The dense Corvallis array deployed in January of 2022 aided in the high-resolution study of local geology. This array was made of 177 SmartSolo 3-component 5 Hz geophones around Corvallis, with a 93 geophone profile going west towards Bald Hill for approximately 5 km at an average of 64 m...
In eastern Washington and western Oregon, southwest-northeast striking thrust faults and folds of the Yakima Fold and Thrust Belt (YFTB) and northwest-striking dextral strike-slip faults accommodate north-south contraction resulting from clockwise rotation of the North American Plate. Though present to the east and west of the Cascade Range, the connectivity...
In this study, 3D finite difference and 2D finite element forward modeling were used to create an electromagnetic sensitivity analysis for the Cotopaxi volcano in Ecuador. Magnetotellurics (MT) is a natural-source electromagnetic geophysical technique that images electrical conductivity. Measuring strong contrasts in electrical conductivity in volcanic materials allows for the...
Studies reveal differences in slip segmentation and plate coupling along the Cascadia subduction zone. The segment between 44.0°N and 45.0°N exhibited reduced slip in the 1700 megathrust earthquake (Wang et al., 2013) and corresponds with previous rupture boundaries inferred from paleoseismic data (Leonard et al., 2010). Notably, this segment of...
Changes in the stable carbon isotope composition of carbonate rocks (𝛿13Ccarb) are used to establish the relative temporal framework for geological events, such as evolutionary extinction or radiation, between two or more locations. As every local stratigraphic record is intermittent, aligning 𝛿13Ccarb records from two or more locations, a process...
Oregon’s foredunes are part of a dynamic coastal environment that constantly evolves in response to both ecological and physical forces. Invasive beachgrasses have outcompeted native dune grass in the region and have influenced the shape of Oregon’s foredunes via species-specific biophysical feedback mechanisms. As climate change induced sea-level rise will...
Rates of sediment transport were determined using tracer gravel and a RFID antenna array at Oak Creek (Oregon) to compare a new method with an existing transport relation created from data previously collected in the same study reach. Close to 3,000 tracers were deployed throughout the study reach and were...
Oceanic plateaus are regions of overthickened oceanic crust and are often thought to form from the interaction of mantle plumes with oceanic lithosphere. These regions can cover vast areas of the ocean basins and represent a highly elevated magmatic flux relative to normal mid-ocean ridge spreading. Oceanic plateaus are considered...
This research presents a u-channel based study of the natural remanent magnetization (NRM), the laboratory magnetization, Anhysteretic Remanent Magnetization (ARM), and magnetic susceptibility (k), from the upper 100 m of International Ocean Discovery Program (IODP) Expedition 383 Site U1543 in the eastern South Pacific sector of the Southern Ocean. Alternating...
Magmatic-hydrothermal ore deposits are giant geochemical anomalies in the earth’s crust most often generated by normal magmatic terrestrial processes. They are often associated with oxidized and hydrous intermediate to highly evolved magmas that have concentrated metals and have the necessary components to efficiently extract and transport them as ascending magmatic-hydrothermal...
The ~5 km3, 4.54 to 4.09 Ma Caspana Ignimbrite of the Altiplano-Puna Volcanic Complex (APVC) of the Central Andes records the eruption of an andesite and two distinct rhyolitic magmas. It provides a unique opportunity to investigate the production of silicic magmas in a continental arc flare-up, where small volumes...
The imposing andesite stratovolcano is the characteristic expression of subduction zone magmatism, posing hazards to coastal populations and bearing insight into deep Earth processes. On a map of a typical volcanic arc, one can easily distinguish the approximately linear alignment and regular spacing of these major edifices that stand out...
Near-surface advanced argillic hydrothermal alteration zones, also referred to as lithocaps, are characterized by quartz, alunite, clays (pyrophyllite and kaolinite group minerals), and minor F-bearing aluminosilicates (i.e., topaz, zunyite, diaspore, and APS) that form where water-, SO2-, and HF-rich gas condenses into shallow groundwater, acidifies, and reacts with rocks. The...
Large silicic magmatic systems are responsible for producing the largest explosive volcanic eruptions on earth. These phenomena, although infrequent (i.e., 1 per 100,000 years), impact the global climate, deposit ash over continent sized regions, and significantly alter landscapes. Silicic magmatism also plays important roles in the formation and ongoing evolution...
The 180,000 km² of Arabian lava fields (“harrats” in Arabic) form one of the largest distributed basaltic provinces in the world. Approximately 50% of these are located in Saudi Arabia. The most recent eruption in 1256 AD, as well as seismicity and ground deformation associated with shallow dike emplacement in...
Floodplain forests play many important roles in the fluvial processes and environments of large alluvial rivers, including acting as geomorphological influences and habitat for native fish during high flows. Many large, gravel-bed river systems have undergone substantial change in recent centuries, resulting in loss of forested area to agriculture, reduction...
Magneto- and chemostratigraphic correlation underpins much of our understanding of Earth history, yet typical correlation techniques are neither quantitative nor objective. Within this dissertation, I detail my efforts to develop and apply dynamic programming-based algorithms that accomplish optimal and reproducible stratigraphic alignment. I apply these algorithms to three geologic intervals:...
The word orogenesis is derived from the Greek words oros meaning mountains and genesis meaning creation and refers to the study of the complex processes involved in the growth and evolution of mountain ranges (orogens). Orogens develop where crustal deformation builds topography and forms landscapes. This dissertation explores the role...
The global mid-ocean ridge system is the largest magmatic system encompassing over 75% of the Earth’s total volcanism. As magmas ascend through the vertically variable oceanic crust, melts begin to crystallize and diversify and subsequently erupt at the surface. The interpretation of these erupted products observed on the seafloor requires...
Porphyry Cu-(Au-Mo) deposits are critical sources of several economically important metals. The processes governing the total metal endowment and relative proportions of ore metals at these large magmatic-hydrothermal deposits remain uncertain. The Sulphurets porphyry district, in northwestern British Columbia, Canada, contains four porphyry Au-Cu-Mo deposits that each feature distinct Cu/Au...
Explosively erupting volcanoes and megathrust earthquakes (Mw 8+ magnitude) occur at subduction zones and adjacent volcanic arcs. Volcanic eruptions are observed occurring close in time to megathrust earthquakes in the historical record from at least the 18th century CE to present in locations globally, including Japan in 1707 CE (Chesley...
Hydrogeologic systems in the southern Cascade Range develop in volcanic rocks where volcanic morphology, stratigraphy, extensional structures and attendant basin geometry play a central role in groundwater-flow paths, groundwater/surface-water interactions, and spring discharge locations. High-volume springs (> 3 m3/s) flow from young (< 1 Ma) volcanic rocks in the Hat...
This thesis focuses on the investigation of extraterrestrial tracers Ir, Pt and 3He in polar ice cores. These tracers may be used to identify characteristics of interplanetary dust particles, and to quantify the flux of extraterrestrial material during impact events, certain volcanic eruptions, and stable background periods. In the first...
Understanding the degree to which topography of erosional landscapes in active mountain belts encode the rates and patterns of active deformation in the upper crust is a primary goal in the field of tectonic geomorphology. In particular, the convolved influence of variations in rock mass quality and the erodibility of...
This study evaluates ore transport and other mining activities on metal levels in the remote Arctic ecosystem of Cape Krusenstern National Monument (CAKR) in northwestern Alaska. This monument is 50 km SW of Red Dog Mine, one of the world’s largest Pb–Zn mines. The Delong Mountain Transportation System (DMTS) haul...
Silicic caldera-forming eruptions are some of the largest and most destructive volcanic eruptions known, and present significant local and global hazards. The underlying processes within crustal magma plumbing systems that lead to the accumulation and eruption of large volumes of evolved magma remain enigmatic, yet there is broad consensus that...
A feature of large continental magmatic systems is voluminous dacite ignimbrites erupted from upper crustal magma reservoirs. In the Altiplano Puna Volcanic Complex (APVC) of the Central Andes, a major ignimbrite and caldera plateau, magma systems are found to be long-lived and remarkably homogeneous requiring that they be maintained by...
Glacial isostatic adjustment (GIA) alters the amplitude and timing of ‘glacioeustatic’ sea level maxima and minima around the globe. No study has examined the intrinsic distance that one can correlate marine stratigraphic records of glacial–interglacial sedimentation across continental shelves subject to varying amounts of GIA. Here, we seek to model...
Discrete fault systems accommodate both N-S contraction and dextral shear in concert with clockwise rotational deformation of the North American plate above the Cascadia Subduction Zone. In Washington, the Yakima Fold and Thrust Belt (YFTB) accommodates N-S contraction as a series of ENE-WSW trending thrust faults and folds. NW-striking, predominantly...
The archaeological record of the First Americans is known almost exclusively from interior sites located away from coastal margins. While archaeologists hypothesize that early peoples initially migrated into the Americas along the Pacific coast, environmental changes associated with postglacial sea level rise may have destroyed or obscured such early sites....
The Inmaculada Mine is located in the Miocene belt of epithermal deposits that extends from southern Peru to northern Chile and Bolivia. This belt is known for its silver-rich epithermal veins that have been worked since colonial times. The Inmaculada Mine belongs to a mining district that includes, from north...
Disentangling sediment source from sediment transport is a fundamental marine geologic challenge critical to the interpretation of any sedimentary record. The Eirik Ridge, a sediment drift south of Greenland, receives terrigenous sediment primarily from subglacial erosion of south Greenland’s Precambrian bedrock and Paleogene volcanics that outcrop in east Greenland and...
The Panamint Valley fault zone (PVFZ) is an active, dextral-oblique normal fault that partially accommodates dextral shear across the Eastern California Shear Zone (ECSZ). The fault system has a complex geometry, characterized by a relatively high-angle dextral oblique normal fault in the south and a low-angle detachment system that accommodates...
Western Saudi Arabia hosts a number of young volcanic fields, known as “Harrats”. Harrats cover a significant proportion of western Saudi Arabia and are associated with significant volcanic hazards. However, the ultimate cause of volcanic activity remains unclear. Younger volcanism (<12 Ma) is clearly represented by the north-south-trending region known...
Cinder cones are useful geomorphic features for geological analysis because they generally have known initial states and follow a similar pattern of degradation as they are exposed to erosive processes. This is largely because cinder cones are produced by monogenetic eruptions. Characterizing large cinder cone fields in terms of age...
By inverting EarthScope long-period magnetotelluric (MT) data from the southeastern United States (SEUS), we obtain electrical conductivity images that provides key insights into the geodynamics of this region. Significantly, we resolve a highly electrically resistive block that extends to mantle depths beneath the modern Piedmont and Coastal Plain physiographic provinces....
Mount Sinabung, Sumatra, Indonesia initiated eruptive activity in 2010 with the addition of a magmatic component in 2013, after a 3 year period of quiescence. Observations of magmatic activity began with phreatomagmatic eruption starting July 2013 closely followed by extrusion of andesitic lava in December 2013. Lava effusion has persisted...
Reconstructing the sensitivity of past climate to forcings, and of ancient glaciers and ice sheets to this climate, can allow us to better understand the range of climate and cryosphere behavior we may see in the coming centuries. The Arctic is a region of particular importance due to its well-documented...
This dissertation is concerned with the behavior of sulfur in intermediate-silicic arc magmas associated with subduction at convergent margins. In particular it focusses on oxidized, sulfur-rich magmas, the conditions at which they might reach sulfate saturation, and implications of sulfate saturation. It is divided into an investigation of natural samples...
Oblique subduction of the Juan de Fuca plate beneath the North American plate characterizes the tectonic setting of the Pacific Northwest. North American plate deformation at the latitude of central Oregon consists of the clockwise-rotation of the Siletzia block in the forearc and the extensional Basin and Range province in...
Numerous studies have explored how alluvial channel size and morphology are adjusted to different sediment and flow conditions, yet we still know very little about how and to what degree the flow regime controls channel form and processes. We use the term ‘channel form’ to refer to the size and...
A synthesis of over 2000 paleoclimate proxy records is performed via a data assimilation framework that expands upon previous efforts by implementing a suite of physically-based proxy system models, and which provides the first example of an observationally independent, multi-seasonal (DJFM, JJAS) paleoclimate reanalysis. This methodology is contrasted against previous...
To understand the processes that lead to the formation of the oceanic crust, one must know the composition and the depth at which primary melts originate. Towards this end, this dissertation focuses on plagioclase-hosted melt inclusions from plagioclase ultraphyric basalts (PUBs). Plagioclase is usually considered to be the second phase,...
Bedrock meandering rivers are sinuous channels that pair steep bedrock outside banks with lower gradient slip-off slopes on the inside of bends. These rivers have the potential to record information on climatic and tectonic “external” forcings in their morphology (e.g., longitudinal profiles, strath terraces, channel and valley dimensions). However, geology...
Continental flood basalts represent short-lived but immense blasts of mafic magma to the continental crust. The youngest and smallest continental flood basalt worldwide, the Columbia River Basalt, initiated with the eruption of the most mafic member, the Steens Basalt (~16.9 Ma). The Steens Basalt is exposed in southeast Oregon, southwest...
The details of the 1700 Cascadia Subdction Zone earthquake and tsunami can be better constrained using data from tsunami sand sheets, provided knowledge of the waveform, estuary geometry and bed roughness controls on the deposition pattern of the sand sheet. In this study, we use the hydrodynamic and sediment transport...
Coastal flooding and erosion are major concerns for low lying coastal communities -- particularly in light of accelerated sea level rise and climate change. To improve quantitative understanding of the physical drivers of both flooding and coastal landscape change, this dissertation explores coastal morphodynamics bridging the land-sea interface on modally...
Around 74 ka, a supervolcano, Toba Caldera in Sumatra, Indonesia erupted, producing the Youngest Toba Tuff and its associated caldera. After this catastrophic eruption, a lake filled the caldera, sedimentation within the lake occurred, and the process known as resurgence began. Today, the resurgent dome, Samosir Island, is uplifted 700...
The nature of upper plate deformation along the Cascadia subduction zone (CSZ) is poorly understood. Systematic covariation among topographic relief, geodetically determined uplift rates, decadal to millennial erosion rates, and the frequency of episodic tremor and slip (ETS) along the Cascadia forearc suggest a genetic association between forearc topography and...
This dissertation is divided into two major chapters. The first chapter covers the geologyof the Encuentro deposit with emphasis in the intrusion sequence, vein mineral assemblages and distribution, and age of mineralization. The data used for this section includes field mapping, petrography, elemental analysis of biotite, and isotopic geochronology. The...
Understanding groundwater flow in faulted and fractured rock is an important frontier in the field of environmental remediation and in the management of water resources. One example of a site where this is particularly evident is the Santa Susana Field Laboratory (SSFL) in Ventura County, CA where environmental remediation activities...
The eruptive history of the Quaternary Cascades arc has been relatively well characterized. However, much less is known about the frequency and sizes of explosive eruptions produced by earlier stages of the arc. The Late Neogene Deschutes Formation of Central Oregon preserves a remarkable record of heightened pyroclastic activity during...
The Toba Caldera Complex is the youngest resurgent caldera in the last 100 kyrs, formed from four overlapping eruptions starting 1.2 Myrs ago. The last caldera-forming eruption, the Youngest Toba Tuff eruption, occurred ~74 kyrs ago, emitting 2800 km3 of ash and pumice into the atmosphere and forming the caldera...
Earth’s mantle extends to nearly 3000 km depth, comprises >80 % of Earth’s total volume, and has the largest influence on the primordial and radiogenic heat budget. Despite its importance, the structure and composition of the mantle is still debated. There are three primary models for Earth’s mantle structure that...
In volcanic systems, magma is generally stored in the shallow crust prior to eruption. The conditions of this storage directly impact whether the magma eventually erupts, or crystallizes within the crust to form a pluton. In this dissertation I present four studies that investigate the storage conditions of a number...
When people think of fossils, they generally imagine the bones of large, charismatic animals. However, small mammals are an ecologically important group of organisms that show up frequently in the fossil record, and can frequently function as indicators for local environmental and ecological conditions (Terry, 2007, 2010). Rodent and rabbit...
This dissertation explores one overarching question relevant to the
paleoclimate of the latest Pleistocene glacial cycle (approximately the last
130,000 years): “How did spatial and temporal evolution of ocean
temperature, both at the surface and interior, relate to other parts of the
climate system in the late Pleistocene?” Results from...
The Botija Cu-Mo-Au porphyry deposit is located in the Cobre Panamá mining district, which contains several deposits with a global measure and indicated and inferred resource of 14.8 MT of Cu. These deposits are associated with the Cerro Petaquilla batholith, which has U/Pb zircon ages of 26-33 Ma (Whattam et...
The goals of this dissertation are centered on understanding changes in Earth surface and climate systems through the use of geologic proxies as records of past changes in these systems. Specifically, this dissertation (1) establishes a new chronology for retreat of the Ross Sea sector of the West Antarctic Ice...
Despite more than two centuries of exploration, including more than six million deep wellbores with depths exceeding 40,000 feet in some parts of the world, our ability to constrain subsurface processes and properties remains limited. Characteristics of the subsurface vary and can be analyzed on a variety of spatial scales....
The Ratio Mountain Quadrangle is located in Southwest Montana, East of the city of
Butte. This quadrangle features two major geologic units; the Elkhorn Mountain
Volcanics, a series of several ignimbrites of varying composition, and the Boulder
Batholith, a large granite pluton that rose through the EMV. Previous studies in...
The goal of dissertation research was to use geochemical, statistical and geological methods to constrain and understand climate variability over several different time scales. Specifically, I have addressed three questions regarding past climate change: (1) how does the record of Irish cirque glaciers constrain the dimensions of the Irish Ice...
Numerous investigations demonstrate that mantle convective processes such as upwelling affect the surface topography of the overriding plate. The surface expression of mantle flow has been coined ‘transient topography’. Transient topography in the North American plate is thought to result from a mantle thermal anomaly beneath the Yellowstone volcanic center,...
This dissertation uses argon geochronology and cosmogenic nuclide surface exposure dating methods to address three research questions. The first question concerns a geomagnetic instability recorded in lava flows on the island of Floreana in the Galapagos Archipelago. Changes in the Earth’s magnetic field (intensity and orientation) occur frequently throughout geologic...
The Boulder Batholith and Elkhorn Mountains Volcanics (EMV) formed concurrently during shortening between ~85-76 Ma near the end of Mesozoic Cordillera arc magmatism. Together they represent an exceptionally well-preserved and voluminous record of continental arc magmatism. We report field and analytical results from studies of the EMV and Boulder Batholith...
The Boulder Batholith and Elkhorn Mountains Volcanics (EMV) formed concurrently during shortening between ~85-76 Ma near the end of Mesozoic Cordillera arc magmatism. Together they represent an exceptionally well-preserved and voluminous record of continental arc magmatism. We report field and analytical results from studies of the EMV and Boulder Batholith...
The Eastern California Shear Zone (ECSZ) is a broad zone of dextral shear inboard of the North American - Pacific plate boundary. Despite decades of study, the significance of a mismatch between geodetic velocities and geologic fault slip rates across the ECSZ remains incompletely understood. Geodetically determined interseismic strain across...
The Hampton Tuff is a 3.9 ± .02 Ma (2σ) ignimbrite sheet from the High Lava Plains of central Oregon. The majority of known outcrops exist to the north, within ~22 mi (~35 km) of the Frederick Butte Volcanic Center, the proposed source of the tuff. Thickness of the tuff...
To investigate the dynamic response of the outer accretionary wedge updip from the patch of greatest slip during the Mw8.8 2010 Maule earthquake, 10 Ocean Bottom Seismometers (OBS) were deployed from May 2012 to March 2013 in a small array with an inter-instrument spacing of ~10 km. Nine instruments were...
This dissertation is informally divided into three major sections. In the first section (Chapter 2) I use data from field mapping, isotopic geochronology, whole rock geochemistry and trace element concentrations in zircons to examine the petrology, geochemistry and ages of the Haquira East porphyry copper deposit of southern Peru. In...
Volcanic and sedimentary deposits of the Mount Jefferson area (MJA) record a fourmillion-year history of arc-related volcanism related to the subduction of the Juan de Fuca plate beneath North America. 171 mapped stratigraphic units over an area of 150 km² reveal four periods of volcanic activity resulting in diverse composition...
The Cook-Austral island chain has been the center of debate for many years. Contrary to the classical hotspot hypothesis, this volcanic island chain does not exhibit a linear age progression with a single node of active volcanism, but instead shows evidence of young volcanism at several points along the chain....
Supervolcanic eruptions are among the most catastrophic phenomena on Earth,
erupting 100s-1000s of cubic kilometers of magma, and producing devastating local effects and global climate perturbations. The largest supervolcanic eruption of the last 28 Ma was the 74 ka Youngest Toba Tuff (YTT) eruption from Sumatra, Indonesia, which erupted 2,800...
The volcanic (~45-10 Ma) and plutonic rocks (~37-12 Ma) comprising the Western Cascades extend from northernmost California to southern British Columbia and are ancestral to modern arc magmatism. The ancestral arc hosts a series of small plutons that are locally associated with porphyry (Cu-Mo) and epithermal (Au) ore deposits. Three...
Crystal-rich (40-50 vol.%) intermediate lava has been the primary eruptive product of several recent hazardous eruptions: Mt. Pinatubo, Philippines (1991), Soufriere Hills, Montserrat (1995-present), and Unzen, Japan (1990-1995). Despite this association with such devastating eruptions, the formation, timing, and evacuation of such magma is not well understood: do such eruptions...
The Emigrant Pass volcanics (EPV) are a 38.3 to 36.4 Ma calc-alkaline volcanic center that erupted andesite and dacite, and a late series of felsic dikes along the south flank of the Carlin gold district in north-central Nevada. The EPV includes dacite and rhyolite porphyry dikes indistinguishable from porphyry dikes...
The relationship between carbon burial and sedimentation in reservoirs is unknown, exposing gaps in our fundamental understanding of the transport, processing, and deposition of sediment and organic matter in fluvial and lacustrine systems and contributing to uncertainty in our understanding of the net impact of dams to the global carbon...
The Pebble porphyry Cu-Au-Mo deposit in Alaska is one of the world's largest Cu-Au mineral resources. Late Cretaceous magmatic evolution in the Pebble district culminated with the intrusion of the Kaskanak Batholith and associated porphyry copper-gold-molybdenum mineralization. The Kaskanak Batholith is a multiphase granodiorite intrusion with an estimated footprint of...
Active tectonics of a deformation front constrains the kinematic evolution and structural interaction between the fold-thrust belt and the most-recently accreted foreland basin. At the Himalayan deformation front, the thrust front is blind, characterized by a broad fold (the Suruin-Mastgarh anticline (SMA)), and displays no emergent faults cutting the southern...
The state of the knowledge for fault behavior in the northwest Himalaya and California varies dramatically. In the Pakistan and Kashmir Himalaya, few data constrain the role that individual active faults play in accommodating Indo-Eurasian convergence and the relative earthquake hazard across the region. By contrast, the San Andreas fault...
The Pastos Grandes Caldera Complex (PGCC) in southwest Bolivia has produced two large-volume (≥800 km³ DRE) dacite ignimbrites from a nested caldera source over a period of 5.5 Myr. In addition to the large-volume ignimbrites, a small-volume ignimbrite shield and post-climactic lavas define this composite system. Based on detailed field...
Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into the magmagenesis that results in the formation of the Central Volcanic Zone (CVZ) in the Andes of South America, situated atop...
For many years, scientists worldwide have been using glacial ice to reconstruct and study Earth’s past climates. While the most continuous records we have are from sites near both poles, there is also mid-latitude perennial ice in the form of mountain glaciers and cave ice. Very little is known about...
The ~1 Myr history of the Purico-Chascon volcanic complex (PCVC) records significant changes in the production and storage of magmas in the crust. At ~1 Ma activity at the PCVC initiated with the eruption of a large 80-100 km³ crystal-rich dacite ignimbrite with restricted whole rock ⁸⁷Sr/⁸⁶Sr isotope ratios between...
The Jewett Mine is a hard rock mine located on the southern flank of Mount Baldy, approximately 1.6 km from Grants Pass in Josephine County, Oregon on the Grants Pass mining district. The Jewett Group contains 7 separate claims totaling approximately 1.42 km² and consists of several workings including an...
The three studies that comprise this dissertation seek to answer significant
questions in paleoclimatology through unconventional applications of ice core
greenhouse gas data. These studies involve different gases and span the interval of time
between the Last Glacial Maximum and the Industrial Revolution, but are united by their
nontraditional use...
Semi-volatile trace metals like Li, Cu, Mo, Sn, In, and Pb have the potential to track mobility of a volatile phase in volcanic systems. In this dissertation four studies are presented that either directly investigate or are motivated by observations of trace metal behavior in volcanic systems. A common tool...
The subsurface microbial biosphere in the igneous oceanic crust has implications for global geochemical cycling, early life on Earth, and the search for life on Mars. Microscopic evidence of a subsurface microbial ecosystem includes biotic alteration textures associated with basaltic glass. The exact conditions in the basaltic layer that make...
Passive hydrophone technologies and a variety of acoustic methods are applied in
the deep-ocean and shallow water coastal environments of the northeast Pacific. A
catalog derived from U.S. Navy regional hydrophone array recordings of acoustic T- phases from seafloor earthquakes is examined, describing space/time patterns through
empirical orthogonal function analysis...
The exchange of carbon on earth is one of the fundamental processes that sustains life and regulates climate. Since the onset of the Industrial Revolution, the burning of fossil fuels and anthropogenic land conversion have altered the carbon cycle, increasing carbon dioxide in the atmosphere to levels that are unprecedented...
Prior to eruption at mid-ocean ridges, melts must travel through >6 km of crust from their origin in the mantle. The final composition of the melts is dependent on both the melting conditions and magmatic processes within the crust. While mid-ocean ridge basalt (MORB) glasses are commonly used to infer...
The Mount Polley copper-gold deposit is one of a series of porphyry copper deposits that occur in a belt of accreted Mesozoic age island arc terranes in the Canadian Cordillera. The deposit comprises three breccia-hosted Cu-Au ore zones that are associated with a series of monzodiorite to monzonite intrusions emplaced...
The Curaçao Lava Formation (CLF) records the magmatic and tectonic processes that formed the Caribbean Large Igneous Province (CLIP). A model of the petrogenesis of the CLF was developed using new geochemical and geochronological data. These data include major element compositions obtained using X-ray fluorescence spectroscopy (XRF), trace element concentrations...
Debris flows, which occur in mountain settings worldwide, have been particularly damaging in the glaciated basins flanking the stratovolcanoes in the Cascade Range of the northwestern United States. This thesis contains two manuscripts that respectively investigate the (1) initiation processes of debris flows in these glaciated catchments, and (2) debris...
Ice cores are considered the gold standard for recording past climate and biogeochemical changes. However, gas records derived from ice core analysis have until now been largely limited to centennial and longer timescales because sufficient temporal resolution and analytical precision have been lacking, except during rare times when atmospheric concentrations...
In an attempt to understand the phase equilibria and petrogenesis of MORB anorthitic plagioclase, Cr-spinel commonly hosted within anorthitic plagioclase has been investigated petrographically and compositionally. Based on spinel-anorthite relationships from three samples of plagioclase ultra-phyric basalt (PUB; Southeast Indian Ridge, Axial Seamount and West Valley Segment, Juan de Fuca...
Oxidized hydrous intermediate composition magmas are responsible for porphyry copper (Cu ±Mo ±Au) deposits and epithermal Au ore deposits formed globally in the shallow crust (Sillitoe, 2010; Seedorff et al., 2005). Recently, zircon geochemistry has been used to characterize both productive and barren intrusions associated with porphyry Cu-Au ore deposits....
The Glass Buttes volcanic complex is a cluster of bimodal (basalt-rhyolite), Miocene to Pleistocene age lava flows and domes located in Oregon's High Lava Plains province, a broad region of Cenozoic bimodal volcanism in south-central Oregon. The High Lava Plains is deformed by northwest-striking faults of the Brothers Fault Zone,...
Understanding sandbar dynamics and variability is integral to developing a predictive
capacity for nearshore flows, sediment transport, morphological change, and
ultimately for determining coastline exposure to damaging storm waves. Along the
high-energy U.S. Pacific Northwest (PNW) coast, sandbars typically dominate the
bathymetry of the active zone. Here we report on...
The sheeted complex of the ~92 Ma Tenpeak pluton, in the Northern Washington Cascades crystalline core, forms a <1.5-km wide zone with a moderate, NE-dip at the SW margin of the pluton. Sheeted magmatic complexes, such as the one in the Tenpeak pluton, are common in plutons and represent examples...