Les sédiments déposés dans les fjords norvégiens contiennent des informations précieuses sur la dynamiquepassée de la circulation de surface en mer de Norvège (Courant Nord Atlantique –NAC- et Courant Côtier deNorvège –NCC-), ainsi que sur le climat régional du continent bordier et du domaine océanique adjacent. Letransport méridien par le NAC d’eaux chaudes et salées participe efficacement au fonctionnement de la bouclethermohaline globale. Le NCC, alimenté par les apports continentaux depuis la mer Baltique, contrôlel’hydrologie des fjords norvégiens. L’objectif de la présente étude est de tester l’utilisation, dans le fjord deTrondheim, des isotopes stables benthiques et des assemblages de dinokystes en tant que traceur de lavariabilité hydrologique et climatique locale et régionale. Ce travail repose sur une série exceptionnelle desédiments de surface et de carottes d’interface, recouvrant de façon équilibrée l’ensemble des sous-systèmesdu fjord. Les changements climatiques et océanographiques modernes et récents (derniers 35 à 50 ans) décritspar nos traceurs sont comparés à plusieurs séries temporelles instrumentées de paramètres hydrologiques etclimatiques clés, afin de déterminer les différents mécanismes à l’origine de la signature spatiale et temporelledes proxies. Nos résultats montrent que les isotopes stables benthiques et les assemblages de dinokystestraduisent efficacement les variations hydrologiques et climatiques locales et régionales, le gradient spatial desalinité, l’efficacité du mélange vertical, la température des eaux atlantiques entrantes, et le budget de lasédimentation de matière organique (quantité et origine) expliquant de façon importante les variabilitésspatiales et temporelles de nos traceurs. La dynamique atmosphérique liée à l’Oscillation Nord Atlantiqueexplique l’essentiel des changements récents de la circulation interne du fjord et de la nature de lasédimentation (marine vs. continentale). / Sedimentary archives in Norwegian fjords contain valuable highly resolved information on the past dynamics ofmajor surface circulation features of the Norwegian Sea (North Atlantic Current and Norwegian CoastalCurrent), as well as on the regional climate of the Norwegian continental and surrounding oceanic realms. TheNAC transports significant amounts of warm and saline water poleward and constitutes an essentialcomponent of the global thermohaline circulation. The NCC is supplied by Norwegian rivers and fjords and itslateral and vertical distribution fundamentally controls the hydrology of Norwegian fjords. In the present studywe examine the use of benthic stable isotopes and dinocyst assemblages in the Trondheimsfjord, centralNorway, as proxies of the local and regional hydrological and climate changes. This study is essentially based onan exceptional set of surface sediment samples and multi-cores which are evenly distributed within the variousfjord subsystems. Modern and recent (last 35 to 50 years) oceanographic and climatic changes inferred fromour proxies are discussed in view of time-series of key hydrological and climatic parameters in order todetermine the various mechanisms driving the spatial and temporal variabilities of the proxies. Our resultsshow that benthic stable isotopes and dinocyst assemblages reliably record the local and regional hydrologicalvariations in the Trondheimsfjord and associated climate changes linked to key characteristics and processessuch as salinity gradients, water column mixing, temperatures of the incoming Atlantic water. Changes inatmospheric processes alike the North Atlantic Oscillation explain most of the recorded recent changes in thefjord internal circulation and nature of sedimentation (marine vs. continental).

Marine palynomorph assemblages from the Campanian-Maastrichtian Bearpaw Formation, consisting of 34 genera and 69 species of dinoflagellate cysts and 8 forms of acritarchs, were recovered from a composite section in the Cypress Hills and the Research Council of Alberta Castor borehole in southern Alberta, Canada. Correlation of the sections with magnetostratigraphy and radiometric dates of bentonites within the Bearpaw Formation provided a chronostratigraphic control that enabled correlation between the two sections and the Campanian-Maastrichtian Boundary Global Stratotype Section and Point at Tercis les Bains, France. Correlation of first and last occurrence data of key taxa in the boundary section at Tercis with the same taxa in the studied sections support the placement of the Campanian-Maastrichtian Boundary at the transition between magnetochrons 32n.1n and 31r within the <i>Baculites baculus</i> ammonoid range zone of the Western Interior of North America.<p>Semi-quantitative analyses of the assemblages record the transgressive-regressive episodes of the Bearpaw cyclothem. Increases in the relative abundances of gonyaulacacean cysts, numbers of dinocysts compared to terrestrial palynomorphs and assemblage diversity correlate with transgressive episodes, with the richest assemblages occurring during periods of open, offshore to neritic conditions correlated with the cyclothems transgressive peak.<p>Two new species of dinoflagellate cyst are described. The first, Dinoflagellate sp. 1, is a novel taxon, while the second, Downiesphaeridium sp. A, is a chorate cyst similar to Mesozoic forms previously ascribed to <i>Cleistosphaerdium diversispinosum</i> Davey et al. emend. Eaton et al.

Marine palynomorph assemblages from the Campanian-Maastrichtian Bearpaw Formation, consisting of 34 genera and 69 species of dinoflagellate cysts and 8 forms of acritarchs, were recovered from a composite section in the Cypress Hills and the Research Council of Alberta Castor borehole in southern Alberta, Canada. Correlation of the sections with magnetostratigraphy and radiometric dates of bentonites within the Bearpaw Formation provided a chronostratigraphic control that enabled correlation between the two sections and the Campanian-Maastrichtian Boundary Global Stratotype Section and Point at Tercis les Bains, France. Correlation of first and last occurrence data of key taxa in the boundary section at Tercis with the same taxa in the studied sections support the placement of the Campanian-Maastrichtian Boundary at the transition between magnetochrons 32n.1n and 31r within the <i>Baculites baculus</i> ammonoid range zone of the Western Interior of North America.<p>Semi-quantitative analyses of the assemblages record the transgressive-regressive episodes of the Bearpaw cyclothem. Increases in the relative abundances of gonyaulacacean cysts, numbers of dinocysts compared to terrestrial palynomorphs and assemblage diversity correlate with transgressive episodes, with the richest assemblages occurring during periods of open, offshore to neritic conditions correlated with the cyclothems transgressive peak.<p>Two new species of dinoflagellate cyst are described. The first, Dinoflagellate sp. 1, is a novel taxon, while the second, Downiesphaeridium sp. A, is a chorate cyst similar to Mesozoic forms previously ascribed to <i>Cleistosphaerdium diversispinosum</i> Davey et al. emend. Eaton et al.