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

Receive updates for this collection

Recent deglacierization of the upper Wheaton River Watershed, Yukon

Author: 
Date created: 
2010-11-08
Abstract: 

My research involves the study of Wheaton Glacier, the largest glacier in the Wheaton River watershed in southern Yukon Territory. Since the Little Ice Age, Wheaton Glacier has lost 50% of its area and 58% to 63% of its volume. Despite increasing winter snowfall, rising temperatures tied partially to negative PDO phase changes continue to drive the persistent negative mass balance of the glacier. Periglacial activity, extreme precipitation events and glacier recession are altering sediment delivery in the upper Wheaton River watershed. Sediment is moving downstream from the Wheaton Glacier forefield and large, out-of-channel debris flows are affecting the fan at the mouth of the valley. Evidence from sediment cores collected on the distal part of the fan suggests that debris flows have dominated sedimentation at the mouth of the valley during the last half of the Holocene, coincident with Neoglacial advances and the historic period of rapid glacier retreat.

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

Characterizing the plumbing systems of active volcanoes through potential field studies

Date created: 
2010-11-16
Abstract: 

The processes involved with mass transport through a volcanic plumbing system are poorly understood. Through the use of potential field studies, this thesis aims to identify volcanic structures, processes and Earth properties that control volcanic activity. Gravity and total magnetic surveys at Kĩlauea (Hawaii, USA), Masaya (Nicaragua) and South Sister (Oregon, USA) volcanoes, allowed for development of models to investigate magma transport at different spatial and temporal resolutions. At Kĩlauea rapid, short term mass flux perturbations were characterized within the shallow plumbing system and long term mass increases were inferred in the creation of a large intrusive complex. Constraints on crustal viscosity were obtained at South Sister through gravity and deformation models. At Masaya, constraints were obtained for void space in the active crater and shallow geologic properties. Potential field studies at active volcanoes can clearly bring insight into the fundamental processes of magma transport and emplacement.

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

Multi-scale characterization of rock mass discontinuities and rock slope geometry using terrestrial remote sensing techniques

Date created: 
2010-06-29
Abstract: 

Terrestrial remote sensing techniques including both digital photogrammetry and laser scanning, represent useful complements to conventional field mapping and rock mass discontinuity characterization. Several studies have highlighted practical advantages at close-range (< 300 m), including the ability to map inaccessible rock exposures and hazard reduction related to both traffic and rockfall along investigated outcrops. In addition, several authors have demonstrated their potential to provide adequate quantification of discontinuity parameters. Consequently, their incorporation into rock slope stability investigations and design projects has grown substantially over recent years.As these techniques are increasingly applied by geologists and geological engineers, it is important that their use be properly evaluated. Furthermore, guidelines to optimize their application are required in a similar manner to standardization of conventional discontinuity mapping techniques. An important thesis objective is to develop recommendations for optimal applications of terrestrial remote sensing techniques for discontinuity characterization, based on a quantitative evaluation of various registration approaches, sampling bias and extended manual mapping of 3D digital models. It is shown that simple registration networks can provide adequate measurement of discontinuity geometry for engineering purposes. The bias associated with remote sensing mapping is described. The advantages of these techniques over conventional mapping are demonstrated, including reliable discontinuity orientation measurements. Persistence can be precisely quantified instead of approximately estimated, resulting in a new class for extremely persistent discontinuities being suggested. Secondary roughness and curvature can also be considered at larger scales. The techniques are suitable for the definition of discontinuity sets, and the estimation of both trace intensity and block size/shape, if sampling bias is correctly accounted for. A new type of sampling window, suitable for the incorporation of remote sensing data into discrete fracture network models is presented.Another significant thesis objective is the extension of terrestrial digital photogrammetric methods to greater distances (> 1 km), using f = 200-400 mm lenses. This has required a careful investigation of the observation scale effects on discontinuity parameters. The method has been applied in a large open-pit mine and on the Palliser Rockslide. It allows detailed characterization of the failure surfaces, volume estimations and pre-slide topography reconstruction.

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

Geology and geochronology of the southern Okanagan Valley shear zone, southern Canadian Cordillera, British Columbia

Author: 
Date created: 
2010-06-01
Abstract: 

The Eocene Okanagan Valley shear zone (OVSZ) is a major extensional detachment within the southern Canadian Cordillera in British Columbia. The OVSZ delineates the western margin of the Shuswap metamorphic complex juxtaposing mid-crustal, sillimanite-gradecrystalline rocks against dominantly non-metamorphosed sedimentary and volcanic rocks. The OVSZ is a 1.5 km-thick, shallowly-west-dipping ductile shear zone with an upper brittle detachment fault; the shear zone grades upward from mylonitic amphibolite-facies gneiss (theOkanagan gneiss) to cataclasite. Extension across the OVSZ is estimated at 32-90 km; however, this has recently been challenged in adjacent areas where the presence of a major, crustal-scale detachment is questioned. Based on data from this study, extension across the southern OVSZ is now estimated at 29-86 km. The Okanagan gneiss is the dominant lithological unit within the footwall of the OVSZ, and is composed of felsic orthogneiss and amphibolite-facies paragneiss and migmatite. The gneiss and cross-cutting Eocene felsic intrusions have undergone polyphase, non-coaxial deformation and significant flattening (general shear). Ductile deformation and migmatization of the gneiss continued until at latest ca. 48 Ma. High-precision in situ U-Pb dating of zircon demonstrates that metabasic rocks within the paragneiss were intruded into marine sedimentary rocks at ca. 160 Ma (Jurassic). Contrary to previous studies, the Okanagan gneiss is demonstrably Eocene in age and genetically-related to the OVSZ; therefore, not an exposed slice of Precambrian cratonic basement, and is unlike other gneisses exposed east and northeast of the Okanagan Valley within the Shuswap metamorphic complex. During motion on the OVSZ a series of E-W trending corrugations were developed that resulted in preservation of semi-continuous belts of hanging wall rocks in synformal keels interspersed with antiformal domes of footwall crystalline rocks well east of the present exposure of the OVSZ. Recognition of these corrugations can be used to reconcile the apparent absence of major extension along portions of the OVSZ with the available geological mapping and structural, petrological, and thermobarometric data. Therefore, the importance of the OVSZ as a major crustal-scale detachment that exhumed mid-crustal rocks is confirmed.

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

2009 accumulation area ratios and little ice age equilibrium line altitude depression of Mount Baker glaciers, Washington state, USA

Date created: 
2011-10-04
Abstract: 

Measurements made from a 2009 NAIP (National Agriculture Imagery Program) orthoimage covering the Mount Baker area indicate that 2009 was a negative mass balance year: On average, the accumulation areas of the glaciers occupied only 37 percent of total glacier area at the end of August. An accumulation area of at least 62 percent is required for Mount Baker glaciers to be in equilibrium. Through the use of spreadsheet models, the modern and Little Ice Age thicknesses of these glaciers are compared. During the Little Ice Age, glaciers on Mount Baker were, on average, 1.6 times larger and approximately 20 m thicker than present. The equilibrium line altitudes of these glaciers were, on average, 300 m lower at the maximum of the Little Ice Age than today. The average ablation season temperature was about 2.0°C lower at the peak of the Little Ice Age than today, assuming that precipitation was 7% greater at that time.

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

Investigation of the iron-oxide mineralization at the Iron Range, Southeastern BC

Author: 
Date created: 
2011-08-26
Abstract: 

The Iron Range iron oxide occurrence in south eastern British Columbia consists of massive lenses and veins of hematite and martite with lesser magnetite that pinch and swell along the Iron Range fault zone. It is hosted within the Proterozoic Aldridge Formation and Moyie Sills and forms a central massive iron-oxide corridor flanked by albite-quartz iron-oxide breccia. The most common alteration assemblage is albite-chlorite-hematite-magnetite +/- silica, which is locally overprinted by later iron-oxide, silica, sericite or carbonate alteration. Oxygen isotope analyses in conjunction with fluid inclusions indicate precipitation temperatures for the mineralized zones in the range 340 to 400 °C and 1750 to 4500 bars. The Iron Range iron oxide mineralized rock shares many characteristics of major IOCG deposits and alkali porphyry systems, however the exposed rocks lack economic Cu (+-Au)-concentration. Magnetite trace element chemistry is consistent with IOCG and porphyry mineralization worldwide and recent drilling intersected minor sulphide (chalcopyrite and pyrite) and gold mineralization at 200 m and 20 m depths, respectively. Paleomagnetic studies in conjunction with Ar-Ar dating of regional (magnetite-rich) intrusions support a Cretaceous hydrothermal event responsible for the alteration and mineralization at the Iron Range.

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

Cenozoic drainage history of southern British Columbia

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2004
Document type: 
Thesis
File(s): 
Supervisor(s): 
John Clague
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Dissertation) Ph.D.

Facies architecture and stratigraphy of the Paleogene Huntingdon Formation at Abbotsford, British Columbia

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2003
Document type: 
Thesis
File(s): 
Supervisor(s): 
Peter Mustard
Department: 
Science: Earth Sciences
Thesis type: 
Thesis (M.Sc.)

The role of aquifer heterogeneity in saltwater intrusion modeling, Saturna Island, B.C., Canada

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2003
Document type: 
Thesis
File(s): 
Supervisor(s): 
Diana Allen
Department: 
Science: Earth Sciences
Thesis type: 
Thesis (M.Sc.)