Volcanology Commons^™

Petrogenetic Processes Characterizing The Mount Bachelor, Oregon Magmatic System: Open- Versus Closed-System Processes, Sara Elizabeth Johnson

All Master's Theses

Mount Bachelor volcanic chain (MBVC), located in central Oregon, is one of the larger basalt and basaltic-andesite edifices in central Oregon. Preliminary studies have defined how eruptions have changed composition with time, but a detailed assessment of magma chamber processes has not been conducted. To gain a more thorough understanding of the magmatic processes that have contributed to the observed compositional evolution, this study focuses on one of four eruptive episodes, specifically episode III, the most voluminous episode of the four. Magmatic processes are assessed by focusing on both whole-rock and single crystal data.

The geochemistry and textural diversity of …

Plagioclase Populations And Zoning In Dacite Of The 2004–2005 Mount St. Helens Eruption: Constraints For Magma Origin And Dynamics, Martin J. Streck, Cindy A. Broderick, Carl R. Thornber, Michael A. Clynne, John S. Pallister

Geology Faculty Publications and Presentations

We investigated plagioclase phenocrysts in dacite of the 2004–5 eruption of Mount St. Helens to gain insights into the magmatic processes of the current eruption, which is char­acterized by prolonged, nearly solid-state extrusion, low gas emission, and shallow seismicity. In addition, we investigated plagioclase of 1980–86 dacite.

Light and Nomarski microscopy were used to texturally characterize plagioclase crystals. Electron microprobe analy­ses measured their compositions. We systematically mapped and categorized all plagioclase phenocrysts in a preselected area according to the following criteria: (1) occurrence of zones of acicular orthopyroxene inclusions, (2) presence of dissolution surface(s), and (3) spatial association of 1 …

Energy-Constrained Recharge, Assimilation, And Fractional Crystallization (Ec-Raxfc): A Visual Basic Computer Code For Calculating Trace Element And Isotope Variations Of Opensystem Magmatic Systems, Wendy A. Bohrson, Frank J. Spera

All Faculty Scholarship for the College of the Sciences

Volcanic and plutonic rocks provide abundant evidence for complex processes that occur in magma storage and transport systems. The fingerprint of these processes, which include fractional crystallization, assimilation, and magma recharge, is captured in petrologic and geochemical characteristics of suites of cogenetic rocks. Quantitatively evaluating the relative contributions of each process requires integration of mass, species, and energy constraints, applied in a self-consistent way. The energy-constrained model Energy-Constrained Recharge, Assimilation, and Fractional Crystallization (EC-RaxFC) tracks the trace element and isotopic evolution of a magmatic system (melt + solids) undergoing simultaneous fractional crystallization, recharge, and assimilation. Mass, thermal, and compositional (trace …

Unlv Magazine, Cate Weeks, Erin O'Donnell, Shane Bevell, Barbara Cloud, Joy Drohan, Adam Baer, Holly Ivy De Vore, Gian Galassi, Eric Leake

UNLV Magazine

No abstract provided.

Microbial Observatories: Kilauea Volcano Observatory For Carbon Monoxide-Oxidizing Bacteria, Gary M. King

University of Maine Office of Research Administration: Grant Reports

Volcanic activity regularly creates new landforms from deposits of tephra, ash and lava. These initially sterile, pristine deposits undergo a range of physical, chemical and biological transformations that lead in some cases to diverse, complex ecosystems such as Hawaiian rainforests. Recent activity by the Kilauea volcano has created unique opportunities to understand the timing and controls of complex ecosystem development, and to analyze the roles of microbes as pioneering colonists that contribute to plant development and succession. The newly established Kilauea Volcano Microbial Observatory will compare the diversity and activity of carbon monoxide-oxidizing bacteria colonizing two different deposits currently 45 …

Risk Perception, Warning Systems And Evacuation Plans For Volcanic Hazards, Matt Davis, David Johnston, Julia Becker

Collected Faculty and Staff Scholarship

No abstract provided.

1991: Pinatubo Eruption, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

Date: June 12-16, 1991

Place: Luzon, Philippines

Result: About 350 dead (mostly from collapsed roofs); extensive damage to homes, bridges, irrigation-canal dikes, and cropland; 20 million tons of sulfur dioxide spewed into the stratosphere up to an elevation of 15.5 miles

Prior to the 1991 eruption, Pinatubo had the appearance of a steep, domelike spheroid that rose about 2,297 feet (700 meters) above a gently sloping apron made of pyroclastic and epiclastic materials. Such a volcano belongs to the class of stratocones, of which such 803 well-known exemplars as Fuji and Mayon are considerably larger than Pinatubo. The extensive pyroclastic …

In The Heat Of The Law, It's Not Just Steam: Geothermal Resources And The Impact On Thermophile Biodiversity, Donald J. Kochan, Tiffany Grant

Donald J. Kochan

Significant research has been conducted into the utilization of geothermal resources as a ‘green’ energy source. However, minimal research has been conducted into geothermal resource utilization and depletion impacts on thermophile biodiversity. Thermophiles are organisms which have adapted over millions of year to extreme temperature and chemical compositions and exist in hot springs and other geothermal resources. Their ability to withstand high temperatures makes them invaluable to scientific and medical research. Current federal and California case law classify geothermal resources as a mineral, not a water resource. Acquisition of rights to develop a geothermal resource owned or reserved by the …

Marine Investigations Of Greece's Santorini Volcanic Field, Haraldur Sigurdsson, Steven Carey, Matina Alexandri, Georges Vougioukalakis, Katherine Croff, Chris Roman, Dimitris Sakellariou, Christos Anagnostou, Grigoris Rousakis, Chrysanti Ioakim, Aleka Goguo, Dionysis Ballas, Thanassis Misaridis, Paraskevi Nomikou

Graduate School of Oceanography Faculty Publications

The most recent major explosive eruption of the Santorini volcano in Greece—around 3600 years before present (B.P.), often referred to as the Minoan eruption—is one of the largest volcanic events known in historical time and has been the subject of intense volcanological and archeological studies [Druitt et al., 1999]. The submarine volcano Kolumbo, located seven kilometers northeast of Santorini and associated with Santorini's tectonic system, erupted explosively in 1650 A.D., resulting in fatalities on the island of Thera [Fouqué, 1879]. A large fraction of the erupted products from the Minoan eruption has been deposited in the …

Unlv Magazine, Carol C. Harter, Karen Sharp, Gian Galassi, Tony Allen, Jennifer Lawson, Shane Bevell, Lori Bachand, Regina Vaccari, Pete Codella, Cate Weeks, Erin O'Donnell, Diane Russell, Phil Hagen

UNLV Magazine

No abstract provided.

Petrogenesis Of Pleistocene Basalts In The Norris-Mammoth Corridor, Yellowstone National Park, Kristeen Marie Bennett

UNLV Theses, Dissertations, Professional Papers, and Capstones

The basalts of the Norris-Mammoth corridor within the Yellowstone Plateau volcanic field have an outcrop erupted volume of ~94 km³. Basalt in the Yellowstone Plateau volcanic field is minor in volume compared to 3,700 km³ of felsic lavas, domes, and pyroclastic rocks. The tholeiitic eruptive products formed small Hawaiian-style shield volcanoes. A newly identified volcanic vent, called the Panther Creek vent, within the Swan Lake Flat basalt stratigraphic unit, was primarily Strombolian in its eruption style. This vent is the first recognized cinder cone in Yellowstone National Park.

All basaltic units within the Norris-Mammoth corridor, and the …

Fluvial Response To Intra-Canyon Lava Flows, Owyhee River, Southeastern Oregon, Cooper Cooke Brossy

All Master's Theses

At least six lava flows have entered the Owyhee River Canyon north of Rome, Oregon, since the Pliocene and directly impacted the Owyhee River. The effects on the river of the two youngest lava flows, the West Crater (60–80 ka) and Saddle Butte (> 60–90 ka), are readily apparent. These two lava flows entered a paleo-Owyhee Canyon several kilometers wide via three different tributary drainages. The flows dammed the Owyhee River, created lakes, and effectively confined the river to the opposite side of the valley from the flows’ entrance. Lava from these flows filled a paleo-Owyhee Canyon to depths of …

Deciphering The Signature Of Magma Mixing: Examples From The Castle Creek Eruptive Period, Mount St. Helens, Washington, Seth Taylor Mattos

All Master's Theses

Mount St. Helens (MSH) volcano in southwestern Washington has intermittently erupted dacitic products for the last 40,000 years. On limited occasions, the volcano has produced andesite lava flows, and during one short-lived period, basaltic lava flows. This time interval has been termed the Castle Creek eruptive period and occurred between approximately 2500 and 1700 years B.P. The Castle Creek period erupted dacite, andesite and basalt within this short span of time. Andesite and dacite eruptions dominate the first approximately 700 years of the period, and all basaltic units were erupted in approximately the last 100 years of the period. This …

Earthquake Triggering At Alaskan Volcanoes Following The 3 November 2002 Denali Fault Earthquake, Seth C. Moran, John A. Power, Scott D. Stihler, John J. Sa´Nchez, Jacqueline Caplan-Auerbach

Geology Faculty Publications

The 3 November 2002 M_W 7.9 Denali fault earthquake provided an excellent opportunity to investigate triggered earthquakes at Alaskan volcanoes. The Alaska Volcano Observatory operates short-period seismic networks on 24 historically active volcanoes in Alaska, 247–2159 km distant from the mainshock epicenter. We searched for evidence of triggered seismicity by examining the unfiltered waveforms for all stations in each volcano network for ~1 hr after the M_W 7.9 arrival time at each network and for significant increases in located earthquakes in the hours after the mainshock. We found compelling evidence for triggering only at the Katmai volcanic cluster …

Long-Term Mechanical Behavior Of Yucca Mountain Tuffs, And Its Variability, Jaak J.K. Daemen, George Danko, Jaime Gonzalez, Amy J. Smiecinski, Raymond E. Keeler

Publications (YM)

We propose to continue the investigation of the long term strength of Yucca Mountain tuffs, with particular emphasis on tuffs from and near the emplacement horizon. We propose to also continue and expand the investigation of the spatial variability of rock strength and stiffness. An intrinsic component of this planned rock testing is the testing of rock joints. Although the emphasis is on tests aimed at determining long term strength, as part of the testing measurements of stiffness also are collected, and will be collected, reported, and analyzed.

Influence Of Lithophysae Geometry And Distribution On Mechanical Properties Of Topopah Spring Tuff, Mohammad Shahidul Islam, Justin Fenton, Moses Karakouzian, Jaime Gonzalez, Amy J. Smiecinski, Raymond E. Keeler

Publications (YM)

The current Site Recommendation study for the proposed high level nuclear waste repository at Yucca Mountain locates the repository emplacement drifts approximately 81% within the lower lithophysal unit of the Topopah Springs Formation (Tptpll), 4% within the upper lithophysal unit of the Topopah Springs Formation (Tptpul), and roughly 15% within the middle, non-lithophysal unit (Tptpmn) of the same formation. A major geomechanical issue facing the Yucca Mountain Project is to understand the thermomechanical behavior of lithophysal tuff, which comprises roughly 85% of the repository host rock.

Magmatic To Solid-State Fabric Transition In A Post-Tectonic Tonalite Pluton, Scott E. Johnson

University of Maine Office of Research Administration: Grant Reports

Magma chambers are an essential component in the construction of oceanic and continental lithosphere, and profoundly influence the thermal and mechanical behavior of the crust and mantle. The mechanical properties of a magma chamber change during cooling and crystallization, as accommodation of deformation changes from magmatic flow to solid-state processes. Thus, to understand the thermo-mechanical evolution of magma chambers, it is crucial to understand the relative importance of magmatic and solid-state flow, and the nature of the transition between them. This project is investigating such a transition preserved in the San Jose pluton, Baja California, Mexico. The pluton postdates the …

Compositional And Mineralogical Relationships Between Mafic Inclusions And Host Lavas As Key To Andesite Petrogenesis At Mount Hood Volcano, Oregon, Melinda Michelle Woods

Dissertations and Theses

Throughout its eruptive history, Mount Hood has produced compositionally similar calc-alkaline andesite as lava flows and domes near the summit and basaltic andesitic flows from flank vents. Found within the andesite are slightly more mafic inclusions that are compositionally similar to the host andesite (or host lavas); no inclusions were found in the flank lavas. Host lavas and inclusions have the following mineral assemblage: plag + opx ± cpx ± amp + oxides. Flank lava mineralogy is similar to the inclusions and host lavas, but since they are more mafic they contain olivine instead of amphibole. Average silica content among …

Current Perspectives On Energy And Mass Fluxes In Volcanic Arcs, William Leeman, Jon Davidson, Tobias Fischer, Anita Grunder, Mark Reagan, Martin J. Streck

Geology Faculty Publications and Presentations

Volcanoes of the Pacific Ring of Fire and other convergent margins worldwide are familiar manifestations of nature's energy, account for about 25% of global volcanic outputs, dominate volcanic gas emissions to the atmosphere, and pose significant physical threats to a large human population. Yet the processes behind this prolific activity remain poorly understood.

An international "State of the Arc" (SOTA) conference was held in August on the slopes of Mt. Hood, Oregon, to address current views on the energy and mass fluxes in volcanic arcs. This meeting brought together some 90 leading experts and students of subduction zones and their …

Collaborative Research: Volcanic Records From The Siple And Taylor Dome Ice Cores, Antarctica, George A. Zielinski

University of Maine Office of Research Administration: Grant Reports

The primary goals of this project were to, 1) evaluate the volcanic acidity record in the Siple Dome A (SDMA) and B (SDMB) ice cores and the Taylor Dome ice core available through the sulfate time series developed by the glaciochemistry group at the University of Maine, 2) undertake a continuous scan of the SDMA core and scan specific sections in the SDMB core to locate and analyze volcanic glass to determine glass composition, and thus source eruptions for the glass and potentially for volcanic sulfate found in the same layer, and 3) evaluate specific sections containing volcanic glass in …

Ashfall Historic Park: Field Trip 5, Robert F. Diffendal Jr.

Robert F. Diffendal, Jr., Publications

Ashfall Fossill Beds: A State Historical Park. Brochure. Nebraska Game and Parks Commission and University of Nebraska State Museum

Research Reports, 1978. Projects: A Miocene Rhinoceros Herd Buried in Volcanic Ash. Grant Recipient: Michael R. Voorhies, Division of Vertebrate Paleontology, University of Nebraska State Museum, Lincoln, Nebraska.

Geologic Framework of the Niobrara River Drainage Basin and Adjacent Areas in South Dakota Generally East of the 100th Meridian West Longitude and West of the Missouri River Robert F. Diffendal, Jr. and Michael R. Voorhies. Nebraska Geological Survey Report of Investigations, number 9.

The Influence Of Lithophysal Porosity On The In-Situ Stress-Strain Properties Of Topopah Spring Tuff, Bahri B. Avar, Moses Karakouzian, Amy J. Smiecinski

Publications (YM)

Numerical analysis and a laboratory testing program were conducted in order to investigate the effect of lithophysal porosity on the elastic stress-strain properties of the lithophysae-rich tuff specimens and to find the locations of cavities in both analog and tuff specimens. In the first part of the study, a finite difference mesh containing circular holes was modeled for varying porosity ranges between 5 and 40% using commercially available software FLAG20' version 3.5. Elastic (Young's) modulus and Poisson's ratio were calculated for each setup and normalized with respect to matrix elastic modulus and Poisson's ratio. The moduli calculated through numerical analysis …

Energy‐Constrained Open‐System Magmatic Processes Iv: Geochemical, Thermal And Mass Consequences Of Energy‐Constrained Recharge, Assimilation And Fractional Crystallization (Ec‐Rafc), Wendy A. Bohrson, Frank J. Spera

All Faculty Scholarship for the College of the Sciences

A wealth of geochemical and petrological data provide evidence that the processes of fractional crystallization, assimilation, and magma recharge (replenishment) dominate the chemical signatures of many terrestrial igneous rocks. Previous work [Spera and Bohrson, 2001; Bohrson and Spera, 2001] has established the importance of integrating energy, species and mass conservation into simulations of complex magma chamber processes. An extended version of the energy‐constrained formulation, Energy‐Constrained Recharge, Assimilation, Fractional Crystallization (EC‐RAFC), tracks mass and compositional variations of melt, cumulates, and enclaves in a magma body undergoing simultaneous recharge, assimilation, and fractional crystallization [Spera and Bohrson, 2002]. …

Extensional Folds Associated With Paleogene Detachment Faults In Se Part Of The Salmon Basin, Susanne U. Janecke, J. C. Blankenau

Susanne U. Janecke

No abstract provided.

Energy‐Constrained Open‐System Magmatic Processes 3. Energy‐Constrained Recharge, Assimilation, And Fractional Crystallization (Ec‐Rafc), Frank J. Spera, Wendy A. Bohrson

All Faculty Scholarship for the College of the Sciences

Geochemical data for igneous rock suites provide conclusive evidence for the occurrence of open‐system processes within thermally and compositionally evolving magma bodies. The most significant processes include magma Recharge (with possible enclave formation and magma mixing), Assimilation of anatectic melt derived from wallrock partial melting and formation of cumulates by Fractional Crystallization (RAFC). In this study, we extend the Energetically Constrained Assimilation and Fractional Crystallization (EC‐AFC) model [Spera and Bohrson, 2001; Bohrson and Spera, 2001] to include the addition of compositionally and thermally distinct recharge melt during simultaneous assimilation and fractional crystallization. Energy‐Constrained Recharge, Assimilation, and Fractional …

Hugo:The Hawaii Undersea Geo-Observatory, Fred K. Duennebier, David Harris, James Jolly, Jacqueline Caplan-Auerbach, Robert Jordan, Kurt Stiffel, Jeff Bosel

Geology Faculty Publications

The Hawaii Undersea Geo-Observatory, HUGO, was installed with the intent of supplying infrastructure for researchers interested in studies of undersea volcanism and associated phenomena at Loihi, the newest volcano of the Hawaiian chain. Much like an astronomical observatory, HUGO is a facility where scientists can perform experiments while sharing resources with others. The main components of HUGO are the shore station, supplying power to the observatory and recording data; the main cable-an electro-optical cable connecting the shore station to the summit of Loihi; the Junction box-the power distribution and data collection center on Loihi; multiplexing (mux) nodes-secondary distribution points; and …

Ascent And Decompression Of Viscous Vesicular Magma In A Volcanic Conduit, Helene Massol, Claude Jaupart, Darrell Pepper

Mechanical Engineering Faculty Research

During eruption, lava domes and flows may become unstable and generate dangerous explosions. Fossil lava-filled eruption conduits and ancient lava flows are often characterized by complex internal variations of gas content. These observations indicate a need for accurate predictions of the distribution of gas content and bubble pressure in an eruption conduit. Bubbly magma behaves as a compressible viscous liquid involving three different pressures: those of the gas and magma phases, and that of the exterior. To solve for these three different pressures, one must account for expansion in all directions and hence for both horizontal and vertical velocity components. …

Lava And Ice Interaction At Stratovolcanoes: Use Of Characteristic Features To Determine Past Glacial Extents And Future Volcanic Hazards, David T. Lescinsky, Jonathan H. Fink

Geology Faculty Publications and Presentations

Structures resulting from lava and ice interaction are common at glaciated stratovolcanoes. During summit eruptions at stratovolcanoes, meltwater is produced and travels freely down steep slopes and thin permeable valley glaciers, eroding the ice and enlarging preexisting glacial drainages. As a result, in this environment have produced few catastrophic floods. Lava flowing into the open channels and voids in the glaciers becomes confined and grows thicker, filling the available space and producing steep-sided bodies with smooth, bulbous contact surfaces. Quenching of lava against ice or by water forms small-scale features such as tensional fractures and glass. As the amount of …

Origin Of Intraplate Volcanoes From Guyot Heights And Oceanic Paleodepth, Jacqueline Caplan-Auerbach, Fred Duennebier, Garrett Ito

Geology Faculty Publications

The height of a guyot as measured from the surrounding regional sea floor to the volcano's slope break records the water depth at the time the guyot submerged. Thus guyot heights may be used as indicators of the paleodepth of the surrounding ocean floor. We compile data on the heights of 68 intraplate guyots and atolls in the Pacific Ocean as well as 46 volcanic islands in the Pacific, Atlantic, and Indian Oceans. We find that guyot heights generally increase with the age of the lithosphere upon which they were emplaced, although there is a large amount of scatter. In …

Geochemistry And Petrogenesis Of The Bonanza King Mafic Intrusive Complex, Trinity Terrane Ophiolite, California, Keith R. Willse

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Bonanza King mafic intrusive complex (MIC) (>25 km^2₎ of the Trinity terrane ophiolite, northern California, consists of cogenetic plutonic and dike lithologies. Steep intrusive contacts exist between cumulate pyroxenite, isotropic gabbro, and peridotite country rock. Near vertical east-west trending, bimodal dikes intruded gabbro and are centered within the complex. Geochemical modeling indicates taht accumulation/fractionation of a gabbroic parental magma produced lithologic trends of cumulate pyroxenite and fractionated gabbro and dike lithologies. Similarities between all lithologies suggest cogenetic formation of all the elements of the Bonanza King MIC during the Late Silurian (431 +/- 3).

Parental magma …