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Full-Text Articles in Earth Sciences

Critical Metals: From Granitic Pegmatites To The Anthropogenic Cycle, Dalton Mccaffrey May 2023

Critical Metals: From Granitic Pegmatites To The Anthropogenic Cycle, Dalton Mccaffrey

UNLV Theses, Dissertations, Professional Papers, and Capstones

Critical metals are vital to the functionality of the modern world. The increased diversity and usage intensity of these commodities in defense-related and strategic technologies (e.g., jet engines, rocket assemblies), modern infrastructure and products (e.g., high-strength steel, cellular phones, laptop computers), and energy-related, low-emissions technologies (e.g., nuclear reactors, solar panels, wind turbines, hybrid and electric vehicles) has drastically increased our reliance on critical metals and, thus, the United States (and global) exposure to supply restrictions. Granitic pegmatites are unique mineral deposits that represent a past, present and future resource for many (approximately half) of these critical resources. Even with the …


Morphologic Comparisons Of Recrystallized And Neocrystallized Fibrous Amphibole Asbestos: Implications For Corresponding Health Risk Potential, Natalie G. Renkes May 2023

Morphologic Comparisons Of Recrystallized And Neocrystallized Fibrous Amphibole Asbestos: Implications For Corresponding Health Risk Potential, Natalie G. Renkes

UNLV Theses, Dissertations, Professional Papers, and Capstones

The presence of naturally-occurring asbestos (NOA) is increasingly concerning for scientists, health and regulatory agencies, and citizens living in impacted areas. It is commonly believed that fibrous amphibole asbestos can only form through neocrystallization. In southern Nevada, NOA occurs as a result of hydrothermal alteration of granitic rock producing fibrous amphibole both as cross-cutting neocrystallized veins and via recrystallization of original magmatic hornblende crystals. Fibers with a greater aspect ratio are known to have increased toxicity. This study measured the maximum length and average width of both neocrystallized and recrystallized fibers to see if the morphologies were similar. Neocrystallized and …


The Impact Of Glacial Proximity On The Elemental Composition Of Leachate Derived From Sediment Weathering, Karoline Ford May 2023

The Impact Of Glacial Proximity On The Elemental Composition Of Leachate Derived From Sediment Weathering, Karoline Ford

Theses/Capstones/Creative Projects

This study assesses chemical weathering trends as they relate to glacial retreat. The chemical environment of surfaces exposed to the atmosphere differs significantly from beneath a glacier. As a glacier melts, changes to the biogeochemical processes generate environmental gradients. This study analyzed chemical weathering signals at different distances from a glacial front by comparing the elemental composition of leachate derived from sediments in southeastern Greenland. Samples from proglacial, nonglacial, and moraine locations were weathered in a laboratory setting, and ion chromatography was used to determine the elemental composition of the products. Divergent trends in leachate composition were observed as distance …


Quantifying Heterogeneity Along A Hillslope Using Seismic Refraction, Structure From Motion, And X-Ray Fluorescence In The Piedmont, South Carolina, Leah Topping May 2023

Quantifying Heterogeneity Along A Hillslope Using Seismic Refraction, Structure From Motion, And X-Ray Fluorescence In The Piedmont, South Carolina, Leah Topping

All Theses

The critical zone (CZ) is the life sustaining outer layer of the earth that spans from the top of unweathered bedrock to the tops of the trees. This dynamic zone is always evolving because a variety of chemical, physical, and biological processes transform bedrock into regolith, creating a spatially heterogeneous CZ architecture. This study aims to investigate the relationships between regolith thickness, seismic velocities, and chemical profiles as a function of slope position and it is hypothesized bedrock composition, fracture density, and foliation are the key factors controlling the physical heterogeneity in the top 1-2 meters of the CZ. To …


Evaluating Bulk Carbon And Nitrogen Isotope Compositions Of Acidic Hydrothermal Sediments On Earth– Implications For Mars Astrobiology, Chance Sturrup May 2023

Evaluating Bulk Carbon And Nitrogen Isotope Compositions Of Acidic Hydrothermal Sediments On Earth– Implications For Mars Astrobiology, Chance Sturrup

Masters Theses

Carbon isotopes have been widely used as unique biosignatures because biologic processes commonly result in distinctive negative delta 13C values (-35 to -10 ‰) within organic material on Earth. However, the bulk delta 13C analysis in Gale crater sediments on Mars revealed a wider range of values, from -25 to +56 ‰ (Franz et al., 2020), which suggests a more complex origin. To determine if bulk isotope analysis can be successfully used to detect a microbial signature in a martian analog environment, we analyzed concentrations and isotope compositions of C within hydrothermal sediments in Iceland (Námafjall, Krýsuvík, Hveragerdi) …


Glacialwater: A Dynamic Microbial Medium, Gilda Varliero, Pedro H. Lebre, Andrew G. Fountain, Beat Frey, Alexandre M. Anesio, Don A. Cowan May 2023

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.


Lesson Plans In Astronomy, Ecology And Biology, Admin Stem For Success Apr 2023

Lesson Plans In Astronomy, Ecology And Biology, Admin Stem For Success

STEM for Success Showcase

This document contains various lesson plan ideas for concepts within the fields of biology, ecology, astronomy, and geology.


Testing Pedagogical Approaches To Online Lecture: Effects Of Background Music And Interactive Video Series On Student Retention Of Prior Conception-Correcting Information On Climate Change, Roya Franseth Apr 2023

Testing Pedagogical Approaches To Online Lecture: Effects Of Background Music And Interactive Video Series On Student Retention Of Prior Conception-Correcting Information On Climate Change, Roya Franseth

Honors Projects

Climate change is a pervasive element in our modern lives, yet many harbor ideas about climate change and associated climate mechanisms that are misinformed or incorrect. Ideas like these – prior conceptions (ideas that people carry with them into learning experiences about a subject) – are studied in varying degrees across fields. The geosciences do not have a particularly robust collection of research on the subject of geoscience-specific prior conceptions. At the same time, due to the COVID-19 pandemic, alternatives to in-person lecture such as online lecture have become normalized. The original aim of this paper was to determine if …


Glass: The Material That Defines Us, Madisyn Rex Apr 2023

Glass: The Material That Defines Us, Madisyn Rex

Honors Projects

This Honors Project is an exploration of the intersections between glass science, geology, glass art, and my own personal experience with glass.


Organic Matter Quality Influences Aerobic And Anaerobic Respiration Rates In Peatland Soils, Rachel Shaw, Lauren Bryan, Madison Smith, Christian Lundy, Alexis Koehl, Grace Behrens, Mackenzie Dole, Madeleine O'Donnell Apr 2023

Organic Matter Quality Influences Aerobic And Anaerobic Respiration Rates In Peatland Soils, Rachel Shaw, Lauren Bryan, Madison Smith, Christian Lundy, Alexis Koehl, Grace Behrens, Mackenzie Dole, Madeleine O'Donnell

22nd Annual Celebration of Undergraduate Research and Creative Activity (2023)

The vulnerability of peatland carbon reservoirs to decomposition in a warming climate remains a key uncertainty in Earth System Models. This will be determined in part by the "quality" of the peatland organic matter, i.e. the ease by which it is decomposed by the microbial community. We developed an index of organic matter quality based on the biochemical composition of the peat. The index uses a principal components analysis of proxies based on the carbohydrate composition, hydrolysable amino acids, C:N, pH, and nutrient availability in the peat porewater. The index was compared with measurements of aerobic and anaerobic respiration rates …


Temperature Sensitivity Of Nitrogen Mineralization In Peat From A Southwestern Michigan Bog, Madison Smith, Lauren Bryan, Rachel Shaw, Mackenzie Dole, Madeleine O'Donnell Apr 2023

Temperature Sensitivity Of Nitrogen Mineralization In Peat From A Southwestern Michigan Bog, Madison Smith, Lauren Bryan, Rachel Shaw, Mackenzie Dole, Madeleine O'Donnell

22nd Annual Celebration of Undergraduate Research and Creative Activity (2023)

In this study, we measured inorganic nitrogen (nitrate and ammonium) released from peat cores from Miner Lake bog at two temperatures to analyze the impact of climate warming on the peatland nitrogen cycle. We hypothesized a higher nitrogen release in samples incubated at warmer temperatures. Furthermore, previous research indicates shallow peat decomposes faster than deeper peat. Therefore, we hypothesized faster nitrogen mineralization in shallow samples. We collected peat cores from two locations from Miner Lake Bog in Allegan County, Michigan: a plot in the center of the bog and a sedge meadow site near the edge. Two samples for each …


Interspecies Differences In Food Sources For The Tropical Callichirid Shrimp Neocallichirus Spp. On San Salvador Island, Bahamas, Koji Seike, H. Allen Curran Apr 2023

Interspecies Differences In Food Sources For The Tropical Callichirid Shrimp Neocallichirus Spp. On San Salvador Island, Bahamas, Koji Seike, H. Allen Curran

Geosciences: Faculty Publications

At least 4 species of callichirid shrimp coexist in the shallow marine settings of San Salvador Island, an isolated, small platform of the all-carbonates Bahama Archipelago, implying that interspecific competition or trophic niche segregation occurs between these shrimp species. Carbon and nitrogen stable isotope analyses were conducted on soft tissues of 3 callichirid species, Neocallichirus cacahuate, N. grandimana, and N. maryae, to determine the food sources for each species. These analyses revealed that the isotopic trophic niches for these 3 species do not overlap. The most important food source for all 3 species was manatee grass Syringodium filiforme …


Carbonate Microfacies Of The Middle To Upper Pennsylvanian Cache Creek Group At Meadow Lake, British Columbia, Canada, Brennen Leidy Apr 2023

Carbonate Microfacies Of The Middle To Upper Pennsylvanian Cache Creek Group At Meadow Lake, British Columbia, Canada, Brennen Leidy

Undergraduate Research Conference

No abstract provided.


Modeling Spatial Distributions Of Tidal Marsh Blue Carbon Using Morphometric Parameters From Lidar, Bonnie Turek Apr 2023

Modeling Spatial Distributions Of Tidal Marsh Blue Carbon Using Morphometric Parameters From Lidar, Bonnie Turek

Masters Theses

Tidal marshes serve as important “blue carbon” ecosystems that accrete large amounts of carbon with limited area. While much attention has been paid to the spatial variability of sedimentation within salt marshes, less work has been done to characterize spatial variability in marsh carbon density. Driven by tidal inundation, surface topography, and sediment supply, soil properties in marshes vary spatially with several parameters, including marsh platform elevation and proximity to the marsh edge and tidal creek network. We used lidar to extract these morphometric parameters from tidal marshes to map soil organic carbon (SOC) at the meter scale. Fixed volume …


Snow Distribution And Influence In Taylor Valley, Antarctica, Using Remote Sensing, Katherine Mcnulty, Peter Doran, Mark Salvatore, Suniti Karunatillake Apr 2023

Snow Distribution And Influence In Taylor Valley, Antarctica, Using Remote Sensing, Katherine Mcnulty, Peter Doran, Mark Salvatore, Suniti Karunatillake

LSU Master's Theses

The McMurdo Dry Valleys is the largest ice-free area in Antarctica, but seasonal snow covers the valley floors sporadically throughout the year. In this study, a model to estimate areal snow coverage from satellite imagery was created. An area-volume model was created to estimate the amount of snow water equivalent (SWE) from the snow area extracted from the imagery. Snow cover influences the total albedo, the hydrologic budget, and the soil moisture and soil temperature in Taylor Valley (TV). Quantifying snow precipitation in TV is challenging because snow redistributes with winds, sublimates, or melts within a short period. Previous estimates …


Geomorphology Of Tidal Wetlands: Impacts Of Extreme And Annual Flood Events To Salt Marsh And Mangrove Systems, Frances R. Griswold Apr 2023

Geomorphology Of Tidal Wetlands: Impacts Of Extreme And Annual Flood Events To Salt Marsh And Mangrove Systems, Frances R. Griswold

Doctoral Dissertations

Tidal wetlands are vital for buffering coastal settings from the threats of accelerated sea level rise and storms. Understanding the factors that are most influential for the maintenance and recovery of tidal wetlands after extreme events compounded by future accelerated sea level rise is of the utmost importance, yet this knowledge is not well established. Two tidal wetland schemas investigated in this dissertation are mangrove systems in Vieques, Puerto Rico (including robust lagoonal-mangrove forest systems and fringing mangrove forests), and salt marshes in New England. While the climatic forcings, vegetation type, and locations are vastly different for these two tidal …


Evaluation Of Fluvial Package Amalgamation In Medial Dfs Deposits, Angel Peak Area, Nacimineto Formation, Sarah R. Rysanek Apr 2023

Evaluation Of Fluvial Package Amalgamation In Medial Dfs Deposits, Angel Peak Area, Nacimineto Formation, Sarah R. Rysanek

Earth and Planetary Sciences ETDs

Fluvial packages are the hypothetical groupings of facies that make up the fluvial succession consisting of channel belt sandstones and associated levee, floodplain, and avulsion deposits. This study attempted to describe a single fluvial package laterally using the new technologies of UAV imaging and 3D photogrammetry; however, amalgamation of channel belts and erosion from this amalgamation made long-distance lateral correlation difficult. This analysis of medial deposits in the Nacimiento Formation in the Angel Peak Area, Northwestern New Mexico evaluates the degree of amalgamation of fluvial packages across the study area while identifying facies associated with the hypothetical fluvial package. This …


Alfred Russel Wallace Notes 25. Wallace And The 'Physical Environment'., Charles H. Smith Apr 2023

Alfred Russel Wallace Notes 25. Wallace And The 'Physical Environment'., Charles H. Smith

Faculty/Staff Personal Papers

Alfred Russel Wallace’s natural selection essay of 1858 has been held to frame a greater role for the physical environment in forcing selection regimes than we find in Darwin’s writings, but here that verdict is challenged by a re-examination of both the essay itself, and period usage of the term ‘physical.’


Stratigraphic Architecture Of Pozuelo Mounds As Revealed By Earth Resistivity Tomography, Caeli Connolly Apr 2023

Stratigraphic Architecture Of Pozuelo Mounds As Revealed By Earth Resistivity Tomography, Caeli Connolly

Honors College

This study is a geoarchaeological analysis using earth resistance tomography (ERT) surveys of two of four mounds at Pozuelo (Formative Period, cal yr 3000 BP) in the Chincha Valley of coastal, southern Peru. Layers identified in the subsurface were to determine the presence or absence of regional continuity between the mounds. This effort is part of a larger investigation examining the paleoenvironmental setting of the site, and its influence on site location and use. Ten earth resistance tomography profiles were collected using an ABEM Terrameter LS2 and 81 pin array. These profiles were then topographically corrected using topographic survey data …


Exploring The Current Training Of Undergraduate Geology Students And Teaching Spatial Skills To Improve Student Outcomes, Ann Marie Klyce Apr 2023

Exploring The Current Training Of Undergraduate Geology Students And Teaching Spatial Skills To Improve Student Outcomes, Ann Marie Klyce

Theses and Dissertations

Spatial skills, which represent the ability to mentally manipulate objects (Schneider & McGrew, 2012; Atit et al., 2020) have been shown to be correlated with entrance, persistence and success in STEM (Shea et al., 2001; Wai et al., 2009). Specifically, these skills have been shown to be necessary to geologists and geoscientists (Hegarty, 2014; Gagnier et al., 2016). While we recognize the importance of these skills, explicit training in them is rarely offered (NRC 2006). Consequently, cognitive scientists and discipline based education researchers have begun concerted efforts to offer training in spatial skills to improve student outcomes (e.g. Uttal et …


Dust Production And Transport In A Long-Lived Fluvial-Eolian System In The Pampas Of South America, Blake Marcus Stubbins Apr 2023

Dust Production And Transport In A Long-Lived Fluvial-Eolian System In The Pampas Of South America, Blake Marcus Stubbins

Theses and Dissertations

Wind-blown dust from southern South America links the terrestrial, marine, atmospheric, and biologic components of Earth’s climate system. The Pampas of central Argentina (~33-40° S) contain an extensive upper Miocene to Holocene eolian record that spans the relatively warm conditions of the Late Miocene to cooler climates of the Plio-Pleistocene and Holocene. We collected 13 loess, paleosol, and fluvial samples from the upper Miocene Cerro Azul and Rio Negro Formations which resulted in n = 5129 new detrital zircon U-Pb ages. Late Miocene rivers conveyed sediment from northern Patagonia, the Andes adjacent to the Pampas, and the Sierras Pampeanas to …


Using Mineral Magnetism To Characterize Compositions Of Fe-Ti Oxide Phases Of The Sulphur Creek Lava Flow (Kulshan), Elika Zilis Apr 2023

Using Mineral Magnetism To Characterize Compositions Of Fe-Ti Oxide Phases Of The Sulphur Creek Lava Flow (Kulshan), Elika Zilis

WWU Honors College Senior Projects

The aim of this study is to examine variations in the composition of Fe-Ti oxide minerals in the Sulphur Creek lava flow (SE margin of Kulshan), using magnetic techniques and electron microscopy. Geochemical and petrological data from these rocks dated ~9.8 ka may be a product of two distinct magma pulses (Garvey, 2002) with two distinct compositions: andesitic basalt and basalt. The composition of cubic oxides (magnetite and ulvöspinel) is influenced by the geochemistry of the crystallizing magma and can be used to provide information about the chemical evolution of these magmas, but also to help frame future paleomagnetic studies …


A Seismic Investigation Of Uturuncu Volcano And The Lazufre Volcanic Complex, Heather L. Mcfarlin Mar 2023

A Seismic Investigation Of Uturuncu Volcano And The Lazufre Volcanic Complex, Heather L. Mcfarlin

USF Tampa Graduate Theses and Dissertations

The following dissertation is a study of three seismological techniques used to determine the geophysical properties of two large, inflating magma bodies in the upper crust in South America: one under Uturuncu volcano and one beneath Lastarria and Cordon del Azufre volcanoes. First, I use the method of teleseismic receiver functions to image the top and bottom of the magma body beneath Uturuncu volcano. Depths to the top of this body vary between 6 and 12 km below sea level, while depths to the bottom vary between 13 and 22 km below sea level, with the thickness ranging from 6 …


2021 Particle Grain-Size And Total Organic Content Analyses Of Surface Sediments From Puget Sound And Elliott Bay Near Seattle, Wa, Ethan Hoang Mar 2023

2021 Particle Grain-Size And Total Organic Content Analyses Of Surface Sediments From Puget Sound And Elliott Bay Near Seattle, Wa, Ethan Hoang

Environmental Science Undergraduate Theses

Seattle’s Elliott Bay has been a particularly intriguing area in regards to anthropological activities and their effects on the surrounding environment. The construction of the city brought about the displacement of sediment around the bay, resulting in lower quality sediments that negatively impact the nutrient cycles in the benthic zone. This project’s examination of total organic carbon and particle size in sediment serves as a baseline to which scientists can refer in monitoring future sediment health. To determine this baseline, UW Tacoma obtained sediment samples from Washington State Department of Ecology’s Puget Sound Ecosystem Monitoring Program. The samples were analyzed …


New Surficial Geologic Mapping In Kentucky (2021-2022), Matthew Massey, Antonia Bottoms, Max Hammond Iii, Ann Hislop, Meredith Swallom, Michele M. Mchugh Mar 2023

New Surficial Geologic Mapping In Kentucky (2021-2022), Matthew Massey, Antonia Bottoms, Max Hammond Iii, Ann Hislop, Meredith Swallom, Michele M. Mchugh

Research Data--KGS

New surficial geologic mapping was performed in nine new 7.5-minute quadrangles in Hardin, Meade, Breckinridge, Grayson, Hart, and Larue Counties, Kentucky.

Quadrangles include Big Clifty, Big Spring (Hardin county only), Custer (Hardin County only), Flaherty, Madrid (Hardin county only), Millerstown, Summit, Tonieville (Hardin county only), and Upton.

Mapping data for each of the nine quadrangles is captured in a ZIP file that contains an ESRI geodatabase and associated FGDC-compliant metadata files (.xml).

The geodatabase is a relational geodatabase of spatial and non-spatial data that conforms to "GeMS (Geologic Map Schema)--a standard format for digital publication of geologic maps", available at …


Are Natural Fractures In Sandstone Reservoir: Water Wet – Mixed Wet – Or Oil Wet?, Salah Almudhhi, Laila Abdullah, Waleed Al-Bazzaz, Saleh Alsayegh, Hussien Alajaj, Ralph E. Flori Mar 2023

Are Natural Fractures In Sandstone Reservoir: Water Wet – Mixed Wet – Or Oil Wet?, Salah Almudhhi, Laila Abdullah, Waleed Al-Bazzaz, Saleh Alsayegh, Hussien Alajaj, Ralph E. Flori

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This study accurately measures the wettability contact angle of native Kuwaiti sandstone reservoir that hosts mixed pore size distributions in both the tight sandstone matrix as well as the natural fracture (NF) embedded in it. Also, this study, effectively, investigates the geometrical size and shape of natural available voids whether matrix voids or NF voids captured in the rock 2D image frame system. Correspondingly, this study is, successfully, measure tight matrix, NF Pore wall, and NF pore opening wettability performance and recovery efficiency contributions inside the sandstone reservoir. A model pore/ grain contact angle wettability is generated. Therefore, this study …


Kentucky Geological Survey Landslide Inventory [2023-03], Matthew M. Crawford Mar 2023

Kentucky Geological Survey Landslide Inventory [2023-03], Matthew M. Crawford

Research Data--KGS

The KGS landslide inventory provides the locations of known landslides and areas susceptible to debris flows. Various types of landslides are represented including slides, flows, rockfalls, and creep. The data are available as ArcGIS geodatabase feature classes. Landslide locations and associated attributes are compiled from Kentucky Geological Survey research, published maps, state and local government agencies, the public, and media reports. A confidence ranking system assigns a value to each feature. A description of the feature classes is here: https://kgs.uky.edu/kgsmap/helpfiles/landslide_help.shtm

The inventory viewed in a GIS with geology, soils, slope or other terrain-based data can serve as a basis for …


Nebraska Statewide Groundwater-Level Monitoring Report 2022, Aaron R. Young, Mark E. Burbach, Sue Olafsen Lackey, Robert Matthew Joeckel, Jeffrey Westrop Mar 2023

Nebraska Statewide Groundwater-Level Monitoring Report 2022, Aaron R. Young, Mark E. Burbach, Sue Olafsen Lackey, Robert Matthew Joeckel, Jeffrey Westrop

Conservation and Survey Division

No abstract provided.


Late Neoarchean To Middle Paleoproterozoic Geology Of Devon And Ellesmere Islands, Canadian Arctic, Joshua P. Laughton Feb 2023

Late Neoarchean To Middle Paleoproterozoic Geology Of Devon And Ellesmere Islands, Canadian Arctic, Joshua P. Laughton

Electronic Thesis and Dissertation Repository

The northernmost exposure of the Laurentian shield in Canada outcrops on Devon and Ellesmere islands within the Canadian Arctic Archipelago. Due to the remote location, the basement rocks of these islands have received little attention. From this study, zircon crystallization ages demonstrate that Devon Island is underlain by a late Neoarchean terrane comprising orthogneisses emplaced at ca. 2.55–2.51 Ga and an interleaved metasedimentary sequence deposited at ca. ≥2.47 Ga. On northern Devon Island, younger metasedimentary sequence(s) were deposited at ca. 2.2–1.9 Ga and intruded by ca. 2.01–1.95 Ga granitoids. Devon and Ellesmere islands experienced widespread metamorphic activity associated with the …


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 Feb 2023

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 …