Geology Commons^™

Modeling Surface Roughness As An Indicator Of Age And Landslide Susceptibility, And The Spatial Inventory Of Prehistoric Landslides: Green River Valley, Washington, Rebecca Naomi Garriss

Dissertations and Theses

Developing detailed landslide inventory maps of prehistoric landslides is essential to interpret the frequency and conditions under which slopes have failed. When coupled with age estimates, landslide inventories can yield better predictions for future slope failures, thereby improving hazard assessments and increasing chances for mitigation. Developing proxies for landslide age is an important area of research, but age dating prehistoric landslides can be challenging due to sparse datable organic material within landslide deposits, and to time or access constraints. In this thesis, surface roughness of the landslide deposit is used to construct a best-fit age-roughness model that quantitatively assigns age …

Assessment Of Cluster Chondrite Accretion Temperature Using Electron Backscatter Diffraction And Implications For Chondrule Formation Models, Secana Portia Goudy

Dissertations and Theses

This thesis studies ordinary chondrites with cluster chondrite lithologies using electron backscatter diffraction so as to measure the temperatures of their olivine grains during deformation, for the purpose of constraining the accretion temperatures of cluster chondrites and creating new constraints on chondrule formation models. Samples analyzed with the technique are shock classified in this thesis as S1 and are type 3, so the deformation analyzed is interpreted to represent the temperatures of the chondrules during accretional deformation. It is found that the studied samples are primarily composed of chondrules at hot temperatures (>850°C) during deformation, mixed with a questionable …

The Spatial And Temporal Evolution Of The Portland And Tualatin Basins, Oregon, Usa, Darby Patrick Scanlon

Dissertations and Theses

The Portland and Tualatin basins are part of the Puget-Willamette Lowland in the Cascadia forearc of Oregon and Washington. The Coast Range to the west has undergone Paleogene transtension and Neogene transpression, which is reflected in basin stratigraphy. To better understand the tectonic evolution of the region, I modeled three key stratigraphic horizons and their associated depocenters (areas of maximum sediment accumulation) through space and time using well log, seismic, outcrop, aeromagnetic, and gravity data. Three isochore maps were created to constrain the location of Portland and Tualatin basin depocenters during 1) Pleistocene to mid-Miocene (0-15 Ma), 2) eruption of …

Regional Modeling Of The Glaciers Of The North Cascades Mountains, Washington, Usa, Christina Eileen Gray

Dissertations and Theses

Glaciers in the North Cascades store winter snowfall as ice and release it in late summer as melt, providing an important regional source of water and hydroelectric energy. The future of glaciers in the North Cascades, Washington, were evaluated using a regional glaciation model driven by the Community Climate System Model 4 global climate model. The climate model was coupled with three Representative Concentration Pathways (RCPs), 2.6, 4.5, and 8.5. These RCPs provide a business-as-usual scenario (RCP 8.5), which assumes society makes little to no efforts to reduce greenhouse gas emissions, a best-case scenario (RCP 2.6) with strong attempts to …

Bleached Chondrules And The Possible Influence Of Aqueous Alteration, Robert P. Kostynick

Geology Undergraduate Honors Theses

Aqueous alteration, chemical or petrologic change through the addition of water, is a proposed secondary effect of ordinary chondrites. Some minimally metamorphosed chondrites have been noted to have strong signs of aqueous alteration (Weisberg et al., 2006), but the degree of the effect in other chondrites is not clear. There is a specific chondrule type called “bleached chondrules” in which aqueous alteration is proposed to occur in a widespread fashion for all metamorphic grades (Grossman et al., 2000). Using transmitted optical microscopy (OM) and scanning electron microscopy (SEM) at Portland State University, this report obtained chemical and petrological data of …

Geothermometry Of H6 And L6 Chondrites And The Relationship Between Impact Processing And Retrograde Metamorphism, Michael Tyler Ream

Dissertations and Theses

Ordinary chondrites are the most common type of meteorite to fall to Earth and are composed of lithified primitive nebular materials which have experienced variable extents of thermal metamorphism and shock processing. They were subjected to radiogenic heating by incorporation of unstable short lived radionuclides such as ²⁶Al in the early solar system.

The relationship between metamorphism and impact processing in ordinary chondrites is not fully understood. An unresolved issue in the study of ordinary chondrites is whether their original parent bodies were fragmented by impacts into rubble-pile bodies while they were still hot, or whether they retained their …

Distribution And Origin Of Carbide In Ordinary Chondrites, Karla Rae Farley

Dissertations and Theses

To understand the occurrence and distribution of carbide minerals in ordinary chondrites, thirty meteorites were examined, twenty-eight ordinary chondrites and two iron meteorites. The occurrence of carbide, textures, and chemical compositions were examined in the 7 carbide-bearing meteorites. Two formation methods for carbide have been presented in previous research. These are aqueous alteration and shock heating, and they are examined for validity in this thesis. Additionally, one other formation method for carbide formation through impact and brecciation is put forth and examined. Textural differences between the carbide-magnetite assemblages (CMAs) observed by Krot et al., (1997) and those seen in this …

Glacial Meltwater Modeling To Simulate Streamflow And Lake Levels In Taylor Valley, Antarctica, Julian M. Cross, Andrew G. Fountain

Student Research Symposium

The McMurdo Dry Valleys (MDV) are the largest ice-free region (4,500 km²) in Antarctica. The MDV are a polar desert with an average annual temperature of -18˚C and minimal precipitation, < 50 mm w.e. a^-1. In Taylor Valley (77°35’ S, 163°00’ E), a closed-basin, perennially ice-covered lakes occupy the valley floor. Ephemeral streams transfer glacier meltwater for ~10 weeks each summer. Glacial meltwater accounts for nearly the total inflow to these streams and lakes, groundwater is essentially non-existent. A microbially-dominated ecosystem in Taylor Valley depends on glacier runoff and thus is highly sensitive to changes to the hydroclimatic regime. A model …

Cluster Chondrite Accretion Temperatures Determined With Electron Backscatter Diffraction, Secana Goudy, Alexander Ruzicka

Student Research Symposium

We studied ordinary chondrites with cluster chondrite lithologies using electron backscatter diffraction to measure the temperatures of their olivine grains during deformation. Samples analyzed with the technique are shock classified as S1 and are type 3, so the deformation analyzed is inferred to represent the temperatures of the chondrules during accretional deformation. It was found that the studied samples are of a mixture of chondrules at mostly hot temperatures (>850°C) and some at cold.

A Characterization Of Structures Across The Hurricane Ridge Fault In The Southeastern Olympic Peninsula, Wa, Hamma Hamma River Transect, Veronica Catherine Biesiada

Dissertations and Theses

The Olympic Mountains in northwestern Washington, USA are defined by the arcuate shape of the basaltic Crescent Formation (Fm.) that wraps a faulted and folded meta-sedimentary core. This area was developed through accretion and exhumation by subduction-related processes, but how this relates to the deformational history of the area is not fully understood. The region has been mapped geologically, however little focus has been placed on interpreting meso-scale structures. This study investigates structures along a transect where the Hamma Hamma River crosses the Hurricane Ridge Fault, which juxtaposes the meta-sedimentary core (west) and the basaltic Crescent Fm. (east). In the …

Comparison Of Microbial Communities In The Sediments And Water Columns Of Frozen Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Pacifica Sommers, John L. Darcy, Dorota L. Porazinska, Eli M. S. Gendron, Andrew G. Fountain, Felix Jacob Zamora, Kim Vincent, Kaelin M. Cawley, Adam J. Solon, Lara Vimercati, Jenna Ryder, Steven K. Schmidt

Geology Faculty Publications and Presentations

Although cryoconite holes, sediment-filled melt holes on glacier surfaces, appear small and homogenous, their microbial inhabitants may be spatially partitioned. This partitioning could be particularly important for maintaining biodiversity in holes that remain isolated for many years, such as in Antarctica. We hypothesized that cryoconite holes with greater species richness and biomass should exhibit greater partitioning between the sediments and water, promoting greater biodiversity through spatial niche partitioning. We tested this hypothesis by sampling frozen cryoconite holes along a gradient of biomass and biodiversity in the Taylor Valley, Antarctica, where ice-lidded cryoconite holes are a ubiquitous feature of glaciers. We …

Globally Detected Volcanic Lightning And Umbrella Dynamics During The 2014 Eruption Of Kelud, Indonesia, Kirstin A. Hargie, Alexa R. Van Eaton, L. G. Mastin, Robert H. Holzworth, John W. Ewert, Michael Pavolonis

Geology Faculty Publications and Presentations

Volcanic lightning shows considerable promise as a monitoring and research tool to characterize explosive eruptions. Its key strengths are rapid and remote detection, because the radio signals produced by lightning can propagate thousands of km at the speed of light. Despite these tantalizing properties, the scientific work on volcanic lightning has only recently started gaining momentum. Much more is needed to understand what lightning reveals about the evolution of an eruption in near-real time. Here we examine the timing and energy release of lightning generated by the eruption of Kelud volcano in Indonesia on 13 February 2014, as detected by …

The Isotopic Composition Of Meteoric Water Along Altitudinal Transects In The Tian Shan Of Central Asia, John Bershaw, Alex R. Lechler

Geology Faculty Publications and Presentations

The Tian Shan in Central Asia are a unique mountain range in that they are in the world's most continental location. Seasonal precipitation in the northern Tian Shan is segregated into distinct elevation bands where high elevations receive precipitation primarily during summer and low elevations to the north receive precipitation primarily during the late winter and spring. In this study, we sampled stream water along multiple altitudinal transects to determine the effect unique seasonal patterns of precipitation have on the isotopic composition of surface water. Our results suggest that the northern Tian Shan exhibits an isotopic lapse rate for waters …

Volcanic Glass As A Proxy For Cenozoic Elevation And Climate In The Cascade Mountains, Oregon, Usa, John Bershaw, Elizabeth J. Cassell, Tessa Boe Carlson, Ashley R. Streig, Martin J. Streck

Geology Faculty Publications and Presentations

After deposition, volcanic glass hydrates with ambient water, recording the average hydrogen isotope ratio (δD or δ2H) of local meteoric water during the hydration period. Previous researchers have used ancient glass δD values to reconstruct paleotopography and paleoclimate, while others have questioned the long-term reliability of the proxy as a recorder of ancient meteoric water. In this study, we sampled volcanic glasses ranging in age ~33 Ma to(east) side of the Oregon Cascade Mountains. Our results strongly suggest that volcanic glass acquires and preserves δD values that are proportional to the stable isotopic composition of environmental water at the time …

Reanalysis Of The Us Geological Survey Benchmark Glaciers: Long-Term Insight Into Climate Forcing Of Glacier Mass Balance, Shad O’Neel, Christopher Mcneil, Louis Sass, Caitlyn Florentine, Emily Baker, Andrew G. Fountain, Multiple Additional Authors

Geology Faculty Publications and Presentations

Mountain glaciers integrate climate processes to provide an unmatched signal of regional climate forcing. However, extracting the climate signal via intercomparison of regional glacier mass-balance records can be problematic when methods for extrapolating and calibrating direct glaciological measurements are mixed or inconsistent. To address this problem, we reanalyzed and compared long-term mass-balance records from the US Geological Survey Benchmark Glaciers. These five glaciers span maritime and continental climate regimes of the western United States and Alaska. Each glacier exhibits cumulative mass loss since the mid-20th century, with average rates ranging from −0.58 to −0.30 m w.e. a−1. We produced a …

Measuring And Modeling Evolution Of Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Felix Jacob Zamora

Dissertations and Theses

Cryoconite holes are vertical columns of meltwater within the shallow subsurface of glaciers. In the McMurdo Dry Valleys (MDV) of Antarctica cryoconite holes are a source of meltwater and harbor microbial communities in an otherwise arid environment with low biologic activity. The holes form as sediments on the ice surface, which are darker than the surrounding ice, are preferentially heated by solar radiation. The warm sediments melt the underlying ice and migrate downwards. An ice lid forms, isolating them from the below-freezing atmosphere enabling them to remain thawed. In this study, field observations, laboratory experiments, and numerical modeling are used …

Gps Constraints On Deformation In Northern Central America From 1999 To 2017, Part 1 – Time-Dependent Modelling Of Large Regional Earthquakes And Their Post-Seismic Effects, A. Ellis, Charles Demets, P. Briole, Beatriz Cosenza, Omar Flores, Shannon E. Graham, Robert Mccaffrey, Multiple Additional Authors

Geology Faculty Publications and Presentations

We use continuous and campaign measurements from 215 GPS sites in northern Central America and southern Mexico to estimate coseismic and afterslip solutions for the 2009 M_w = 7.3 Swan Islands fault strike-slip earthquake and the 2012 M_w = 7.3 El Salvador and M_w = 7.4 Guatemala thrust-faulting earthquakes on the Middle America trench. Our simultaneous, time-dependent inversion of more than 350 000 daily GPS site positions gives the first jointly consistent estimates of the coseismic slips for all three earthquakes, their combined time-dependent post-seismic effects and secular station velocities corrected for both the coseismic and post-seismic …

Gps Constraints On Deformation In Northern Central America From 1999 To 2017, Part 1 – Time-Dependent Modelling Of Large Regional Earthquakes And Their Post-Seismic Effects, A. Ellis, Charles Demets, P. Briole, Beatriz Cosenza, Omar Flores, Shannon Graham, Marco Guzmán-Speziale, Douglas Hernandez, Vladimir Kostoglodov, Peter Lafemina, Neal Lord, Cécile Lasserre, Hélène Lyon-Caen, Manuel Rodriguez Maradiaga, Robert Mccaffrey, Enrique Molina, Jeffrey Rivera, Robert Rogers, Alejandra Staller

Geology Faculty Publications and Presentations

We use continuous and campaign measurements from 215 GPS sites in northern Central America and southern Mexico to estimate coseismic and afterslip solutions for the 2009 Mw = 7.3 Swan Islands fault strike-slip earthquake and the 2012 Mw = 7.3 El Salvador and Mw = 7.4 Guatemala thrust-faulting earthquakes on the Middle America trench. Our simultaneous, time-dependent inversion of more than 350 000 daily GPS site positions gives the first jointly consistent estimates of the coseismic slips for all three earthquakes, their combined time-dependent post-seismic effects and secular station velocities corrected for both the coseismic and post-seismic deformation. Our geodetic …

Decadal Topographic Change In The Mcmurdo Dry Valleys Of Antarctica: Thermokarst Subsidence, Glacier Thinning, And Transfer Of Water Storage From The Cryosphere To The Hydrosphere, J. S. Levy, Andrew G. Fountain, M. K. Obryk, J. Telling, Craig Glennie, M. Gooseff, David J. Van Horn

Geology Faculty Publications and Presentations

Recent local-scale observations of glaciers, streams, and soil surfaces in the McMurdo Dry Valleys of Antarctica (MDV) have documented evidence for rapid ice loss, glacial thinning, and ground surface subsidence associated with melting of ground ice. To evaluate the extent,magnitude, and location of decadal-scale landscape change in the MDV, we collected airborne lidar elevation data in 2014–2015 and compared these data to a 2001–2002 airborne lidar campaign. This regional assessment of elevation change spans the recent acceleration of warming and melting observed by long-term meteorological and ecosystem response experiments, allowing us to assess the response of MDV surfaces to warming …

Electron Backscatter Diffraction (Ebsd) Study Of Seven Heavily Metamorphosed Chondrites: Deformation Systematics And Variations In Pre-Shock Temperature And Post-Shock Annealing, Alexander M. Ruzicka, Richard C. Hugo

Geology Faculty Publications and Presentations

We used electron backscatter diffraction (EBSD) methods to study the crystallography of olivine and other minerals in seven heavily metamorphosed (petrographic type 6 or 6/7) but variably shocked ordinary chondrites from the H (Kernouvé, Portales Valley), L (Leedey, Bruderheim, Morrow County, Park) and LL (Miller Range (MIL) 99301) groups. MIL 99301 contains a large clast that was analyzed separately. Mesoscale (EBSD) data support and extend inferences based on microscale (TEM) observations and provide good evidence that chondrites were shock-deformed at different temperatures and were variably annealed (sintered) after deformation. Various EBSD deformation intensity metrics adequately and quantitatively represent olivine deformation …

Dynamics Of Magma Recharge And Mixing At Mount Hood Volcano, Oregon -- Insights From Enclave-Bearing Lavas, Molly Kathryn Ellowitz

Dissertations and Theses

Magma recharge events and subsequent mixing processes are understood to precede volcanic eruptions. Textural evidence of intrusion of hot, mafic magma into a cooler, rheologically locked silicic magma is commonplace. Solidified "blobs" of injected magma, called enclaves, are evidence of magma mixing, but the petrological and mechanical conditions during their formation are debated. Mount Hood, Oregon consistently erupts andesite bearing compositionally similar enclaves. These enclaves are evidence of mingling and mixing of two magmas. However, due to the compositional similarity between enclave and host lava (e.g. ~1-5 wt.% difference in SiO₂), it is unclear whether the preserved enclaves …

Beyond Spatial Autocorrelation: A Novel Approach Using Reconstructability Analysis, David Percy, Martin Zwick

Complex Systems Faculty Publications and Presentations

Raster data are digital representations of spatial phenomena that are organized into rows and columns that typically have the same dimensions in each direction. They are used to represent image data at any scale. Common raster data are medical images, satellite data, and photos generated by modern smartphones.
Satellites capture reflectance data in specific bands of wavelength that correspond to red, green, blue, and often some infrared and thermal bands. These composite vectors can then be classified into actual land use categories such as forest or water using automated techniques. These classifications are verified on the ground using hand-held sensors. …

Contrasting Governance Learning Processes Of Climate-Leading And -Lagging Cities: Portland, Oregon, And Phoenix, Arizona, Usa, Jonathan H. Fink

Geology Faculty Publications and Presentations

The contrasting histories and political ecologies of two U.S. cities—Portland Oregon and Phoenix Arizona—shed light on their ability to learn from and influence the climate governance of their peers. Portland's populace, political leadership, and business sectors are motivated by environmental and social values, resulting in a collective sense of responsibility for fixing global problems like climate change. The city's pioneering land-use policies, green infrastructure, and multimodal transportation systems solidify its place at the climate action forefront. In contrast, libertarian Phoenix prioritizes real estate, efficient government, tourism, and protection of individual rights—the antithesis of Portland's altruism. However, because Phoenix's economic success …

Transient Reactivation Of A Deep-Seated Landslide By Undrained Loading Captured With Repeat Airborne And Terrestrial Lidar, Adam M. Booth, Justin Mccarley, Jason Hinkle, Jean-Paul Ampuero, Michael P. Lamb

Geology Faculty Publications and Presentations

Landslides reactivate due to external environmental forcing or internal mass redistribution, but the process is rarely documented quantitatively. We capture the three-dimensional, 1-m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar. Undrained loading by two debris flows in the landslide’s head, rather than external forcing, triggered reactivation. After that loading, the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping. The displacement field over those 2 years implies that the slip surface gained 1 kPa of shear strength, which was likely accomplished by …

Estimating Sand Loss: Using Eolian Sand Ramps As A Proxy For Estimating Past Erosion Within The Lincoln City Dune Sheet; Lincoln City, Oregon, Kara E. P. Kingen, John Bershaw, Curt D. Peterson

Student Research Symposium

Eolian sand ramps are features that are sculpted from beach sand blowing up against sea cliffs or bluffs. In some coastal areas, sand ramp deposits only appear as the erosional remnants of pre-existing ramps that have been truncated at eroded shorelines, separating them from their previous sediment supply. Although sand ramp features have been observed in other areas on the western coast of the United States , they had not been studied or documented within the Lincoln City Dune Sheet (LINC) prior to this study – which documents the existence of truncated eolian sand ramps in LINC and uses them …

Areal Extent And Volumes Of The Dinner Creek Tuff Units, Eastern Oregon Based On Lithology, Bulk Rock Composition And Feldspar Mineralogy, Teresa Rae Hanna

Dissertations and Theses

The Dinner Creek Tuff erupted during a period of rhyolitic volcanism coeval to the flood volcanism associated with the Columbia River Basalt Group. The High Rock Caldera Complex, Lake Owyhee and McDermitt volcanic fields account for ~90% of the rhyolites erupted between 16.7-15.0 Ma. Situated at the northern end of the Lake Owyhee volcanic field, the Dinner Creek Tuff was originally mapped as a ~2,000 km² single ignimbrite confined to the Malheur Gorge. Streck et al. (2015) correlated tuff outcrops previously mapped as generic Miocene welded tuff as well as local units such as the "Mascall" or "Pleasant Valley" …

Using Repeat Terrestrial Laser Scanning And Photogrammetry To Monitor Reactivation Of The Silt Creek Landslide In The Western Cascade Mountains, Linn County, Oregon, Justin Craig Mccarley

Dissertations and Theses

Landslides represent a serious hazard to people and property in the Pacific Northwest. Currently, the factors leading to sudden catastrophic failure vs. gradual slow creeping are not well understood. Utilizing high-resolution monitoring techniques at a sub-annual temporal scale can help researchers better understand the mechanics of mass wasting processes and possibly lead to better mitigation of their danger. This research used historical imagery analysis, precipitation data, aerial lidar analysis, Structure from Motion (SfM) photogrammetry, terrestrial laser scanning (TLS), and hydrologic measurements to monitor displacement of the Silt Creek Landslide in the western Cascade Mountain Range in Linn County, Oregon. This …

Quantifying Knickpoint Behavior And Erosion Mechanisms In An Urbanized Watershed, Bull Mountain, Washington County, Oregon, Max Gregory Bordal

Dissertations and Theses

Quantifying spatial and temporal patterns of rapid channelized erosion, on human time scales, is critical to understanding its processes and their consequences. This investigation utilized field observations, repeat terrestrial laser scanning (TLS), and Structure-from-Motion photogrammetry (SfM) to document the size and retreat rates of a knickpoint, defined as a localized near-vertical reach of a fluvial channel, and its contribution to erosion, in an urbanizing landscape with a loess substrate. The Bull Mountain area, in Washington County, southwest of Portland, Oregon, is an ideal study area, offering a measurable knickpoint that translates the response of the rapid erosion throughout this transient …

The Wildcat Creek Tuff, Eastern Oregon: Co-Eruption Of Crystal-Poor Rhyolite And Fe-Rich Andesite With Implication For Mafic Underpinnings To Voluminous A-Type Rhyolites, Hillarie Jaye Sales

Dissertations and Theses

The Wildcat Creek Tuff is a thin (~3-12 m), rhyolite to andesitic ash-flow tuff with a minimal extent of 1500 km² in Malheur county, eastern Oregon. The previously undated tuff yielded a single crystal, anorthoclase ⁴⁰Ar/³⁹Ar age of 15.49±0.02 Ma and thus is closely related to mafic and silicic volcanism of the Columbia River Province. The tuff texturally stands out by its high proportion of co-mingled mafic inclusions appearing as dark, scoriaceous, and phenocryst-poor fragments, and their proportion dictate bulk tuff compositions ranging from rhyolite (74% SiO2) to andesite (59% SiO₂). Glass analyses confirm …

Glacier Inventories And Change In Glacier National Park, Melissa Carrie Brett

Dissertations and Theses

Glacier National Park, in northwestern Montana, is a unique and awe-inspiring national treasure that is often used by the media and public-at-large as a window into the effects of climate change. An updated inventory of glaciers and perennial snowfields (G&PS) in the Park, along with an assessment of their change over time, is essential to understanding the role that glaciers are playing in the environment of this Park. Nine inventories between 1966 and 2015 were compiled to assess area changes of G&PS. Over that 49-year period, total area changed by nearly -34 ± 11% between 1966 and 2015. Volume change, …