Physical Sciences and Mathematics Commons^™

Documenting The Origin Of Compositional Diversity Of Subduction Zone Magmatism, Alicudi, Aeolian Arc (Southern Tyrrhenian Sea, Italy) Using In Situ Plagioclase Data, Rachel Hunt

All Master's Theses

Processes that generate magma compositional diversity are important to document because composition affects degree of explosivity, which impacts hazard mitigation. Magnesium to silicon rich magmas are produced by processes such as magma recharge, assimilation, and fractional crystallization (RAFC) that occur in subvolcanic magma chamber(s). This study evaluates how magma chamber processes contribute to compositional diversity at Alicudi Volcano, Italy. Analytical and petrographic data from ten samples that span the subaerial history include whole rock major and trace elements and strontium/neodymium isotopes, and plagioclase textural types, major and trace elements, and strontium isotopes; numerical modeling was also conducted. Integration of these …

Documenting Magma Evolution Of The Fossa Delle Felci (Salina Island, South Tyrrhenian Sea) By Integrating In Situ Plagioclase Data With Quantitative Modeling, Aaron Mayfield

All Master's Theses

Compositional diversity occurs via processes dominated by recharge, assimilation and fractional crystallization (RAFC), quantification of which can provide insights into eruption catalysts, and therefore assist in hazard mitigation. This study evaluates the relative roles of RAFC processes in Fossa delle Felci (Salina Island, Italy) magmas, which span the basalt to dacite range (52-65 wt% SiO2). Integration of petrographic, whole rock, and in situ plagioclase data with quantitative magma chamber models suggests differentiation dominated by fractional crystallization and magma recharge/mixing in reservoirs located at different crustal levels. At ~12 km depth, magma evolved through crystallization of a pyroxene dominated assemblage; plagioclase …

Documenting Magnatic Processes At Filicudi Island, Aeolian Arc, Italy: Integrating Quantitative Modeling And Plagioclase Textural And In Situ Compositional Data, Michelle Harris

All Master's Theses

Documenting the physiochemical processes that influence magma composition is critical for forecasting eruption styles and managing volcanic hazards. Compositional diversity of magmas develops through recharge, assimilation, and fractional crystallization (RAFC) within subvolcanic magma reservoirs. Integration of MELTS modeling, whole rock, plagioclase textural and in situ elemental and isotopic data from Filicudi Island, Italy allow documentation of the roles and relative chronology that RAFC played in the magmatic evolution and elucidates aspects of the magma plumbing system structure.

Results indicate a polybaric magma plumbing system with deeper (3.5-4 kilobars) and shallower (0.5-1.2 kilobars) storage regions. Within the deeper system, FC acted …

Surface Wave Inversion Of The Upper Mantle Velocity Structure In The Ross Sea Region, Western Antarctica, James D. Rinke

All Master's Theses

The Ross Sea in Western Antarctica is the locale of several extensional basins formed during Cretaceous to Paleogene rifting. Several seismic studies along the Transantarctic Mountains and Victoria Land Basin’s Terror Rift have shown a general pattern of fast seismic velocities in East Antarctica and slow seismic velocities in West Antarctica. This study focuses on the mantle seismic velocity structure of the West Antarctic Rift System in the Ross Embayment and adjacent craton and Transantarctic Mountains to further refine details of the velocity structure.

Teleseismic events were selected to satisfy the two-station great-circle-path method between 5 Polar Earth Observing Network …

Relationships Between Snake River Paleofloods, Occupational Patterns And Archaeological Preservation At Redbird Beach Archaeological Site In Lower Hells Canyon, Idaho, Tabitha Trosper

All Master's Theses

The Snake River basin drains 282,000 km² of the northwestern U.S. and is the largest tributary to the Columbia River. Redbird Beach, an archaeological site located in the lower Hells Canyon reach of the Snake River, contains extensive vertical exposures of archaeological materials interbedded with Snake River flood sediments. Redbird Beach formed in the lee of the Redbird Creek debris fan, is composed of interfingering deposits from large floods on the Snake River and locally-derived alluvial sediments from Redbird Creek. Through stratigraphic analyses of slackwater deposits, this study compares the temporal and spatial patterns of human occupation at Redbird …

Geochemistry, Geothermobarometry And Geochronology Of High-Pressure Granulites And Implications For The Exhumation History Of Ultrahigh-Pressure Terranes: Dulan, Western China, Benjamin David Joseph Christensen

All Master's Theses

The Dulan ultrahigh-pressure (UHP) rocks of the North Qaidam terrane, Western China, represent continental crust that has been subducted ~100 km during continental collision. Adjacent granulites representing burial to ~50 km could either be overprinted eclogites or a separate high-pressure-high-temperature (HP-HT) granulite unit. Overprinted eclogites and HP-HT granulites imply different P-T-t paths for UHP rocks. Metamorphic conditions for the granulites are 750–880 °C and 14–17 kbar. Zircon U-Pb geochronology, REE patterns and Ti-in-zircon thermometry indicate an increase in temperature from ~800 °C (449 Ma) to ~900 °C (418 Ma). This temperature increase could explain the presence of granulite leucosomes and …

Lacustrine Sediment Record Of Multiple Quaternary Lava Dams On The Owyhee River, Southeastern Oregon, Caitlin Anne Orem

All Master's Theses

Multiple lava dams and correlating lakes impacted the Quaternary evolution of the Owyhee River. Sediment records from lava-dammed lakes were investigated to understand effects of the West Crater (WC) lava dam (~70 ka), the Saddle Butte 2 lava dam (~144 ka), and the Bogus Rim lava dam (~1.9 Ma). Evidence from the WC lava dam and related features indicates that dam duration consisted of five stages (1) dam and lake formation at ~70 ka; (2) dam overflow and lake sedimentation from ~70–46 ka; (3) removal of lava dam and lake termination from ~46 ka to at least 36 ka; (4) …

Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille

All Master's Theses

Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (Wm), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, Wm in schists and orthogneisses range from 0.52–0.84 (63–36% pure shear). Wm for quartzites ranges from 0.9–0.99 (27–1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanite-zone and were recorded between ~35–16 Ma. These patterns …

Transient Detection And Modeling Of Continuous Geodetic Data, Walter Michael Szeliga

All Master's Theses

Transient surface deformation has been observed by continuously operating Global Positioning System stations in the Puget Sound area during the past decade. This surface deformation is associated with processes occurring on or near the subducting plate boundary between the Juan de Fuca and North American plates. This thesis is composed of two studies of transient deformation along the Cascadia plate margin and a discussion of the methodologies employed in these studies. We model one 7-week episode of transient deformation that occurred during 2003 beneath the Puget Sound area. Additionally, we utilize a combination of continuous Global Positioning System and seismic …

A Large Late Pleistocene Outburst Flood From Pluvial Lakes Alvord And Coyote Into The Owyhee River, Oregon, Deron Torrey Carter

All Master's Theses

A large late-Pleistocene flood traveled into the Owyhee River as a result of a rise and subsequent outburst from pluvial Lake Alvord in southeastern Oregon. Lake Alvord breached Big Sand Gap after reaching an elevation of 1292 m, releasing 11.3 km3 into the adjacent Coyote Basin before stabilizing at an elevation of about 1280 m. Overflow then spilled out of the Coyote Basin through two outlets at 1278 m and into the Crooked Creek drainage of the Owyhee River. The flood created a series of deeply incised canyons, scabland topography and deposited numerous boulder bars containing imbricated clasts up to …

Factors Contributing To Landslide Activity In The Winter Of 1995-96, Clearwater County Near Orofino, Idaho, Aaron Paul Wisher

All Master's Theses

Significant landslide activity occurred in Clearwater County, Idaho in November 1995 and February-May 1996. Mass wasting in the study area consisted of debris slides and earthflows triggered by rain-on-snow weather events. It is important to determine what factors contribute to landsliding in this area so that reliable prediction can reduce the destruction of property. Through field observation and aerial photo analysis, the factors contributing to landslides were studied. The objectives included a study of the geology, soils, aspect, slope gradient, vegetation and slope position related to each slide. Also a goal was to assess the role of land use in …