Geology Commons^™

Ureilite Meteorite Petrofabrics: Evolution And Formation Deformational Conditions, Benjamin Botwe Agyemang

Dissertations and Theses

This thesis examines the origin and development of crystallographic fabrics in ureilites, which are primitive achondritic meteorites interpreted as residues of partial melting from a differentiated parent body. In this study, we evaluate three fabric-forming mechanisms: gravitational cumulate crystallization, shock-induced deformation, and flow alignment associated with melt extraction and convective stirring. A quantitative Electron Backscatter Diffraction (EBSD) analysis was conducted on six ureilitic meteorites to assess olivine Lattice Preferred Orientation (LPO), Shape Preferred Orientation (SPO), the connection between SPO and LPO, and other deformation metrics, including Grain Orientation Spread (GOS), and Crystal Rotation Axis (CRA). Our results suggest that most …

Orphan Basalts: Understanding The Origins Of Unassigned Eastern Oregon Basalts, Angela Rae Stetson

Dissertations and Theses

For more than a century, scientists have studied the geologic stratigraphy of eastern Oregon, which chronicles a rich history of volcanic activity spanning millions of years. Recent and ongoing geologic mapping of the northeastern Harney Basin -- along a corridor east of Highway 395 between the towns of Burns and John Day -- provides a more detailed understanding of an area originally mapped only in reconnaissance during the 1960s. At that time, geologic units were poorly delineated, often with entire quadrangles mapped as a single unit. For example, over 90% of the Calamity Butte quadrangle was previously mapped as 'Tba' …

A Groundwater Flow System Investigation In The Upper Rowena Creek Drainage, Oregon, Catelee Yamei Kambur

Dissertations and Theses

Groundwater level declines are a growing concern within the upper Rowena Creek drainage, Oregon. This area is home to a small community located on the upper limb of the Columbia Hills anticline, where local residents rely on aquifers within the Columbia River Basalt Group (CRBG) for domestic water supplies. Groundwater level declines in CRBG aquifers have been studied more extensively in the Mosier area, which lies approximately 5 miles to the northwest of Rowena, but there has been little research conducted specifically on the upper Rowena Creek drainage area. Rowena is located higher up the dip of the Columbia Hills …

Magma Evolution And Eruptive History Of Three Fingered Jack: A Mafic Composite Volcano In The Central High Cascades Of Oregon, Javaria Aziz

Dissertations and Theses

The central High Cascades graben in Oregon has been a center for mafic volcanism since its initiation. Three Fingered Jack is one of the larger mafic composite cones in the graben, located 20km south of Mount Jefferson. Three Fingered Jack erupted between 142.1 - 150.8ka, based on Ar⁴⁰/Ar³⁹ age dates. This study provides stratigraphic, compositional and petrographic evidence to understand the eruptive history of Three Fingered Jack and the processes involved in generating compositionally diverse basaltic andesites here.

The basaltic andesites of Three Fingered Jack show three compositional trends of magma evolution: 1) enrichment, 2) depletion and …

The Geologic History Of The Chehalis Forearc Basin, Washington State, Usa, Rud Lamb Moe

Dissertations and Theses

The Chehalis Basin, in southwest Washington, is one of a series of forearc basins between the Cascade Arc and the Coast Range in the Pacific Northwest. While the Seattle basin to the north, and the Portland-Tualatin basins to the south are both relatively well studied, the geologic evolution of basins in between is poorly constrained. The Chehalis basin is underlain by accreted Eocene oceanic basalt of the Crescent Formation. The basin fill consists of sedimentary rocks and volcanic rocks deposited throughout the Cenozoic. It has undergone N-S shortening driven by transpressional stress from oblique subduction of the Juan de Fuca …

Estimated Amounts Of Terrestrial Carbon Mobilized And Sequestered By The 1980 Mount St. Helens Eruption, Washington State, Usa, Lizzet G. Reyes

Dissertations and Theses

Volcanic eruptions significantly influence the geologic carbon cycle by emitting CO₂ and mobilizing terrestrial carbon pools. The 1980 Mount St. Helens (MSH) eruption offers a unique case study, triggering a massive landslide that displaced 2.7 km³ of sediment, buried 600 km² of forest, and disrupted regional carbon dynamics. Pre-eruption terrestrial carbon stocks, including aboveground biomass (AGB), dead biomass (D), and soil organic carbon (S), averaged 209.5 tC/ha. Post-eruption, total carbon density fell to 118.7 tC/ha, driven mainly by a 51% reduction in AGB, modest declines in D, and redistribution of S. Over 36 years, ecosystem recovery increased …

Shock Effects Including Maskelynite Formation In Three Shergottite Meteorites From Mars, George Ayeh Anim

Dissertations and Theses

Martian meteorites result from large impact events on the surface of Mars that cause intense shock metamorphism. This study examines the shock metamorphic features of three shergottite meteorites, Dho 019, NWA 12241, and NWA 15628, to better understand shock impact events. The research uses petrographic analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD) to analyze the meteorites. A key focus of this research is the formation of maskelynite, a glass with plagioclase composition, whose formation mechanism has been the substance of debate among researchers. This study proposes that maskelynite forms through a transient intermediary …

Using Trace Gas Measurements As A Transport Diagnostic For Tropical Convection: A Combined Model And Observation Study, Albane Hoxha

Dissertations and Theses

No abstract provided.

Applying Positive Unlabeled Learning Techniques And Using The Kullback-Leibler Divergence To Improve Geothermal Surveying Assessments, Martín Thomas Rodriguez

Dissertations and Theses

As we face the current climate crisis, the discovery of geothermal energy resources has the potential to greatly reduce our dependence on fossil fuels worldwide. However, the development of any new energy infrastructure is expensive and depends on the willingness of energy agencies and developers to make initial investments based on calculated risk measures. One such measure, called geothermal favorability, is the likelihood that a site has conditions favorable for geothermal systems containing recoverable energy potential. Its prediction from existing geophysical datasets proves to be a nontrivial task. The prediction of geothermal favorability can be framed as a binary classification …

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 …

A Field-Based Study Of Dust Emissivity In The Northern Chihuahuan Desert, U.S.: Testing The Preferential Dust Source Scheme, Gwenn L Harsha

Dissertations and Theses

We characterized spatiotemporal dust emissivity in the Northern Chihuahuan Desert (New Mexico, Texas, and Arizona, U.S.) using the Portable In-Situ Wind Erosion Lab (PI-SWERL) and measurements of soil crust strength, soil texture and soil moisture. Field-based measurements of emissivity were compared to the results of the Preferential Dust Source (PDS) scheme (Bullard et al., 2011) in the Chihuahuan Desert (Baddock et al., 2011) where 48% of satellite-observed plumes were sourced from ephemeral and dry lakes. Six landforms were tested: 1) ephemeral and 2) dry lake, 3) high and 4) low relief alluvial, and aeolian 5) sand sheet and 6) dunes. …

Evaluation Of The Slip History And Holocene Activity Of The Strawberry Fault, Grant County, Oregon, Andrew Dunning

Dissertations and Theses

Lidar topographic data for the Strawberry Mountains, Oregon has revealed youthful fault scarps that likely result from Holocene-age earthquakes. We have mapped 27 km of fault scarps striking roughly east-west across the northern foothills of the Strawberry Mountains (Strawberry Fault, SBF) and another scarp lineament striking north-south along the uppermost John Day River 10 km to the south. SBF scarps are aligned with the bedrock John Day Fault, a reactivated Miocene structure that is accommodating distributed extension north of the Basin and Range region. The Strawberry Mountains sit near the interface of the extensional Basin and Range province to the …

A Field, Petrological, And Geochronological Investigation Of The Chief Joseph Dike Swarm, Mary Joyce Mass

Dissertations and Theses

The Columbia River Basalt Group is the youngest continental flood basalt province in the world and covers an aerial extent of 210,000 km² covering Oregon, southern Washington, and eastern Idaho. Eruptions occurred between approximately 17 million and 6 million years ago, with 92% of eruptions occurring within the first million-year interval. Aside from mapping and some bulk compositional data, few studies have focused on the Chief Joseph dike swarm in NE Oregon, the main eruptive center of the Columbia River Basalt Group. Prior to this study there were no published age dates for the Chief Joseph dike swarm.

This …

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 …

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 …

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 …

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 …

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 …

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 …

New Perspectives On Prolific And Voluminous Rhyolite Volcanism Of The Mahogany Mountain--Three Fingers Rhyolite Field, Eastern Oregon, Robert Andrew Jackson

Dissertations and Theses

Voluminous silicic volcanism of the Mahogany Mountain--Three Fingers rhyolite field (MM--TFrf) is spatially and temporally associated with mid-Miocene flood basalts of the Columbia River Basalt province. Early studies of the area advocated for a two-caldera model consisting of the Mahogany Mountain and the slightly younger Three Fingers caldera with pre- and post-caldera effusive rhyolite eruptions. Although close in time, the calderas were thought to be spatially offset producing the tuff of Leslie Gulch and the tuff of Spring Creek. Finding that the tuff of Spring Creek, that is exposed in Leslie Gulch, is an altered product of the tuff of …

From Molecules To Mountains: A Multi-Proxy Investigation Into Ancient Climate And Topography Of The Pacific Northwest, Usa, Alex Mclean

Dissertations and Theses

The modern Cascades are a north-south striking mountain range that intercepts Pacific Ocean-derived moisture resulting in orographic precipitation on the western flank and a relatively arid rain shadow in the lee. Because of the strong coupling between topography and climate and consistent moisture source (Pacific Ocean) throughout the year, the region is ideally situated for paleoclimate studies that utilize the isotopic composition (δ¹⁸O and δD) of meteoric water to determine when uplifts occurred. Here, I synthesize the spatial and temporal evolution of stable isotopes in paleowater proxies across the Pacific Northwest during the Cenozoic. New volcanic glass (δD) …

Reassessing Hydrothermal Heat Discharge And The Relationship Of Hot Springs In The North Oregon Cascades, Aaron Alexander Orr

Dissertations and Theses

Reservoir temperatures of hydrothermal systems in the Pacific Northwest reflect the feasibility of geothermal energy production and the tectonic framework of the region. Multicomponent geothermometry techniques were applied to new and historic water chemistry data in the north-central Oregon Western Cascades and the lower Wind River Valley in southern Washington in order to recalculate reservoir temperatures. Revised reservoir temperatures, water chemistry, and isotope data were used to determine relationships between hot springs in the north-central Oregon Cascades. Geothermal reservoir temperatures were estimated for the lower Wind River Valley (98.44 ± 0.96°C) and for Austin and Bagby Hot Springs (100.10 ± …