Physical Sciences and Mathematics Commons^™

Mitigating Non-Linearity In Full Waveform Inversion Using Scaled-Sobolev Norms, Mohammad Akbar Hosain Zuberi

Electronic Thesis and Dissertation Repository

Seismic full waveform inversion (FWI) is a non-linear problem. The Born approximation provides a way to linearize FWI and obtain a gradient in a computationally efficient manner. However, this linearization is only valid if the background velocity is sufficiently known, which often is not possible in practice. There have been various attempts at solving problems associated with the non-linearity of FWI by separating the problems of background and scatterer inversion. Most of the methods, however either depend on the availability of low frequencies and large offsets in the data, or separate the spatial scales completely, which removes the scattered information …

Rethinking Holocene Ecological Relationships Among Caribou, Muskoxen, And Human Hunters On Banks Island, Nwt, Canada: A Stable Isotope Approach, Jordon S. Munizzi

Electronic Thesis and Dissertation Repository

This dissertation explores the ecology of caribou (Rangifer tarandus spp.) and muskoxen (Ovibos moschatus), and its relevance to human hunters on Banks Island, NWT, Canada, over the last 4000 years, primarily through the isotopic analysis of modern and archaeological faunal remains.

First, we establish baseline carbon and nitrogen isotope relationships between modern vegetation and caribou and muskox bone collagen using Bayesian mixing models. The models indicate that dwarf shrub (Salix arctica) does not contribute significantly to bone collagen isotopic compositions in either species, while sedges and yellow lichen (Cetraria tilesii) do. These findings …

Polarimetric Synthetic Aperture Radar (Sar) Application For Geological Mapping And Resource Exploration In The Canadian Arctic, Byung-Hun Choe

Electronic Thesis and Dissertation Repository

The role of remote sensing in geological mapping has been rapidly growing by providing predictive maps in advance of field surveys. Remote predictive maps with broad spatial coverage have been produced for northern Canada and the Canadian Arctic which are typically very difficult to access. Multi and hyperspectral airborne and spaceborne sensors are widely used for geological mapping as spectral characteristics are able to constrain the minerals and rocks that are present in a target region. Rock surfaces in the Canadian Arctic are altered by extensive glacial activity and freeze-thaw weathering, and form different surface roughnesses depending on rock type. …

Ordovician Continental Paleogeography And Paleoenvironment For The Michigan Basin From Paleomagnetic Analysis, Michelle Macrae

Electronic Thesis and Dissertation Repository

This study investigates the paleomagnetic record of Paleozoic rocks from two Michigan basin localities in southwestern Ontario to help close the 40 myr gap in Paleozoic paleomagnetic data. Paleomagnetic data from the Queenston (Upper Ordovician) formation consistently exhibits easily removed viscous remanence, an intermediate and a high temperature component consistent with the unblocking temperatures of magnetite and hematite respectively. Alternating-field and thermal demagnetization in 16–20 steps up to 670º C typically reveal a southeastern, shallow up direction removed from magnetite, and a southwestern, steep up direction removed from hematite. A Late Paleozoic overprint was preserved in the magnetite and a …

A Method For The Geometric Analysis Of Rugose Coral Growth Ridges As Paleoenvironmental Indicators In The Middle Devonian Hungry Hollow Member Of Widder Formation, Michigan Basin, Andrew Thomson

Electronic Thesis and Dissertation Repository

Skeletons of Devonian rugose corals feature submillimetre-scale growth ridges on their outer surface (epitheca) that record the successive positions of the coral polyp during longitudinal corallite growth. Specimens of rugose corals Eridophyllum and Cystiphylloides from the Hungry Hollow Member of the Middle Devonian Widder Formation were sectioned longitudinally and imaged by SEM, and image processing techniques were applied to extract a line representing the epithecal surface. Local extrema found through peak detection allowed growth ridges to be represented as simplified triangles, so that geometric measurements (area, length) could be related to coral growth and analyzed in reference to possible paleoenvironmental …

Stable Cu, Fe, And Ni Isotopic Systematics Of The Sudbury Offset Dikes And Associated Rocks, Peter Christoffersen

Electronic Thesis and Dissertation Repository

The stable isotope ratio compositions of Fe, Ni, and Cu (δ⁵⁶Fe, δ⁶⁰Ni, and δ⁶⁵Cu) are reported for the first time in rocks from the Sudbury Igneous Complex (SIC). Massive sulfide ores, Quartz Diorite (QD), Inclusion bearing Quartz Diorite (IQD), and rocks from members of the Main Mass of the SIC were analyzed. The objective was to better understand the origin(s) and source(s) of the Offset Dikes and the associated sulfide mineralization. Based on stable isotope ratios and petrographic observations, two distinct types of sulfide mineralization hosted within the Offset Dikes are identified. Massive sulfide …

Investigating The Mechanism Of Deep-Focus Earthquakes Via In-Situ Acoustic Emission Experiments On Fe2sio4 At High Temperature And Pressure, Timothy Officer

Electronic Thesis and Dissertation Repository

In subduction zones, earthquakes are thought to be associated with faulting that arises from phase transformations. In order to test the viability of this mechanism experimentally, it was necessary to make microseismic measurements while the mineral under investigation was subjected to the pressure and temperature (P,T) conditions corresponding to their environment at depth. A system has been developed capable of making in situ acoustic emission (AE) measurements on samples under P,T conditions representative of the upper mantle and transition zone. Experiments were performed in a 3000-ton multi-anvil press using an 18/11 octahedral cell with 6 piezoelectric transducers mounted on the …

Time Series Analysis Of Surface Deformation Associated With Fluid Injection And Induced Seismicity In Timpson, Texas Using Dinsar Methods, Simon Thorpe

Electronic Thesis and Dissertation Repository

In recent years, a rise in unconventional oil and gas production in North America has been linked to an increase in seismicity rate in these regions (Ellsworth, 2013). As fluid is pumped into deep formations, the state of stress within the subsurface changes, potentially reactivating pre-existing faults and/or causing subsidence or uplift of the surface. Therefore, hydraulic fracturing and/or fluid disposal injection can significantly increase the seismic hazard to communities and structures surrounding the injection sites (Barnhart et al., 2014). On 17th May 2012 an Mw4.8 earthquake occurred near Timpson, TX and has been linked with wastewater injection operations in …

Geophysical Study Of Complex Meteorite Impact Structures, William Zylberman

Electronic Thesis and Dissertation Repository

Hypervelocity impact craters are the most abundant morphologic features on rocky planetary bodies of the Solar System, except on Earth where they have mostly been erased by plate tectonics, erosion, or are buried under sediments. The internal structure of complex impact craters can only be studied on Earth by using ground-truth geophysical and geological studies. Such approaches - combined with modeling - can reveal how impact cratering, target geological composition, erosion and other post-impact processes can lead to the observed geophysical anomalies, which could also be detected by remote geophysical data on other planetary surfaces. In this work, a multidisciplinary …

Geochemistry Of The Dome Mine Ankerite Veins: Insights Into The Multi-Stage Enrichment Of A World-Class Orogenic Gold Deposit, Jessica M. Stromberg

Electronic Thesis and Dissertation Repository

The Dome Mine in the world-class Timmins camp has produced over 16 Moz of gold during its 108 year production history. This gold endowment is the result of multistage enrichment of which the first stage is a set of ankerite veins that extend over 5,400 m in strike and 1,500 m vertically. A deposit wide geochemical study of the Dome ankerite veins was undertaken to characterize their genesis, geochemistry, and role in the deposit mineralization history. Samples and mapping from new and historic mine workings, bulk rock geochemistry, and stable isotope geochemistry were used to constrain the depositional context of …

Paleogeography Of Early Paleozoic Laurentia And Meguma, Avalonia Terranes Via Paleomagnetism And Faunal Review, Halima S. Warsame

Electronic Thesis and Dissertation Repository

Paleomagnetic assessment of 821 Cambrian to Silurian-aged rock specimens of igneous and sedimentary origin was used as a means to provide insight on the ancient geographies of the region in which these rocks are currently found. The Earth’s magnetic field direction can be recorded at the time of rock formation and/or at a later significant event by magnetic minerals, allowing these signatures to be used to track the past motions of the continents. Stepwise demagnetization of the Port au Port, St. George and Table Head Groups in western Newfoundland, and the Mavillette gabbro (426 +/- 2 Ma, U-Pb baddeleyite) of …

Metallogenic Setting Of High-Grade Gold Mineralization In The Neoarchean Hearne Craton, Kivalliq Region, Whale Cove, Nunavut, Canada, Mo Asmail

Electronic Thesis and Dissertation Repository

The Pistol Bay Gold Project is located on the northwestern shores of Hudson Bay, in the Tavani Segment of the Neoarchean Kaminak Greenstone Belt in the Hearne Craton of the Western Churchill Province. This project covers several gold prospects whose genesis is hotly debated. The primary objectives of this research are to answer critical questions regarding the nature and timing of gold mineralization. The investigation includes: (1) establish the absolute age of the felsic and mafic intrusions and the relative timing of gold mineralization; (2) document the nature of primary and hydrothermal mineral assemblages related to gold mineralization; and (3) …

New Gps Time Series Analysis And A Simplified Model To Compute An Accurate Seasonal Amplitude Of Tropospheric Delay, Hadis Samadi Alinia

Electronic Thesis and Dissertation Repository

Horizontal and vertical deformation of the Earth’s crust is due to a variety of different geophysical processes that take place on various spatiotemporal scales. The quality of the observations from spaced-based geodesy instruments such as Global Positioning System (GPS) and differential interferometric synthetic aperture radar (DInSAR) data for monitoring these deformations are dependent on numerous error sources. Therefore, accurately identifying and eliminating the dominant sources of the error, such as troposphere error in GPS signals, is fundamental to obtain high quality, sub-centimeter accuracy levels in positioning results.

In this work, I present the results of double-differenced processing of five years …

A Comparison Of Ground Motion Characteristics From Induced Seismic Events In Alberta With Those In Oklahoma, Krista M. Kaski

Electronic Thesis and Dissertation Repository

Ground motions from potentially-induced seismic events in Alberta of magnitude (M) > 3, recorded within 100 km, are empirically characterized in terms of their response spectral shapes and amplitudes. Ground motions are compared statistically to those from induced events in Oklahoma, as well as to three benchmark ground motion prediction equations (GMPEs), derived from natural events. Discrepancies between Alberta and Oklahoma events appear to be magnitude-dependent, and distance-independent. For events greater than M~4, the ground motions appear equivalent in the two regions. High-frequency motions from M< 3.5 events in Alberta are weaker than those of natural events, even those at shallow focal depths. For larger magnitudes, the residuals between the Alberta motions and benchmark GMPEs (Yenier and Atkinson, 2015; Atkinson, 2015; Abrahamson et al., 2014) suggest that observations are in reasonable accord with the models. These results provide a further understanding of ground motions from induced events in Alberta.

Allostratigraphy, Paleogeographic Evolution And Accommodation Controls Of The Lower Colorado Allogroup In West-Central Alberta, Canada (Western Canada Foreland Basin), Steve Morrow

Electronic Thesis and Dissertation Repository

The Lower Colorado allogroup of the Western Canada Foreland Basin is a mud-dominated rock succession of marine, estuarine, and coastal plain depositional origin. Relative sea-level oscillations produced bounding discontinuities that allow the allogroup to be divided into four alloformations: the Joli Fou, Viking, Westgate, and Fish Scales.

Rocks of the Lower Colorado allogroup within the study area record marine depositional environments represented by 9 facies. The facies represent depositional environments ranging from offshore marine to lower shoreface through to upper shoreface and river mouth environments.

Geometric analysis of the isopach maps of the regional allomembers of the Lower Colorado allogroup …

Assessment Of Earthquake Site Amplification And Application Of Passive Seismic Methods For Improved Site Classification In The Greater Vancouver Region, British Columbia, Frederick Andrew Jackson

Electronic Thesis and Dissertation Repository

There is renewed interest to improve seismic microzonation mapping in Greater Vancouver, British Columbia (BC). We investigate local geology as the cause of observed variable ground shaking from the 2015 M 4.7 Vancouver Island earthquake. We observe high amplification at 4-6 Hz on thick sediment and the northern edge of the Fraser River delta, and disparities with current regional seismic microzonation mapping. Site amplification and shear-wave velocity (V_S) are assessed from the first borehole earthquake recordings in BC. We also perform ambient vibration analyses at 13 new locations in southwest BC to highlight suitability of passive seismic methods …

Petrophysical Investigations Of The Marathon Cu-Pge Deposit, Marathon, On, Hiruni Gunawardana

Electronic Thesis and Dissertation Repository

Drill core samples obtained from four mineralized zones of the Marathon Cu-PGE deposit in the Coldwell igneous complex have been investigated for their petrophysical characteristics. Remanent magnetization was used as a possible tool to reorient core samples but a drilling induced overprint magnetization dominated the record. Anisotropy of magnetic susceptibility was measured to provide a proxy for the petrofabric of samples obtained from oriented drill cores; a well-defined planar fabric was found to strike 177 and dip 25°W, with down-dip lineation, in excellent agreement with inferred magmatic flow direction based on 3D modeling of mineralized footwall troughs. Magnetite rich lithologies …

Linking Mining Wastewater Discharge To Methylmercury Production In A Sub-Arctic Peatland, Lauren E. Twible

Electronic Thesis and Dissertation Repository

It is well established that the addition of sulphate (SO₄^2-) to peatlands increases methylmercury (MeHg) concentrations in pore waters via microbial methylation. Less information exists about the effects of different concentrations and sources of SO₄^2- loading on MeHg production in remote, non- SO₄^2- impacted regions like Canada’s north, where increased SO₄^2- loadings come not from the atmosphere, but often from mining waste water and rock tailings. A three year field study (two years of loading; one year of recovery) examined the effects of simulated wastewater (containing 27.2 mg/L SO₄^{2- …}

Depositional And Environmental Controls On Oxygen And Carbon Isotope Compositions Of Late Pleistocene To Mid-Holocene Shelly Fauna From The Huron Basin, Ontario, Canada, Jane Wilson

Electronic Thesis and Dissertation Repository

The δ¹⁸O and δ¹³C of aragonitic mollusc shells were analyzed from nine sites in the Huron Basin, Ontario, Canada. These sites represent three lake phases spanning the Late Pleistocene to the mid-Holocene (Algonquin, Transitional, and Nipissing) and three depositional environments (fluvial, estuarine, and lacustrine). Depositional environment controls mollusc δ¹⁸O more strongly than climate. The source of carbon and climate control the δ¹³C of the shelly fauna. Shells from fluvial sites are most depleted of ¹⁸O and exhibit the greatest antipathetic δ¹³C-δ¹⁸O covariation. This reflects the dynamic nature of this system. Lacustrine sites have …

The First Earthquake Site Assessments In Alberta, Canada, Joseph J. Farrugia

Electronic Thesis and Dissertation Repository

A thorough characterization of the site conditions at Alberta seismic stations is a vital component in assessing seismic hazard in the province. This thesis provides the first earthquake site characterizations in Alberta, including shear-wave velocity (V_S) depth profiles, estimates of the average shear-wave velocity in the upper 30 m (V_S30) and peak frequency (f_peak), and their validation for prediction of earthquake site amplification. National Building Code of Canada site classes are limited to C and D based on V_S30 estimates, with D being the predominant site class. Three …

Planform Change And Bedload Transport In Braiding Rivers, Lara Middleton

Electronic Thesis and Dissertation Repository

Proglacial gravel-bed braided rivers have a dynamic planform composed of multiple unstable channels and ephemeral bars. The planform position is seen to change during high flows as the position of channels and bars is seen to change. These changes are produced as pulses of bedload transport are mobilized and transported downstream, causing an observable change in the river planform and morphology. While it is known that bedload transport, morphological change and planform change in a braided river are inter-related the relationships have not been quantified. The first component of this research was to build on previous results by re-analyzing daily …

Nitrogen And Carbon Isotopic Dynamics Of Subarctic Soils And Plants In Southern Yukon Territory And Its Implications For Paleoecological And Paleodietary Studies, Farnoush Tahmesabi, Fred J. Longstaffe, Grant Zazula, Bruce Bennett

Earth Sciences Publications

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C₃ plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ¹⁵N and organic carbon δ¹³C than plants from the same sites with a …

New Biotite And Muscovite Isotopic Reference Materials, Usgs57 And Usgs58, For Δ2h Measurements–A Replacement For Nbs 30, Haiping Qi, Tyler B. Coplen, Matthias Gehre, Torsten W. Vennemann, Willi A. Brand, Heike Geilmann, Gerald Olack, Ilya N. Bindeman, Jim Palandri, Li Huang, Fred J. Longstaffe

Earth Sciences Publications

The advent of continuous-flow isotope-ratio mass spectrometry (CF-IRMS) coupled with a high temperature conversion (HTC) system enabled faster, more cost effective, and more precise δ²H analysis of hydrogen-bearing solids. Accurate hydrogen isotopic analysis by on-line or off-line techniques requires appropriate isotopic reference materials (RMs). A strategy of two-point calibrations spanning δ²H range of the unknowns using two RMs is recommended. Unfortunately, the supply of the previously widely used isotopic RM, NBS 30 biotite, is exhausted. In addition, recent measurements have shown that the determination of δ²H values of NBS 30 biotite on the VSMOW-SLAP …

Using Bolide Airwaves To Estimate Meteoroid Source Characteristics And Window Damage Potential, Nayeob Gi

Electronic Thesis and Dissertation Repository

We examined the far-field infrasonic signals produced by 78 bolides simultaneously detected by U.S. government sensors to determine the mechanisms responsible for interstation spreads in infrasound signal period. These signal period spreads lead to large variances in source energy estimates. Our analysis suggests that while acoustic source height contributes to some extent to the variance in signal periods, the range from the source to the station and in particular station noise plays a more significant role.

By simulating the near-field weak shocks from a suite of well-observed energetic fireballs, we have empirically estimated how often fireball shocks produce overpressure ( …

Enstatite Achondrites As Indicators Of Processes And Environments In The Early Solar System, Diego David Uribe

Electronic Thesis and Dissertation Repository

This thesis investigates the processes and environments of formation of the anomalous enstatite achondrites NWA 4301, Zakłodzie, and NWA 8173 to determine how they relate to other enstatite meteorites (chondrites, impact melt rocks, aubrites, and so-called “primitive enstatite achondrites”). Observations of Zakłodzie and NWA 4301 showed both meteorites may share a common parent body, but experienced different metamorphic conditions. Different zonation patterns in plagioclase, silica polymorphs and associations, and sulfide assemblages indicate Zakłodzie experienced higher metamorphic temperatures and cooled faster than NWA 4301, therefore NWA 4301 was buried deeper in the parent body relative to Zakłodzie. In NWA 8173, mineral …

Methylmercury Production In Two Northern Fen Peatlands, Mikhail J. Mack

Electronic Thesis and Dissertation Repository

Northern peatlands provide conditions favourable for sulphate reducing bacteria, microorganisms responsible for producing methylmercury, an aquatic pollutant. An expected climate driven shift from moss- to sedge-dominance may alter mercury biogeochemistry. Observations from a moss-dominated poor fen and sedge-dominated intermediate fen were used to compare methylmercury to assess if contrasting plant communities, nutrients status and/or hydrologic regime control production. Chapter 2 compared porewater methylmercury and ancillary chemistry across two Northern Ontario fens. The lower water table, greater dissolved organic carbon, and lower pH in the poor fen resulted in 3.1 times greater methylmercury. Chapter 3, riparian zones in intermediate fen were …

Using Fluid-Mobile Elements To Decipher An Aqueous History Preserved In The Sedimentary Rocks Of Gale Crater, Mars, Jeff A. Berger

Electronic Thesis and Dissertation Repository

Fluid-mobile elements preserve a record of the aqueous history of Mars in the sedimentary rocks of Gale Crater, and they are traceable with the rover Curiosity’s Alpha Particle X-ray Spectrometer (APXS). This is the fundamental principle behind the scientific questions addressed in the four main chapters of this dissertation. First, we conducted a field study at Hawai’i, an established Mars analogue, to investigate sedimentary processes and alteration in rocks comparable to those in Gale Crater. We conclude that open system, circumneutral weathering is very limited in Gale rocks; acid sulfate alteration and sedimentary mixing of diverse rocks is likely. Second, …

Developing And Testing A Model Of Site Amplification For Southern Ontario, Sebastian Braganza

Electronic Thesis and Dissertation Repository

Commonly-applied methods to estimate ground-motion amplification for earthquake hazard applications in southern Ontario are highly generalized. Site amplification effects have typically been estimated by a parameter that is not well-known in the region, the time-averaged shear-wave velocity in the top 30 metres of soil; V_S30. Moreover, V_S30 is not well correlated with site amplification in this region. This study develops a model that can better estimate ground motions and shaking intensities in southern Ontario based on readily-available information. The model is based on a site’s peak response frequency (f_peak), which can be estimated from depth-to-bedrock. …

Experimental Studies Of Electrical Resistivity Behavior Of Cu, Zn And Co Along Their Melting Boundaries: Implications For Heat Flux At Earth’S Inner Core Boundary, Innocent Chinweikpe Ezenwa

Electronic Thesis and Dissertation Repository

Abstract

The electrical resistivity of high purity Cu, Zn and Co has been measured at pressures (P) up to 5GPa and at temperatures (T) in the liquid phase. The electrical resistivity of solid state Nb was also measured up to 5GPa and ~1900K. All measurements were made in a large volume cubic anvil press. Using two thermocouples placed at opposite ends of the sample wire, serving as temperature probes as well as resistance leads, a four-wire technique resistivity measurement was employed along with a polarity switch. Post-experiment compositional analyses were carried out on an electron microprobe.

The expected resistivity decrease …

Cu-Pd Mineralization And Exploration Geochemistry Of The Eastern Gabbro, Coldwell Alkaline Complex, On, Canada, Yonghua Cao

Electronic Thesis and Dissertation Repository

The Eastern Gabbro forms the northern and eastern margin of the Coldwell Alkaline Complex. It contains three magma series: the barren meta-basalt, the Layered Series, and the Marathon Series which hosts all known PGE mineralization. The Marathon Series can be distinguished from other Series using the combination of portable X-ray fluorescence (pXRF) and benchtop scanning electron microscope (bSEM). Whole-rock Ba, Mg# (molar Mg/(Mg+Fe)*100), Zr and V/Ti values acquired from pXRF, and Mg#s of olivine and clinopyroxene, and anorthite content (molar Ca/(Ca+Na)*100) of plagioclase acquired from bSEM-EDS are key parameters. The Layered Series generally contains higher Ba and lower V/Ti than …