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

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The northern Cache Creek terrane: record of Middle Triassic arc activity and Jurassic-Cretaceous terrane imbrication

Author: 
Date created: 
2014-01-24
Abstract: 

The northern termination of the Cache Creek terrane in the Cordillera contains oceanic crustal lithologies including subalkaline mafic intrusive rocks with an arc geochemical signature, mafic volcanics with arc to back-arc signatures, and an arc-flanking volcaniclastic succession informally termed the Michie formation. This formation contains unimodal zircon populations with U-Pb dates of 245.85 ± 0.07 and 244.64 ± 0.08 Ma. These dates differ from the dominant detrital zircon age population of ca. 190 Ma found in the adjacent Whitehorse trough, but are similar to igneous crystallization ages of the Kutcho arc of northern British Columbia. Two main faults record oppositely verging deformational events: 1) The Judas Mountain thrust, a west-verging structure that emplaced Cache Creek terrane rocks above Stikinia and the Whitehorse trough, and 2) the Mount Michie thrust, an east-verging second phase structure that imbricated Stikinia and Whitehorse trough rocks onto and replaced them over the Cache Creek terrane.

Document type: 
Thesis
Senior supervisor: 
Dan Gibson
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Multiphase flow and reactive transport modelling of CO2 storage in heterogeneous reservoirs

Date created: 
2013-12-06
Abstract: 

This study addresses how physical heterogeneity, representing different sedimentary rock layers and the relationships between those layers, impacts the distribution of CO2, and thus the type and extent of mineral dissolution and precipitation reactions during CO2 geologic storage in deep saline aquifers. Numerical multiphase flow (TOUGH2) and reactive transport codes (TOUGHREACT) were used to construct a series of reservoir scale simulations to investigate how the flow controlling parameter values, distribution, and grid refinement of various hydrostratigraphic units (HSUs) affect the distribution of CO2, pH and mineral reactions. Physical heterogeneity is critical for controlling the distribution of supercritical and dissolved CO2, the redistribution of ions from geochemically reactive materials to more stable portions of the reservoir, mixing and dilution of CO2-rich waters, and the extent of mineral dissolution and precipitation reactions. The highest magnitude of carbonate mineral precipitation occurs at the sandstone-siltstone interface and along the extent of the CO2-water contact.

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

Facies Modelling of a Tide-Influenced, River-Dominated Delta, Fraser River Delta, British Columbia, Canada

Author: 
Date created: 
2014-01-27
Abstract: 

The Fraser River delta is a tide-influenced, river-dominated delta that exhibits distinct asymmetry in sedimentological and neoichnological character between the updrift (south) and downdrift (north) sides of the delta front and upper prodelta (< 200 m water depth). The updrift portion consists mainly of sands and heterolithic sand and mud bedsets with low bioturbation intensities (BI 0-3). Trace suites are sporadically distributed and include elements of the Skolithos Ichnofacies. The downdrift portion is composed of homogeneous mud beds and bedsets with significantly higher intensity of bioturbation (BI 3-6). Trace suites are attributable to the Cruziana Ichnofacies. The asymmetrical distribution of sediment and burrows on the delta is primarily controlled by strong northward-directed tidal currents. Physical sedimentary processes differ significantly between updrift and downdrift sides of the delta. The updrift delta is mainly an area of erosion in which strong tidal currents scour previously deposited sediments. This scouring reveals underlying sandy paleo-distributary channel deposits. The downdrift delta, on the other hand, is an area of net sediment (predominantly mud) accumulation. Sandy material eroded from the updrift delta is trapped within a deep submarine channel and does not get redistributed to the downdrift delta. This results in contrasting substrate types between the updrift and downdrift delta. The asymmetrical character of the Fraser River delta is similar in its sedimentological signature, but ichnologically distinct, from the wave-dominated asymmetric delta model. Neoichnological trends are opposite to that observed in wave-dominated asymmetrical deltas, in that the trace diversity and density are higher on the downdrift side of the delta front than the updrift side. Based on the results presented herein, a new tidally asymmetric delta model is proposed which, overall, leads to a more robust asymmetric delta model. The most important aspect of this new model is that tidally-influenced asymmetric deltas are not depth-dependent, and therefore, they have greater potential to develop in deep water settings than wave-dominated asymmetric deltas.

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

Flood hazard and risk in Lillooet River valley, British Columbia, Canada

Author: 
Date created: 
2013-09-09
Abstract: 

This thesis examines flood hazard in Lillooet River valley in the southern Coast Mountains of British Columbia, Canada. My research is multi-disciplinary: I used earth science methods to estimate pre-historical flood frequency and sediment yield, as well social science theory to study the process of knowledge transfer between the scientific community and local stakeholders. The results from this thesis contribute to and complement previous earth science and natural hazard studies in Lillooet River valley, while furthermore providing knowledge for river and floodplain management. The results also shed a light on the communication of scientific knowledge to local emergency managers and the use of such information at the local level.My thesis comprises three studies. First, I compiled a varve chronology spanning 825 years (AD 1179-2004) from annually layered sediments (varves) recovered from Lillooet Lake. I compared twentieth-century discharge records of Lillooet River to the contemporary part of the varve chronology to determine the relation between river discharge and varve thickness. Based on this relation, I examined the entire 825-year varve chronology for the floods it might record. Second, I made annual sediment yield estimates for the period AD 1629-1997 and compared them to estimates derived from Lillooet Lake cores by previous researchers. I compared times of anomalously high sediment yield to ages of large landslides and floods in the watershed, and to times of marked glacier advance and retreat in order to understand controls on sediment delivery. I assessed the persistence of high sediment input episodes using statistical methods. Third, I assessed the history and current flood management policy landscape at the federal, provincial, and local levels. In the context of the transfer of flood management responsibility from the British Columbia Government to municipalities in 2003, I interviewed local floodplain and emergency managers on their use of scientific knowledge in preparing for flooding in Lillooet River valley.

Document type: 
Thesis
File(s): 
Senior supervisor: 
John Clague
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.

Boiling as a mechanism for colour zonations observed at the Byrud emerald deposit, Eidsvoll, Norway

Date created: 
2013-12-13
Abstract: 

The Byrud emerald deposit was first discovered in the early 1860s, near Lake Mjøsa, southern Norway. From a geological, gemmological, and geochemical perspective, the Byrud emeralds are of great interest as they are vanadium-rich rather than chromium-rich, which is uncommon for the majority of emeralds worldwide. The emerald deposit genesis is consistent with a typical granite-related emerald vein system from dominantly magmatic fluid sources. Emerald mineralization occurs within pegmatite veins which are hosted within Cambrian black shale and Late Carboniferous quartz syenite sills, and intruded by a Permo-Triassic alkaline granite. Muscovite from an emerald-bearing pegmatite at Byrud yielded an Ar-Ar plateau age of 233.4 ± 2.0 Ma. The emerald display colour zonation alternating between emerald and beryl. Two dominant fluid inclusions types are identified: two-phase (vapour+liquid) and three-phase (brine+vapour+halite) fluid inclusions. Raman analyses indicate molar gas fractions for CO2, N2, CH4, and H2S are approximately 0.8974, 0.0261, 0.0354, and 0.0410, respectively. Formational temperatures and pressures of approximately 160 °C to 385 °C and below 1000 bars were derived from fluid inclusion data and lithostatic pressure estimates from fluid inclusion studies within the Oslo Paleorift.The emerald from the Byrud mine displays growth zoning and banding from green emerald to colourless beryl. The use of chemical analyses, fluid inclusions and petrography is consistent with boiling as a mechanism for this distinct ‘striped’ colour zonation or banding. These zones are due to enrichment of vanadium and chromium in the green bands which host salt-saturated aqueous primary fluid inclusions with an overall 31 mass percent NaCl equivalent salinity. Vapour-rich primary fluid inclusions dominate within the colourless bands of the zoned emerald. The chemical compositions of the salt-saturated and the vapour-rich inclusions indicate they represent the coexisting liquid and vapour portions of a two-phase boiling system. This “boiling” formational model has application to not only other emerald deposits, but also other zoned gem deposits worldwide.

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

Deep-seated gravitational slope deformations near the Trans-Alaska Pipeline, east-central Alaska Range

Date created: 
2013-09-03
Abstract: 

I investigated active deep-seated gravitational slope deformation (DSGSD) near the Trans-Alaska Pipeline and Richardson Highway in the east-central Alaska Range, Alaska, USA. I documented the presence, spatial extent, and rates of DSGSD using field-geology methods and optical, SAR, and D-InSAR remote-sensing images. I also documented and mapped many of the morphological, geological, and structural characteristics of slopes undergoing DSGSD, and constructed conceptual numerical models to better understand potential deformation mechanisms. Results confirm that many large DSGSD slopes in the study area are actively deforming. Deformation rates range from less than a millimetre per month to more than ten centimetres per month, and are spatially and temporally varient within each slope. Deforming slopes are characterized by differential movement of kilometre-scale rock blocks. Recent climatic changes and strong seismic shaking, especially during the recent 2002 Denali Fault earthquake, have exacerbated ongoing deformation. Study-area DSGSDs should be considered capable of generating long-runout rock avalanches that could directly sever the Trans-Alaska Pipeline and Richardson Highway, or that could dam up valleys and lead to the buildup and catastrophic failure of landslide-dammed lakes capable of impacting said infrastructure.

Document type: 
Thesis
Senior supervisor: 
John Clague
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Geophysical investigations of magma plumbing systems at Cerro Negro volcano, Nicaragua

Date created: 
2013-11-27
Abstract: 

Cerro Negro near Léon, Nicaragua is a very young (163 years), relatively small basaltic cinder cone volcano that has been unusually active during its short lifespan (recurrence interval 6-7 years), presenting a significant hazard to nearby communities. Previous studies have raised several questions as to the proper classification of Cerro Negro and its relation to neighboring Las Pilas-El Hoyo volcano. Analysis of Bouguer gravity data collected at Cerro Negro has revealed connected positive density anomalies beneath Cerro Negro and Las Pilas-El Hoyo. These findings suggest that eruptions at Cerro Negro may be tapping a large magma reservoir beneath Las Pilas-El Hoyo, implying that Cerro Negro should be considered the newest vent on the Las Pilas-El Hoyo volcanic complex. As such, it is possible that the intensity of volcanic hazards at Cerro Negro may eventually increase in the future to resemble those pertaining to a stratovolcano.

Document type: 
Thesis
Senior supervisor: 
Glyn Williams-Jones
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Evolution of the Coast Cascade Orogen by Tectonic Thickening and Magmatic Loading: The Cretaceous Breakenridge Complex, Southwestern British Columbia

Author: 
Date created: 
2013-09-18
Abstract: 

A model for the tectono-magmatic mid-Cretaceous (110-80 Ma) evolution of the southern Coast belt is proposed. The first magma pulse represented by the 107-100 Ma Breakenridge pluton intruded within a magmatic arc as a set of shallow sills. It was initially buried by orogen-parallel contraction, followed by the emplacement of the 96-94 Ma Snowshoe pluton, which belongs to the second magma pulse. The Snowshoe pluton was emplaced by similar mechanisms in structurally higher levels of the crust. Orogen-normal compression was the final mechanism for deep burial and attainment of peak metamorphic conditions (500-680°C at 6.5-10.3 kbar) of the study area between 91-86 Ma. Following orogen-normal contraction and regional folding, oblique right-lateral strike-slip shearing occurred while rocks were in a ductile environment. The third magma pulse (86-84 Ma) was synchronous with the late stages of high-grade metamorphism and early stages of oblique strike-slip movement.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Dan Gibson
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Palynology and geochemistry of sediments in the tidally influenced lower Fraser River, British Columbia

Date created: 
2013-08-29
Abstract: 

In the tidally influenced Fraser River and adjacent Strait of Georgia (SoG), Canada, palynological and carbon isotope (δ13Corg) signatures of channel-margin sediments are compared to environmental parameters (e.g., substrate grain size, water salinity) in order to establish how these vary across the tidal-fluvial transition. Palynological assemblages in both the Fraser River and SoG (delta front and prodelta) are dominated by tree pollen, which comprises between 85% and 95% of all assemblages. Relative abundances of marine dinocysts are markedly low, and the maximum abundance of dinocysts is 6.8% or 1,023 cysts g-1 of sediment in samples recovered from the prodelta. Dinocyst abundances do not exceed 2% of the total palynological assemblage in the Fraser River, and the number and diversity of dinocysts gradually decreases landward. Organic carbon-13 enrichment values range from -26.55‰ in sediments deposited in the freshwater-tidal reach of the Fraser River, to -21.08‰ in prodeltaic sediments. The δ13Corg and palynological signatures of river, delta front, and prodelta sediments indicate a dominance of terrestrially sourced organic matter regardless of brackish-water and tidal influence on sediment deposition.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Shahin Dashtgard
Rolf Mathewes
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

Simulation of failure mechanisms around underground coal mine openings using discrete element modelling

Author: 
Date created: 
2013-09-06
Abstract: 

Roof failure has always been a major concern in underground coal mine roadways. Understanding the failure mechanism of roadway roofs is important for improving the safety of underground coal mines and reducing economic loss. In this research, a numerical modelling methodology named UDEC Trigon in 2D and 3DEC Trigon in 3D and based on a discrete element framework is developed to model rock mass behaviour, with a particular focus on the damage process including generation and propagation of fractures, and heavy dilation in the post-peak failure stage. Simulation of compression and Brazilian tests indicates that the methodology can capture different failure mechanisms under verying loading conditions. The UDEC Trigon is then used to investigate shear failure mechanism in roadway roofs. The results suggest that shear cracking plays a dominant role in the roof shear failure. Rock bolts can aid in ensuring the retention of more rock bridges which is critical to the roof stability. Cutter roof failure, which is a three-dimensional roadway rock failure mechanism, is studied using both PFC3D and 3DEC Trigon. The 3D models explicitly capture the cutter roof failure process and found that incorporating bedding planes and corss joints results in a more distinct cutter failure. Roadway squeezing failure mechanism is studied using the UDEC Trigon approach. The results show that the UDEC Trigon approach is able to reproduce the large dilation due to fracturing of rock mass surrounding a roadway under two distinct situations: high mining-induced stress and strength degradation of moisture sensitive rocks. In addition, the UDEC Trigon approach is used to simulate the progressive caving process of a longwall panel of coal. It is found that compressive shear failure, rather than tensile failure, is the dominant failure mechanism in the strata above the goaf. A further demonstration of the potential of UDEC Trigon in capturing roadway failure is presented as a case study of a roadway driven adjacent to unstable goaf in the Wuyang Coal Mine. The case study reveals that the combination of Synthetic Rock Mass (SRM) and UDEC Trigon is able to evaluate failure mechanisms in underground coal mines.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Douglas Stead
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.