Increased interest in deep-water sedimentation processes over the past two decades has revealed the ubiquity of submarine slope mass failures on continental margins. Slope failure appears to be a particularly critical process in the development of large deep-water sedimentary fans. A 7,000 km² 3D and a regional 2D seismic grid of hydrocarbon seismic reflection exploration data are used to construct a Quaternary stratigraphy and assess controls on sedimentation processes for the central and western deep-water Nile fan, offshore Egypt. These results will help understand the role of mass failure processes in the Quaternary construction of the Nile fan.

The deep-water Nile fan is a high sedimentation rate environment in an active seismogenic zone. The Quaternary section, locally up to a kilometre thick, is dominated by submarine channel systems and mass transport deposits. Regional mapping within the central and western Nile Fan reveals the presence of seven large mass transport complexes (MTCs) within this section, each comprising greater than 100 km³ of sediment. These large MTCs are used to separate the Quaternary Nile fan into seven stratigraphic units.

Six of the MTCs were apparently deposited as large cohesive slides, each comprising up to 2,000 km³ of sediment. These MTCs are interpreted to contain large cohesive blocks (generally up to 500 m by 300 m and up to 75 m thick), sometimes showing either compressional or extensional structures, as well as basal shear structures. These six MTCs are each overlain by extensive submarine channel systems that are connected updip to headwall-scar confined submarine canyons. These MTCs may have formed in response to high sedimentation rates and seismic ground shaking. The seventh large MTC comprises as a series of interpreted debris flows originating near two large gas chimneys and a normal fault located on the upper slope.

These data show a link between large slope failure events and the development of submarine canyons and channel systems. These particular large slope failures initiate on the upper slope creating extensive regions of sediment evacuation, extensive headwall scarps, and are accompanied by thick accumulations of MTCs on the mid-slope. Submarine canyons appear to establish on the upper slope within headwall scarps immediately following a major slope failure event. These canyons then serve as the principal conduits for sediment transport to deepwater, probably as turbidity current. By this mechanism, large slope failures may mark major shifts in deepwater turbidite depocenters that can be traced on regional seismic data. This model of fan development is important to explorationists in searching for turbidite-hosted hydrocarbon plays.

Supervisors: David Mosher (GSC-A) / Grant Wach

Landscapes of northern Canada are often associated with subglacial erosion during the Quaternary glaciations; however, the rates and spatial pattern of subglacial erosion are unknown. Terrestrial in situ cosmogenic nuclides (TCN) extracted from glaciated bedrock and till provide a new method to identify paleo-glacier basal thermal conditions. Differential preservation of pre-glacially produced TCN reflects the degree of glacial erosion. In warm-based zones, subglacial erosion stripped the upper few metres of regolith and bedrock and effectively removed the pre-glacial TCN. In cold-based subglacial conditions, the ice was frozen to the bed and the inherited TCN concentration survived.

Measurements of TCN concentrations from bedrock indicate that the valleys were eroded > 2.5 metres during a glacial-interglacial cycle. On summit plateaus, however, the long-term erosion rate is < 1.4 m/Ma. The juxtaposition of erosive ice in valleys and non-erosive ice atop interfluve plateaus has generated relief in arctic and sub-arctic regions.

Tills with monolithologic, angular clasts associated with cold-based ice contain 2-50 times the TCN concentration of silt-rich tills with polylithologic, striated clasts associated with warm-based ice. Measurement of minimum ice burial durations of >3 Ma suggest that recently deglaciated surfaces near modern ice caps may have been covered by cold-based ice since Pliocene time. Identifying cold-based anomalies in basal sliding is an obstacle to interpreting glacial dispersal patterns for mineral exploration.

Glacial erosion and till production are inferred to be functions of the thermal regime at the base of glacier ice and are tested by linking the distribution of TCN in bedrock and till with modelled basal thermal conditions using the University of Maine Ice Sheet Model (UMISM). TCN-derived glacial erosion rates vary linearly with modelled average sliding velocity by a glacial erosion coefficient of 5x10-7 – three orders of magnitude lower than in other regions.

Quaternary ice sheets and the driving global cooling during glaciations cause synoptic atmospheric pressure fluctuations from katabatic winds and atmospheric compression. Modelled atmospheric pressure changes due to presence of global ice sheets produces up to a 10% difference in TCN production rates for samples exposed near ice sheets and at high elevations during glaciations when compared to present-day production rates.

Supervisor:John Gosse

High-resolution laser altimetry (LIDAR) is applied to geological problems such as bedrock and surficial mapping and local surface processes in the Fundy Basin of Nova Scotia. Two GIS-based validation methods were developed to compare points and derived "bald earth" DEM from two LIDAR acquisition methods with checkpoints from GPS and traditional surveys. A systematic height error between flight lines for one of the LIDAR acquisition methods was detected that related to the calibration procedures used in the survey. As a result, an area of 350 km2 is the focus of this thesis where DEM errors are less than 0.2 m (1 ) in open areas and less than 1.3 m (1 ) in densely vegetated terrain.

Subtle topographical differences among three flow units of the Jurassic North Mountain Basalt (NMB) are clearly visible on a LIDAR DEM. Boundaries between flow units extracted from the DEM were verified by field mapping. The variable resistance of the flow units to erosion, documented by shatterbox experiments and down-core fracture density data, has a measurable control on incision by post-glacial consequent streams. Several ring structures in the lower flow unit, distinguishable only in the LIDAR data, are interpreted to be the remnants of rootless phreomagmatic cones. Two new sets of surficial landforms have been identified that indicate ice was directed northwestward into the Bay of Fundy during the late stages of glaciation depositing a blanket of till over half of the catchments draining the NMB into the bay. In catchments where till cover is thick, greater surface run-off and weaker infiltration increases incision by as much as 43% for a given flow unit. Till cover therefore is expected to impede the achievement of steady state conditions and may also delay the onset of stream power law relationships in larger catchments until till cover has been effectively stripped. This thesis demonstrates through a range of examples that the high-precision and resolution of LIDAR can improve our understanding of how landscapes form and evolve.

Supervisor: J. Brendon Murphy

In 1971, dinosaur bones were discovered during uranium exploration in the Sustut Basin in northern British Columbia, Canada, and were donated to Dalhousie University in Nova Scotia in 2004. Although dinosaur bones have been reported from British Columbia previously, this specimen is the earliest recorded discovery of dinosaur bones from the province. The specimen also represents one of the westernmost discoveries of dinosaur bones in Canada. The bones were collected from loose blocks in a talus slope, near the intersection of Birdflat Creek and Sustut River.

The fossils are encased in a hard siltstone that shares characteristics with both the Early Albian to Late Cenomanian Tango Creek Formation and the Late Campanian to late Early Maastrichtian Brothers Peak Formation, making a more precise age estimate for this specimen difficult. Bones collected include the right humerus, a radius, the distal portion of the right tibia and fibula, several pedal phalanges including two unguals, and several unidentifiable fragments. A small block of matrix removed from the tibia contains additional small bones, but further preparation is not possible at this time.

Comparison of the material with specimens at the Royal Ontario Museum and descriptions in the literature indicates that a relatively small (less than three metres in length), bipedal ornithischian is represented. General features of the tibia and phalanges are consistent with the ornithopod Thescelosaurus, but a low deltopectoral crest on the humerus matches closely with Stegoceras and other pachycephalosaurs. The specimen may represent a new taxon unique to British Columbia.

Supervisor:Milton Graves

The Scotian Basin, offshore Nova Scotia, is a passive margin made up of Triassic evaporites overlain by several kilometres of carbonates, shales, and deltaic sediments, which were deposited as a basinward prograding wedge. The progradation of sediments caused the basinward migration of salt in the paleoslope area with thin-skinned extension in the overburden. Complex salt structures and stratigraphic relationships exist as a result of dynamic depositional systems, sny-depositional salt mobilzation, and brittle faulting of the overburden. The Scotian Shelf has been well explored and has proven to be an economic source of hydrocarbons. The Scotian Slope, however, has provided disappointing exploration results and is still not well understood. Lack of knowledge and technically challenging environments has made deepwater exploration on the Scotian Slope a high risk.

This study applies physical experiments with high resolution Particle Imaging Velocimetry (PIV) optical strain monitoring to simulate gravity-driven deformation in passive margin sedimentary wedges overlying a mobile substratum under varying sedimentation patterns and rates. The spatial and temporal structural evolution as well as the salt-sediment interactions is analyzed. The results of this study can help develop mechanically constrained concepts and templates for the interpretation of geological and geophysical data. This thesis used six experiments which explored stagnation, low sedimentation and high sedimentation rates, on horizontal and tilted bases. The results show that structures are controlled by strain rates, which are controlled by sedimentation patterns and rates.

Supervisors: D. Grujic / J. Adam

The geology of southwestern Nova Scotia is characterized by plutons of varying compositions intruding a Meguma host rock. Onshore, the Shelburne and Barrington Passage plutons intrude the folded Halifax and Goldenville Formations of the Meguma Group. The striped magnetic signature of the Meguma contrasts with a smooth, relatively uniform signature, in some cases positive, associated with the plutons. Previous studies of southwestern Nova Scotia have used gravity and aeromagnetic data to extend interpretations of this onshore lithology into the offshore. More recently, swath bathymetric studies have shown granite bedrock exposed at the surface. This study correlates between the coast and the outer portion of the continental shelf based on forward modelling of magnetic data. A series of profiles constrained by magnetic susceptibility values were used to create 2D cross-sections of lithology. An onshore profile investigates the Shelburne and Barrington Passage plutons. A database of magnetic susceptibility values measured for each lithologic unit provided information on composition and the possible genetic relationships between plutons. These onshore results were extrapolated into the offshore to develop a profile through Mud and Seal Islands to determine the relationship to the onshore plutons and put limits on the extent of the Seal Island Pluton. Areas of positive anomaly on the continental shelf were investigated and linked to the Seal Island profile. The extent of plutons in the offshore has been mapped and correlated to regional geology based on their magnetic anomaly and other geophysical characteristics.

Supervisor: S. Dehler

Carbonate mounds that have been dragged up from the seafloor during fishing offshore the Northern Cape Breton Highlands are very distinctive in their nature. The carbonate mounds range in size from a few cm3 to larger than an m3 in size. Worldwide, other carbonate mounds have been documented, but they are either much larger or formed in different settings. By studying seismic sections and sampling the hand specimens, the process of their formation can be proposed. Using both Huntec and Airgun seismic data, distinct areas of hydrocarbon mixing with the sediments can be detected. The seismic data also showed a distinct layering between glacial deposits and more recent sediments. Carbon 13 values determined form isotope analysis of shelly debris encased in the mounds showed a distinct negative value in each of the samples. The range for the C13 values is -9.41 to -35.27, with one outlier at -61.38. Considering the isotopic analysis and the seismic data it seems likely that these carbonate mounds were formed by methanogenesis of hydrocarbon from slow seeps on the seafloor.

Supervisor:P. Wallace

Supervisor:M. Gibling

The Hamilton Spur is a large late Cenozoic sediment drift feature, that trends northeastward between 300 m and 3000 m water depth on the Labrador continental margin. The objective of this study is to understand the Quaternary development of this large deep water drift which formed by the southward flowing Labrador Current and Western Boundary Undercurrent reworking and depositing continental margin sediments. To gain a better understanding of the processes that directly influence the Hamilton Spur, 289 km of single channel air gun seismic reflection, Huntec subbottom data and three piston cores were examined. The study mapped a major near surface unconformity that marks the initiation of the Labrador Current, defined by the erosion of a pre-existing sediment drift. Overlying the unconformity, 5 key horizons were mapped indicating a southward migration of the Hamilton Spur. The northern flanks of the spur are subjected to intense current velocities and current reworking, with subsequent deposition on the southern flanks of the ridge where decreases in current velocities cause a loss of sediment suspension within the water column, evident in thickened units. Six seismic facies have been established on the Hamilton Spur indicating variations of depositional environmental over the spur depending on depth and location to current axis. Piston cores support the idea of current influenced deposition in which increased sediment thickness is observed. Cores contain 5 lithofacies, indicating changes in depositional patterns over the ridge The outer margin and upper slope (~300-1200 m) of the northern flanks are controlled mainly by the deeper Labrador Current component where clays and silty sediments are subjected to winnowing, leaving more coarse sands and lag deposits. The middle slope region (~1200 m) is considered to be unaltered by currents defined by a Azone of minimum motion@. The lower base and northern flanks (1200-3000 m) are subject to the intense axis of the Western Boundary Under Current, responsible for considerable reworking of bottom material and the presence of considerable amounts of sands, and minor traces of silts. Seismic reflection data and piston cores collected support the idea of southward flow of the Labrador Current and Western Boundary Undercurrent. Sedimentation processes such as mass transport deposits and glacial melt-water deposits followed the development of the unconformity. Under modern conditions, current intensity and sedimentation rates have decreased on the Spur, however the Hamilton Spur=s depocenter continues its southward migration.

Supervisor: D. Mosher

The contact aureole of the South Mountain Batholith cuts the Halifax Formation in the area of the Halifax peninsula. Isograds have been mapped based on outcrops on the Dalhousie University campus, railroad cuts, Point Pleasant Park and scattered outcrops and construction sites throughout the peninsula. Within the study area two lithological units are recognized based on contrasts in lithology, bulk composition and contact metamorphic mineral assemblages. The Cunard member is an aluminous, graphitic black slate with sparse metasiltstone layers and characteristic rusty weathering, which extends from the southeast side of the Dalhousie campus north to the Fairview area. The "Bluestone" member (informal name), which stratigraphically overlies the Cunard member, is a blue-grey slate with abundant metasiltstone layers and local calcareous concretions. It is exposed from the vicinity of Oakland Road to Point Pleasant Park, and underlies the Williams Lake area on the west side of the Northwest Arm. Prior to the intrusion of the South Mountain Batholith, the Halifax Formation was regionally deformed into NE-SW trending upright folding with associated slaty cleavage and a chlorite zone regional metamorphic assemblage. Contact metamorphism overprinted the chlorite zone assemblage and progressively annealed the slaty cleavage proximal to the contact. The outer limit of the aureole, about two kilometers from the contact, is defined by sparse cordierite "spots" in both the Cunard and Bluestone members. The biotite isograd, which is continuous between the Cunard and Bluestone members is marked by nucleation of biotite within the muscovite/chlorite stacks inherited from the regional meteamorphism. Between the biotite-in isograd and the contact, the modal abundances of both cordierite and biotite increase in both units. In contrast, there is a striking difference in the texture and first occurrence of andalusite between the Cunard and Bluestone members. In the Cunard member idioblastic chiastolite appears after cordierite, but before biotite. Its early appearance is attributed to the reaction Pg + Qtz - And + Ab + L. Crystal size and modal abundance increase towards the contact. In the less aluminous Bluestone member andalusite first appears as ovoid xenoblastic aggregates within 300 metres of the contact, probably as a result of the reaction Ms + Crd - And + Bt + Qtz + L. Adjacent to the contact the assemblage And + Crd + Kfs + Bt + Qtz + Sil (Fibrolite) is present in both the Cunard and Bluestone members. ThermoCalc P-T estimates show a pressure of 3.3 kb + 2.2 kb and a temperature of 645^oC +- 16^oC nearest the contact and 551^oC +- 6^oC at approximately 2 km from the contact.

Supervisor: B. Jamieson

Numerical modelling is used to investigate for the first time the interactions between a petroleum system and sill intrusion in the NE Sverdrup Basin, Canadian Arctic Archipelago. Although hydrocarbon exploration has been successful in the western Sverdrup Basin, the results in the NE part of the basin have been disappointing, despite the presence of suitable Mesozoic source rocks, migration paths and structural/stratigraphic traps, many involving evaporites. This was explained by (i) the formation of structural traps during basin inversion in the Eocene, after the main phase of hydrocarbon generation, and/or (ii) the presence of evaporite diapirs locally modifying the geothermal gradient, leading to thermal overmaturity of hydrocarbons. This study is the first attempt at modelling the intrusion of Cretaceous sills in the east-central Sverdrup Basin, and to investigate how they may have affected the petroleum system.

A one-dimensional numerical model, constructed using PetroMod9.0®, investigates the effects of rifting and magmatic events on the thermal history and on petroleum generation at the Depot Point L-24 well, eastern Axel Heiberg Island (79o23’40”N, 85o44’22”W). The thermal history is constrained by vitrinite reflectance and fission-track data, and by the tectonic history. The simulation identifies the time intervals during which hydrocarbons were generated, and illustrates the interplay between hydrocarbon production and igneous activity at the time of sill intrusion during the Early Cretaceous. The comparison of the petroleum and magmatic systems in the context of previously proposed models of basin evolution and renewed tectonism was an essential step in the interpretation of the results from the Depot Point L-24 well.

The model results show that an episode of minor renewed rifting and widespread sill intrusion in the Early Cretaceous occurred after hydrocarbon generation ceased at about 220 Ma in the Hare Fiord and Van Hauen Formations. We conclude that the generation potential of these deeper formations in the eastern Sverdrup Basin was not likely to have been affected by the intrusion of mafic sills during the Early Cretaceous. However, the model suggests that in shallower source rocks such as the Blaa Mountain Formation, rapid generation of natural gas occurred at 125 Ma, contemporaneous with tectonic rejuvenation and sill intrusion in the east-central Sverdrup Basin.

A sensitivity study shows that the emplacement of sills increased the hydrocarbon generation rates in the Blaa Mountain Formation, and facilitated the production of gas rather than oil.

Supervisors: Marie Claude Williamson/Marcos Zentilli/Hans Wielens

Groundwater is an important resource in Nova Scotia, with about 46% of the population relying on groundwater for their water supply. Groundwater quality has been assessed in various parts of the province during provincial water resource evaluations, and several province-wide studies have been carried out to assess specific chemicals in groundwater, such as arsenic and uranium. However, to date there has not been a province-wide quantitative analysis of the general chemical quality of groundwater. Nova Scotia Environment and Labour (NSEL) has compiled a database of registered and municipal water supplies across the province, and this represents a good opportunity to complete a quantitative assessment of groundwater quality.

Water is called the universal solvent. As groundwater passes through geologic materials, it participates in various chemical processes. The resulting water chemistry will vary with geology and contact time. Groundwater regions in Nova Scotia can be broken down into five major hydrostratigraphic units: igneous, metamorphic, sedimentary, carbonate and evaporite, and surficial aquifers.

This reports reviews groundwater chemical results, especially trace metals, from about 1000 samples from the NSEL database. A typical water quality report includes major and minor ions, physical properties, trace metals, total dissolved solids and pH. The various individual parameters are compared to the Guidelines for Canadian Drinking Water Quality, which are based on both health and aesthetic considerations.

This study represents a Afirst cut@, one point in time, approach to assess groundwater quality on a province-wide scale. Further work could involve more detailed resolution of data issues, use of more sophisticated statistical software tools, additional sampling to ensure adequate coverage of hydrostratigraphic units and geographical areas, analysis of seasonal variations in water quality, and location of data points for a GIS-based database.

Supervisor:Heather Cross

From 1862 to 1939, intermittent gold mining and milling at Wine Harbour, Guysborough County, Nova Scotia produced a total of 42,726 oz. of Au from 72, 413 tonnes of crushed rock. The gold occurs in a series of quartz veins, typically associated with arsenopyrite, that are hosted by the Goldenville Formation of the Meguma Group. Stamp milling and mercury amalgamation were the primary gold extraction methods. The tailings were slurried directly into surrounding streams and low-lying areas around the shores of Wine Harbour. In July 2005, mine tailings, waters and marine sediment samples were collected throughout the Wine Harbour gold district. Chemical analyses of 10 tailings samples collected on-land show very high concentrations of both As (200 to 200,000 ppm) and Hg (4900 to 320,000 ppb). The distribution of As and Hg in marine sediments confirms that most areas of Wine Harbour have been impacted by historical gold milling activities. Chemical analyses of 233 marine sediment subsamples show a wide range in both As (4 to 1500 ppm) and Hg (5 to 9500 ppb) concentrations. In general, the highest As and Hg values are located close to known stamp mill structures along the shores of Wine Harbour. However, high levels of both As and Hg also occur in the bottom sediments of a small inlet at the western end of the harbour, within the bounds of an active mussel aquaculture operation. Contamination of this latter site is likely related to a mill site(s) that is not shown on the historical maps for this gold district. The investigation is part of an ongoing multidisciplinary project which is assessing the marine and terrestrial environmental impacts of historical gold mining activities throughout Nova Scotia. Results from this study can be used to help assess potential ecosystem and human health risks associated with high levels of As and Hg in Wine Harbour.

Supervisor: Michael Parsons

Analysis of sediments was performed on two box cores collected as part of the Canadian Arctic Shelf Exchange Study (CASES). The two stations examined (stations 403B (59 m) and 415B (56 m)) are located in the Amundsen Gulf. The study was undertaken in order to develop a record of changes in the sedimentologic and oceanographic history of the area. Arctic benthic foraminiferal assemblages of the Late Holocene (403B) and Pleistocene (415B) have contrasting sedimentation rates. Core 403B is from an area of high sedimentation from on the Beaufort Shelf, where the Mackenzie River outputs sediments. Core 415B is from an area of low sedimentation on the steep slope of Banks Island, and lacks sediment input form a large river system. Core 415B is from a location that has drumlin-like features and ice-scouring, which are revealed with multibeam sonar. By comparing and contrasting 403B and 415B, a broader interpretation of the natural history of the Amundsen Gulf is revealed. Foraminifera >63 µ from 403B revealed that this is a shelf environment abundant in Cassidulina reniforme, Islandiella teretis, Spiroplectammina biformis, and Elphidium spp., with an interval barren in foraminifera, except for a rare assemblage of Reophax spp. The most abundant foraminifera >45-63 µ from 403B were Bolivina arctica, Texturlaria earlandi, Reophax scotti and Egerella advena. There were more foraminifera > 63 µ than >45-63 µ. Foraminifera >63 µ from 415B revealed that this was once a Pleistoce shoreline abundant in Bolivina arctica, as well as Spiroplectammina biformis and Reophax arctica. The environment gradually became a shelf environment abundant in Spiroplectammina biformis, Textularia earlandi, and Trochammina globigerinformis. The most abundant foraminifera >45-63 µ from 415B were Bolivina arctica, Textularia earlandi, and Spiroplectammina bioformis. There were significantly more foraminifera >63 µ than >45-63 µ. More individuals were found in 415B than in 403B, and the species diversity was slightly higher in 415B than in 403B. Core 403B represents approximately the last 350 years of a shelf environment with an interval barren in foraminifera. This barren zone could be due to carbonate dissolution. When trying to find similar past environments such as this one, only deep-water environments seem to match. Core 415B is a progressively deep environment, which starts as a Pleistocene shoreline and becomes deeper with the abundance of deep-water species and shelf species. Both cores seem to show that they have been influenced by either Arctic Surface Water or Arctic Intermediate Water in their natural history. This study will contribute to the assessment of factors that presently influence sea ice cover, a key element of the Arctic ecosystem.

Supervisor: David Scott

Through the interpretation of one cored section located within the Provost Oil Field of east central Alberta, the late Aptian to early Albian Cummings Formation, found within the Lower Mannville Group, has been interpreted as a transgressive estuary deposit. Basal channel incision followed by valley-fill deposits exhibit progressive marine influence through the presence of characteristic tidal bundles and asymmetrical current ripples demonstrating subordinate current flow. A low diversity suite of biogenic sedimentary structures, mixed Skolithos and Cruziana ichnofacies, also adhere to a transgressive estuarine depositional model. Abundant detrital chert, volcanic and lithic fragments observed through mineralogical analyses indicate a Cordilleran provenance. Organic petrographic analyses of organic matter within the Cummings Formation suggest a terrestrial source of potential gas producing type III kerogen. Vitrinite reflectance and rock evaluation results suggest the Cummings Formation is thermally immature. Poor total organic carbon percentages designate the Cummings Formation as being inadequate as a secondary source rock for the Provost Oil Field. Further understanding of depositional environments and sequence stratigraphic relationships within the Western Canadian Sedimentary Basin (WCSB) provides insight into hydrocarbon emplacement. This study also provides further stratigraphic resolution of the complex interval between the Lower and Upper Mannville Groups.

Supervisor: Grant Wach

Northeast Fan is a submarine fan developed seaward of Northeast Channel, located on the southwestern part of the Scotian Margin. Northeast Channel has been recognized as a major ice-stream outlet during the last glacial maximum (18 ka). Seaward of Laurentian Channel, the other major ice stream outlet off Nova Scotia, is the well known Laurentian Fan. The scope of this study is to explore the late Quaternary architecture of Northeast Fan with the use of six strike seismic lines and four piston cores, to test the hypothesis that Northeast Fan resembles a smaller version of Laurentian Fan.

Creation of a detailed contour map of bathymetry for the Northeast Fan showed that the axes of three main channels could be traced, called Western, Central and Eastern channel. The interpretation of acoustic facies within the upper 50 m through the use of the high-resolution reflection seismic profiles (Huntec sparker) provided an acoustic facies distribution map. This map showed that the southwestern and upper slope portion of Northeast Fan is composed mainly of dissected reflectors or stratified and dissected reflectors, while the southeast and northeast portions of the Northeast Fan predominantly comprise of mass-transport deposits (MTDs) and highly stratified and stratified reflectors. Six reflection markers in the Huntec seismic profiles were correlated across most of the Fan, thus creating a stratigraphic framework. Cores showed the existence of one or two distinct units of brick red muds (>b= and >d=) and some contained a small tan mud layer identified as Heinrich layer H1. Turbidite sands found in cores were high above channel floors and some were deposited within the time interval of 18 ka and 14 ka.

On the continental slope northeast of the Northeast Fan, three distinct high amplitude reflectors were observed in a Huntec profile, which show similar features to an area off the St. Pierre slope. They were interpreted to represent ice-proximal deposition at glacial maximums and correlated to Marine Isotope Stage (MIS) 4 and MIS 6. The MIS 6 reflector corresponds to the Pink marker of the study, which allowed the dating of two major MTDs in Northeast Fan. Although Northeast Fan does share some features with Laurentian Fan such as the development of channels across the slope and rise, major differences exist. The upper portion of Northeast Fan rather resembles The Gully or Banquereau canyons with the presence of shelf-breaching canyons.

Supervisor: David J.W. Piper

Landsat remote sensor imagery from 1978-2001 and GIS software were used to classify thermokarst lake area and determine changes in lake coverage on the Tuktoyaktuk Peninsula in Northwestern Canada. Study area segments were constructed to examine total lake area changes for multiple lake class sizes between periods ranging form 1-22 years. Climatological data were obtained to compare trends in studied years to thermokarst lake growth factors including mean annual temperature, thaw temperature, and cumulative precipitation. Substantial lake area growth (up to 15%) and shrinkage (up to 11%) were detected, with growth occurring primarily between 1978-1992 and shrinkage between 1991-2001. These changes correlate strongly with cumulative precipitation data (r2 = 0.823) and suggest that this is the primary factor influencing lake growth detectable on a large scale when relatively coarse resolution remote sensing is used. These results also suggest that long-term lake area changes are well masked by short-term climatological changes, contrasting recent studies showing sustained long-term changes attributed to Arctic climate change.

Supervisors: Lawrence Plug / Charlie Walls

Point Pleasant Park has been a landmark of the city of Halifax for over 200 years. Originally built as a military base in 1796, Point Pleasant Park was leased to the people of Halifax in 1873 by Queen Victoria for a shilling a year for 999 years. The Park was recommissioned during the two world wars and since has been a municipal park for all of the residents in Halifax to enjoy. The devastation brought about by Hurricane Juan provided an opportunity to study the bedrock geology within Point Pleasant Park. The bedrock geology of the Halifax peninsula was originally assigned to the Cunard member of the Halifax Formation. After careful observation, the bedrock geology within the park has been assigned to a different unit, informally named the Bluestone member after an old quarry on the western side of the North West Arm. The Bluestone member is an interlayered metasiltstone-slate turbidite unit lying gradationally on top of the Cunard member. Two subdivisions of the Bluestone member have been identified within the Park. Unit A is interlayered metasiltstone and slate containing abundant calcareous concretions. This unit starts at the southern tip of the park and continues north until the last occurrence of calcareous concretions at Cable Rock. Unit B is similar in lithology to unit A but has no observed concretions. The lithology of the park has been folded into a large-west plunging syncline with the fold axis located at the northern edge of the park. Two different metamorphic events have affected the rocks within the park. Regional metamorphism occurred along with the folding during the Acadian Orogeny (ca. 390 Ma) and has metamorphosed the Bluestone member to greenschist (chlorite zone) facies. Contact metamorphism caused by the intrusion of the South Mountain Batholith (ca. 380 Ma) overprinted the regional metamorphism producing cordierite, which has weathered out to give the rocks their characteristic Aspotted@ appearance.

Supervisor: B. Jamieson

In the of fall 2005, a study in Dartmouth, Nova Scotia was performed on the concentration and grain size distribution of suspended particulate mass (SPM) that entered Lake Charles, the Shubenacadie Canal Park and Lake Micmac, during heavy rainfall events. The study area had a history of increased SPM concentrations due to urban development since the early 1970's. New constructions began in the spring and summer of 2005, west of the study site and public concern was raised as the sites were not required to perform provincial or federal environmental impact assessments. Spring storms provided an indication that SPM should be considered a significant problem, however, it was not resolved. In the fall of 2005 large rainfall events, again resulted in SPM entering the lakes system. Weekly sampling was carried out to determine background concentrations in the region, and event sampling was performed during heavy rainfalls. One example of a large rainfall event during the October 7th-10th weekend when Dartmouth received over 150 mm of rain. Sampled water was highly discoloured and the resulting SPM concentrations ranging between 0.2-100 mg L-1. During the peak of the Thanksgiving Storm SPM concentrations exceeded water quality guidelines set by the Canadian Counsel of Resource and Environment Ministers. SPM concentrations were in the higher range in the northern Canal and Grassy Brook. Measurements of the sediment grain size entering the lakes, using the Coulter Multisizer IIe showed that the sediments were clay/silt sized (ranging from 10 to less than 63 µm). Storm samples and background samples showed different DIGS distributions indicating the source of sediment were not the same. After the Thanksgiving Storm, SPM concentrations were reduced as the methods of water retention at both construction sites were improved. After the initial Thanksgiving SPM overflow, the concentrations of sediments entering the lake system during subsequent rainfall events were reduced.

Supervisor: Paul Hill

The post-rift structural evolution of many rifted continental margins has been affected by the mobilization and continued flow of weak syn- or early post-rift salt layers. Driven primarily by regional differential sediment loading, salt flow can deform the sedimentary overburden into a range of complex structures, many of which can become effective hydrocarbon traps. In this thesis, controls on salt mobilization and resulting structural styles are investigated using 2D finite element modelling, analytical mechanics, and reflection seismic data from the Scotian Margin.

Lubrication theory combined with limit analysis is used to determine an analytical stability criterion for simple systems where a sediment overburden of laterally varying thickness overlies a linear viscous salt layer. The differential loading produces a pressure gradient and induces salt flow. If the differential loading is large enough, the overburden fails developing a region of landward extension compensated by basinward contraction. For submarine systems, water loading increases solid and fluid pressures in the sediments, reduces the pressure gradient on the salt, and buttresses the overburden.

Slow sediment progradation causes a diachronous structural evolution comprising four main phases: 1) initiation of salt flow and the formation of salt withdrawal mini-basins and diapirs; 2) onset of normal growth faulting and extension of the overburden; 3) large-scale evacuation of the salt, and overburden rafting; 4) formation of an allochthonous salt nappe that overthrusts the depositional limit of the salt. Seaward margin tilt increases the rate of salt flow and overburden deformation, while flexural isostatic adjustment has the opposite effects.

The formation of mini-basins, where the overburden is less dense than salt, requires a dynamical stress to create the necessary dynamic bathymetry. Numerical results indicate that the toe-of-slope contractional domain is one region of a passive margin where this dynamical stress amplifies mini-basins.

Numerical modelling, in conjunction with seismic interpretation, has allowed the development of a new conceptual model for the post-rift structural evolution of the northeastern Scotian Margin. Here, Jurassic deltaic sedimentation squeezed salt basinward producing an open-toed salt nappe. Subsequent sedimentation caused gravity spreading over the nappe and produced regional extensional structures characterized by landward dipping sigmoidal stratigraphy.

Supervisor: Chris Beaumont

For generations, fishermen in Atlantic Canada have known about corals or “trees” growing in the deep waters along the shelf break. Scientific interest dates back to the 1880s, when Gloucester Fisheries collected specimens for the Smithsonian.

In recent years, growing concern about the rate and scale of climate change has prompted an examination of climate records encoded in deep-sea coral skeletons.

Focusing on the gorgonian species Primnoa resedaeformis, this thesis examines the paleoceanographic utility of deep-sea octocorals. With a lifespan of 700+ years, P. resedaeformis is the longest-living octocoral, and one of the oldest animals in the sea. Unlike their aragonitic counterparts, the scleractinians, octocorals secrete a 2-part skeleton of calcite and gorgonin, a protein. The calcite is derived from dissolved inorganic carbon at depth, while the gorgonin is derived from recently exported particulate organic matter. The gorgonin is resistant to organic diagenesis, as revealed by the amino acid composition of a nearly 2000 year old sub-fossil specimen. Clues about past environmental conditions are encoded in the chemical make-up of annual rings secreted over the lifetime of the coral. The 2-part skeleton of calcite and gorgonin thus constitutes a record of surface- and deep- water properties alike.

Development of calcite- and gorgonin-based proxy records from P. resedaeformis sheds new light on the slopewater system off the Scotian Shelf/Gulf of Maine. From the skeletal calcite, a record of ¹⁴C documents decadal-scale shifts in the presence of southern- (Antarctic) and northern-(Labrador) derived source waters over most of the 20th century. From the skeletal gorgonin, stable C and N isotopic composition presents a more complicated picture of the surface water environment. Following nearly 2000 years of relatively constant values, ¹⁵N rapidly decreased during the 20th century. As a possible cause for the observed trend, a weakening of the Labrador Current is suggested, but a trophic cascade presents a plausible alternative hypothesis.

Supervisor: David Scott

The South Mountain Batholith (SMB) of southern Nova Scotia is a large composite, peraluminous granitoid complex, intruded dominantly into metapsammitic to metapelitic rocks of the Meguma Group. Field and textural relations reveal evidence for contamination of the SMB by rocks of the Meguma Group in the form of xenoliths, xenocrysts, and former partial melt, and assimilation of the country-rock material through a combination of fracturing, dispersal, partial melting, dissolution, and ion exchange reactions. Assimilation of the metapsammitic rocks released orthoxenocrysts of quartz, biotite, and plagioclase, and up to 50 vol% of partial melt into the SMB magmas, whereas assimilation of the metapelitic rocks released paraxenocrystic garnet and cordierite, and up to 80 vol% of partial melt. In the SMB rocks remote from contacts with Meguma Group rocks, textural relations, chemical compositions, and/or zoning patterns permit the identification of xenocrystic garnet and cordierite with confidence. On the other hand, deciphering the origin of any given quartz, biotite, and plagioclase crystal in the SMB has a considerable uncertainty, because textures and compositions of country rock-derived and fine-grained cognate magmatic crystals are similar. Despite these difficulties, assuming that all suspect crystals are true xenocrysts, and that all xenocrysts present in a given rock are physically detectable, xenocrysts make up <= 4 vol% in the marginal rocks and <= 3 vol% in the more central rocks of the SMB. Using ratios of xenocrysts to partial melt determined in melting experiments employing rocks of the Meguma Group, the abundance of xenocrysts may suggest that <= 10 vol% of physically invisible, complementary former country-rock partial melt is present in the SMB rocks, and together, <= 16 and <= 8 vol% of Meguma Group country-rock material appears to occur in the marginal and more central rocks of the SMB, respectively. However, existing whole-rock isotopic data indicate that at least the most evolved, and typically the more central, rocks of the SMB may consist of up to 56 vol% of additional country rock-derived partial melt, which may have been added to the SMB magmas through the assimilation of Meguma Group rocks, or by a Meguma Group source contribution. Energy-constrained numerical modelling of the assimilation of Meguma Group rocks in the SMB magmas shows that all former country-rock partial melt present in the exposed SMB rocks may be explained by country-rock assimilation through partial melting, if the exposed rocks were selectively contaminated, but cannot rule out that the former Meguma Group partial melt added to the SMB as part of the source until further whole-rock and mineral isotopic analyses are available.

Supervisor: Barrie Clarke

Supervisor:

Supervisor: Marcos Zentilli