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Articles 1 - 30 of 193
Full-Text Articles in Geology
Crossing Boundaries: Brachinites And Their Diverse Asteroidal Origins, B. G. Rider-Stokes, F. A. Davies, T. H. Burbine, E. Maclennan, R. C. Greenwood, S. L. Jackson, M. Anand, Daniel Sheikh, M. M. Grady
Crossing Boundaries: Brachinites And Their Diverse Asteroidal Origins, B. G. Rider-Stokes, F. A. Davies, T. H. Burbine, E. Maclennan, R. C. Greenwood, S. L. Jackson, M. Anand, Daniel Sheikh, M. M. Grady
Geology Faculty Publications and Presentations
Brachinite meteorites are typically linked to the olivine-rich A-type asteroids. In this study, however, they appear to exhibit unexpected spectral diversity. Spectroscopic analysis of seven meteorites from the brachinite clan reveals two distinct populations in band parameters, overlapping with both the A-type and S-complex asteroids. This dual association shows that a single meteorite group can originate from multiple asteroid taxonomies. Notably, one S-complex-like specimen, Northwest Africa (NWA) 14,635, displays band parameters similar to those of asteroid (65803) Didymos, the target of the European Space Agency's (ESA) ongoing Hera mission. These results underscore the value of spectroscopic characterization of poorly understood …
Microbial Communities And Biogeochemistry Of A Melting Rocky Mountain Glacier, Pacifica Sommers, Elizabeth Traver, Alison Orthel, Andrew G. Fountain, Jacki Klancher, Steven K. Schmidt
Microbial Communities And Biogeochemistry Of A Melting Rocky Mountain Glacier, Pacifica Sommers, Elizabeth Traver, Alison Orthel, Andrew G. Fountain, Jacki Klancher, Steven K. Schmidt
Geology Faculty Publications and Presentations
Mountain glaciers are disappearing rapidly, and with their disappearance, we may be losing unstudied biodiversity and genetic resources. A variety of habitats for microorganisms exist on glaciers, especially within pockets of supraglacial sediments (cryoconite) that support high levels of biological activity and diversity. We used biogeochemical approaches, high-throughput DNA sequencing, and microscopy to describe the biogeochemistry and microbial communities of supraglacial sediments on the Dinwoody Glacier in the Wind River Range, Wyoming. Carbon (C) and nitrogen (N) concentrations were high, and C:N ratios were close to the Redfield ratio indicating active nutrient cycling. We found unique microbial communities in sediments …
An Introduction To Field Excursions For The 2026 Geological Society Of America Cordilleran Section Meeting In Loreto, Baja California Sur, México, Scott E.K. Bennett, Michael H. Darin, Genaro Martínez Gutiérrez
An Introduction To Field Excursions For The 2026 Geological Society Of America Cordilleran Section Meeting In Loreto, Baja California Sur, México, Scott E.K. Bennett, Michael H. Darin, Genaro Martínez Gutiérrez
Geology Faculty Publications and Presentations
The 122nd annual meeting of the Geological Society of America (GSA) Cordilleran Section will be held in Loreto, Baja California Sur, México, an idyllic and historic Sonoran Desert city nestled on the eastern shore of the Baja California peninsula. The 2026 Loreto meeting marks a milestone for GSA as it is the first time in the Section’s century-plus history that the meeting has been held on the Baja California peninsula and only the third time that the meeting has been held in México. Thus, the 2026 Loreto meeting and related field trips represent a meaningful expansion of the Section’s engagement …
Climatic Controls On Soil Production, Transport And Chemical Erosion: Insights From Modelling Topography, Soils And Cosmogenic Nuclides At Little Lake, Oregon, Miles M. Reed, Ken L. Ferrier, Jill A. Marshall, Josh J. Roering, J. Taylor Perron
Climatic Controls On Soil Production, Transport And Chemical Erosion: Insights From Modelling Topography, Soils And Cosmogenic Nuclides At Little Lake, Oregon, Miles M. Reed, Ken L. Ferrier, Jill A. Marshall, Josh J. Roering, J. Taylor Perron
Geology Faculty Publications and Presentations
Predicting physical and chemical erosion rate responses to climate change are an ongoing challenge in geomorphology. A promising approach for investigating this is by measuring transient variations in physical and chemical erosion rates during climatically variable time periods, which can be accomplished by measuring cosmogenic nuclide concentrations and chemical depletion in sedimentary deposits. Interpreting such measurements warrants applying landscape evolution models that track variations in topography, cosmogenic nuclide concentrations and chemical depletion in soils. We applied a recently developed model that tracks these quantities at Little Lake, Oregon. Previous studies documented variations in cosmogenic nuclide concentrations and chemical depletion in …
The Hydro-Geomorphic Response Of The Ephemeral Lower Nahal Tzalmon Stream To Experimental Flow Releases Towards Replenishment Of The Sea Of Galilee, Ne Israel, Nathaniel Bergman, Noam Greenbaum, Eyal Weinberg, Iyad Swaed
The Hydro-Geomorphic Response Of The Ephemeral Lower Nahal Tzalmon Stream To Experimental Flow Releases Towards Replenishment Of The Sea Of Galilee, Ne Israel, Nathaniel Bergman, Noam Greenbaum, Eyal Weinberg, Iyad Swaed
Geology Faculty Publications and Presentations
Study region:
The Sea of Galilee’s western watershed includes the Lower and Upper Galilee subregions in northern Israel. Nahal Tzalmon stream (110 km2) is one of the major gravel-bed channels draining those subregions into the lake. Study focus: The study focus was to monitor the immediate effects of introducing “hungry water” from the newly mega-project of the “Reverse National Water Carrier” (RNWC). The project was designed to convey desalinated water from the Mediterranean coastal desalination plants through a 5 km open channel into the lower Nahal Tzalmon stream in order to replenish the Sea of Galilee. During a 2-day experimental …
Multi-Sensor Remote Sensing Captures Geometry And Slow-To-Fast Sliding Transition Of The 2017 Mud Creek Landslide, Alexander L. Handwerger, Pascal Lacroix, Andrew F. Bell, Adam M. Booth, Mong-Han Huang, Simon M. Mudd, Roland Bürgmann, Eric J. Fielding
Multi-Sensor Remote Sensing Captures Geometry And Slow-To-Fast Sliding Transition Of The 2017 Mud Creek Landslide, Alexander L. Handwerger, Pascal Lacroix, Andrew F. Bell, Adam M. Booth, Mong-Han Huang, Simon M. Mudd, Roland Bürgmann, Eric J. Fielding
Geology Faculty Publications and Presentations
Landslides pose a significant hazard worldwide. Despite advances in landslide monitoring, predicting their size, timing, and location remains a major challenge. We revisit the 2017 Mud Creek landslide in California using radar interferometry, pixel tracking, and elevation change measurements from satellite and airborne radar, lidar, and optical data. Our analysis shows that pixel tracking of optical imagery captured the transition from slow motion to runaway acceleration starting ~ 1 month before catastrophic failure—an acceleration undetected by satellite InSAR alone. Strain rate maps revealed a new slip surface formed within the landslide body during acceleration, likely a key weakening mechanism. Failure …
Short Communication: Multiscale Topographic Complexity Analysis With Pytopocomplexity, L. S.-H. Lai, Adam Booth, A. R. Duvall, E. Herzig
Short Communication: Multiscale Topographic Complexity Analysis With Pytopocomplexity, L. S.-H. Lai, Adam Booth, A. R. Duvall, E. Herzig
Geology Faculty Publications and Presentations
TopoComplexity is a Python package designed for efficient and customizable quantification of topographic complexity using four advanced methods: two-dimensional continuous wavelet transform analysis, fractal dimension estimation, rugosity index, and terrain position index calculations. This package addresses the lack of open-source software for these advanced terrain analysis techniques essential for modern geomorphology and geohazard research, enhancing data comparison and reproducibility. By assessing topographic complexity across multiple spatial scales, pyTopoComplexity allows users to identify characteristic morphological scales of studied landforms. The software repository also includes a Jupyter Notebook that integrates components from the surface-process modeling platform Landlab (Hobley et al., 2017), facilitating …
Permafrost And Structural Controls On Holocene Bedrock Landslide Occurrence Around Eyjafjörður, North‐Central Iceland, Adam Booth, Halldór G. Pétursson
Permafrost And Structural Controls On Holocene Bedrock Landslide Occurrence Around Eyjafjörður, North‐Central Iceland, Adam Booth, Halldór G. Pétursson
Geology Faculty Publications and Presentations
Rapid, transient, landscape‐scale changes associated with deglaciation can condition slopes for failure and trigger bedrock landslides. However, the mechanisms leading to paleo rock slope failures following the last glacial period are challenging to infer because observations of how both landsliding and potential driving factors were distributed in space and time are limited. Here, we map and analyze the spatiotemporal pattern of 676 post‐glacial bedrock landslides around Eyjafjörður in north‐central Iceland using 2‐m resolution digital elevation data generated from optical stereo satellite imagery. Frequency‐ratio analysis demonstrates that after controlling for slope, landslides are most overrepresented within 2.6 km horizontal distances from …
The Petrology Of The Ozerki Meteorite Constrained By Electron Backscatter Diffraction And X-Ray Computed Tomography, Alice Macente, Luke Daly, Sammy Griffin, Maria Gritsevich, Jarmo Moilanen, Josh Franz Einsle, Patrick Trimby, Chris Mulcahy, Jonathan Moffat, Alexander M. Ruzicka
The Petrology Of The Ozerki Meteorite Constrained By Electron Backscatter Diffraction And X-Ray Computed Tomography, Alice Macente, Luke Daly, Sammy Griffin, Maria Gritsevich, Jarmo Moilanen, Josh Franz Einsle, Patrick Trimby, Chris Mulcahy, Jonathan Moffat, Alexander M. Ruzicka
Geology Faculty Publications and Presentations
Combining electron backscatter diffraction (EBSD) with X-ray computed tomography (XCT) offers a comprehensive approach to investigate shock deformation and rock texture in meteorites, yet such integration remains uncommon. In this study, we demonstrate the synergistic potential of XCT and EBSD in revealing deformation metrics, thereby enhancing our understanding of petrofabric strength and shock-induced deformation. Our analysis focuses on the Ozerki (L6, S4/5, W0) meteorite fall, which was instrumentally observed on June 21, 2018, and subsequently recovered by the Ural's branch of the Russian Fireball Network (UrFU) recovery expedition a few days later. The trajectory analysis conducted by the Finnish Fireball …
Global Patterns Of Coseismic Landslide Runout Mobility Differ From Aseismic Landslide Trends, Alex R. R. Grant, Natalie K. Culhane
Global Patterns Of Coseismic Landslide Runout Mobility Differ From Aseismic Landslide Trends, Alex R. R. Grant, Natalie K. Culhane
Geology Faculty Publications and Presentations
Coseismic landslides significantly contribute to human and economic losses during and immediately following earthquakes, yet very little data on the runout of such landslides exist. While well-established behavior of aseismic (e.g., hydrologically triggered) landslide runout mobility suggests strong correlation between landslide size and mobility, limited studies of coseismic landslide runout find conflicting mobility trends. We present a global dataset of runout lengths produced from a new automated method for estimating landslide runout, developed and validated using 1726 manually mapped landslides from five unique earthquakes. We then apply the automated runout tool to 23 global earthquake-induced landslide inventories, producing a compiled …
Re-Evaluating Hypertragulid Diversity In The John Day Basin, Oregon, Usa, Nicholas A. Famoso, Lana K. Jewell
Re-Evaluating Hypertragulid Diversity In The John Day Basin, Oregon, Usa, Nicholas A. Famoso, Lana K. Jewell
Geology Faculty Publications and Presentations
Despite their relative abundance, members of the family Hypertragulidae (Artiodactyla, Mammalia) have proved a conundrum regarding species diversity in the Turtle Cove Member (Oligocene) of the John Day Formation, located in central and eastern Oregon. Three species and two separate genera are described in the area, but previous research lacks statistical support for this level of variation. We use coefficients of variation (V) on measurements of dentition and astragali of hypertragulid specimens designated Hypertragulus hesperius, Hypertragulus minutus, and Nanotragulus planiceps as a metric for determining whether there were multiple species present in the population. Asymptotic and modified signed-likelihood ratio V …
Projected Loss Of Rock Glacier Habitat In The Contiguous Western United States With Warming, Abigail C. Lute, John T. Abatzoglou, Andrew G. Fountain, Timothy C. Bartholomaus
Projected Loss Of Rock Glacier Habitat In The Contiguous Western United States With Warming, Abigail C. Lute, John T. Abatzoglou, Andrew G. Fountain, Timothy C. Bartholomaus
Geology Faculty Publications and Presentations
Rock glaciers support alpine biodiversity and may respond more slowly to warming than snow or glaciers. While responses of snow and glaciers to climate change are relatively well understood, a robust assessment of rock glacier environmental niche, future distributions of rock glaciers and potential for development of rock glaciers from current glaciers is lacking. Using process-relevant, high-resolution environmental descriptors, we develop a species distribution model of the topographic, geologic and hydroclimatic niche of rock glaciers that provides novel estimates of potential rock glacier distributions for different climates. We identify mean annual air temperature and headwall area as the dominant controls …
Information-Theoretic Modeling Of Categorical Spatiotemporal Gis Data, David Percy, Martin Zwick
Information-Theoretic Modeling Of Categorical Spatiotemporal Gis Data, David Percy, Martin Zwick
Geology Faculty Publications and Presentations
An information-theoretic data mining method is employed to analyze categorical spatiotemporal Geographic Information System land use data. Reconstructability Analysis (RA) is a maximum-entropy-based data modeling methodology that works exclusively with discrete data such as those in the National Land Cover Database (NLCD). The NLCD is organized into a spatial (raster) grid and data are available in a consistent format for every five years from 2001 to 2021. An NLCD tool reports how much change occurred for each category of land use; for the study area examined, the most dynamic class is Evergreen Forest (EFO), so the presence or absence of …
Regiongrow3d: A Deterministic Analysis For Characterizing Discrete Three-Dimensional Landslide Source Areas On A Regional Scale, Nicolas W. Mathews, Ben A. Leshchinsky, Benjamin B. Mirus, Michael J. Olsen, Adam M. Booth
Regiongrow3d: A Deterministic Analysis For Characterizing Discrete Three-Dimensional Landslide Source Areas On A Regional Scale, Nicolas W. Mathews, Ben A. Leshchinsky, Benjamin B. Mirus, Michael J. Olsen, Adam M. Booth
Geology Faculty Publications and Presentations
Regional-scale characterization of shallow landslide hazards is important for reducing their destructive impact on society. These hazards are commonly characterized by (a) their location and likelihood using susceptibility maps, (b) landslide size and frequency using geomorphic scaling laws, and (c) the magnitude of disturbance required to cause landslides using initiation thresholds. Typically, this is accomplished through the use of inventories documenting the locations and triggering conditions of previous landslides. In the absence of comprehensive landslide inventories, physics-based slope stability models can be used to estimate landslide initiation potential and provide plausible distributions of landslide characteristics for a range of environmental …
Accretion Of Warm Chondrules In Weakly Metamorphosed Ordinary Chondrites And Their Subsequent Reprocessing, Alex M. Ruzicka, Richard C. Hugo, Jon M. Friedrich, Michael T. Ream
Accretion Of Warm Chondrules In Weakly Metamorphosed Ordinary Chondrites And Their Subsequent Reprocessing, Alex M. Ruzicka, Richard C. Hugo, Jon M. Friedrich, Michael T. Ream
Geology Faculty Publications and Presentations
To better understand chondrite accretion and subsequent processes, the textures, crystallography, deformation, and compositions of some chondrite constituents in ten lithologies of different cluster texture strength were studied in seven weakly metamorphosed (Type 3) and variably shocked ordinary chondrites (Ragland—LL3 S1, Tieschitz—H/L3 S1, NWA 5421—LL3 S2, NWA 5205—LL3 S2, NWA 11905—LL3-5 S3, NWA 5781—LL3 S3, NWA 11351—LL3-6 S4) using optical and electron microscopy and microtomography techniques.
Results support a four-stage model for chondrite formation. This includes 1) limited annealing following collisions during chondrule crystallization and rapid cooling in space prior to accretion, as evidenced by olivine microstructures consistent with dislocation …
Debris Fan Produced By Failure Of Canyon-Blocking Pyroclastic Flows, Michael L. Cummings
Debris Fan Produced By Failure Of Canyon-Blocking Pyroclastic Flows, Michael L. Cummings
Geology Faculty Publications and Presentations
Ash-rich pyroclastic flows from the cataclysmic eruption of Mount Mazama (~7700 yr. B. P.), Cascade volcanic arc, Oregon, entered and blocked the narrow, bedrock-lined canyon of the Williamson River approximately 35 to 44 km from the source volcano. The blockage impounded a body of water which then released producing four stratigraphic units in the downstream debris fan. The four stratigraphic units are a boulder core comprised of locally sourced bedrock boulders and three sand-rich units including a fine-grained sand unit, a sandy pumice gravel (±basalt/hydrovolcanic tuff) unit, and a pumice pebble-bearing, crystal-rich sand unit. Hand-drilled auger holes up to ~1.6 …
Mantle Sources And Geochemical Evolution Of The Picture Gorge Basalt, Columbia River Basalt Group, Emily B. Cahoon, Martin J. Streck, Richard W. Carlson, Ilya N. Bindeman
Mantle Sources And Geochemical Evolution Of The Picture Gorge Basalt, Columbia River Basalt Group, Emily B. Cahoon, Martin J. Streck, Richard W. Carlson, Ilya N. Bindeman
Geology Faculty Publications and Presentations
The Columbia River Basalt Group (CRBG) is the youngest continental flood basalt province, proposed to be sourced from the deep-seated plume that currently resides underneath Yellowstone National Park. If so, the earliest erupted basalts from this province, such as those in the Picture Gorge Basalt (PGB), aid in understanding and modeling plume impingement and the subsequent evolution of basaltic volcanism. Using geochemical and isotopic data, this study explores potential mantle sources and magma evolution of the PGB. Long known geochemical signatures of the PGB include overall large ion lithophile element (LILE) enrichment and relative depletion of high field strength elements …
Extreme Heat & Public Perception In Portland, Oregon: Evidence Of A Compounding Vulnerability Effect For Climate Hazards, Brianne Suldovsky, Molly Baer Kramer, Jonathan Fink
Extreme Heat & Public Perception In Portland, Oregon: Evidence Of A Compounding Vulnerability Effect For Climate Hazards, Brianne Suldovsky, Molly Baer Kramer, Jonathan Fink
Geology Faculty Publications and Presentations
Extreme heat events are a global public health threat, and the frequency of these events are projected to increase significantly in the coming decades. Responding to extreme heat requires that municipalities communicate with public audiences. Generally speaking, risk communication and public engagement efforts are more effective when they are responsive to current risk perception trends. This social scientific study examines extreme heat risk perceptions, emergency response needs, and level of trust in first responders among residents of the Portland (OR) Metro Area. Using quantitative survey data, it demonstrates the compounding influence of three previously identified vulnerability indicators–poverty, disability, and race–on …
Volcanic Glass As A Proxy For Paleotopography Suggests New Features In Late-Miocene Oregon, Julian Cohen, John Bershaw, Richard Hugo
Volcanic Glass As A Proxy For Paleotopography Suggests New Features In Late-Miocene Oregon, Julian Cohen, John Bershaw, Richard Hugo
Geology Faculty Publications and Presentations
Volcanic glass has been used extensively as a paleoaltimeter. Deuterium (2H) concentrations in glass have been found to be stable over geologic timescales, making δ2H (also known as δD) a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in volcanic ash. Here, we analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ash-flow tuff, and create a paleoisoscape to assess variations in δD across Oregon during that time. To this end, 16 ash samples were collected across central and eastern Oregon from …
Evidence Of Seattle Fault Earthquakes From Patterns In Deep-Seated Landslides, Erich Herzig, Alison Duvall, Adam Booth, Ian Stone, Erin Wirth, Sean Lahusen, Joseph Wartman, Alex Grant
Evidence Of Seattle Fault Earthquakes From Patterns In Deep-Seated Landslides, Erich Herzig, Alison Duvall, Adam Booth, Ian Stone, Erin Wirth, Sean Lahusen, Joseph Wartman, Alex Grant
Geology Faculty Publications and Presentations
Earthquake‐induced landslides can record information about the seismic shaking that generated them. In this study, we present new mapping, Light Detection and Ranging‐derived roughness dating, and analysis of over 1000 deep‐seated landslides from the Puget Lowlands of Washington, U.S.A., to probe the landscape for past Seattle fault earthquake information. With this new landslide inventory, we observe spatial and temporal evidence of landsliding related to the last major earthquake on the Seattle fault ∼1100 yr before present. We find spatial clusters of landslides that correlate with ground motions from recent 3D kinematic models of Seattle fault earthquakes. We also find temporal …
Deep Structure Of Siletzia In The Puget Lowland: Imaging An Obducted Plateau And Accretionary Thrust Belt With Potential Fields, Megan L. Anderson, Richard J. Blakely, Ray E. Wells, Joe D. Dragovich
Deep Structure Of Siletzia In The Puget Lowland: Imaging An Obducted Plateau And Accretionary Thrust Belt With Potential Fields, Megan L. Anderson, Richard J. Blakely, Ray E. Wells, Joe D. Dragovich
Geology Faculty Publications and Presentations
Detailed understanding of crustal components and tectonic history of forearcs is important due to their geological complexity and high seismic hazard. The principal component of the Cascadia forearc is Siletzia, a composite basaltic terrane of oceanic origin. Much is known about the lithology and age of the province. However, glacial sediments blanketing the Puget Lowland obscure its lateral extent and internal structure, hindering our ability to fully understand its tectonic history and its influence on modern deformation. In this study, we apply map-view interpretation and two-dimensional modeling of aeromagnetic and gravity data to the magnetically stratified Siletzia terrane revealing its …
Brief Communication: Recent Estimates Of Glacier Mass Loss For Western North America From Laser Altimetry, Brian Menounos, Caitlyn Forentine, Alex A. Gardner, Andrew G. Fountain
Brief Communication: Recent Estimates Of Glacier Mass Loss For Western North America From Laser Altimetry, Brian Menounos, Caitlyn Forentine, Alex A. Gardner, Andrew G. Fountain
Geology Faculty Publications and Presentations
Glaciers in western North American outside of Alaska are often overlooked in global studies because their potential to contribute to changes in sea level is small. Nonetheless, these glaciers represent important sources of freshwater, especially during times of drought. Differencing recent ICESat-2 data from a digital elevation model derived from a combination of synthetic aperture radar data (TerraSAR-X/TanDEM-X), we find that over the period 2013–2020, glaciers in western North America lost mass at a rate of 12:3+3:5 Gt yr-1. This rate is comparable to the rate of mass loss (11:71:0 Gt yr1) for the period 2018– 2022 calculated …
The Magmatic Origin Of The Columbia River Gorge, Usa, Nathaniel Klema, Leif Karlstrom, Charles Cannon, Chengxin Jiang, Jim O'Connor, Ray E. Wells, Brandon Schmandt
The Magmatic Origin Of The Columbia River Gorge, Usa, Nathaniel Klema, Leif Karlstrom, Charles Cannon, Chengxin Jiang, Jim O'Connor, Ray E. Wells, Brandon Schmandt
Geology Faculty Publications and Presentations
Along subduction zones, high-relief topography is associated with sustained volcanism parallel to the plate margin. However, the relationship between magmatism and mountain building in arcs is poorly understood. Here, we study patterns of surface deformation and correlated fluvial knickpoints in the Columbia River Gorge to link long-term magmatism to the uplift and ensuing topographic development of the Cascade Range. An upwarped paleochannel exposed in the walls of the Gorge constrains unsteady deep magma flux, the ratio of intrusive to extrusive magmatic contributions to topography, and the impact of magmatism on Columbia River incision since 3.5 million years ago. Geophysical data …
Province-Wide Tapping Of A Shallow, Variably Depleted, And Metasomatized Mantle To Generate Earliest Flood Basalt Magmas Of The Columbia River Basalt, Northwestern Usa, Martin J. Streck, Luke James Fredenberg, Lena M. Fox, Emily B. Cahoon, Mary J. Mass
Province-Wide Tapping Of A Shallow, Variably Depleted, And Metasomatized Mantle To Generate Earliest Flood Basalt Magmas Of The Columbia River Basalt, Northwestern Usa, Martin J. Streck, Luke James Fredenberg, Lena M. Fox, Emily B. Cahoon, Mary J. Mass
Geology Faculty Publications and Presentations
The Miocene Columbia River Basalt Group (CRBG) of the Pacific Northwest of the United States is the world’s youngest and smallest large igneous province. Its earliest formations are the Imnaha, Steens, and now the Picture Gorge Basalt (PGB), and they were sourced from three different dike swarms exposed from SE Washington to Nevada to northcentral Oregon. PGB is often viewed to be distinct from the other formations, as its magmas are sourced from a shallow, relatively depleted, and later subduction-induced metasomatized mantle, along with its young stratigraphic position. It has long been known that the lowermost American Bar flows (AB1&2) …
Inventory Of Glaciers And Perennial Snowfields Of The Conterminous Usa, Andrew G. Fountain, Bryce Glenn, Christopher Mcneil
Inventory Of Glaciers And Perennial Snowfields Of The Conterminous Usa, Andrew G. Fountain, Bryce Glenn, Christopher Mcneil
Geology Faculty Publications and Presentations
This report summarizes an updated inventory of glaciers and perennial snowfields of the conterminous United States. The inventory is based on interpretation of mostly aerial imagery provided by the National Agricultural Imagery Program, US Department of Agriculture, with some satellite imagery in places where aerial imagery was not suitable. The inventory includes all perennial snow and ice features ≥ 0.01 km2. Due to aerial survey schedules and seasonal snow cover, imageries acquired over a number of years were required. The earliest date is 2013 and the latest is 2020, but more than 73 % of the outlines were …
Evaluating How Well Active Fault Mapping Predicts Earthquake Surface-Rupture Locations, Chelsea Scott, Ramon Arrowsmith, Rachel Adam, Christopher Madugo, Joseph Powell, John Ford, Brian Gray, Ashley Streig, Multiple Additional Authors
Evaluating How Well Active Fault Mapping Predicts Earthquake Surface-Rupture Locations, Chelsea Scott, Ramon Arrowsmith, Rachel Adam, Christopher Madugo, Joseph Powell, John Ford, Brian Gray, Ashley Streig, Multiple Additional Authors
Geology Faculty Publications and Presentations
Earthquake surface-fault rupture location uncertainty is a key factor in fault displacement hazard analysis and informs hazard and risk mitigation strategies. Geologists often predict future rupture locations from fault mapping based on the geomorphology interpreted from remote-sensing data sets. However, surface processes can obscure fault location, fault traces may be mapped in error, and a future rupture may not break every fault trace. We assessed how well geomorphology-based fault mapping predicted surface ruptures for seven earthquakes: 1983 M 6.9 Borah Peak, 2004 M 6.0 Parkfield, 2010 M 7.2 El Mayor–Cucapah, 2011 M 6.7 Fukushima-Hamadori, 2014 M 6.0 South Napa, 2016 …
Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum
Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum
Geology Faculty Publications and Presentations
Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past1,2,3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or by mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical …
Effects Of Landslides On Terrestrial Carbon Stocks With A Coupled Geomorphic-Biologic Model: Southeast Alaska, United States, Adam M. Booth, Brian Buma, S. Nagorski
Effects Of Landslides On Terrestrial Carbon Stocks With A Coupled Geomorphic-Biologic Model: Southeast Alaska, United States, Adam M. Booth, Brian Buma, S. Nagorski
Geology Faculty Publications and Presentations
Landslides influence the global carbon (C) cycle by facilitating transfer of terrestrial C in biomass and soils to offshore depocenters and redistributing C within the landscape, affecting the terrestrial C reservoir itself. How landslides affect terrestrial C stocks is rarely quantified, so we derive a model that couples stochastic landslides with terrestrial C dynamics, calibrated to temperate rainforests in southeast Alaska, United States. Modeled landslides episodically transfer C from scars to deposits and destroy living biomass. After a landslide, total C stocks on the scar recover, while those on the deposit either increase (in the case of living biomass) or …
Glacialwater: A Dynamic Microbial Medium, Gilda Varliero, Pedro H. Lebre, Andrew G. Fountain, Beat Frey, Alexandre M. Anesio, Don A. Cowan
Glacialwater: A Dynamic Microbial Medium, Gilda Varliero, Pedro H. Lebre, Andrew G. Fountain, Beat Frey, Alexandre M. Anesio, Don A. Cowan
Geology Faculty Publications and Presentations
Microbial communities and nutrient dynamics in glaciers and ice sheets continuously change as the hydrological conditions within and on the ice change. Glaciers and ice sheets can be considered bioreactors as microbiomes transform nutrients that enter these icy systems and alter the meltwater chemistry. Global warming is increasing meltwater discharge, affecting nutrient and cell export, and altering proglacial systems. In this review, we integrate the current understanding of glacial hydrology, microbial activity, and nutrient and carbon dynamics to highlight their interdependence and variability on daily and seasonal time scales, as well as their impact on proglacial environments.
Picture Gorge Basalt: Internal Stratigraphy, Eruptive Patterns, And Its Importance For Understanding Columbia River Basalt Group Magmatism, Emily Bogdan Cahoon, Martin J. Streck, Anthony A.P. Koppers
Picture Gorge Basalt: Internal Stratigraphy, Eruptive Patterns, And Its Importance For Understanding Columbia River Basalt Group Magmatism, Emily Bogdan Cahoon, Martin J. Streck, Anthony A.P. Koppers
Geology Faculty Publications and Presentations
The Picture Gorge Basalt (PGB) of the Columbia River Basalt Group (CRBG) has been previously thought to be limited in its eruptive volume (<3000 >km3) and thought to not extend far from its type locality. At present, PGB represents only 1.1 vol% of the CRBG with a relatively limited spatial distribution of ~10,000 km2. New age data illustrate that the PGB is the earliest and longest eruptive unit compared to other main-phase CRBG formations and that some dated basaltic flows reach far (~100 km) beyond the previously mapped extent. This study focuses on extensive outcrops of …3000>