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Full-Text Articles in Volcanology

Investigation Of Cryptotephra In Polar Ice Cores, Meredith Helmick Dec 2022

Investigation Of Cryptotephra In Polar Ice Cores, Meredith Helmick

Electronic Theses and Dissertations

Volcanic ash (tephra) present within polar ice cores greatly supplements our understanding of past volcanism and its impacts on society and the state of the climate system. This thesis investigates the utility and limitations of ice core tephrochronology in answering questions related to volcanic source identification of ice core glaciochemical signals, tephrostratigraphy of an Antarctic ice core, and the timing of major and climate forcing eruptions. This thesis explores the efficacy of SEM-EDS measurements on ultra-fine (µm) volcanic particles for the purpose of geochemically characterizing a non-visible ice-embedded tephra and the subsequent identification of the volcanic source. In combination with …


Natural, Experimental, And Educational Explorations Of The Interiors Of Terrestrial Planetary Bodies, Nadine L. Grambling Dec 2022

Natural, Experimental, And Educational Explorations Of The Interiors Of Terrestrial Planetary Bodies, Nadine L. Grambling

Doctoral Dissertations

Planetary interiors are enigmatic, inaccessible, and vital to the processes that have formed the rocks we see on the surface of bodies in the inner Solar System today. Based on geophysical explorations of the Moon and Earth, along with information gleaned from rocks at the surface today, there is understanding of the basic structure and processes at depth. Using a combination of natural samples and experimental studies, we attempt to learn more about the physical conditions beneath the surface, and their effect on material properties and tectonics processes in the mantle.

On Earth, mid-ocean ridge processes have long been debated, …


Sulfur Behavior In The 1257 Ce Samalas Magma (Lombok, Indonesia) As Revealed By Volcanic Apatite, Yasmin Jackson Oct 2022

Sulfur Behavior In The 1257 Ce Samalas Magma (Lombok, Indonesia) As Revealed By Volcanic Apatite, Yasmin Jackson

Earth Sciences Theses and Dissertations

Explosive volcanic eruptions can inject massive amounts of volatiles, including SO2 and H2S, into the stratosphere, inducing drastic tropospheric cooling via sulfate aerosols. Greenland and Antarctic ice cores record evidence of these substantial releases of SO2 and H2S, including the massive release during the ultraplinian 1257 CE Samalas eruption. The 1257 CE Samalas eruption is estimated to have released ~158 Tg of SO2, making it the largest volcanogenic release of SO2 within the last 2000 years. Vidal et al. (2016) propose that most of this sulfur (S) was hosted in a …


A Transformer-Based Classification System For Volcanic Seismic Signals, Anthony P. Rinaldi, Cindy Mora Stock, Cristián Bravo Roman, Alexander Hemming Aug 2022

A Transformer-Based Classification System For Volcanic Seismic Signals, Anthony P. Rinaldi, Cindy Mora Stock, Cristián Bravo Roman, Alexander Hemming

Undergraduate Student Research Internships Conference

Monitoring volcanic events as they occur is a task that, to this day, requires significant human capital. The current process requires geologists to monitor seismographs around the clock, making it extremely labour-intensive and inefficient. The ability to automatically classify volcanic events as they happen in real-time would allow for quicker responses to these events by the surrounding communities. Timely knowledge of the type of event that is occurring can allow these surrounding communities to prepare or evacuate sooner depending on the magnitude of the event. Up until recently, not much research has been conducted regarding the potential for machine learning …


Differentiating Fissure-Fed Lava Flow Types And Facies Using Radar And Lidar: An Example From The 2014–2015 Holuhraun Lava Flow-Field, Gavin Douglas Tolometti, Catherine D. Neish, Christopher W. Hamilton, Gordon R. Osinski, Antero Kukko, Joana R.C. Voigt Jun 2022

Differentiating Fissure-Fed Lava Flow Types And Facies Using Radar And Lidar: An Example From The 2014–2015 Holuhraun Lava Flow-Field, Gavin Douglas Tolometti, Catherine D. Neish, Christopher W. Hamilton, Gordon R. Osinski, Antero Kukko, Joana R.C. Voigt

Earth Sciences Publications

Distinguishing between lava types and facies using remote sensing data is important for interpreting the emplacement history of lava flow-fields on Earth and other planetary bodies. Lava facies typically include a mixture of lava types and record the collective emplacement history of material preserved at a particular location. We seek to determine if lava facies in the 2014–2015 Holuhraun lava flow-field are discernible using radar roughness analysis. Furthermore, we also seek to distinguish between lava types using high resolution Light Detection and Ranging (LiDAR) data. We extracted circular polarization ratios (CPR) from the Uninhabited Aerial Vehicle Synthetic Aperture Radar and …


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 Jun 2022

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 …


Pre-Eruptive Magma Configurations And Petrogenetic Relationships Of The Rattlesnake Tuff, Oregon–Insights From Spectacularly Banded High-Silica Rhyolite Pumices, Vanessa M. Swenton, Martin J. Streck May 2022

Pre-Eruptive Magma Configurations And Petrogenetic Relationships Of The Rattlesnake Tuff, Oregon–Insights From Spectacularly Banded High-Silica Rhyolite Pumices, Vanessa M. Swenton, Martin J. Streck

Geology Faculty Publications and Presentations

The 7.1Ma Rattlesnake Tuff (RST) of eastern Oregon is a widespread and voluminous (>300 km3) ignimbrite composed of 99% crystal poor (≤1%) high-silica rhyolite (HSR) and


Understanding Hydrogen Variations In Silicate Glasses As A Result Of Degassing: Fire-Fountaining On The Moon And Earth, Erin M. Recchuiti May 2022

Understanding Hydrogen Variations In Silicate Glasses As A Result Of Degassing: Fire-Fountaining On The Moon And Earth, Erin M. Recchuiti

Masters Theses

Volatiles, particularly hydrogen, play a key role in volcanic eruptions, especially explosive eruptions like fire-fountaining [e.g., Saal et al. 2002; Dixon 1997; Arndt & von Engelhardt 1987; Yoder 1976]. Discerning volatile abundance and behavior during ascent and eruption can aid in understanding the source melt and primary volatile content of planetary interiors. Volcanic glasses are samples closest to the primary melt, as they quench quickly enough to limit fractionation or crystallization. This is paramount for volatile studies, especially pertaining to water as its constituents are oxygen and hydrogen. Hydrogen is the most volatile element and one of the first to …


The Significance Of A New 11,000-Year Volcanic Record From The South Pole And Inferences From Comparisons With Other Volcanic Records, Derek Lee Brandis Jan 2022

The Significance Of A New 11,000-Year Volcanic Record From The South Pole And Inferences From Comparisons With Other Volcanic Records, Derek Lee Brandis

Electronic Theses and Dissertations

Snow accumulation at the polar regions of the planet preserves chemical substances from the atmosphere creating natural archives. Records of the atmospheric environment including atmospheric chemical composition and the climate can be reconstructed from ice cores from the polar ice sheets. Sulfur emitted by explosive volcanic eruptions is preserved as sulfate in polar snow and can be used to reconstruct the record of volcanic eruptions. Since large volcanic eruptions impact the environment and climate, records of volcanic eruptions from ice cores can help us to study and understand climate change and model the future climate environment. A 1750-m ice core …


Structural And Petrologic Insights Into The Emplacement Of Effusive Silicic Lavas: Inyo Domes, California, Shelby L. Isom Jan 2022

Structural And Petrologic Insights Into The Emplacement Of Effusive Silicic Lavas: Inyo Domes, California, Shelby L. Isom

Graduate Theses, Dissertations, and Problem Reports

The Long Valley volcanic region, eastern California, USA is most famous for the caldera-forming eruption which produced the Bishop Tuff ~760,000 years ago. Over the last 3,000 years volcanism has been focused in the western margin of the region through punctuated eruptions of silicic lavas and domes. Three simultaneous effusive silicic eruptions, ~600 years ago, generated three lava domes: Obsidian Dome; Glass Creek Dome; and Deadman Dome which erupted onto vastly different topographies. These domes are exceptionally unique as they erupted variable amounts of two textural and chemical endmember lavas (crystal-rich and crystal-poor) that intimately mixed. The overarching goal of …


Aucanquilcha Volcanic Cluster Magma Evolution And Magma Plumbing System Architecture During The Gordo Stage (6-4 Ma), Kasey Lynn Buckley Jan 2022

Aucanquilcha Volcanic Cluster Magma Evolution And Magma Plumbing System Architecture During The Gordo Stage (6-4 Ma), Kasey Lynn Buckley

MSU Graduate Theses

Aucanquilcha Volcanic Cluster (AVC) is an 11 m.y. volcanic system in the central Andes that is evolving over four distinct stages of activity. Stages include the Aloncha (11-8 Ma), Gordo (6-4 Ma), Polán (4-2 Ma), and Aucanquilcha (Ma) stages. The AVC evolved from a series of magmatic underpinnings during the Aloncha Stage to a larger zone of melting, assimilation, storage, and homogenization (MASH) by the Polán Stage. The transition from smaller underpinnings to MASH zones began during the Gordo Stage. At ~5-2 Ma the AVC reached thermal maturity before beginning its volcanic death during the Aucanquilcha Stage. This study focuses …


Thermomechanical Evolution Of A Magmatic System During A Caldera Cycle: Okataina Volcanic Center, New Zealand, Jacob Bonessi Jan 2022

Thermomechanical Evolution Of A Magmatic System During A Caldera Cycle: Okataina Volcanic Center, New Zealand, Jacob Bonessi

Dissertations, Master's Theses and Master's Reports

Caldera forming eruptions represent some of the largest simultaneous releases of mass and energy on the planet and pose a looming risk on a global scale. The study of the underlying magmatic systems is integral in understanding what leads to these large eruptions. This approach pairs a suite of major and trace element profiles from plagioclase with a grain texture classification and statistical analysis using Polytopic Vector Analysis (PVA) as proxies to explore potential changes in the thermomechanical state of the magmatic system at Okataina Volcanic Complex (OVC), New Zealand through its most recent caldera cycle. Results indicate systematic changes …


Chemical And Thermal Influence On Intermediate Magma Storage Conditions: Volcán Ollagüe, Chile-Bolivia, Central Andes, Drew Allen Laviada-Garmon Jan 2022

Chemical And Thermal Influence On Intermediate Magma Storage Conditions: Volcán Ollagüe, Chile-Bolivia, Central Andes, Drew Allen Laviada-Garmon

MSU Graduate Theses

Continental arc volcanoes are the single best portrayal of the evolution of recycled earth material stemming from subduction, one of the most important and foundational phenomena in global tectonics. Understanding the genesis of intermediate-composition magmas produced at arc volcanoes is a difficult process making them a focal point for investigation. Geochemical investigation of zircon and plagioclase mineral phases erupted from continental arcs can provide insight into magma process, generation, storage conditions, timescales and differentiation of sub-volcanic plumbing systems prior to eruption events. The Central Volcanic Zone is a prime example of continental arc volcanism through subduction, and is host to …


Disequilibrium Melting Of The Continental Crust During Emplacement Of The Mt. Princeton Batholith, Central Colorado Volcanic Field, Loren A. Bohannon Jan 2022

Disequilibrium Melting Of The Continental Crust During Emplacement Of The Mt. Princeton Batholith, Central Colorado Volcanic Field, Loren A. Bohannon

MSU Graduate Theses

Assimilation and crystallization are difficult to constrain at magmatic boundaries, including the interactions of magma with the surrounding country rock. The assumption of the relationship between a magma and what it is intruding upon is relegated to homogenous bodies or epizonal plutons. Realistically, wall rock influences chemical heterogeneity and isotopic variance at the outcrop scale and changes depending on distance from the magma-wall rock interface. Here, we present a case study of the 35 Ma Mt. Princeton Batholith and the host Precambrian rocks of the Central Colorado Volcanic Field. We assess chemical heterogeneity by whole rock and mineral trace element …


Environmental And Societal Impacts In New England Following A Potential Yellowstone Eruption, Serena L. Butler Jan 2022

Environmental And Societal Impacts In New England Following A Potential Yellowstone Eruption, Serena L. Butler

Honors Theses and Capstones

Yellowstone National Park is famously known for its history of “super-volcano” eruptions. From the evidence of volcanic deposits, scientists know that the ash cloud that erupted from Yellowstone covered most of the western U.S. states, but until recently, models have not shown the ash could also have reached eastern states. The scope of this investigation is to determine what would happen to New England if Yellowstone were to erupt today in terms of health, agriculture, transportation, relocation, economy, and climate. In order to do so, three significant eruptions during human history are considered as case studies in order to compare …


A Global Survey Of Volcanic So2 Emissions And Heat Flux Measured From Space, Nelmary Rodríguez-Sepúlveda Jan 2022

A Global Survey Of Volcanic So2 Emissions And Heat Flux Measured From Space, Nelmary Rodríguez-Sepúlveda

Dissertations, Master's Theses and Master's Reports

Over the past two decades, the availability of satellite measurements of volcanic gas emissions and heat flux has driven the development of new methodologies to improve global-scale volcano monitoring. In this work we explored the relationship between volcanic sulfur dioxide (SO2) emissions and radiant heat flux (RHF) measurements from NASA’s Ozone Monitoring Instrument (OMI) and Moderate Resolution Imaging Spectroradiometer (MODIS), respectively, to gain insight into how it associates to volcanic processes and eruption styles. The OMI SO2 emissions data are derived from existing databases developed by using the methodology in Fioletov et al. (2016), which contain global, …


Geochemical Investigation Of Monogenetic Volcanoes From The Pribilof Islands, Bering Sea, Alaska, Clayton L. Reinier Dec 2021

Geochemical Investigation Of Monogenetic Volcanoes From The Pribilof Islands, Bering Sea, Alaska, Clayton L. Reinier

MSU Graduate Theses

Small-volume basaltic magmas found at continental intraplate environments have not been as extensively studied compared to their polygenetic counterparts. Specifically, regions such as the Bering Sea basalt province, described as a diffuse igneous province, have commonly been overlooked. Assumptions that these systems are invoked by simple, single batches of magma has subsequently left a gap in understanding the processes responsible for primary magma generation away from plate boundaries with little tectonic influence. The following studies that constitute this thesis focus on an in-depth geochemical investigation at the crystal and sub-crystal scale to evaluate lithospheric mantle heterogeneities, processes that govern primary …


Using Sedimentary Mercury Geochemistry To Evaluate The Niagara-Salina Transition, Silurian Michigan Basin, Usa, Sara Hayes Dec 2021

Using Sedimentary Mercury Geochemistry To Evaluate The Niagara-Salina Transition, Silurian Michigan Basin, Usa, Sara Hayes

Masters Theses

The Niagara-Salina boundary in the Michigan Basin is marked by an abrupt transition from carbonates to evaporites. Though the cause is uncertain, previous work suggests the onset of Salina evaporites was driven by basin restriction, but the presence of several global carbon isotope excursions (CIE) suggest a global driver. This study builds on this discussion using two relatively new geochemical proxies - elemental mercury concentrations [Hg] and Hg isotopes.

Mercury concentrations [Hg] were measured in 88 samples from the State Kalkaska #2-15 core from 6604.03 ft to 6797.42 ft. [Hg] ranges from 0.11 to 0.62 mg/kg and [Hg]/TOC from 0.038 …


Tracking Secondary Lahar Flow Paths And Characterizing Pulses And Surges Using Infrasound Array Networks At Volcán De Fuego, Guatemala, Ashley R. Bosa, Jeffrey B. Johnson, Silvio De Angelis, John J. Lyons, Amilcar Roca, Jacob F. Anderson, Amando Pineda Oct 2021

Tracking Secondary Lahar Flow Paths And Characterizing Pulses And Surges Using Infrasound Array Networks At Volcán De Fuego, Guatemala, Ashley R. Bosa, Jeffrey B. Johnson, Silvio De Angelis, John J. Lyons, Amilcar Roca, Jacob F. Anderson, Amando Pineda

Geosciences Faculty Publications and Presentations

Lahars are one of the greatest hazards at many volcanoes, including Volcán de Fuego (Guatemala). On 1 December 2018 at 8:00 pm local Guatemala time (~2:06:00 UTC), an hour-long lahar event was detected at Volcán de Fuego by two permanent seismo-acoustic stations along the Las Lajas drainage on the southeast side. To establish the timing, duration, and speed of the lahar, infrasound array records were examined to identify both the source direction(s) and the correlated energy fluctuations at the two stations. Co-located seismic and acoustic signals were also examined, which indicated at least five distinct energy pulses within the lahar …


Timescales Of Magma Transport In The Columbia River Flood Basalts, Determined By Paleomagnetic Data, Joseph Biasi, Leif Karlstrom Oct 2021

Timescales Of Magma Transport In The Columbia River Flood Basalts, Determined By Paleomagnetic Data, Joseph Biasi, Leif Karlstrom

Other Staff Materials

Flood basalts represent major events in Earth History, in part because they are linked to large climate perturbations and mass extinctions. However, the durations of individual flood basalt eruptions, which directly impact potential environmental crises, are poorly constrained. Here we use a combination of paleomagnetic data and thermal modeling to create a magnetic geothermometer (MGT) that can constrain the active transport lifetime of magmatic conduits and intrusions. We apply the MGT technique to eight feeder dike segments of the Columbia River basalts (CRB), demonstrating that some dike segments were actively heating host rocks for less than one month, while other …


Rhyolite Stratigraphy Along Succor Creek: Insights Into The Eruptive History Of The Three Fingers And Mahogany Mountain Volcanic Field, Cassandra Caryl Black Aug 2021

Rhyolite Stratigraphy Along Succor Creek: Insights Into The Eruptive History Of The Three Fingers And Mahogany Mountain Volcanic Field, Cassandra Caryl Black

Dissertations and Theses

The Mahogany Mountain and Three Fingers calderas with their associated tuffs, the tuff of Leslie Gulch and tuff of Spring Creek, respectively, were the centerpiece of a larger rhyolite center that developed in response to Columbia River Basalt volcanism as numerous other mid Miocene rhyolite centers in a corridor from Baker City in the north to northern Nevada. Previous studies suggest a two caldera model, while others advocated for a single large caldera producing solely the tuff of Leslie Gulch. This study refines the eruptive stratigraphy along the northeastern margin of this rhyolite field with important implications for the entire …


The Physical Properties Of Volcanic And Impact Melt, Gavin Douglas Tolometti Aug 2021

The Physical Properties Of Volcanic And Impact Melt, Gavin Douglas Tolometti

Electronic Thesis and Dissertation Repository

The emplacement mechanisms of lunar impact melt flows, that form from hypervelocity impact events, have been a subject of debate in the lunar science community, because of their unique physical properties that separate them from other geologic features. Understanding how lunar impact melt flows were emplaced on the surface of the Moon will not only grant us new information about the flow dynamics of impact melt but provide insight into the production and distribution of impact melt and how it built and modified the surfaces of planetary surfaces.

Lunar impact melt flows exhibit surface roughness textures and morphologies that are …


Experimental Alteration Of Venusian Surface Basalts In A Hybrid Co2-So2 Atmosphere, Robert B. Reid Aug 2021

Experimental Alteration Of Venusian Surface Basalts In A Hybrid Co2-So2 Atmosphere, Robert B. Reid

Masters Theses

Venus’ surface and interior dynamics remain largely unconstrained, due in great part to the major obstacles imposed by its 470°C, 90 bars surface conditions and its thick, opaque atmosphere. Orbiter-based thermal emission data provide an opportunity to characterize the Venus surface. However, interpretations of such spectra critically depend on understanding interactions between the planet’s surface basaltic rocks and its caustic, SO2-bearing CO2 atmosphere. Several studies, using remote sensing, thermodynamic modeling, and laboratory experiments have placed constraints on alteration mineralogies and rates. Yet constraint with respect to SO2-mediated reactions with basalts of contrasting compositions remains incomplete. …


Simplified Volcano Hazard Maps: Two Groups User-Experience (Ux) Study Results, Rachel Volentine Jul 2021

Simplified Volcano Hazard Maps: Two Groups User-Experience (Ux) Study Results, Rachel Volentine

User eXperience Lab

The purpose of this research is to identify any usability issues and opportunities to improve the design for superb communication of volcanic hazards and risks. From this research, insights into the intuitiveness and risk-communication deficiencies of these hazard maps will help create a new methodology for evaluation map-based communication products implemented by USGS and its partners/stakeholders, Risk COP members, and practitioners around the world to alleviate volcanic risk and hazards.


Simplified Volcano Hazard Maps User-Experience (Ux) Study Results, Rachel Volentine Jun 2021

Simplified Volcano Hazard Maps User-Experience (Ux) Study Results, Rachel Volentine

User eXperience Lab

The purpose of this research is to identify any usability issues and opportunities to improve the design for superb communication of volcanic hazards and risks. From this research, insights into the intuitiveness and risk-communication deficiencies of these hazard maps will help create a new methodology for evaluation map-based communication products implemented by USGS and its partners/stakeholders, Risk COP members, and practitioners around the world to alleviate volcanic risk and hazards.


Using Gis To Create Hazard Maps And Assess Evacuation Routes Around “The Gate To Hell”; Masaya Volcano, Nicaragua, Rebecca Hedges, Stevie Mcdermaid, Jason Kaiser, David Maxwell, Kathy Matthews May 2021

Using Gis To Create Hazard Maps And Assess Evacuation Routes Around “The Gate To Hell”; Masaya Volcano, Nicaragua, Rebecca Hedges, Stevie Mcdermaid, Jason Kaiser, David Maxwell, Kathy Matthews

The Compass: Earth Science Journal of Sigma Gamma Epsilon

Volcán Masaya in Nicaragua is made of a series of calderas and craters that lies 7 km from the city of Masaya with a population of over 100,000. Masaya is part of the Central American Volcanic Arc (CAVA) which contains hundreds of volcanoes. While many of the volcanoes of the arc produce small, quiescent eruptions, some are capable of large explosive events. The recent cycle of volcanism at Masaya began 7000 years ago. Initial eruptions were primarily lava, small ash flows, ashfalls, and degassing events which eventually gave way to climactic Vulcanian eruptions. The hazards presented from this system affect …


Serial Interaction Of Primitive Magmas With Felsic And Mafic Crust Recorded By Gabbroic Dikes From The Antarctic Extension Of The Karoo Large Igneous Province, Jussi S. Heinonen, Arto V. Luttinen, Frank J. Spera, Saku K. Vuori, Wendy A. Bohrson Mar 2021

Serial Interaction Of Primitive Magmas With Felsic And Mafic Crust Recorded By Gabbroic Dikes From The Antarctic Extension Of The Karoo Large Igneous Province, Jussi S. Heinonen, Arto V. Luttinen, Frank J. Spera, Saku K. Vuori, Wendy A. Bohrson

Geological Sciences Faculty Scholarship

Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 m (West-Muren) crosscut continental flood basalts in the Antarctic extension of the ~ 180 Ma Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. The dikes exhibit unusual geochemical profiles; most significantly, initial (at 180 Ma) εNd values increase from the dike interiors towards the hornfelsed wallrock basalts (from − 15.3 to − 7.8 in East-Muren and more gradually from − 9.0 to − 5.5 in West-Muren). In this study, we utilize models of partial melting and energy-constrained assimilation‒fractional crystallization in deciphering the …


Quantifying Shape Of Star-Like Objects Using Shape Curves And A New Compactness Measure, Gopal K. Mulukutla, Emese Hadnagy, Matthew Fearon, Edward Garboczi Jan 2021

Quantifying Shape Of Star-Like Objects Using Shape Curves And A New Compactness Measure, Gopal K. Mulukutla, Emese Hadnagy, Matthew Fearon, Edward Garboczi

Earth Systems Research Center

Shape is an important indicator of the physical and chemical behavior of natural and engineered particulate materials (e.g., sediment, sand, rock, volcanic ash). It directly or indirectly affects numerous microscopic and macroscopic geologic, environmental and engineering processes. Due to the complex, highly irregular shapes found in particulate materials, there is a perennial need for quantitative shape descriptions. We developed a new characterization method (shape curve analysis) and a new quantitative measure (compactness, not the topological mathematical definition) by applying a fundamental principle that the geometric anisotropy of an object is a unique signature of its internal spatial distribution …


Characterizing The Geomagnetic Field At High Southern Latitudes: Evidence From The Antarctic Peninsula, Joseph Biasi, Joseph Kirschvink, Roger Fu Jan 2021

Characterizing The Geomagnetic Field At High Southern Latitudes: Evidence From The Antarctic Peninsula, Joseph Biasi, Joseph Kirschvink, Roger Fu

Other Staff Materials

Due to a dearth of data from high-latitude paleomagnetic sites, it is not currently clear if the geocentric axial dipole (GAD) hypothesis accurately describes the long-term behavior of the geomagnetic field at high latitudes. Here we present new paleomagnetic and paleointensity data from the James Ross Island (JRI) volcanic group, located on the Antarctic Peninsula. This data set addresses a notable lack of data from the 60°–70°S latitude bin and includes 251 samples from 31 sites, spanning 0.99–6.8 Ma in age. We also include positive fold, conglomerate, and baked contact tests. Paleointensity data from three methods (Thellier- Thellier, pseudo-Thellier, and …


Independent, Semi-Automated Classification Of Petrographic Features In Volcanic Rocks Using Fiji And Weka, Holly Danielle Pettus Jan 2021

Independent, Semi-Automated Classification Of Petrographic Features In Volcanic Rocks Using Fiji And Weka, Holly Danielle Pettus

Graduate Theses, Dissertations, and Problem Reports

Traditional methods of collecting quantitative petrographic data from thin sections (modal mineralogy, size distribution, shapes, etc.) are time- and labor-intensive, and rarely have sample sizes adequate to statistically describe complex rocks (i.e. volcanic rocks). Although manual counting and measurements are now routinely supplemented by digital image analysis, the majority of quantitative petrographic studies still go through a manual digitization stage where object classes are traced before further analyses. This is a major rate-limiting step that reproduces the same problems of small n-values resulting from significant effort. We have valuated the potential and limitations of using the Trainable Weka Segmentation (TWS) …