis Of Olivine In Ureilite Meteorites: Evaluation Of The Partially Magmatic Catastrophic Disruption Model Of The Ureilite Parent Body (Upb), James Karl Frye

Dissertations and Theses

Past studies of olivine have yielded insights into crystallographic slip systems and how they are activated thermally. Using this information in conjunction with Electron Backscatter Diffraction (EBSD) analysis and metrics developed for chondrites, I constrained the thermal environment and the cooling rate for four ureilite meteorites in an attempt to test the model of catastrophic disruption of the ureilite parent body while it was partly molten. Present evidence for deformation, along with thermal metrics, were examined in order to conclude the following: Deformation of the meteorites took place at high temperatures followed by swift cooling, leaving little time for annealing. …

Geochronological And Geochemical Investigation Into Rhyolite Volcanism Of The High Lava Plains And Columbia River Basalt Group Provinces Of Eastern Oregon, Usa, Vanessa Marie Swenton

Dissertations and Theses

Voluminous and widespread bimodal volcanism has significantly impacted the Pacific Northwest, USA, throughout the Miocene to present day. The two primary volcanic provinces of eastern Oregon include the Columbia River Basalt Group (CRBG) province and the High Lava Plains (HLP) trend. The magmatic and tectonic processes responsible for generating bimodal volcanism, and particularly rhyolites of the ~17-15 Ma CRBG and 12-0 Ma HLP provinces has recently been a popular topic of debate. Rhyolite volcanism of the HLP province has been ascribed to either buoyancy-driven westward plume spreading or to slab rollback and mantle convection spanning from southeast Oregon to Newberry …

Stratigraphic And Geochemical Evaluation Of Distal Flows Of The Columbia River Flood Basalts In The Greater Vale Area, Southeastern Oregon, Lena Marie Fox

Dissertations and Theses

Exposures of Columbia River Basalt Group (CRBG) in southeastern Oregon are dominated by the four main phase CRBG units: Steens Basalt, Imnaha Basalt, Grande Ronde Basalt (GRB), and Picture Gorge Basalt (PGB). These units are best seen in stratigraphic sequence along the Malheur Gorge corridor of southeastern Oregon, between the towns of Vale and Juntura, with flows of Steens Basalt from the south overlain by flows of Imnaha and GRB from the north. Recently, PGB flows were found to be part of the eastern Malheur Gorge stratigraphy as well.

In Malheur Gorge, local units of Birch and Hunter Creek Basalt …

Spatial And Seasonal Variations Of Microplastic Concentrations In Portland's Freshwater Ecosystems, Rebecca Talbot

Dissertations and Theses

Microplastics are a pollutant of growing concern and are ubiquitous in a variety of environmental compartments. The majority of microplastics research to date has been conducted in marine waters, and less is known regarding the sources and delivery pathways of microplastics in urban rivers. The first chapter is comprised of a review of the scientific literature regarding the spatial and temporal factors affecting global freshwater microplastic distributions and abundances. Microplastic spatial distributions are heavily influenced by anthropogenic factors, with higher concentrations reported in regions characterized by urban land cover, high population density, and wastewater treatment plant effluent. Temporal variables of …

Inverse Modeling Of Atmospheric Ch4 And Δ13C-Ch4 Measurements From Surface Observation Sites To Understand Trends In Global Methane Emissions Over More Than Three Decades, Sayantani Karmakar

Dissertations and Theses

Methane (CH₄) is the second most important greenhouse gas with a radiative forcing of 0.97 W/m² including both direct and indirect effects and a global warming potential of 28 over a 100-year time horizon. Unlike CO₂ whose rate of growth in the atmosphere has remained positive and increased in recent decades, the behavior of atmospheric methane is considerably more complex and is much less understood on account of the spatiotemporal variability of its emissions which include biogenic (e.g., wetlands, ruminants, rice agriculture), thermogenic (fossil fuels), and pyrogenic (i.e., biomass burning) sources. After sustained growth during most …

Sea Surface Temperatures And Vertical Wind Shear As Precursors To Tropical Cyclone Activity In The Caribbean And An Expanding Main Developing Region, Keneshia Hibbert

Dissertations and Theses

Sea surface temperatures and vertical wind shear are essential to tropical cyclone formation. TCs need warm SSTs and low shear for genesis. Increasing SSTs and VWS changes influence storm development. This work analyzes SST and VWS trends for the Caribbean, surrounding region, and the Atlantic hurricane main developing region from 1982 to 2020. Storm intensity increases significantly during this period. Annual and seasonal trends show regional SSTs in the MDR are warming annually (0.0219°C yr^-1) and per season (0.0280°C yr^-1). Simultaneously, VWS decreases during the late rainfall season at 0.0556m/s yr^-1 in the MDR and …

The Derivation Of Geologic Ecosystem Services From Geodiversity In The Black Hills Region Of South Dakota And Wyoming, James Campbell Cooke

Dissertations and Theses

The ecosystem services approach seeks to recognize the benefits that people obtain from ecosystems, in order to highlight society’s dependence on natural systems. Ecosystem services fall into four categories: provisioning, regulating, cultural, and supporting services. Most of the ecosystem services research literature is focused on services that arise from biotic components of ecosystems. Ecosystems are dynamic complexes of biotic communities and their physical, non-living environment, interacting as a functional unit. The emphasis on biotic ecosystem services leaves understudied and undervalued the role of the abiotic, physical environment, especially in providing geologic ecosystem services. Geologic ecosystem services have been the focus …

Evaluation Of Snow And Streamflow In The National Water Model With Analysis Using Machine Learning, Engela Sthapit

Dissertations and Theses

Snow has great influence on land-atmosphere interactions and snowmelt from the mountains is a vital water source for downstream communities dependent on snow fed lakes, rivers and streams. This study explored the snow and streamflow prediction capabilities of process-based numerical prediction and data-driven machine learning models.

The overall goal of this study was to understand the deficiencies in the NOAA’s National Water Model (NWM) to represent snow, subsequently streamflow, and recognize the areas where it could be improved for future model developments. The goal was also to evaluate if the recent advancements in machine learning techniques is useful for predicting …

Data Fusion And Synergy Of Active And Passive Remote Sensing; An Application For Freeze Thaw Detections, Zahra Sharifnezhadazizi

Dissertations and Theses

There has been a recent evolvement in the field of remote sensing after increase of number satellites and sensors data which could be fused to produce new data and products. These efforts are mainly focused on using of simultaneous observations from different platforms with different spatial and temporal resolutions. The research dissertation aims to enhance the synergy use of active and passive microwave observations and examine the results in detection land freeze and thaw (FT) predictions. Freeze thaw cycles particularly in high-latitude regions have a crucial role in many applications such as agriculture, biogeochemical transitions, hydrology and ecosystem studies. The …

Distribution And Characterization Of Rhyolites Of The Strawberry Volcanics -- Evolution Of A Major Rhyolite Field Associated With Columbia River Basalt Magmatism, Eastern Oregon, Usa, Chanel Leigh Dvorak

Dissertations and Theses

The Strawberry Rhyolites constitute a significant rhyolite field among the largest in Oregon. Aerial coverage of approximately 386 km² and an overall estimated volume of ~67 km³ using a median thickness for each unit. On the other hand, the total volume could be greater than 100 km³ if greater thicknesses apply. The Strawberry Rhyolites, a largely unknown mid-Miocene silicic volcanic rocks, crop out amongst voluminous flood basalt flows of the Columbia River Basalt Group (CRBG) in eastern Oregon. The eruptive activity of the Strawberry Rhyolites is currently constrained to span a period of about 2 million years, …

Characterization And Interpretation Of Feldspathic Chromite Assemblages (Fcas) In Four Ordinary Chondrites: An Electron Backscatter Diffraction (Ebsd) Study, Kimberly Louisa Maccini

Dissertations and Theses

Feldspathic Chromite Assemblages (FCAs) are chemically distinctive assemblages rich in Na, Al, and Cr that are found in a variety of chondrites. They consist of concentrations of chromite associated mainly with feldspathic material, either feldspar or the glassy material known as maskelynite. Professor Alan Rubin (2003) has proposed that some FCAs formed by shock melting, but the origin of different types of feldspathic chromite assemblages are unclear and have not been studied with more modern techniques such as Electron Backscatter Electron Diffraction (EBSD).

Here EBSD was used to study FCAs in four metamorphosed ordinary chondrites of different shock stages, including …

Community College Geoscience Faculty Perspectives On Critical Thinking Instructional Tools, Mariela Salas Bao

Dissertations and Theses

Research has shown that modern courses and programs designed to foster critical thinking vary in both content and delivery, in turn leading to differences in their effectiveness. Few studies have investigated critical thinking among nontraditional students at community colleges taking STEM courses, especially within the geosciences. Furthermore, such research has focused primarily on the students with few if any studies involving faculty. This study examined the perceptions held by community college geoscience faculty regarding critical thinking and how such perceptions influenced their choice of instructional strategies. This study used a basic qualitative methodology and a maximum variation sampling to select …

Major Controls On Diagenesis In The Martin Bridge Formation: Wallowa Mountains, Oregon, Jane Lyra Eisenberg

Dissertations and Theses

Diagenetic alteration in carbonates has long frustrated scientists who wish to use their chemistry and/or texture to understand conditions at the time of deposition. Though indicators of diagenesis are well documented, their interpretation is not always straightforward. Despite the large volume of research on the subject, the positive identification and interpretation of diagenesis is a source of ongoing debate in the scientific community.

The goal of this study is to better understand the timing of, and controls on, diagenetic alteration in the Martin Bridge Formation (MBF), a Triassic-aged limestone that was altered following deposition. Thirty-nine samples of MBF with differing …

Mid-Miocene Icelandites Of Eastern Oregon: Petrogenesis And Magmatic Lineage To Main-Phase Crbg With Constraints On Storage Sites, Melissa Aileen Carley

Dissertations and Theses

The La-Grande Owyhee eruptive axis is a mid-Miocene to Pliocene ~300 km long volcanic belt located at the eastern margin of the Columbia River Basalt Group (CRBG) in Oregon. Within this volcanic belt there are numerous vents that have produced a large volume of petrologically diverse rocks ranging from the tholeiitic flood basalts of the CRBG to rhyolitic tuffs of caldera complexes such as the Lake Owyhee Volcanic field. Icelandites, which are iron rich andesites, are known to occur in association with silica saturated to oversaturated tholeiitic basalts as a minor part of continental flood basalt volcanism. This study investigates …