Submitted by William Justo Figueiro (williamjf) on 2015-07-02T22:29:44Z No. of bitstreams: 1 15.pdf: 39663757 bytes, checksum: 35a8b1465596e46a11f9214e5848bf7c (MD5) / Made available in DSpace on 2015-07-02T22:29:44Z (GMT). No. of bitstreams: 1 15.pdf: 39663757 bytes, checksum: 35a8b1465596e46a11f9214e5848bf7c (MD5) Previous issue date: 2011 / UNISINOS - Universidade do Vale do Rio dos Sinos / O zoneamento climático estabelecido a partir de foraminíferos planctônicos para dois testemunhos coletados no talude da bacia de Santos demonstrou o registro das oscilações climáticas dos últimos ~620 ka. Foram reconhecidas sete zonas e 14 subzonas, representadas por intervalos glaciais (zonas U, W e Y; subzonas U2, U1, W2, W1, Y2, Y1B e Y1A) e interglaciais (zonas T, V e X; subzonas V3, V2B, V2A, V1, X3 a X1) do Pleistoceno e o Holoceno (Zona Z). O plexo Pulleniatina permitiu a divisão da subzona V2 em duas (V2B e V2A) e forneceu ao longo das subzonas V3 e V2 oito horizontes para a correlação regional. O controle do sentido de enrolamento de Globorotalia truncatulinoides auxiliou o reconhecimento dos limites entre as subzonas U2/U1, V2B/V2A, X3/X2 e X2/X1, demonstrando ser uma ferramenta útil para o refinamento das zona/subzonas do Quaternário. A permanente presença de Globorotalia inflata sugere uma constante influência de águas frias e produtivas ao longo dos últimos ~620 ka, em especial na região sul da área de estudo. / QUATERNARY PALEOCLIMATIC ZONATION OF SANTOS BASIN BASED ON PLANKTONIC FORAMINIFERA. The climatic zones based on planktonic foraminifera, from two piston cores collected on the slope of the Santos Basin, has shown the record of climate oscillations over the last ~ 620 ka. Were recognized seven zones and 14 subzones, represented by glacial (zones U, W and Y; subzones U2, U1, W2, W1, Y2, Y1B, Y1A) and interglacial interval (zones T, V and X; subzones V3, V2B, V2A, V1, X1 to X3) of Pleistocene and the Holocene (zone Z). The Pulleniatina plexus permitted the division of subzone V2 into two (V2B and V2A) and provides eight regional correlation horizon along the subzones V3 and V2. The coiling direction of Globorotalia truncatulinoides helped the recognition of boundaries between subzones U2/U1, V2B/V2A, X3/X2 and X2/X1, showing as useful tool for the refinement of the zones and subzones of the Quaternary. The permanent presence of Globorotalia inflata suggests a constant influence of cold and productive waters over the past ~ 620 ka, especially in the southern of the study area.

Les zones à oxygène minimum (OMZs) sont des régions océaniques pratiquement dépourvues d'oxygène. Au cours des derniers milliers d'années, des changements climatiques globaux ont influencé l'intensité et l'extension spatiale de ces zones. Cette thèse propose de reconstruire les concentrations en oxygène dissous des eaux de fond au large de la marge Nord Est du Pacifique pour le Quaternaire supérieur à travers trois méthodes indépendantes, ayant pour dénominateur commun l'enregistrement fossile des foraminifères benthiques. Une première méthode dite micropaléontologique, basée sur l’abondance relative de trois assemblages, est développée dans un premier article. Un second article établit une relation entre l’oxygénation et la porosité de l'espèce Bolivina seminuda, caractérisée par une variation de couverture de pores de la [O$_2$]. Un troisième article est consacré à une méthode morphométrique, basée sur un indice prenant en compte la taille et la circularité des spécimens de chaque échantillon. Chacune de ces méthodes a pu être calibrée grâce aux foraminifères benthiques prélevés dans des sommets de carottes dont la teneur actuelle en oxygène dissous est connue. Ainsi, les estimations quantitatives montrent des valeurs d'oxygène faibles ($\sim$ 0.05 mL.L$^{-1}$) durant les évènements climatiques chauds (évènements de Dansgaard-Oeschger) et plus élevées ($\sim$ 0.5 mL.L$^{-1}$) pendant les évènements froids, pouvant atteindre $\sim$ 1 mL.L$^{-1}$ durant les stades associés aux évènements de Heinrich. Dans un dernier chapitre, ces trois méthodes sont appliquées à l'OMZ de la Mer d'Arabie, et un lien entre oxygénation, mousson indienne, et régime des vents est discuté. / Oxygen minimum zones (OMZs) are areas in the ocean that are almost completely devoid of dissolved oxygen. For several decades, global climate changes are known to be responsible for fluctuations in the intensity and spatial extent of these OMZs. In this thesis, three independent methods were developed for reconstructing the oxygen concentration of OMZ bottom waters during the late Quaternary. All these methods are based on benthic foraminifera preserved in the fossil record. A micropaleontological method is described in a first publication. This approach is based on the relative abundance of three benthic foraminiferal assemblages. A second publication explores the connection between oxygenation and porosity of the benthic foraminiferal species Bolivina seminuda, characterised by a pore surface area that depends on the [O$_2$]. A third article describes a morphometric approach to past oxygen reconstruction based on a semi-automatic method used to calculate an averaged size and roundness index for each sample. Recent benthic foraminifera, recovered from core-top sediments for which the modern bottom water dissolved oxygen content is known, are used to calibrate the three methods. It is found that warm interstadials (corresponding to Dansgaard-Oeschger events) exhibit conditions almost depleted in [O$_2$] ($\sim$ 0.05 mL.L$^{-1}$) while cold stadials show higher values ($\sim$ 0.5 mL.L$^{-1}$) reaching $\sim$ 1 mL.L$^{-1}$ during stadials associated with Heinrich events. In the final chapter, all three methods are successfully applied to the Arabian Sea OMZ, and a link between oxygenation, the indian monsoon, and the local wind regime is discussed.

Heteromorph ammonites and dinoflagellate cysts from the Upper Cretaceous Northumberland Formation on Hornby Island, British Columbia, Canada are examined. The collection and preparation of new material has enabled the recognition of eleven species of which only three have been reported from the locality. Of these taxa represented from three heteromorph ammonite families in the study area, five are new occurrences and three are new to science. This expansion of the Hornby Island ammonite fauna is presented alongside a pioneering taxonomic survey of dinoflagellate cysts from the same rocks. Together, these macro- and microfossils reinforce a late Campanian age for the Northumberland Formation with the upper extent of the section approaching the Campanian-Maastrichtian boundary (CMB) interval. The palaeoecology and evolutionary relationships of these heteromorph ammonoids are considered with new insights into their ontogenetic development and neritic palaeoenvironmental circumstances. The dinoflagellate cysts and associated terrestrial palynomorphs have also allowed for enhanced palaeoenvironmental reconstruction and depositional setting inference. The scope of the studied material, and the presence of key index taxa, enables refined biostratigraphy and a stronger basis for correlation of the Hornby Island succession with neighboring coeval biotic provinces. / Graduate / 2018-08-10

The biostratigraphy and isotope stratigraphy of the upper Aptian to lower Cenomanian interval including oceanic anoxic events OAE1b, 1c and 1d are investigated in ODP Site 763, drilled on the Exmouth Plateau offshore northwest Australia. Benthic foraminifera suggest that Site 763 was situated in outer neritic to upper bathyal water depths (~150-600 m). OAEs of the Atlantic basin and Tethys are typically associated with organic carbon-rich black shales and δ13C excursions. However, OAEs at this high latitude site correlate with ocean acidification and/or pyrite formation under anoxic conditions rather than black shales. Ocean acidification maybe responsible for sporadic low abundances of planktic foraminifera compared to radiolarians and benthic foraminifera associated with increased volcanogenic CO2 production during the formation of the Southern and Central Kerguelen Plateaus. Sea surface temperature may have cooled to 11°C in the late Aptian but increased gradually during the Albian. The Aptian/Albian boundary is placed at a negative carbon isotope excursion associated with the lowest occurrence of Microhedbergella renilaevis, typically found within the Niveau Kilian black shale of OAE1b. Third-order sea level cycles, particularly in the middle Albian, produced cyclic changes in the abundance of inoceramid prisms that increased during inferred times of falling sea level. The late Albian OAE1c and OAE1d coincide with horizons of intense pyritization and the absence of all biocomponents suggesting the development of euxinia. Warm Tethyan waters reached the Exmouth Plateau during the latest Albian based on the presence of thermocline dwelling keeled planktic foraminifera including Planomalina buxtorfi.

The central objective of this study is to understand phytoplankton community response following the global mass extinction event at the Cretaceous–Paleogene (K/Pg) boundary. The objective is approached through analysis of dinoflagellate cyst assemblages across the boundary interval in the North Pacific. Dinoflagellate cysts are powerful tools for deep time paleoenvironmental reconstructions and this group of microfossils has been vastly underutilized in this region of the world. On this premise, comprehensive marine palynological surveys were undertaken for the Oyster Bay Formation of eastern Vancouver Island, British Columbia, Canada and Shatsky Rise in the northwest Pacific. The Oyster Bay Formation work resulted in the discovery of the first K/Pg boundary succession west of the Rocky Mountains based on biostratigraphic controls and refined taxonomy for the genus Cannosphaeropsis found within these strata. Three new taxa are described: Cannosphaeropsis franciscana subsp. vacuoseptata subsp. nov., Cannosphaeropsis franciscana subsp. vesiculata subsp. nov. and Phelodinium fensomei sp. nov. The cyst assemblages reveal endemic associations and signals of transition between offshore coastal to estuarine settings in keeping with global eustatic trends. Oyster Bay Formation results and interpretations are compared to analyses of core samples from Deep Sea Drilling Project Site 577 at Shatsky Rise. Contrast is seen between a diverse, highly productive coastal to estuarine environment in the Oyster Bay Formation as represented by organic-walled taxa and an oligotrophic bathyal environment at Shatsky Rise during the same interval as represented by a small number of calcareous taxa. These two regions form the basis for comparison between differing assemblages in order to ascertain the extent to which phytoplankton communities were affected by changes in sea-surface and water mass conditions in conjunction with the K/Pg event. The findings reveal measurable impacts of climate and paleoenvironmental change reflected by shifts in assemblage composition and cyst morphology. A lack of extinction among many forms is consistent with studies from around the globe as presented in an exhaustive review of the literature. The dinoflagellates were marginally impacted with the most specialized taxa presenting a record of sea-surface temperature fluctuation, nutrient supply and opportunistic niche exploitation. / Graduate / 2022-08-20

Le Jurassique supérieur est une période qui présentait une paléogéographie et des conditions climatiques globales favorables au développement des systèmes sédimentaires dominés par les tempêtes. L’objectif de ce travail est de comprendre les facteurs contrôlant la dynamique de ces systèmes, ainsi que la relation entre les variations de fréquences et d’intensité des tempêtes et les changements climatiques. Trois coupes ont été choisies pour cette étude : les Pas (passage Oxfordien – Kimméridgien) et la coupe du Rocher d’Yves (Kimméridgien supérieur), près de La Rochelle ; la coupe du Cap de la Crèche (Kimméridgien supérieur – début du Tithonien), dans le Boulonnais. Ces coupes sont analysées pour la sédimentologie, les palynofaciès et les nannofossiles calcaires. Pour chacune d’elles, un modèle de faciès détaillé est établi, permettant de proposer une interprétation séquentielle et cyclostratigraphique précise. L’interprétation cyclostratigraphique permet d’interpréter les dépôts de tempêtes en terme de variations de fréquence des tempêtes. L’interprétation séquentielle permet de s’affranchir des variations du niveau marin relatif pour interpréter les dépôts de tempêtes en terme de variations d’intensité des tempêtes. Les points communs et les différences entre ces deux systèmes sont discutés, tant du point de vue de la dynamique sédimentaire que de l’enregistrement et de la préservation des dépôts de tempêtes. Enfin, la relation entre les variations de fréquence et d’intensité des tempêtes et les changements climatiques est discutée. Les faciès sédimentaires de La Rochelle et du Boulonnais présentent une organisation spatiale relativement similaire. La production carbonatée des systèmes présente des similitudes et des différences. Elle semble capable de réagir très rapidement aux variations du niveau marin relatif, augmentant avec l’élévation du niveau marin relatif. Les deux systèmes ont également une évolution similaire dans le temps. Les dépôts de tempêtes des deux sites montrent des morphologies similaires, liées aux conditions de dépôt et de préservation. Il a été possible de mettre en relation les variations d’intensité, de fréquences, et les changements du climat. Ainsi, les variations d’intensité des tempêtes semblent évoluer en parallèle des variations de fréquence, les valeurs d’intensité les plus élevées correspondant aux valeurs de fréquences les plus élevées. De plus, ces augmentations de fréquence et d’intensité ont lieu en même temps que l’augmentation des températures, indiquant un lien entre le réchauffement du climat et l’augmentation de l’activité des tempêtes / The Late Jurassic was a period with paleogeography and global climatic conditions that favor the development of sedimentary systems dominated by storms. The purpose of this study is to better understand the controlling factors on the dynamic of these systems. Three sections are chosen. The Pas (Oxfordian – Kimmeridgian transition) and the Rocher d'Yves (Late Kimmeridgian) sections, near La Rochelle (Western France), correspond to a muddy, mixed carbonated – siliciclastic platform. The Cap de la Crèche section (Late Kimmeridgian – Early Tithonian) corresponds to a mixed carbonated – siliciclastic ramp, dominated by coarse material. Sedimentary, palynofacies, and calcareous nannofossil analyses are performed. For each section, a detailed facies model is proposed, allowing precise sequence- and cyclostratigraphic interpretations. The sequence and cyclostratigraphic frameworks allow the calculation of the storm frequency. Comparison between host facies and storm deposits allows the estimation of storm intensity. The similarities and differences between these two systems are discussed, for the sedimentary dynamic, and the record and preservation of the storm deposits. Finally, the relation between storm frequency and intensity and climate is discussed. La Rochelle and Boulonnais sedimentary facies have a similar spatial organization. Carbonate production of these systems presents similarities and differences. The carbonate production seems able to react very quickly to relative sea-level variations, increasing when sea-level is high. The two systems also have a similar evolution in time. The storm deposits of the two sites show similar morphologies, related to the conditions of deposition and preservation. It was possible to link the variations of storm intensity and frequency with the climate changes. The variations of storm intensity evolve in parallel of the variations of storm frequency, the highest values of intensity corresponding to the highest values of frequency. Moreover, this increase in frequency and intensity is consistent with increasing temperature, suggesting a link between the increasing storm activity and the climate warming