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

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Sedimentological and paleomagnetic study of glacial Lake Missoula lacustrine and flood sediment

Date created: 
2013-04-04
Abstract: 

During the Fraser Glaciation (marine oxygen isotope stage 2), floods from ice-dammed glacial Lake Missoula affected large parts of Washington and Oregon. Flood deposits are interbedded with glaciolacustrine sediment in glacial Lake Columbia, and occur as thick slackwater sediments in southern Washington and in the Willamette Valley, Oregon. This thesis examines some of the issues surrounding this flooding, such as how many times glacial Lake Missoula emptied, whether glacial Lake Missoula is the only source of the floods, and the timing of these events. The sedimentology and stratigraphy of a new section of rhythmically stratified glaciolacustrine sediment in the glacial Lake Missoula basin confirms that the ice dam failed at least a few dozen times, exposing the lake bottom. Current indicators and clast lithologies of flood sediments in glacial Lake Columbia indicate that glacial Lake Missoula was the source of these flood beds. Additionally, rock magnetic studies identify hematite in fine-grained flood sediment that settled out of the water after the high-energy floodwaters had passed. The source of the hematite is the Belt-Purcell Supergroup in Montana, which supplied sediment to glacial Lake Missoula. Optical ages, a radiocarbon age, and paleomagnetic secular variation records help to constrain the timing of glacial Lake Missoula flooding. Optical dating was successful on three samples of fluvial sand deposited during initial filling of glacial Lake Missoula and on loess deposited above Mount St. Helens set S tephra, which is a time-stratigraphic marker found in glacial Lake Missoula flood deposits. One sample of fossil plant detritus was found below at least 37 flood beds in glacial Lake Columbia. Lastly, four paleomagnetic secular variation records constrain the timing of glaciolacustrine units in glacial Lake Missoula and flood beds in glacial Lake Columbia and the Willamette Valley. All glacial Lake Missoula units and flood units studied in this thesis date to the later part of the Fraser Glaciation, between ~14.2 and 11.6 14C ka BP.

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

Seasonal controls on the development and character of inclined heterolithic stratification in a tide-influenced, fluvially dominated channel, Fraser River, Canada

Date created: 
2011-03-17
Abstract: 

Inclined heterolithic stratification (IHS) is developed on an in-channel bar in the tide-influenced, fluvially dominated reach of the Fraser River, British Columbia, Canada. The vertical bar succession is characterized by a fining-upward profile with an increase in mud-bed thickness and content, from the shallow subtidal to the upper intertidal zone. There is an increase in the number of mud beds as well as their lateral continuity from the upstream to the downstream side of the bar. Sediment deposition is seasonally controlled, wherein sand deposition occurs during periods of high discharge (snowmelt-induced freshet), and mud is deposited during low discharge (ambient flow conditions). The seasonal cyclicity in sediment deposition is also observed in the ichnological character of the IHS. Mud beds are typically moderately to pervasively bioturbated (Bioturbation Index (BI) 2-5), and sand beds exhibit little to no bioturbation (BI 0-2).

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

Distributed energy-balance glacier melt-modelling in the Donjek Range of the St. Elias Mountains, Yukon Territory, Canada: model transferability in space and time

Date created: 
2010-10-20
Abstract: 

Modelling melt from glaciers is crucial to assessing regional hydrology and eustatic sea-level rise. To investigate melt-model transferability, a distributed energy-balance melt model (DEBM) is applied to two glaciers of opposing aspects in the Donjek Range of the St. Elias Mountains, Yukon Territory, Canada. An analysis is conducted in four stages to assess the transferability of the DEBM in space and time: (1) locally derived model parameter values and meteorological forcing variables are used to assess model skill; (2) model parameter values are transferred between glacier sites and between years of study; (3) measured meteorological forcing variables are transferred between glaciers, using locally derived parameter values; (4) both model parameter values and measured meteorological forcing variables are transferred from one glacier site to the other, treating the second glacier site as an extension of the first. The model has high transferability in time, but has limited transferability in space.

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

Modelling the impacts of climate change on groundwater: A comparative study of two unconfined aquifers in southern British Columbia and northern Washington State

Author: 
Date created: 
2005
Abstract: 

A methodology is developed for linking climate and groundwater models to investigate future impacts of climate change on groundwater resources using two case study sites of unconfined aquifers in southern British Columbia and northern Washington State. One semi-arid site is compared with one wet coastal site. The two groundwater systems differ in river-aquifer interactions, recharge, aquifer heterogeneity, scale, and groundwater use. Climate change scenarios from the Canadian Global Coupled Model 1 model runs for 1961-2000,2010-2039,2040-2069 and 2070-2099 are downscaled to local conditions, modelled at daily time scales using a stochastic weather generator, and applied to the spatially-distributed infiltration model. At one site the basin-scale runoff is also downscaled to predict river discharge and river-aquifer interactions in future climates. The impacts of predicted climate change on the groundwater system for each site are modelled in three-dimensions using Visual MODFLOW. Results and methodologies are compared and discussed.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Objective preliminary assessment of outburst flood hazard from moraine-dammed lakes in southwestern British Columbia

Date created: 
2005
Abstract: 

An objective, remote sensing-based procedure is proposed to evaluate the outburst flood hazard posed by moraine-dammed lakes in southwestern British Columbia. Outburst probability is estimated using an expression derived from statistical analysis of data collected from 175 moraine-dammed lakes in the southern Coast Mountains. Logistic regression identified four factors that correctly discriminate 70% of drained and 90% of undrained lakes: moraine height-to-width ratio, presencelabsence of an ice core in the moraine, lake area, and main rock type forming the moraine. Objective methods, which incorporate empirical relations applicable to the study region, are used to predict outburst peak discharge and debris flow volume, travel distance, and area of inundation. Outburst flood hazard is especially sensitive to lake level fluctuations and is greatest for large lakes perched on valley sides behind narrow, ice-free moraine dams composed of sedimentary rock debris.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Occurrence and genesis of alpine linears due to gravitational deformation in South Western British Columbia

Author: 
Date created: 
2004
Abstract: 

Alpine linears are found on many slopes in south western, British Columbia. The genesis of these features is commonly related to gravitational deformation of rock slopes. A preliminary stress analysis of selected ridge morphologies indicates that the resulting stress fields are different for each basic ridge type analysed, indicating that various deformation mechanisms may be active in producing alpine linears. An integrated system of GIs and numerical modelling is applied to a study of Mount Mercer, British Columbia. Detailed geomorphic and engineering geological mapping indicates that linears observed along the ridgeline of Mount Mercer are due to rock slope deformations. Potential failure mechanisms are evaluated for kinematic feasibility and resulting failure morphology. The results of the study indicate that toppling does not appear to be a suitable rock mass deformation mode for the failures at Mount Mercer; bi-planar failure and rock slumping are demonstrated to be suitable for the rock slope failures.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Quaternary stratigraphy and geologic history of the Charlie Lake (NTS 94A) map-area, British Columbia

Author: 
Date created: 
2005
Abstract: 

Two Cordilleran and three Laurentide glacial advances are recorded by Quaternary sediments in the Charlie Lake map-area (NTS 94A). The advances are inferred from the presence of exotic clasts derived from the Canadian Shield, fluvial deposits, glaciolacustrine deposits, and tills within nested paleo-valleys excavated during three interglaciations. The Late Wisconsinan Laurentide glaciation was the most extensive Laurentide glaciation, and the only one recognized in western Alberta south of the study area. Coalescence of Late Wisconsinan Laurentide and Cordilleran Ice Sheets is not recognized within the study area. Advancing Late Wisconsinan Laurentide ice blocked the east-flowing drainage and impounded Glacial Lake Mathews within paleo-Peace River valley and its tributaries. More than 100 m of fine sediment, deposited by suspension settling and density underflows were deposited in the centre of the basin. Weak, plastic clay layers within the glaciolacustrine sequence have developed shear planes on which more than 900 landslides have occurred.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Historical climate variability from the instrumental record in northern British Columbia and its influence on slope stability

Date created: 
2005
Abstract: 

This thesis examines historical climate variability and its effects on slope stability in northern British Columbia. It comprises three parts: (1) an analysis of climate trends and variability from the instrumental climate record; (2) an examination of climate controls on historic, large landslides; and (3) a demonstration of the utility of weather satellite imagery in determining landslide triggers. The climate of northern British Columbia has become wetter and warmer since the beginning of instrumental observations. Documented trends are complex due to ocean-atmosphere oscillations such as the Pacific Decadal Oscillation and the El Niiio Southern Oscillation. Long periods of increasing precipitation and temperature are a~~sociated with most dated, large landslides in the study area. Convective storms, large c:yclonic storms, and other weather events commonly trigger slope failure. Weather satellite images facilitated the analysis of climate triggers of landslides in remote areas and at high elevations.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

The influence of tectonic structures on rock mass quality and implications for rock slope stability

Date created: 
2005
Abstract: 

A field, laboratory and numerical modelling methodology was developed to investigate the influence of tectonic structure on rock mass quality and implications for rock slope stability. The fundamental components of this methodology include a full description of the rock mass (GSI, number of joint sets, block size and shape, weathering) and discontinuities (orientation, surface roughness, spacing, persistence, infill, seepage) in all accessible sections of the landslide, laboratory work (point load testing and thin section descriptions), and numerical modelling (limit equilibrium, finite difference and distinct element). Detailed fieldwork performed at the Aishihik River landslide, Hope Slide, and East Gate Landslide showed that pre-existing tectonic structures can significantly reduce the rock mass quality and facilitate the development of release surfaces. Numerical models of conceptual and natural slopes have shown that different representation of faults and related damage zone has a significant influence on the shape, volume, and failure mechanism of a landslide.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Three-dimensional kinematic controls on rock slope stability conditions

Date created: 
2010
Abstract: 

This thesis investigates the three-dimensional influence of discontinuity sets and topography on kinematics of rock slope stability and failure mechanisms. A field data collection methodology was developed to provide the inputs to a slope stability investigation that utilises three-dimensional geometric, limit equilibrium and distinct element codes. Conceptual slope geometries in addition to three case studies are employed to evaluate the influence of discontinuity set orientation and lateral kinematic confinement on the failure mechanism and slope stability conditions. The influence of varying the discontinuity persistence and block size in a three-dimensional distinct element code are also investigated. Systematic studies of these parameters are performed for the planar sliding and block toppling failure mechanisms. This thesis presents the first detailed description and slope stability analysis of the McAuley Creek Landslide and the Chehalis Lake Landslide. New data and analyses of the potentially unstable rock mass at Third Peak on Turtle Mountain are also presented. Two recently developed representations of complex topography in the three-dimensional distinct element code are applied to the case studies. The results obtained in this thesis are compared to the description of other local and international large rock slope failures published in the literature.

Document type: 
Thesis
File(s): 
Senior supervisor: 
D
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (Ph.D.)