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

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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

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: 
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.

Permeability Heterogeneity in Bioturbated Strata, Cardium Formation, Pembina Field, and the Identification of Potential Waterflood Opportunities

Date created: 
2015-07-23
Abstract: 

Bioturbated sediments representing distal expressions of paralic depositional environments are increasingly being exploited for hydrocarbons in the super-giant Pembina Field (Cardium Formation), Alberta, Canada. These strata were previously considered unproductive due to limited vertical and horizontal connectivity between permeable beds. In these “tight oil” plays (0.1 – 10 md), pressure decay profile permeametry data indicate that sand-filled burrows provide vertical permeable pathways between bioturbated and parallel laminated sandstone beds in the central, north-east and north-west parts of the field. This relationship enables the economic exploitation of hydrocarbons via horizontal drilling and multi-stage hydraulic fracturing. As the exploitation of bioturbated strata progresses in the Pembina Field, additional primary targets are being sought out, and horizontal waterflooding is being considered in areas where current horizontal wells exist. Proximal to historical produced conventional targets, reservoir analyses indicate that areas where the bioturbated facies average permeability lies between 0.35 mD and 0.85 mD and sandstone isopach thicknesses are between 0.25 m and 2.5 m should be targeted in east-central Pembina.

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

Application of seismic interferometry to imaging a crystalline rock environment at an active VMS mine in Flin Flon, Manitoba, Canada

Date created: 
2016-06-13
Abstract: 

Seismic interferometry is a technique by which the Green’s function or impulse response between two receivers is recovered through the cross-correlation of the transmission responses recorded by those receivers. This technique has found several applications, including the generation of virtual shot gathers from ambient seismic noise for use in seismic reflection processing. In March of 2013, 336 receivers were deployed over the volcanogenic massive sulphide (VMS) deposit found at the Lalor mine in Manitoba, Canada. Approximately 300 hours of ambient seismic noise was recorded for the purpose of testing the effectiveness of seismic interferometry in imaging a crystalline rock environment. A time-domain beamforming algorithm was implemented to determine the locations of the sources present during recording. The results indicate that the vast majority of the recorded noise originated from mine and ventilation shafts located at the Lalor mine. Synthetic experiments were conducted to determine the effects such a source distribution would have on the application of seismic interferometry in the presence of dipping reflectors. The experiments show that if sources are located only on one side of a receiver line, the dip and lateral extents of reflectors will not be imaged properly. A technique involving beamforming and F-K filtering was developed to remove surface wave noise originating from near-field sources. Using this technique, the raw data was processed into virtual shot gathers free of surface wave noise. Virtual shot gathers were generated along 4 of the receiver lines and processed as separate 2-D reflection datasets. The resulting reflection profiles are compared against coincident DMO-stacked data from a larger 3-D active seismic survey conducted over the Lalor mine. Using this comparison in conjunction with knowledge of the local geology, events recovered in the passive reflection profiles are interpreted as either real reflections or spurious events, and possible explanations of their origin are given.

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

Age, formation and tectonism of the Neoproterozoic Ruddock Creek zinc-lead deposit and host Windermere Supergroup, northern Monashee Mountains, southern Canadian Cordillera

Author: 
Date created: 
2016-08-24
Abstract: 

The Ruddock Creek property is located in the northern Monashee Mountains, southern British Columbia. The deposit is hosted by Neoproterozoic metasedimentary rocks of the Mica Creek succession within the Windermere Supergroup. Structurally the Ruddock Creek property is interpreted to reside within the base of the Selkirk allochthon, in the immediate hanging wall of the Monashee décollement, a crustal-scale, northeast-directed thrust-sense shear zone. The Neoproterozoic strata have been complexly folded and transposed by Mesozoic deformation. U-Pb dates for deformational events range from ca. 116 to 63 Ma (63 Ma being the end of ductile deformation). The geometry of the main sulphide body indicates that the mineralized horizon was subject to all phases of deformation and was metamorphosed to amphibolite facies. Detrital zircon geochronology provides U-Pb ages that constrain the provenance for the host Windermere Supergroup, and define a maximum depositional age of ca. 663 Ma. The 663 Ma age is not common to the North American Cordillera, and is found almost exclusively in igneous rocks in central Idaho, suggesting south to north transportation of sediment along the Neoproterozoic rifted paleo-margin of western Laurentia. The 206Pb/204Pb isotope ages of galena, pyrite and pyrrhotite from several mineralized horizons that make up the Ruddock Creek deposit indicate an Early Cambrian, 535 ± 30 Ma model age of mineralization. Different colour sphalerites and calcite were analyzed to generate a Rb/Sr errorchron with an age of ore formation of 556 ± 420 Ma. Together the maximum age of deposition, the Pb isotope ages and the Rb/Sr errorchron reveal a spatial and temporal syngenetic relationship of the deposition of the Mica Creek succession within the Selkirk allochthon and the mineralized horizon at the Ruddock Creek property. Local basement topography, such as horst and graben structures resultant from rifting related to the final phase of breakup of Rodinia, may have focused fluid flow into carbonaceous host lithology at Ruddock Creek. Local structural and stratigraphic traps, hydrothermal fluids, as well as the redox state of the basinal brines, would ultimately have localized and controlled the precipitation of the sulphides.

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