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

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Utilizing sedimentology and geochronology to resolve the architecture of paralic strata in low-accommodation systems, McMurray Formation, Canada

Date created: 
2021-09-09
Abstract: 

A combined sedimentological-geochronological approach is employed to unravel the importance of paleoenvironments landward of the shoreline in understanding the stratigraphic architecture, and chronostratigraphy of the McMurray Formation in the Alberta Foreland Basin (referred to herein as the McMurray Depocenter; MDC), Canada. Presently, the McMurray Fm is subdivided based on the presence of regionally mappable mudstones, the bases of which are interpreted as flooding surfaces. However, the McMurray Fm comprises a wide range of paleoenvironments, and the Firebag Tributary in the northeastern MDC hosts a large volume of delta and coastal plain strata, including channels, mires, and interfluves. Facies characteristics, stratigraphic architecture, and geochronology of these deposits are explored and 3 main conclusions are derived. First, petrographic trends in coals sitting at the top of the Lower McMurray formed following increasing rates (0.5-3 mmyr-1) of sea-level rise during the Early Cretaceous. These coals outline the paleo-shoreline in the Firebag Tributary during Lower McMurray times. An ash-bed situated in this coal is dated at 121.39 ± 0.20 Ma, providing the first absolute age in the McMurray Fm. Second, the absolute age at the top of the Lower McMurray is used as a reference point to subdivide the McMurray Fm chronostratigraphically using detrital zircon (DZ). In a new stratigraphic approach to DZ geochronology, DZ samples from 5 stratigraphic intervals are combined to created novel grouped DZ samples. Grouped DZ samples showcase geographical provenance variability within depositional systems of the same stratigraphic interval, and are used calculate novel grouped maximum depositional ages. Third, detailed facies analysis and stratigraphic correlation of paralic strata in the Firebag Tributary allows for the identification of 2 progradational and 2 retrogradational phases of deposition. During Lower McMurray times the paleo-shoreline resided near the western edge of the Firebag Tributary, and mature paleosols underlying coals at its top indicate a potential maximum regressive surface. During the C2-B2 depositional units (DU), regression lead to paleo-shorelines close to the Alberta-Saskatchewan border. This is followed by a phase of progradation during the B1 DU, where paralic strata capping the unit lack evidence of base-level fall and demarcate major flooding. Progressive transgression ensued during deposition of the A2-A1 DUs. An ash-bed at the top of the B1 DU (115.07 ± 0.16 Ma) reveals that Lower McMurray to B1 DUs were deposited over ~1.6 Ma each, followed by ~0.8 Ma and ~0.4 Ma for the A2 and A1 DUs, respectively.

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

The effect of deglacial meltwater processes on kimberlite indicator mineral concentrations in glacial sediments

Date created: 
2021-04-19
Abstract: 

Successful diamond exploration projects in glaciated terrain depend on effective drift prospecting methods. This thesis assesses the effects of deglacial meltwater on kimberlite indicator mineral contents in subglacial meltwater corridor sediments. Located 100 km west of Lac de Gras, NWT, the study area has diamond potential and contains subglacial meltwater corridors and unmodified till. A 1:15 000 surficial geology map was produced. Meltwater corridors bisect areas of till veneer and blanket and contain glaciofluvial deposits including eskers and glaciofluvial hummocks. These hummocks form by subglacial meltwater erosion of till and rapid deposition. Till has more silt and clay than meltwater-affected sediments; this affects normalization of analytical results with glaciofluvial hummocks containing higher counts of pyropes. Identification of subglacial meltwater corridor sediments including glaciofluvial hummocks is crucial as they have different compositions and transport histories than till. These differences must be considered when interpreting surficial exploration datasets and planning sampling programs.

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

Applications of terrestrial LiDAR, infrared thermography, and photogrammetry for mapping volcanic rocks in southern BC

Author: 
Date created: 
2020-08-14
Abstract: 

Remote sensing methods are widely used in geological applications today, as many outcrops are difficult to access. Terrestrial LiDAR, infrared thermography, and photogrammetry are used at two field sites in BC: the Cheakamus Valley Basalts (CVB) and Chilcotin Group basalts (CG). The physical properties of the rock at each field site such as composition, texture and structure were studied through remote sensing, and compared to analyses completed in the laboratory as well as traditional contact mapping. The CVB site consists of two outcrops of isolated lava flows approximately 10 km southwest of Whistler, BC, and the CG basalts are observed at the Chasm, a 7 km-long canyon approximately 20 km northeast of Clinton, BC. A virtual field site of the Chasm site was constructed from the remote sensing data, and in conjunction with these analyses, this research clearly shows that it is possible to remotely map otherwise inaccessible volcanic rock masses.

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

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.