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21	Nanofósseis calcários do Campaniano e Maastrichtiano no Atlântico Sul: bioestratigrafia, paleoceanografia e paleobiogeografia Guerra, Rodrigo do Monte 19 January 2016 (has links) Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-09-21T15:45:10Z No. of bitstreams: 1 Rodrigo do Monte Guerra_.pdf: 12842392 bytes, checksum: b6db9de51a65dd59c144edac22f16cab (MD5) / Made available in DSpace on 2016-09-21T15:45:10Z (GMT). No. of bitstreams: 1 Rodrigo do Monte Guerra_.pdf: 12842392 bytes, checksum: b6db9de51a65dd59c144edac22f16cab (MD5) Previous issue date: 2016-01-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Milton Valente / O final do período Cretáceo é caracterizado por uma gradual transição climática de escala global, fator que modificou a composição das assembleias de nanofósseis calcários e por conta disso vem causando problemas nas interpretações bioestratigráficas entre diferentes faixas latitudinais. Apesar de possuir alguns estudos realizados principalmente entre as décadas de 1980 e 1990, existe uma carência na avaliação do Atlântico Sul como um todo. Desta forma, este estudo objetiva descrever as assembleias de nanofósseis calcários comuns em cada faixa latitudinal e testar o sincronismo dos principais bioeventos. Foram analisadas 649 amostras provenientes de doze seções testemunhadas pelos projetos Deep Sea Drilling Project (DSDP) e Ocean Drilling Program (ODP) nas proximidades da margem brasileira e africana, além de um afloramento na Península Antártica. O estudo taxonômico possibilitou a identificação de 197 espécies de nanofósseis calcários do Campaniano e Maastrichtiano. Através do uso conjunto da bioestratigrafia e magnetoestratigrafia, foram reconhecidos diacronismos em eventos de primeira e última ocorrência de espécies do Campaniano superior e Maastrichtiano superior. Este diacronismo está relacionado a migrações de espécies entre baixas e médias latitudes, decorrentes de mudanças na circulação oceânica e temperatura das águas superficiais. Com base na variação latitudinal das assembleias de nanofósseis calcários, um detalhado estudo bioestratigráfico possibilitou a divisão de três zoneamentos para o Atlântico Sul (baixas, médias e altas latitudes). Além disso, foram definidos os padrões de distribuição de diversas espécies, mostrando uma clara divisão paleobiogeográfica entre espécies que ocorrem somente em latitudes altas e outras limitadas a latitudes médias a baixas. Este padrão possivelmente foi controlado por variações na temperatura das massas de água superficiais. Outras espécies possuem sua distribuição variada em todas as faixas latitudinais, tendo sua distribuição relacionada provavelmente à disponibilidade de nutrientes. / The Late Cretaceous period is characterized by global climatic transition that influenced calcareous nannofossil assemblages posing a challenge for biostratigraphic interpretation between different latitudinal degrees. There are a few studies on South Atlantic calcareous nannofossils from 1980 and 1990 decades, but none of them evaluate the South Atlantic as a whole. Therefore, this study aims to describe the calcareous nannofossils assemblages in each latitudinal zone and test the bioevents synchroneity. It were selected 649 samples from twelve cored sections coming from DSDP (Deep Sea Drilling Project) e ODP (Ocean Drilling Program) close to the Brazilian and African margins, in addition to an outcrop in the Antarctic Peninsula. The taxonomic study allowed the identification of 197 calcareous nannofossils species from the Campanian and Maastrichtian. Using the correlation between the biostratigraphical data and magnetostratigraphy, it was possible to identify diachronism in some bioevents of first and last occurrences during the late Campanian and late Maastrichtian. This diachronism is related to species migration between low and mid-latitudes, due to changes in the ocean circulation and surface water temperature. Based on the latitudinal variation in the calcareous nannofossils assemblages, a detailed biostratigraphic study enabled the South Atlantic division in three zonations (low, medium and high-latitudes). We also defined the distribution pattern of some species, indicating a clear paleobiogeographical division between high latitude species and some species limited to low and mid-latitudes. This pattern was possibly controlled by surface water temperature variation. Other species have a wide distribution across the latitudes probably related to nutrient availability. Atlântico Sul Nanofósseis calcários Cretáceo superior Campaniano- Maastrichtiano Bioestratigrafia Paleoceanografia Paleobiogeografia South atlantic ocean Calcareous nannofossils Late cretaceous Campanian-Maastrichtian Biostratigraphy Paleoceanography Paleobiogeography
22	Late Eocene through Oligocene calcareous nannofossils from the paleo-equatorial Pacific Ocean – taxonomy, preservation history, biochronology and evolution Blaj, Teodora January 2009 (has links) This study aims to unravel the ecological and evolutionary dynamics within the calcareous nannofossil communities at the Eocene/Oligocene (E/O) transition and during the Oligocene time when Cenozoic 'icehouse' conditions were established. The main question this study aims to answer is whether the changes in the nannofossil assemblages were controlled by intrinsic evolutionary trends or if the changes were controlled by environmental factors such as changes in temperature and nutrient availability in the surface water. These questions are addressed with detailed analyses of the taxonomy, biostratigraphy and fluctuations in abundance and diversity of calcareous nannofossil assemblages from a continuous latest Eocene through Oligocene sediment section from the ODP Site 1218 (8°53.38´N, 135°22.00´W), paleo-equatorial Pacific Ocean. An improved nannofossil taxonomy and biostratigraphy has been established. At the E/O transition, changes in the nannofossil preservation mimics changes in calcium carbonate content. A detailed investigation of late Eocene and Oligocene sediments yields age estimates for ten nannofossil bioevents. Morphometric studies of the Reticulofenestra umbilicus-R. hillae show that these cannot be subdivided into two different morphospecies. Based on different morphometry and stratigraphic ranges, the Oligocene Sphenolithus lineage appears to be the result of a combined anagenetic and cladogenetic evolution. A new nannolith species is described: Triquetrorhabdulus longus. High-resolution nannofossil data indicate changes in the composition, abundance and diversity of the mid-Oligocene assemblages. Intervals of high diversity index coincide with Oi-glaciation events. However, visual examination of the variations in abundance of nannofossil taxa do not appear to correlate with changes in either oxygen or carbon isotopes. This presumably indicates that a dynamic equilibrium did not exist between these Oligocene nannoplankton assemblages and changes in surface water temperature or productivity conditions. / Doctoral Thesis in Marine Geoscience at Stockholm University, Sweden 2009 marine sediments calcareous nannofossils late Eocene Oligocene biochronology evolution morphometry taxonomy ODP Leg 199 Site 1218 paleo-equatorial Pacific Ocean Historical geology and palaeontology Historisk geologi och paleontologi
23	Stratigrafie svrchního turonu a spodního coniaku ve vrtu V 800 Střeleč na základě vápnitého nanoplanktonu, česká křídová pánev / Upper Turonian and lower Coniacian calcareous nannoplankton stratigraphy in the borehole V 800 Střeleč, Bohemian Cretaceous Basin Svobodová, Andrea January 2012 (has links) Upper Turonian and Lower Coniacian calcareous nannoplankton stratigraphy in the borehole V 800 Střeleč, Bohemian Cretaceous Basin Number of biostratigraphic studies has been performed within the Upper Cretaceous platform sediments of the NW Europe, however, the problem of Turonian-Coniacan boundary has not yet been satisfactorily resolved using available methods in the field of micropaleontology. The proposed thesis has described the species composition of calcareous nannoplankton assemblages in the Bohemian Cretaceous Basin, across the Upper Turonian- Lower Coniacian interval, focusing on the stratigraphically and paleoecologically important species. Seventy-three taxa of calcareous nannofossils in the studied material have been determined and signifiant species have been discussed (Marthasterites furcatus, Kamptnerius magnificus, Lucianorhabdus sp., Braarudosphaera sp., Nannoconus sp., Watznaueria barnesae, Uniplanarius gothicus, Quadrum gartneri, Thoracosphaera operculata). For purposes of this thesis, a suitable material from the V 800 Střeleč borehole, one of the key cretaceous profil in the Český ráj area, was obtained.
24	La reconnaissance automatisée des nannofossiles calcaires du Cénozoïque / The automatic recognition of the calcareous nannofossils of the Cenozoic Barbarin, Nicolas 14 March 2014 (has links) SYRACO est un SYstème de Reconnaissance Automatisée des COccolithes, développé à son origine par Luc Beaufort et Denis Dollfus à partir de 1995 et plus récemment avec Yves Gally. L'utilité d'un tel système est de permettre aux spécialistes un gain de temps majeur dans l'acquisition et le traitement des données. Dans ce travail, le système a été amélioré techniquement et sa reconnaissance a été étendue aux nannofossiles calcaires du Cénozoïque. Ce système fait le tri entre les nannofossiles et les non-nannofossiles avec une efficacité respectivement estimée à 75% et 90 %. Il s'appuie sur une nouvelle base d'images de référence d'espèces datant de l'Eocène Supérieur aux espèces vivantes, ce qui représente des centaines d'espèces avec une forte variabilité morphologique. Il permet de réaliser une classification en 39 morphogroupes par la combinaison de réseaux de neurones artificiels avec des modèles statistiques. Les résultats sont présentés sous forme de comptages automatisés, de données morphométriques (taille, masse...) et de mosaïques d'images. Il peut ainsi être utilisé pour des analyses biostratigraphiques et paléocéanographiques. / SYRACO is an automated recognition system of coccoliths, originally developed since 1995 by Luc Beaufort and Denis Dollfus, and more recently with the help of Yves Gally. The main purpose of this system is for specialists to save time in the acquisition and treatment of data. By this recent work, the system has been technically improved and its ability of recognition has been extended to calcareous nannofossils of the Cenozoic Era. It sorts nannofossils and non-nannofossils with a reliability respectively estimated to 75% and 90%. It is based on a new reference images database of species from the Upper Eocene up to living species. This represents hundreds of species with a high morphological variability. It leads to the establishment of a classification arranged in 39 morphogroups, combining artificial neural networks to statistical models. The results are presented as automated counting, morphometrical data (size, mass...) and mosaics of images. Those results can be valuable in biostratigraphical and paleoceanographical analyses. Reconnaissance automatique Nannofossiles calcaires Cénozoïque Coccolithophoridés Microscopie optique Traitement d'image Réseaux de neurones artificiels Classifications statistiques Comptage automatique Biostratigraphie Paléocéanographie Automatic recognition Calcareous nannofossils Cénozoic Coccolithophorids Optic microscopy Image processing Artificial neural networks Statistical classifications Automated counting Biostratigraphy Paleoceanography
25	Paleocurrents and Depositional Environments of the Dakota Group (Cretaceous), San Miguel County, New Mexico Bejnar, Craig Russel January 1975 (has links) The Dakota Group surrounding Las Vegas, New Mexico, consists of three units: 1) a basal, predominately trough cross-stratified, conglomeratic sandstone, 2) middle intercalated, thin-bedded sandstone and carbonaceous shale, and 3) upper, predominately tabular-planar cross-stratified, sandstone containing trace fossils. These units represent, respectively, 1) a fluvial piedmont plain, 2) fluvial coastal plain, and 3) a beach, littoral, and shallow marine complex. The cross-stratification in the lower sandstone unit indicates an easterly paleoslope. The cross-stratification in the upper sandstone unit has a bimodal distribution almost at right angles to the paleoslope, suggesting deposition by longshore currents. The standard deviation of the cross-stratification in the lower sandstone unit of 78° is typical of fluvial deposits. The standard deviation in the upper sandstone unit of 97° indicates a marine origin. algae bedding plane irregularities biostratigraphy clastic rocks Cretaceous cross-stratification Dakota Formation depositional environment environment environmental analysis indicators lithostratigraphy marine Mesozoic microfossils Mora County New Mexico nannofossils nearshore New Mexico northeast paleocurrents palynomorphs planar bedding structures Plantae provenance ripple marks San Miguel County New Mexico sandstone sedimentary petrology sedimentary rocks sedimentary structures sedimentation shale shallow stratigraphy streams terrigenous thallophytes United States
26	Late Mesozoic to Cenozoic erosion and sediment dispersal in the Dinaride orogen: a sedimentary provenance approach / Spätmesozoische bis Känozoische Erosion und Sedimentschüttung im Dinarischen Orogen: Ansätze aus der Provenanzanalyse Mikes, Tamás 16 December 2008 (has links) No description available. 550 Geowissenschaften Mathematics and Computer Science Dinariden Alpen Adriatische Platte Metasedimente Granitoid Ophiolith Flysch Sandstein Siliziklastika Jura Kreide Känozoikum Biostratigraphie Kalknannofossilien sedimentäres Liefergebiet Spaltspur-Thermochronologie Geochronology chemische Datierung Mineralchemie Chromspinell Zirkon Monazit Elektronenstrahl-Mikrosonde laser ablation ICP-MS Kernel-density Schätzung Dinarides Alps Adriatic plate metasediments granitoids ophiolite flysch sandstone siliciclastics Jurassic Cretaceous Cenozoic biostratigraphy calcareous nannofossils sedimentary provenance fission-track thermochronology geochronology chemical dating mineral chemistry Cr-spinel zircon monazite electron microprobe laser ablation ICP-MS kernel density estimation 38.03 38.10 38.17 38.28 38.42 VAE 811: Alpidische Orogene {Tektonik} VKB310

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