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

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A comprehensive volcanic hazard assessment for Mount Meager Volcanic Complex, B.C.

Author: 
Date created: 
2020-11-25
Abstract: 

Mount Meager Volcanic Complex located in south-western British Columbia exhibits possible volcanic activity in the form of hydrothermal features such as several hot springs around the base and a fumarole field in the northeast corner of the complex. Operational infrastructure, including a run-of-river hydroelectric project, is present in the vicinity of the volcano and a significant population exists only 60 km downstream. Up until now, no volcanic hazard assessment or accompanying map existed for Mount Meager. Hazard assessments are important tools used to understand, manage and reduce the risks associated with volcanic environments. This thesis investigates the potential primary volcanic hazards associated with a future explosive eruption at Mount Meager. These hazards are identified as lahars, pyroclastic density currents and volcanic ash. With the use of numerical modelling programs, the distribution, timescales, intensity of inundation and other parameters are investigated. Finally, a suite of scenario-based preliminary hazard maps have been produced to visually display these hazards as a communication tool. This information relays hazard information to stakeholders with a vested interest in the potential risks involved with any future explosive volcanic event from Mount Meager.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Glyn Williams-Jones
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Reconstructing depositional architecture and stratigraphy of coastal- to shallow-marine strata in a low-accommodation system: McMurray Formation, Alberta, Canada

Author: 
Date created: 
2020-09-24
Abstract: 

A new and novel sedimentological-statistical approach is applied to Lower Cretaceous McMurray Formation strata in the southwest quadrant of the McMurray depocenter to further comprehend the impact of accommodation space creation on the preserved record of coastal- to shallow-marine deposits in a low-accommodation setting. Across the study area, the McMurray Formation consists of discrete depositional units bounded by flooding surfaces and/or transgressive surfaces of erosion. The facies characteristics, depositional architecture and sequence stratigraphy of these depositional units are investigated, focused in the three main areas: quantitatively defining the controls on localized accommodation creation, recognizing new depositional units within the McMurray Formation, and quantifying and characterizing the speed of the Boreal Sea transgression. First, depositional architecture work tied to statistical analysis in the Sparrow Paleovalley (≈1/3 of the study area) reveals the local overthickening of +21% to +45% of the depositional units. The local accommodation space creation is demonstrated to have resulted from syndepositional epikarst subsidence within the underlying Devonian carbonates. Second, the detailed facies analysis and depositional architecture analysis of the Regional C depositional unit reveals a regionally extensive allogenic flooding surface (Top C2) dividing the Regional C depositional unit. Recognition of this new stratigraphic surface further reinforces the persistent and slow drowning of the McMurray depocenter during accumulation of the McMurray Fm, and that deposition occurred in a low-accommodation setting. Finally, detailed facies analysis, depositional architecture analysis, sequence stratigraphic work and statistical methods applied to the entire McMurray Formation across the study area reveals that the thicknesses of depositional units decrease markedly upward, and that this thickness decrease correlates to a change in the facies character of the transgressive mudstones underlying each depositional unit. Together, these data record the acceleration in the rate of the transgression of the Boreal Sea across the McMurray depocenter.

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

Investigating Canada's deadliest volcanic eruption and mitigating future hazards

Author: 
Date created: 
2020-11-09
Abstract: 

Monogenetic volcanoes are the most common volcanic landforms on Earth and usually form isolated small-volume volcanic centres with a wide range of eruptive styles and products. Here, I focus on the case of Tseax volcano (Wil Ksi Baxhl Mihl) in north-western British Columbia, Canada’s deadliest volcanic eruption; its ~ 1700 CE eruption killed up to 2,000 people of the Nisga’a First Nation. Tseax is composed by two imbricated volcanic edifices (an outer breached spatter rampart and an inner 70 m high tephra cone) and 4 far-travelled, valley-filling lava flows (2 pāhoehoe and 2 ‘a‘ā) for a total volume of 0.5 km3 submerging the former Nisga’a villages. All the erupted products are Fe-, Ti-rich, basanite-to-trachybasalts and their geochemical homogeneity suggests the eruption of a single magma batch that was produced by low partial melting of a cpx-poor wehrlite at 52 - 66 km depth. The magma was stalled for > 10³ days in the upper crust and cooled down to 1094 - 1087 °C prior to eruption. The eruption lasted between 1 to 4 months and was divided in two main periods. The first period occurred in a typical Hawaiian-style with lava fountaining, spatter activity and the eruption of long pāhoehoe flows. Almost half of the total lava volume was erupted in the first days of the eruption with fluxes > 800 m³/s. The lava may have engulfed the Nisga’a villages in a few tens of hours and thus be one of the cause for the fatalities. A ‘vog’ produced when the lava entered the Nass River may have been also responsible for the Nisga’a deaths. The second period of activity was characterized by low intensity Strombolian explosions with the building of the tephra cone and eruption of the shorter ‘a‘ā lava flows. In high speed channelised lava flows, standing waves are often interpreted as hydraulic jumps, indicating supercritical conditions. Using open channel hydraulic theory for supercritical flows, the geometry of the standing waves to constrain eruption flux and viscosity. I propose that investigating standing waves during ongoing eruption is a powerful tool to help for lava flow modelling and hazard mitigation.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Glyn Williams-Jones
Karim Kelfoun
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.

The Murray dyke swarm and its bearing on Cretaceous magmatism and tectonics in the Canadian Cordillera

Author: 
Date created: 
2020-04-17
Abstract: 

The Murray dyke swarm fed the Spences Bridge Group, part of an Early Cretaceous continental arc overlapping the Intermontane terranes. Dykes are well-exposed in a 2x10 km area and strike to the north in a sheeted morphology, consistent with an extensional stress regime and rapid emplacement at 103.7 Ma, based on 40Ar/39Ar and U-Pb geochronology. Dyke compositions range from mafic to felsic. Dykes correspond to three petrological types unrelated through fractional crystallization, reflecting distinct mantle-derived melts that subsequently evolved to various degrees. Two types were generated by flux-melting above a steep slab; the other reflects infiltration of the arc by intraplate-composition melts generated during slab break-off. Subsequent southwest-verging contraction folded the Spences Bridge Group and inverted its forearc basin to the west, shedding detritus that lapped onto the Group with angular unconformity. This evolution is consistent with accretion of the Insular terranes by east-dipping subduction, triggering orogenesis in the mid-Cretaceous.

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

Shoreline geometry and depositional architecture of wave-dominated deltaic successions: Upper McMurray Formation, Central-C Area, Northeast Alberta, Canada

Date created: 
2019-11-18
Abstract: 

To decipher the complex juxtaposition of laterally adjacent depositional environments that occur in the upper member of the McMurray Formation to the Wabiskaw Member, detailed sedimentological and ichnological analyses were undertaken. Thirteen facies and five facies associations are identified. The study interval consists of shallow-water deltaic to embayed shoreface successions, that increase in thickness and marine influence upwards. Allogenic and autogenic flooding surfaces were distinguished based on sedimentological, ichnological, and geophysical properties. Allogenic flooding surfaces were mapped across the study area, to identify the internal stratigraphic architecture of the upper member of the McMurray Formation. The thicknesses of individual deltaic shingles were identified by mapping their bounding autogenic flooding surfaces. Allogenic flooding surfaces were assessed to identify the viability of use as localized supplemental datums. During McMurray deposition the paleoshoreline evolved from an elongated restricted embayment to a less-confined, open embayment with more normal marine processes.

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

Modelling wastewater spills and mapping areas most vulnerable to groundwater quality deterioration in northeast British Columbia

Date created: 
2020-04-20
Abstract: 

This study utilized numerical modelling of spills and leaks of natural gas production wastewater into the shallow subsurface to identify areas most vulnerable to groundwater quality deterioration in Northeast British Columbia. Modelling was conducted using the flow and transport code TOUGH2. The models were designed to address three main factors identified from the DRASTIC method for vulnerability assessment: (1) Depth to water, (2) Impact of vadose zone, and (3) Conductivity of the aquifer materials. Models show that dense saline wastewater will migrate further and faster through highly permeable materials. Lower permeability materials attenuate the wastewater migration resulting in smaller plumes with locally higher brine concentrations. A sensitivity analysis reveals that the vadose zone permeability and depth to water table are significant controls on wastewater migration and footprint. Overall, the vulnerability in the region is relatively low, with some exceptions near river valleys, mountainous regions, and areas with shallow water tables.

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

Sequence stratigraphy and facies analysis of the viking formation in crossfield and adjacent areas, Alberta, Canada

Author: 
Date created: 
2020-03-18
Abstract: 

The Lower Cretaceous Viking Formation is a siliciclastic unit that accumulated in the Western Interior Seaway and produces hydrocarbons in the Crossfield and surrounding area. The study area encompasses Townships 24–31, Ranges 28W4 to 4W5 in Alberta, Canada. Sedimentological and ichnological observations of 54 cored wells, coupled with the analysis of 1415 geophysical well logs allowed the generation of a high-resolution sequence stratigraphic framework. The Viking Formation is subdivided into four discrete depositional sequences (Sequences 1-4), but this study focuses on Sequence 3, as it constitutes the main cored interval in the Crossfield area. Sequence 3 includes eleven sedimentary facies that are grouped into three facies associations (FA1-3). Deposits of FA1 correspond to the transgressive system tract. The overlying highstand system tract encompasses FA2 and FA3. FA3 contains the reservoir sandstone interval, and comprises sanding-upward successions interpreted to represent deposition in a mixed-process wave-dominated, fluvial-influenced symmetric delta.

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

Implications of early halo type veins at the IKE copper-molybdenum-silver porphyry deposit, British Columbia, Canada: alteration studies as a guide to ore grade

Author: 
Date created: 
2020-01-17
Abstract: 

The IKE deposit is a Cu-Mo-Ag porphyry deposit located in the southern portion of the Canadian Cordillera in British Columbia, Canada. Significant amounts of early halo type (EHT) veins are found throughout the deposit, which are typically associated with deep-seated porphyry deposits. This project investigates the geochemical properties of EHT veins and how they relate to mineralization. Petrographic studies were carried out on EHT veins to identify the mineral and fluid inclusion assemblages in the EHT veins, and how IKE compares to other deposits. Cathodoluminescence studies confirm a large overprint of potassic alteration, with a limited expression of alteration zoning typically seen in porphyry deposits. Shortwave infrared spectroscopy was used to identify subtle geochemical changes in the alteration minerals. The primary mineral picks, white mica and chlorite absorption features, and illite crystallinity values were examined to qualitatively determine fluid composition and pathways in the deposit and aid in future exploration.

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

Integrated ichnological, sedimentological, and geochronological analysis of the Late Cretaceous Upper Nanaimo Group, Saltspring Island, B.C., Canada

Author: 
Date created: 
2020-04-08
Abstract: 

Integrated ichnological, sedimentological, and geochronological investigation of the Late Cretaceous Nanaimo Group, Saltspring Island, B.C., Canada was undertaken to examine the existing lithostratigraphic mapping and facies characteristics of deep-water slope deposits. Maximum depositional ages from U-Pb dating of detrital zircon grains (N=3744) provide a geochronologic framework for facies relationships studied at a cm-scale over ~1500 m of stratigraphic thickness. Passive gamma-ray emissions (K, U and Th spectra) were collected using a hand-held gamma-ray scintillometer. The results of this integrated analysis suggests that: (1) almost all of the Cretaceous-aged strata in the study area belongs to the upper Nanaimo Group; (2) the youngest zircon grains in the earliest Nanaimo Basin are Middle Jurassic in age, indicating that further study of basin evolution is needed; and (3) integrated facies analysis of thin-bedded slope deposits provides improved criteria for recognizing their different subenvironments compared to employing sedimentological observations alone.

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

Magmatic sources to volcanic gas emissions: Insight from the Garibaldi Volcanic Belt, western Canada

Author: 
Date created: 
2019-10-18
Abstract: 

Volcanoes are the surficial representation of the complex interplay of magmatic, crustal, and hydrothermal processes operating below the Earth’s surface. Studying volcanic deposits provides a unique snapshot into the composition of the deep mantle source. Melt inclusions, which are small pockets of magma trapped inside growing crystals, preserve multi-faceted records of magma petrogenesis. Additionally, the magma at depth contains a significant proportion of dissolved magmatic gases. Once these gases become saturated in the magma, they exsolve into a separate vapour phase and ascend quickly to the surface, where they are released as volcanic gases. The composition of gases at the surface can provide valuable insight into the composition of the magma at depth, as well as the shallow-level hydrothermal system. Volcanic gases are an important factor controlling whether an eruption is gentle and effusive, or violent and explosive. A greater amount of gas that separates at depth can trigger large, explosive eruptions (Devine et al., 1998; Shinohara, 2008). Therefore, gas detection at the surface is an essential monitoring tool for eruption forecasting. In this thesis, I begin with an in-depth look inside glassy and crystallized olivine-hosted melt inclusions and assess the nature of micron-scale solid phases occupying the vapour bubble. From here, major, volatile and trace element compositions of olivine-hosted melt inclusions from every centre along the Garibaldi Volcanic Belt (GVB) reveals a north to south transition from an enriched mantle signature, to a subduction-modified depleted mantle source. Finally, the recent re-discovery of fumaroles beneath the summit glacier of Mount Meager has prompted the first MultiGAS survey in the GVB. The plumes are H2S, CO2 and H2O rich, and hot enough to melt through the overlying ice. Can the basaltic magma, represented by melt inclusions, produce the volcanic gases currently emitted at the surface? To test this, two different gas modelling software (SolEx and MagmaSat) are used, along with original and recalculated (with the bubble components) as input parameters. The resulting molar ratios are compared with MultiGAS ratios of fumaroles. Overall, SolEx closed-system degassing using recalculated melt inclusions yields the best approximation to MultiGAS ratios. This thesis addresses a compositional knowledge gap within the GVB. By understanding both the distinct magmatic sources underlying the arc, as well as the composition of volcanic gases emanating from summit fumaroles, we gain a broad and comprehensive geochemical overview of the Garibaldi Volcanic Belt.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Glyn Williams-Jones
Severine Moune
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.