Physical Sciences and Mathematics Commons^™

Building Arc Crust: Plutonic To Volcanic Connections In An Extensional Oceanic Arc, The Southern Alisitos Arc, Baja California, Rebecca A. Morris, Susan M. Debari, Cathy Busby, Sarah Medynski, Brian R. Jicha

Geology Faculty Publications

The ~50 km long Rosario segment of the Cretaceous Alisitos oceanic arc terrane provides undeformed three-dimensional exposures of the upper 7 km of an oceanic extensional arc, where crustal generation processes are recorded in both the volcanic and underlying plutonic rocks. These exceptional exposures allow for the study of the physical and chemical links between the rock units and help constrain the differentiation processes active during the growth and evolution of arc crust. This study focuses on the southern third of the Rosario segment, previously referred to as the southern volcano-bounded basin, and its plutonic underpinnings. Upper crustal rocks in …

Subduction Initiation And Early Evolution Of The Easton Metamorphic Suite, Northwest Cascades, Washington, Jeremy L. Cordova, Sean R. Mulcahy, Elizabeth R. Schermer, Laura E. Webb

Geology Faculty Publications

The Easton metamorphic suite, in the northwest Cascades of Washington State, preserves an inverted metamorphic sequence with ultramafic rocks underlain by amphibolite and high-temperature blueschist juxtaposed above low-temperature blueschists. The sequence is interpreted as a metamorphic sole and younger accreted rocks that formed during and after the initiation of Farallon plate subduction beneath North America in Jurassic time. Two high-temperature deformation events are recorded in the metamorphic sole at ∼10 kbar and ∼760 °C to 590 °C between >167 and 164 Ma. High-temperature blueschist partly overprints the amphibolite but may have accreted separately at ∼530 °C between ca. 165 and …

Particle Size Specific Magnetic Properties Across The Norwegian‐Greenland Seas: Insights Into The Influence Of Sediment Source And Texture On Bulk Magnetic Records, Robert G. Hatfield, Benjamin H. Wheeler, Brendan T. Reilly, Joseph S. Stoner, Bernard A. Housen

Geology Faculty Publications

We make fundamental observations of the particle size variability of magnetic properties from 71 core tops that span the southern Greenland and Norwegian Seas. These data provide the first detailed regional characterization of how bulk magnetic properties vary with sediment texture, sediment source, and sediment transport. Magnetic susceptibility (MS) and hysteresis parameters were measured on the bulk sediment and the five constituent sediment particle size fractions (clay, fine silt, medium silt, coarse silt, and sand). The median MS value of the medium silt size fraction is ~3–5 times higher than that of the sand and clay size fractions and results …

Modeling The Effects Of Climate Variability On Hydrology And Stream Temperatures In The North Fork Of The Stillaguamish River, Kyra Freeman

WWU Graduate School Collection

The Stillaguamish River in northwest Washington State, USA, provides water resources to local agriculture, industry and First Nations Tribes, and provides crucial habitat for several endangered species of salmonids. The watershed experiences a mild maritime climate and high relief, with rain and snowmelt dominating the streamflow. In anticipation of shifts in snowpack, streamflow, and stream temperature, I use projected global climate scenarios and numerical models to examine future climatic variability on streamflow and stream temperatures in the snow-melt dominated North Fork of the Stillaguamish River. I calibrated the physically based Distributed Hydrology Soil Vegetation Model (DHSVM) and River Basin Model …

Increased Hydrologic Variability Near The Paleocene-Eocene Boundary (Piceance Creek Basin, Colorado, U.S.A.)), Anna Lesko

WWU Graduate School Collection

The Paleocene Eocene Thermal Maximum (PETM) was a rapid global warming event that occurred approximately 56 million years ago and represents the largest and most abrupt warming event of the Cenozoic Era. The PETM caused mean annual temperatures to increase at least 5°C globally above the already warm, greenhouse climate state of the early Paleogene. The warming and associated perturbation of the carbon cycle had numerous consequences for paleoenvironments and paleobiologic systems. This study investigates the hydrologic response to the PETM within the interior of North America and presents a new d¹³C bulk organic record. This study generates …

Assessing Coastal Vulnerability To Storm Surge And Wave Impacts With Projected Sea Level Rise Within The Salish Sea, Nathan R. Vanarendonk

WWU Graduate School Collection

Sea level rise (SLR) in the Salish Sea, a large inland waterway shared between Canada and the United States, is expected to be 0.3 to 1.8 m by the year 2100. Uncertainty in greenhouse gas emissions, global ice sheet loss, and other controls such as vertical land movement all contribute to this range. Valuable property, infrastructure, and critical habitats for shellfish and threatened salmon populations are at risk to coastal changes associated with SLR. Additionally, development in Washington State is expected to accelerate through the end of the 21st century adding extra pressure on protecting ecosystems and people from natural …

Paleomagnetic Results From Upper Triassic And Middle Jurassic Strata Of East-Central New Mexico, And Implication For North American Apwp, Masoud Mirzaei Souzani

WWU Graduate School Collection

Two contradictory apparent polar wander paths (APWPs) of North America (NA) for most of Jurassic time have been the subject of many studies since the 1990s, and are important to rectify if in order to constrain the tectonic evolution of the continent. Among various efforts to resolve this persistent issue, additional results from well-dated kimberlite volcanics have been used to support a higher-latitude APWP (Kent et al., 2015), and the controversy was blamed on inclination error (IE) in paleomagnetic results of sedimentary units, most of which are from the U.S. South Western interior. Those paleomagnetic poles define the other, lower-latitude …

Slip And Strain Accumulation Along The Sadie Creek Fault, Olympic Peninsula, Washington, Cody Duckworth

WWU Graduate School Collection

Upper-plate faulting in the Olympic Peninsula of Washington State reflects the interaction of crustal blocks within the Cascadia forearc as well as contributions from various earthquake cycle processes along the Cascadia subduction zone (CSZ). These processes include interseismic coupling, megathrust earthquakes, and aseismic slow slip events. In this study I utilize high resolution airborne lidar, field mapping of deformed surficial deposits and landforms, optically stimulated luminescence (OSL) dating and radiocarbon dating to reconstruct fault slip rates since Late Pleistocene deglaciation on the Sadie Creek fault (SCF), located north of the Olympic Mountains. This mapping reveals the SCF as a ~14 …

Photometric Investigations Of Weathering Rinds And Coatings With Implications For Mars, Kathleen Hoza

WWU Graduate School Collection

Reflectance spectroscopy is a major technique for characterizing the composition of planetary surfaces, and has led to many key findings in planetary geology. In laboratory measurements, reflectance spectrometers typically acquire data using a standard, fixed viewing geometry. Measurements from spacecraft, however, may be acquired at a wide range of viewing geometries, depending on the orientation of the instrument relative to the target surface and the Sun. For many materials, the impact of viewing geometry on reflectance is minor; however, some materials’ spectral signatures can be influenced by these photometric effects. In particular, spectra of weathering rinds and rock coatings are …

Quantifying The Magnitude And Spatial Variability Of Bedrock Erosion Beneath The Sisters Glacier, Washington, Using Cosmogenic 3he Concentrations, Sarah W. Francis

WWU Graduate School Collection

Cosmogenic ³He analyses provide a tool to infer spatial variation of cirque-glacial bedrock erosion. ³He accumulates in bedrock exposed at the surface as a result of cosmic ray bombardment; the concentration of cosmogenic ³He increases with exposure time as well as proximity to the surface. The Twin Sisters range, North Cascades, WA is an ideal location to use cosmogenic ³He to infer cirque-glacial erosion depths and rates, due to the dunite bedrock and the detailed record of Holocene glaciation from the nearby Mount Baker. We used field mapping, lidar data and aerial imagery to identify bedrock …

Seismic Structure Of Tanaga Island, Alaska, Kevin F. (Kevin Francis) Lally

WWU Graduate School Collection

Tanaga Island is located in the Central Aleutian Islands and includes four stratovolcanoes: Sajaka, Tanaga, and East Tanaga in the northwest, and Takawangha in the central part of the island. Of these volcanoes, only Tanaga has a record of historical eruptive activity (in 1914). Over 3,000 earthquakes have been recorded beneath the island and the surrounding offshore region since the six-station seismic network was emplaced in 2003. The origin of these earthquakes is not completely understood, and to arrive at this understanding, more accurate hypocenter locations and power spectra need to be determined. A better analyses including improved locations of …

Validation Of Predicted Tsunami Inundation For The Inland Coast Of The Salish Sea Associated With Cascadia Subduction Zone Earthquakes, Paige Morkner

WWU Graduate School Collection

The Cascadia subduction zone is understood to produce large, Mw 9.0, earthquakes every 300-1000 years. As a result of large ruptures along the fault, Washington, Oregon and Northern California, are susceptible large tsunamis along the coast. Hazard modeling and mapping along the Cascadia subduction zone has concluded that large tsunamis are able to travel through the Strait of Juan de Fuca and inundate coastal regions of the Salish Sea and Puget Sound. However, to improve modeling efforts, field validation of models is required. Tsunamis can move material from the near shore and beach and deposit in low-laying coastal marshes and …

Clinopyroxene Trace Element Chemistry As A Proxy For Magma Compositional Variations In The Izu Bonin Rear Arc Over The Last 15 Million Years, Kimberly N. (Kimberly Nicole) Wurth

WWU Graduate School Collection

This study presents major and trace element chemistry of clinopyroxene (CPX) in 0-15 Ma core material recovered from Site U1437 during IODP Expedition 350. Because no fresh glass is present in the core samples older than 4.4 Ma, and hence there is no way to directly determine magma compositions, my study presents the development of a novel method for calculating liquid compositions from CPX grains in volcaniclastic sediments using distribution coefficients and trace elements measured in CPX.

Geochemical data from CPX grains was acquired using a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). These data were used to calculate trace element …