The three approaches followed herein aim to improve our understanding of the paleobiodiversity andevolution of Silurian radiolarians. The first approach provides an exhaustive taxonomic description ofan entirely new radiolarian fauna recovered from two sections of the Cape Phillips Formation in theCanadian Arctic which accumulated in two different paleoenvironmental settings. The samples are datedby graptolites of the Gorstian Lobograptus progenitor Zone. The obtained radiolarian fauna includes 28species, of which 3 are new, and exhibits some of the best preserved Silurian radiolarians known so far.The stratigraphic range of several species was also extended. Then, in a second approach, a CT-Scan3D reconstruction of a specimen of Gyrosphaera cavea was conducted in order to resolve significantinternal structure taxonomic issues. Higher level radiolarian classification is based on internal structures,and classical methods of observing these features repeatedly failed to uncover them. The 3D imagingrevealed a «double» coiling of the specimen that has proved useful in understanding how it grew.Eventually, the third approach is a completion of published taxonomic works in the Silurian with theaim of providing diversity trends through analyses of these radiolarian occurrences. A biotic crisis canbe observed in the Homerian, exhibiting both high extinction and low origination rates, and may belinked with enhanced marine productivity. / De tre projekten som utvecklas här har som mål att fokusera på trender inom evolutionen ochmångfalden av en grupp planktoniska mikroorganismer från Silur (från -443 till -419 Ma). I ett förstaprojekt beskrivs en helt ny fauna radiolarier som hittats i två lokaliteter på de kanadensiska arktiskaöarna, och som har deponerats i olika miljöförhållanden under Silur. Detta material daterades med hjälpav graptoliter, en grupp utdöda svalgsträngsdjur som är mycket användbara för paleozoiska dateringar,till en ålder överensstämmande med Gorstian (-427 till -425 Ma). Denna kanadensisk-arktiska fauna avradiolarier består av 28 arter (varav 3 är nya) och uppvisar några av de bäst bevarade fossilerna frånSilur överhuvudtaget. Den stratigrafiska bredden, vilket är livstiden, av flera arter har också förlängts.Därefter, i ett andra projekt, skapades en 3D-rekonstruktion av ett exemplar av Gyrosphaera cavea medhjälp av mikrotomografi för att observera och beskriva komplexa interna strukturer. Faktum är attklassificeringen av Radiolaria består till stor del av analysen och beskrivningen av dessa internastrukturer och många klassiska metoder som har använts för att observera dem, såsom med hjälp avsvepelektronmikroskop, har misslyckats konsekvent. 3D-avbildningen visade en komplex dubbelrullandeav strukturen i exemplaret, som har visat sig vara användbart i sökandet för att förstå dennesutveckling. Det tredje projektet är slutförandet av en samling av samtliga publicerade arbeten röranderadiolarier från Silur med syfte att klargöra trender inom diversitet för hela perioden genom analyser avförekomsten av dessa radiolarier. Ett utdöende kan observeras under Homerian (-430 till -427 Ma), somtroligen orsakades av frekventa utdöenden och en låg artbildningshastighet.

This study presents the first annually-resolved chronology using Salix alaxensis (Anderss.) Cov from Victoria Island, Northwest Territories, Canada, an area well north of treeline. Forty-one samples were collected and examined for subsequent analysis. However, crossdating was difficult because of locally absent or missing rings and the narrowness of the rings, and ultimately thirteen stems were crossdated and used to evaluate their dendroclimatological potential. The chronology spans 74 years (1927-2000) and could potentially be extended further using subfossil wood. Precipitation data from December of the previous year to March of the current year were the most consistently and highly correlated with ring width. This suggests that the recharge of the soil moisture by early summer snowmelt is a key factor limiting growth of these shrubs.

Climate change, with the possibility of an ice free Arctic ocean by 2015, has generated a renewed interest in the Arctic. This interest is being driven by the possibility of easier access to the abundant supply of resources such as oil, gas, minerals, and fisheries. Interest in Arctic tourism is also growing. Retreating sea ice will provide opportunities to avail of shorter routes for maritime traffic to and from Asia, North America, and Asia via the Arctic Ocean and Northwest Passage. In addition, the rate of population growth of local inhabitants in the Canadian Arctic is the fastest in Canada and one of the fastest in the world. A growing population will increase the demand for sealift resupply to Canada's northern communities. This work presents the first attempt to examine the role of privatization of icebreaking services in light of the present and projected shortages of infrastructure to support development in the Arctic. A unique combination of multiple methods within marine transportation, comprising of Delphi, grounded theory, and quantitative survey, is applied to investigate the potential for private involvement in the delivery of icebreaking services in the Canadian Arctic. This includes a novel application of Strauss and Corbin's Grounded Theory approach to develop hypotheses and relationships grounded in expert opinion. Although the Arctic Ocean may be ice free during the summers, there is still the issue of winter freezing and the threat of lingering multi-year ice which will impede marine transportation especially during periods of darkness and fog. The research shows that the future growth and development of the Canadian Arctic will undoubtedly require the use of designated icebreakers and ice strengthened vessels. However, Canada's fleet of Arctic icebreakers is ageing and considered unsuitable for future demands. While Canada has earmarked CAD $750M for the construction of one new icebreaker scheduled for delivery in 2017, the research shows that Icebreakers can be built outside of Canada for considerably less money and in less time. Also, the management and operation of the Canadian Coast Guard is under considerable security by the Auditor General of Canada. The research shows that not unlike others Arctic nations, there is potential for the creation of private-public partnerships in the delivery of Canadian Coast Guard services, principally icebreaking, in the Arctic.

A 147cm sediment core from Lake DV09, northern Devon Island, Nunavut, Canada (75° 34’34”N, 89° 18’55”W) contains annually-laminated (varved) sediments, providing a 1600-year record of climate variability. A minerogenic lamina deposited during the annual thaw period and a thin deposit of organic matter deposited during the summer and through the winter, together form a clastic-organic couplet each year. The thinnest varves occur from AD800-1050, and the thickest from AD1100-1300, during the Medieval Warm Period. The relative sediment density is also highest during this period suggesting increased sediment transport energy. The coldest period of the Little Ice Age appears to be during the AD1600s. Varve widths over the past century indicate climate warming in the region. / This research program was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC), and the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS). A tuition bursary from Ultramar Inc. also helped in making this research possible. Logistical support was provided by the Polar Continental Shelf Project (PCSP Contribution number 04508).

A 147cm sediment core from Lake DV09, northern Devon Island, Nunavut, Canada (75° 34’34”N, 89° 18’55”W) contains annually-laminated (varved) sediments, providing a 1600-year record of climate variability. A minerogenic lamina deposited during the annual thaw period and a thin deposit of organic matter deposited during the summer and through the winter, together form a clastic-organic couplet each year. The thinnest varves occur from AD800-1050, and the thickest from AD1100-1300, during the Medieval Warm Period. The relative sediment density is also highest during this period suggesting increased sediment transport energy. The coldest period of the Little Ice Age appears to be during the AD1600s. Varve widths over the past century indicate climate warming in the region. / This research program was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC), and the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS). A tuition bursary from Ultramar Inc. also helped in making this research possible. Logistical support was provided by the Polar Continental Shelf Project (PCSP Contribution number 04508).

The Lower Devonian carbonate-clastic sequence of southwest Ellesmere Island accumulated in the Franklinian Basin at approximately 15(DEGREES)N latitude. A variety of depositional settings are represented, ranging from tidal flat to basinal environments. These environments can be recognized in Lower Devonian rocks across the Arctic Islands. / Progradation of the carbonate sequence of southwest Ellesmere Island occurred in the Early Devonian, but was periodically interrupted in the Zlichovian/Dalejan by transgressive events. Upward movement in the newly named Inglefield Uplift occurred throughout the Devonian, and shed clastic sediments westward that, in Middle to Late Devonian time, finally overwhelmed the marine carbonates and resulted in fluvial deposition on southern Ellesmere Island. / Certain formations in the Lower Devonian sequence are profusely fossiliferous, in particular the Blue Fiord Formation, which contains an abundant fauna including numerous species of coral and brachiopods. Both of these groups belong to the Old World Biogeographic Realm, and indicate a Zlichovian age for the lower Blue Fiord Formation of southern Ellesmere Island.

No description available.

A 147cm sediment core from Lake DV09, northern Devon Island, Nunavut, Canada (75° 34’34”N, 89° 18’55”W) contains annually-laminated (varved) sediments, providing a 1600-year record of climate variability. A minerogenic lamina deposited during the annual thaw period and a thin deposit of organic matter deposited during the summer and through the winter, together form a clastic-organic couplet each year. The thinnest varves occur from AD800-1050, and the thickest from AD1100-1300, during the Medieval Warm Period. The relative sediment density is also highest during this period suggesting increased sediment transport energy. The coldest period of the Little Ice Age appears to be during the AD1600s. Varve widths over the past century indicate climate warming in the region. / This research program was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC), and the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS). A tuition bursary from Ultramar Inc. also helped in making this research possible. Logistical support was provided by the Polar Continental Shelf Project (PCSP Contribution number 04508).

The transport of low-salinity waters through the Canadian Arctic Archipelago links the North Pacific, Arctic, and North Atlantic Oceans. This transport is influenced by many related small-scale processes including mixing, internal hydraulics, and internal tide generation. In this thesis, I quantify and elucidate the physics of such processes with aims of addressing discrepancies between observed and simulated fluxes through the Archipelago and advancing the skill of numerical models by identifying shortcomings and informing where and how progress can be achieved. To address the dearth of mixing rates across the network of channels, I first use a large-scale model to obtain baseline estimates of the spatial and seasonal variability of the vertical buoyancy flux. Much of the mixing occurs in the eastern half of the Archipelago and is attributed to the abundance of sills and narrow channels. Indeed, the so-called 'central sills area' is shown to be a mixing hot spot. I investigate this region further using high-spatial-resolution observational transects to examine the role of tides, which are excluded from the large-scale model. The many shallow channels here accelerate tidal currents and thereby induce strong bottom boundary layer dissipation. This is the largest energy sink within an observationally constrained energy budget. The generation of internal tides is another primary sink of barotropic tidal energy. Because the study site lies poleward of the critical latitudes of the dominant tidal constituents, internal tides propagate as internal Kelvin waves. Idealized, process-oriented modelling demonstrates that the amplitudes of such waves, or similarly the energy extracted from the barotropic tide, is sensitive to channel width because waves generated at each side of the channel interfere. Given the multiple connecting channels of the Archipelago, it is difficult to make a priori estimates of internal tide generation for a given channel. Nevertheless, the phenomenology I describe will be detectable in, and a requisite to understanding, pan-Arctic or global three-dimensional tidal models, which are becoming more prevalent. / Graduate

Cette recherche doctorale examine les pratiques figuratives, les représentations symboliques et les enjeux socio-culturels des arts graphiques inuit dans les communautés de Kinngait (Cape Dorset) et de Pangniqtuuq (Pangnirtung) au Nunavut (Arctique canadien). Les notions de dessin (titiqtugaq-) et de parole (uqaq-) se placent au centre de la démarche qui est guidée par une approche interdisciplinaire, dans la perspective d’une ethnohistoire de l’art du dessin inuit. Trois parties structurent la démonstration. La première explore les configurations de la pensée inuit associées aux concepts d’art graphique, de représentation visuelle et de créateur, à partir de leur expression linguistique (chapitre II). Puis, une ethnographie de la scène artistique locale présente le dessin et les activités socio-économiques qui lui sont associées autour de la question du statut de l’artiste (chapitres III et IV). La deuxième partie envisage la figuration en rapport à la parole, à partir de la cosmogénèse et des techniques graphiques anciennes (chapitre V). Elle s’intéresse ensuite aux interactions entre le dessin et la parole sur un plan symbolique : dans le dessin, les pensées et les mots sont mis en actes (chapitres VI et VII). La dernière partie de la thèse définit l’art comme un élément de la dynamique socio-culturelle et politique des Nunavummiut. Le recours au dessin dans le cadre de projets communautaires est étudié à partir d’exemples récents (chapitre VIII), avant d’être replacé au centre des dynamiques relationnelles et des échanges socio-cosmiques dans une dimension ontologique (chapitre IX) / This doctoral research examines the themes of figurative practices, symbolic representations and the socio-cultural stakes specific to Inuit graphic arts in the communities of Kinngait (Cape Dorset) and Pangniqtuuq (Pangnirtung) in Nunavut (the Canadian Arctic). The notions of drawing (titiqtugaq-) and of speech (uqaq-) are central to the thesis, which is guided by an interdisciplinary approach within the perspective of ethno-history of Inuit sketch art. The thesis is organized into three parts. The first explores the configuration of Inuit thought associated with the concepts of graphic art, visual representation and creation, through their linguistic expression (Chapter II). In addition, ethnography of the local art scene looks at drawing and the socio-economic activities that are associated with it, in connection with the status of the artist (Chapters III and IV). The second part looks at figuration in relation to power words, from cosmogenesis and ancient graphic techniques (Chapter V). With this in hand, the second part then looks at the interactions between drawing and speaking from a symbolic perspective: through drawings, the thoughts and words are put into action (Chapters VI and VII). The last part of the dissertation continues the analysis by defining art as part of the socio-cultural and political dynamics of the Nunavummiut. Recourse to drawing, as a community project, is studied with reference to recent examples (Chapter VIII), prior to being placed, within an ontological dimension, at the centre of relational and socio-cosmic exchange dynamics (Chapter IX)