Earth Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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Mount Meager, a glaciated volcano in a changing cryosphere: hazard and risk challenges

Author: 
Date created: 
2018-10-24
Abstract: 

Mount Meager is a glacier-clad volcanic complex in British Columbia, Canada. It is known for its landslides, of which the 2010 is the largest Canadian historical landslide. In this thesis we investigated slope instability processes at Mount Meager volcano and the effects of ongoing deglaciation. We used a variety of methods including field and remote, geological, geomorphological and structural mapping to characterize glacial and landslide activity at Mount Meager. We used Structure from Motion photogrammetry (SfM) and Lidar to produce digital surface models and InSAR to monitor slope deformation. We applied SfM to historic photography to document glacier and landslide activity at Mount Meager. We discussed a model of growth and erosion of a volcano in glacial and interglacial periods, and the scientific and dissemination value of historic 3D topographic reconstruction. We described the 2010 Mount Meager landslide deposit to interpret emplacement dynamics and kinematics. The 2010 landslide separated in water-rich and water-poor phases that had different runout and distinct deposits. We analyzed historic airphotos to constrain the slope deformation prior to the 2010 collapse. The glacier near the toe of the slope retreated in the failure lead up, the collapse evolved in four subfailures involving the whole volcanic sequence and some basement rocks. We estimated 6 × 106 m3 of water in the slope, that allowed the separation of the frontal water-rich phase. The total failure volume was 53 ± 3.8 × 106 m3. We identified 27 large (>5×105 m2) unstable slopes at Mount Meager and calculated ~1.3 km3 of ice loss since 1987. The west flank of Plinth peak and Devastation Creek valley moved up to -34±10 mm and -36±10 mm, respectively, over a 24-day period during the summer of 2016. The failure of these slopes could impact infrastructures and communities downstream of the volcano. The resulting decompression on the volcanic edifice after the failure of Plinth peak would affect the stress field to a depth of 6 km and up to 4 MPa. This sudden decompression could lead to hydrothermal or magmatic eruptions

Document type: 
Thesis
File(s): 
Supervisor(s): 
Brent Ward
Benjamin van Wyk de Vries
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.

Characterization of landform evolution and slope response to the 2015 earthquake sequence and annual monsoon in Central Nepal

Author: 
Date created: 
2018-06-26
Abstract: 

The April 25th, 2015 Mw 7.8 Gorkha earthquake triggered thousands of co-seismic landslides across Central Nepal. This thesis investigates the evolution and controls on co- and post-seismic mass movements at two case study slopes, Tushare and The Last Resort using a range of remote sensing techniques collected prior to and following the 2015 earthquakes over the five-year period from 2012 to 2017. A range of remote sensing techniques including terrestrial laser scanning, digital photography, photogrammetry, and satellite imagery were used to characterize the landslides at these slopes. Engineering geological and geomorphological mapping and three-dimensional rockfall modelling were employed to analyze structural controls on mass movements. Analysis of surface change using change detection techniques was used to evaluate landform evolution at the slopes in response to the earthquakes and 2015 to 2017 annual monsoons. Observed post-seismic instability is dominated by reactivation of colluvium from the co-seismic failures as opposed to initiation of new failures. Elevated landslide hazard associated with loose debris on the slopes is anticipated to continue in future monsoons.

Document type: 
Thesis
Supervisor(s): 
Doug Stead
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Snow drought and streamflow drought in western North America in the context of a warming climate

Author: 
Date created: 
2018-08-17
Abstract: 

In western North America, snowpack supplies much of the water used for irrigation and for municipal and industrial uses, and snowmelt recharges groundwater and provides ecosystem-sustaining baseflow during low flow periods. Continued climate warming is expected to have large impacts on snowmelt hydrology, with subsequent impacts on low flows and snow and streamflow drought regimes. This research combined two separate methodologies, a data-driven (downward) approach and a process-based (upward) approach, to improve our understanding of snow drought and streamflow drought in the context of a warming climate. The data-driven approach combined observed hydroclimatic time series with multiple statistical methods, including bivariate and partial correlation and temporal and spatial analogs. The process-based approach combined climate change projections and hydrological modelling. The two approaches yielded consistent results that, together, illustrate that snow drought, low flows, and streamflow drought are sensitive to winter climate conditions, particularly precipitation and thawing degrees. In the context of climate warming, increased winter season thawing degrees leads to increased warm (temperature-driven) snow drought, shorter and less severe winter low flows, longer and more severe summer low flows, and increased summer streamflow drought risk. Further, both approaches showed that the response of snowmelt hydrology to climate warming is non-linear, and regions with winter temperatures near 0°C exhibit substantially larger impacts from +2°C of warming compared to regions with winter temperatures far below 0°C. Temperature-driven shifts in snow drought, low flows, and streamflow drought regimes will have widespread implications for surface water supply security. Increased frequency of warm snow droughts will likely lead to an increased frequency of mid-winter melt events, which will create challenges for water management. As summer low flow periods become more severe and snow-drought related summer streamflow droughts become more frequent, the potential for more severe summer water shortages increases. The most severe shortages will likely occur due to the co-occurrence of warm and dry conditions.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Diana Allen
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.

Sedimentology, Ichnology and Stratigraphic Architecture of the Viking Formation in the Chedderville Field Area, Alberta, Canada

Date created: 
2018-01-12
Abstract: 

The Late Albian Viking Formation is a siliciclastic unit that accumulated in the Western Interior Seaway. The thesis study area encompasses Townships 36-41, Ranges 3-9W5 in Alberta, Canada, and includes the Chedderville Field, the southern Willesden Green and Farrier fields, the northern Caroline and Garrington fields, and the western Gilby, Medicine River and Sylvan Lake fields. Using sequence stratigraphic principles, the Viking Formation is divided into five depositional sequences (Sequence 1-5), predominantly bound by transgressively modified subaerial unconformities (sequence boundaries). Depositional sequences are arranged in six facies associations (FA1-6) that consist of seventeen facies (F1-17). The study focuses on the wave-dominated, storm-influenced estuarine incised valley deposits of Sequence 2, wave-dominated, fluvial-influenced, storm-affected delta complexes of Sequence 3; and the fluvial successions of Sequence 4. Sequences 2-4 are bounded below by mudstone deposits of the Joli Fou Formation and “regional Viking” (Sequence 1) and above by the Westgate Formation (Sequence 5).

Document type: 
Thesis
File(s): 
Supervisor(s): 
James MacEachern
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Numerical modeling of highly saline wastewater disposal in Northeast British Columbia

Author: 
Date created: 
2018-04-26
Abstract: 

Dense, saline wastewater generated during oil and gas activities (hydraulic fracturing and production) is commonly disposed of in deep formations, but the migration of this wastewater after entering the subsurface is poorly understood. This study uses numerical models to simulate wastewater disposal in the Paddy-Cadotte of Northeast British Columbia using both single-well axisymmetric box models and a regional model of the formation in which multiple disposal and water source wells operate. A sensitivity analysis performed on the box models reveals that dispersivity and permeability exert the strongest control on overall wastewater distribution. Models show that wastewater migrates further than predicted using a simple volumetric calculation, and extends further along the base of the formation than the top due to variations in fluid density. Interference between disposal and source wells is observed to influence wastewater migration, while formation dip and regional groundwater flow have no discernible impact.

Document type: 
Thesis
Supervisor(s): 
Diana Allen
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Investigating regional groundwater flow influences on slope stability in unlithified materials

Author: 
Date created: 
2018-04-17
Abstract: 

Elevated pore pressures play an integral part in slope failure; however, the nature of the regional groundwater flow regime is often not incorporated in slope stability analysis. This research aims to improve our understanding of how the dynamic nature of the groundwater flow regime exerts control on the regional occurrence of landslides in unlithified materials. An integrated hydrogeological – geotechnical methodology is used to investigate the hydrogeological controls on slope stability in Northeast British Columbia. A two-part approach utilized both a series of steady-state groundwater models developed using SVFLUX to investigate the role of geologic contact geometry and hydrogeological characteristics, and a transient groundwater model developed using MIKE SHE to investigate the role of climate. The analysis of these groundwater results highlights implications of regional and local scale hydrogeological processes on pore water pressures. Several challenges were encountered in regard to investigating processes at fine scale resolution within in a large scale groundwater flow model, and an inability to export unsaturated zone results from MIKE SHE limited the slope stability modeling in SV SLOPE.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Diana Allen
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Investigating the geochemistry of selenium in the residual from biologically treated mine-impacted water

Date created: 
2018-04-16
Abstract: 

Bacterially-mediated wastewater treatment is commonly used to prevent selenium (Se) release to the environment. This research focuses on the characterization of a selenium-rich residual, the by-product of industrial wastewater treatment. Solid-phase selenium speciation was investigated through sequential extraction procedures (SEP) and X-ray Absorption near Edge Spectroscopy (XANES). Selenium mobility and changes in Se speciation were tested through batch experiments under varying redox and pH conditions. The residual exhibits some heterogeneity, and is dominated by metal selenide species, with some evidence for less-reduced Se species. The greatest Se mobility was in mildly oxidizing conditions at neutral pH which also showed the least speciation change in the residual. Under highly-oxidizing and/or low-pH conditions Se mobilization was lower and reaction was dominated by oxidation of the metal-selenides to Se0 and/or SeS2. Additionally, unexpected speciation changes in the solid phase during the SEP were observed.

Document type: 
Thesis
Supervisor(s): 
Dirk Kirste
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Structural and mineralogical controls of gold mineralization at the Tajitos project, Sonora, Mexico

Date created: 
2018-04-03
Abstract: 

Tajitos is an orogenic vein-hosted gold deposit in Sonora, Mexico. The local geology is composed of Jura-Cretaceous volcanic and sedimentary strata, with syn-volcanic granodioritic plugs and a post-depositional gabbroic stock. North-northeast directed compression during the Laramide orogeny formed a fold and thrust belt, folding and faulting the local strata. During the late Laramide orogeny, a mineralization event occurred, forming syn-deformational vein-hosted gold, under brittle-ductile conditions in the mid- to upper crust. Post-mineralization Basin and Range extension accompanied the emplacement of lamprophyric dykes and reactivation of mineralized faults with normal movement. Gold mineralization is hosted in steeply dipping, southeast trending fault-fill veins with surrounding coeval zones of extensional veins and quartz-sericite-pyrite alteration. High-grade mineralization shoots within the veins plunge steeply west and moderately to the southeast. Gold in the fault-fill veins primarily occurs along crack-seal laminations associated with galena and chalcopyrite occupying interstities between quartz and rimming pyrite, arsenopyrite, and sphalerite.

Document type: 
Thesis
Supervisor(s): 
Daniel Marshall
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Late Cenozoic glaciations and environments in southernmost Patagonia

Date created: 
2018-04-05
Abstract: 

This thesis advances understanding of late Cenozoic landscape evolution and glaciation in southernmost South America using continental sedimentary deposits and landforms in the Lago Cardiel region in the foothills of the southern Patagonian Andes and along the Atlantic north and south of the Strait of Magellan. The evolution of the landscape in these two areas was determined through landform mapping and relative chronologic landform correlations. Paleomagnetic characteristics of late Cenozoic sediments and basalt flows and the stratigraphy and sedimentology of Pleistocene glacial sediments in sea cliffs and anthropogenic exposures provide a chronology and evidence of depositional environments during Pleistocene glaciations. The landscape in the Lago Cardiel area changed significantly following the last major period of tectonic uplift at the end of the Miocene. Large west-trending valleys that incise Miocene-aged basalt were abandoned by their formative rivers about 4.4 Ma. The closed basin that contains Lago Cardiel began to form on the relict plain surface before 4.0 Ma and grew in size throughout the Pliocene and Pleistocene by a combination of erosion by small streams, deflation, colluviation, and possibly tectonic collapse. Drainage reorganizations occurred at about 4.0 Ma and 3.6 Ma, most likely initiated by increased aggradation or isostasy during Pliocene glaciations. Eolian, fluvial, and mass-movement processes continued to alter the landscape throughout the Pleistocene with higher rates during glacial periods. Evidence of at least three glaciations is recorded in the stratigraphic exposures at the Atlantic Coast and the shores of the Strait of Magellan. At Cabo Vírgenes and Bahía Posesión, two glacial drift units were deposited in a grounding-line environment. These sediments are normally magnetized and date to the Brunhes Chron (<0.78 Ma). The Tres de Enero highway cut exposes three subglacial tills deposited during the Great Patagonian Glaciation (GPG) – two normally magnetized tills that I assign to the early Brunhes Chron and a lower reversely magnetized till deposited during the Matuyama Chron (2.581-0.78 Ma). The reversely magnetized till and other reversely magnetized GPG sediments indicate that the earliest Pleistocene glaciations occurred before 0.78 Ma. In the Río Gallegos Valley, a 0.86 Ma basalt flow caps a thick unit of normally magnetized glaciofluvial gravel, which was probably deposited during the Jaramillo Subchron (1.075-0.991 Ma). This thesis provides a timeline for the evolution of the landscape of the Lago Cardiel region from the Miocene to the present. It also contributes to our understanding of the age and depositional environments of GPG and post-GPG 1 glacial events in the Strait of Magellan region by documenting the magnetic polarity of glacial sediments throughout the region.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Brent Ward
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.

GIS-based analysis of spring occurrence and spring source areas in Peace River Regional District, British Columbia

Author: 
Date created: 
2018-04-12
Abstract: 

Springs in the Peace River Regional District are important fresh water sources for domestic and industrial use, however, little is known about their hydrogeology. This study investigated the controls on spring occurrence and delineated the spring source areas (SSA). Samples from 36 springs were collected and analyzed for chemical and isotopic composition. The chemistry suggested 20 Quaternary and 16 Bedrock aquifer sourced springs. A GIS-based multi-criteria decision analysis integrated spring-related factors (slope, curvature, hydrogeological features, topographic wetness index, surficial geology, and drift thickness) to produce maps showing the likelihood for occurrence of Quaternary or Bedrock-sourced springs. There was a ~70% success rate for correctly identifying sources of the sampled springs. A GIS-based tool was applied to determine topographic SSA’s for 33 springs with varying degrees of success. Although both the maps and SSAs contain uncertainty, there is sufficient information to support decision-making in water resource protection and management.

Document type: 
Thesis
Supervisor(s): 
Dirk Kirste
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.