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

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Developing fluorite as a geochemical pathfinder mineral using globally reported REE-Y contents

Author: 
Date created: 
2017-05-12
Abstract: 

Discrimination diagrams have been created to begin development of fluorite as a geochemical pathfinder mineral based on a compilation of approximately 630 trace-element analyses (ICP-MS, ICP-AES, LA-ICP-MS, NAA, INAA) of fluorite from 183 deposits/localities from nearly 60 regions world-wide. A classification scheme of primary mineralization environments was determined to describe potentially economic deposits in which fluorite commonly occurs as listed here in order of representation quality: 1.) hydrothermal/epithermal vein/replacement in igneous hosts, 2.) MVT, 3.) vein/replacement in carbonate hosts, 4.) carbonatite-related, 5.) vein/replacement in metamorphic hosts 6.) SEDEX, 7.) skarn, 8.) greisen, 9.) intrusion-related Mo, 10.) cryolite, 11.) peralkaline silicate igneous rock, 12.) vein/replacement in sedimentary hosts, 13.) rare-metal pegmatite, 14.) granite-related U, and 15.) IOCG deposits. Discrimination diagrams were created using 67th percentile contours of scatter datafields per primary mineralization environment generated using ratios of REE-Y data and equations created by discriminant projection analyses. These diagrams were tested using FUS-ICP/MS analyses of fluorite handsamples sourced from eight North American deposits with predetermined primary mineralization environments assigned from literature review. Correct assignations were confidently returned for half of eight sampled deposits using 11 analyses of samples and less confidently returned for another quarter. Though the exact mechanisms controlling trace-element partitioning in fluorite are poorly understood, this study provides an improved method to discriminate between fluorite-bearing deposits.

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

Guidance for debris-flow and debris-flood mitigation design in Canada

Author: 
Date created: 
2017-08-03
Abstract: 

Steep creek hazards such as debris flows and debris floods pose considerable risks to mountain communities and infrastructure. In Europe and Japan, centuries of experience in steep creek hazard mitigation have produced substantial practical design knowledge. By comparison, Canadian professionals have limited experience with engineered debris-flow and debris-flood risk management. This thesis aims to close the knowledge gap through three distinct approaches. First, local and international design practices are reviewed, to highlight the unique challenges facing Canadian practitioners. Second, I present a design approach that aims to improve the state of practice in Canada by creating a repeatable and transparent workflow. Finally, a series of case studies emphasize the applicability of decision analysis and integrated river management for debris-flow and debris-flood mitigation design. The results of this study can be used to inform steep creek risk management efforts in Canada.

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

Numerical investigations of subglacial hydrology as a direct and indirect driver of glacial erosion

Author: 
Date created: 
2017-05-26
Abstract: 

Glaciers shape high altitude and latitude landscapes in numerous ways. Erosion associated with glacial processes can limit the average height of mountain ranges, while creating the greatest relief on Earth and shaping the highest mountain peaks, but glaciers can also shield pre-existing topography. Glacial erosion processes, though still enigmatic, are central to the evolution of landscapes, particularly since the onset of the Pleistocene. Glacial erosion comprises three fundamental processes: (1) abrasion, (2) quarrying and (3) the direct action of subglacial water flow in sediment transport and bedrock erosion. Glacier sliding and the hydro-mechanical conditions at the ice--bed interface drive erosion processes, and are themselves controlled by the morphology and state of the subglacial drainage system. Although widely acknowledged, the direct and indirect controls of subglacial water flow on glacial erosion have been largely neglected in previous studies. This thesis focuses on exploring these controls using numerical models with an emphasis on sub-annual to annual timescales. This work has three primary objectives: (1) to investigate how the state and morphology of the subglacial drainage system indirectly drive abrasion and quarrying, (2) to devise the first model of direct bedrock erosion by subglacial water flow and (3) to develop a framework for sediment transport in subglacial channels over a rigid bed. The results show that well-known seasonal variations in subglacial hydrology drive patterns of glacial erosion. Abrasion is favoured where the drainage system is the most dynamic, whereas quarrying calculated using a recently published law is hindered; the latter result is at odds with previous theories. Direct erosion by subglacial water flow can explain bedrock channel excavation, but the resulting erosion rates remain negligible compared to expected basin-wide glacial erosion rates. The models predict a bottleneck in sediment transport near the glacier terminus that is inherent to channel dynamics. The resulting sediment accumulation provides a process-based explanation for esker deposition, and could shape proglacial sediment yields. In focusing on spatial and temporal scales commensurate with subglacial processes, this study challenges some of the common assumptions made in glacial erosion studies and provides a starting point for refining models of landscape evolution.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gwenn E. Flowers
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) Ph.D.

Tectonometamorphic history of mid-crustal rocks at Aishihik Lake, southwest Yukon

Date created: 
2017-04-12
Abstract: 

Field mapping, petrography, thermodynamic modelling, and U-Pb (monazite and zircon) and 40Ar/39Ar geochronology reveal the tectonometamorphic history of polydeformed, amphibolite-facies rocks near Aishihik Lake, Yukon. Detrital zircon U-Pb ages suggest that these rocks are correlative to the Snowcap assemblage of the Yukon Tanana terrane. A penetrative regional foliation (S1) developed during the late Paleozoic, as S1 is cross-cut by a late Permian pluton. Permian plutons also exhibit less strain than Mississippian plutons near Aishihik Lake. The main foliation (S2) reflects west-verging, ductile shear (D2) during amphibolite facies metamorphism. Dating of Low-Y metamorphic monazite constrains the timing of D2 to 200-190 Ma. Peak T and P during D2 were 640-650 °C and ~7 kbar, respectively. High-Y monazite ages date regional decompression at ca. 188 Ma. 40Ar/39Ar thermochronology results indicate regional cooling through muscovite closure at ca. 175 Ma, whereas ca. 126 Ma biotite may reflect cooling following east-verging Jura-Cretaceous deformation (D3).

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

Optical Dating Studies of southeastern Patagonian Sand Wedges in Chile and Argentina

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2016-04-18
Abstract: 

The purpose of this study was to establish a suitable single aliquot regenerative dose (SAR) optical dating protocol for K-feldspar sediments in southeast Patagonia using radiocarbon-dated Holocene dune sediments at Lago Arturo. The established protocol was then applied to sand wedge sediments found in the region in order to date periods of permafrost and to provide limiting ages on glaciation. The suitable SAR protocol incorporates a 200oC/10 s preheat for both the additive-dose and test dose measurements, a hot (290oC) bleach step at the end of each SAR cycle to reduce recuperation, and measurement of the stimulated luminescence at 50oC. A select number of sand wedges found throughout the region were dated using the established protocol. Those that yielded reliable ages date to the last glaciation. Some sand wedges provided older optical ages, however, more testing is required to determine if these ages are accurate.

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

Characterization of blast damage in rock slopes: An integrated field-numerical modeling approach

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2016-07-04
Abstract: 

Consideration of blast damage in rock slope stability has been a challenging task in rock mechanics because blasting results depend on several factors that can lead to different forms of damage. Currently, it is not clear on how to consider blast damage in rock slopes. This thesis investigates the occurrence of blast damage in rock slopes using an integrated field investigation, remote sensing and numerical modelling approach. A framework for defining blast damage in the field and using remote sensing data was developed to provide the input for a blast damage model which can then be used either for numerical analysis or understanding the occurrence of blast damage features in the field. Results of field investigation and numerical simulations show that blast damage on the rock slope surface varies depending on the rock mass quality. Blast fracturing increases with decrease in rock mass quality. Observations on exposed joint surfaces in open pit slopes indicate that the blasting process has induced varying forms of damage on these surfaces. Finite-discrete element numerical modelling of blast induced damage indicates that blast damage develops in different forms from the slope surface. The simulated blast damage zone varied from complete blocks (fully connected blocks), partially connected blocks, dilation and undamaged zone. The extend of the blast damage increased with decrease in strength of the rock. A stronger rock mass show less blast damage thickness compared to a weaker rock mass. Results show that blast damage features such as blast fracture, damage along the joint surface and extension of joints all influence slope stability.

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

Downie Slide: An integrated remote sensing approach to characterization of a very slow moving landslide

Date created: 
2017-04-04
Abstract: 

This study demonstrates the advantages of combining remote sensing with field data in landslide investigations and provides improved data on the structural geology and its influence on slope movements at Downie Slide, a large landslide located in southeastern British Columbia, Canada. The geomorphology of the Downie Slide was studied using airborne LiDAR in a GIS environment to provide new insights on the landslide displacement mechanism. Surface and underground areas of the slide were compared and contrasted using terrestrial laser scanning and photogrammetry. Six joint sets were identified. Some structures and domain boundaries were found to be pervasive throughout the slide. A correlation between slope deformation, and large-scale structural and damage features was made and 12 structural domains defined within the landslide. Large secondary retrogressive-failures were identified for the head scarp and retrogression of the northern boundary, increasing the overall area of slide material by ~ 1 km2.

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

In Search of Cordilleran Point Sources to the Southern McMurray Sub-Basin

Date created: 
2016-12-12
Abstract: 

In the east-central Alberta, isopach values of the McMurray Formation measured from the overlying Wabiskaw Marker datum show that paleotopographic relief on the sub-Cretaceous Unconformity is express by three paleo-valleys carved into the Grosmont-Wainwright Highlands. The paleo-valleys are named herein as: Grouse, Quail, and Ptarmigan. Mineralogical analysis of McMurray Formation sandstones in the paleo-valleys resolves subtle but recognisable vertical and spatial variations in composition. Feldspar contents decrease and lithic contents increase with stratigraphic depth. Based on petrographic analyses, McMurray Formation sandstones are sourced dominantly from a continental-scale drainage across the craton, with secondary input from uplifted sedimentary strata in the west as well as from the Canadian Shield in the east. Probable, paleo-tributaries can be superimposed on isopach maps of the McMurray Formation that, when coupled with net-sand maps, appear to bisect the highlands, suggesting that the Grosmont-Wainwright did not prevent some Cordillera sediment from entering the Ptarmigan and Quail paleo-valleys. This Cordillera-derived sediment was delivered via Edmonton Valley, and is calculated to constitute approximately 35% of the sediment supplied.

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

Response of a fractured bedrock aquifer to recharge from heavy rainfall events

Date created: 
2016-12-07
Abstract: 

The response of a fractured bedrock aquifer in a temperate region (Gulf Islands, British Columbia) to heavy rainfall events is characterized. Of the 14 provincial observation wells with hourly groundwater level data, wells with shallow water levels showed pronounced responses to heavy rain events, a lag less than 12 hours, and a strong correlation to all rain events. Rises in groundwater level at Well 125 appear to be better related to all rain events than exclusively heavy rain during summer, and decrease as the rainfall intensity increases. Thermal infrared images and δ18O and δ2H composition for precipitation and seepage indicate an increase in seepage in the late fall and winter. Solution of the Green-Ampt equation for rainfall events of varying magnitude suggest that an increase in winter rainfall intensity leads to more surface ponding and overland flow. The projected occurrence of more heavy rain events in the future may result in lower net recharge.

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

Sedimentology, Geochemistry, and Geochronology of unit PR1 of the lower Fifteenmile group and the Pinguicula Group, Wernecke and Ogilvie Mountains, Yukon, Canada: Mesoproterozoic environments and paleocontinental reconstructions

Date created: 
2016-12-14
Abstract: 

Unit PR1 of the lower Fifteenmile group and the Pinguicula Group are exposed in Ogilvie and Wernecke mountains, Yukon, Canada. Unit PR1 records deposition of turbiditic interbedded sandstone and mudstone with scattered carbonate olistoliths. The Pinguicula Group records deposition of non-cyclic siliciclastic and carbonate strata on low-energy slopes affected by rare high-energy deposits. The Pinguicula Group comprises three newly formalised formations: the Mount Landreville, Pass Mountain, and Rubble Creek (formerly units A, B, and C, respectively). The older unit PR1 has a near-unimodal detrital zircon population with an age of 1499 ± 2.7 Ma and εNd(t) values from -8.17 to 3.92. Overall, detrital zircon data from the Pinguicula Group display a polymodal detrital zircon population with a maximum age of <1322 ± 23 Ma and εNd(t) values from -1.55 to 1.12. C-isotopic analyses from the Pinguicula Group record average δ13C values ranging from -0.64 to +1.6‰ Vienna Pee Dee Belemnite (VPDB). Stratigraphic correlations between the Pinguicula Group in the Wernecke and Hart River inliers have been confirmed using lithostratigraphy, combined with detrital zircon U-Pb geochronology, Sm-Nd, and C-isotope signatures. The Pinguicula Group and unit PR1 are no longer considered correlative based on differences in detrital zircon signatures and Sm-Nd isotopic data. Detrital zircon ages from unit PR1 fall into the North American Magmatic Gap (NAMG; 1610-1490 Ma) and therefore sediment in unit PR1 is interpreted to have been from the Mt. Isa inlier in northeastern Australia. The PR1 basin may have been deposited as early as 1460 Ma on Laurentia’s northwestern margin, coincident with the Belt-Purcell, Yankee Joe/Defiance, and Trampas basins that formed during the break-up of supercontinent Columbia. These basins derived some or all of their sediment from Australia and the Mawson continent. Younger Mesoproterozoic strata, deposited after 1.45 Ga, including the Missoula Group and Marqueñas Formation, lack NAMG-aged zircons and instead record a shift in sediment provenance to southern Laurentia as north Australia and the Mawson continent rifted from Laurentia’s western margin. The Pinguicula Group (<1322 Ma) was probably fed from southern Laurentian Granite-Rhyolite provinces with NAMG-aged zircons recycled from older Mesoproterozoic strata.

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