Dissertations / Theses on the topic 'Calcareous nannofossil'
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Bornemann, André. "Case studies of Mesozoic calcareous nannofossils implications for palaeoecology, calcareous nannofossil morphology and carbonate accumulation /." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970713509.
Full textVan, Niel Brigitta E. "Early Cretaceous Nannoconus (Calcareous nannofossil, Incertae sedis) in NW Europe." Thesis, University College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307692.
Full textWindley, Dawn Elizabeth. "Calcareous nannofossil applications in the study of cyclic sediments of the Cenomanian." Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306898.
Full textToffanin, Federica. "Biochronologic and evolutionary study of calcareous nannofossil assemblages during the Middle Eocene Climatic Optimum." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422518.
Full textDurante il mio progetto di dottorato ho studiato le associazioni a nannofossili calcarei provenienti da tre siti nell’intervallo corrispondente al Middle Eocene Climatic Optimum (MECO). Il MECO è un episodio ipertermale transitorio e di breve durata, caratterizzato da un’importante perturbazione a livello globale degli isotopi stabili sia dell’ossigeno che del carbonio, osservato alla transizione tra Chron C18r-C18n (ca. 40 Ma) ha una durata di circa 500-600 kyr (Bohaty et al., 2009). Esso rappresenta un’inversione significativa del clima durante il trend di raffreddamento di lunga durata dell’Eocene medio e superiore. Il MECO è uno tra gli eventi ipertermali, assieme al meglio conosciuto Paleocene Eocene Thermal Maximum, riconosciuti nel Paleogene (PETM, Kennett and Stott, 1991). Attualmente l’interesse verso questi argomenti è crescente perché essi sono considerati potenziali analoghi nel passato dell’atteso riscaldamento globale che sarà in atto nel prossimo futuro. L’ipotesi più accreditata riguardo le cause del MECO è connessa ad un enorme evento di degassazione di CO2, legato a una importante riorganizzazione delle placche tettoniche avvenuta durante l’Eocene (Bohaty et al., 2009). Le sezioni studiate sono situate in diversi setting deposizionali e aree geografiche. In particolare la prima successione, la sezione di Alano, è localizzata nelle Alpi nord orientali del Veneto e comprende l’Eocene medio e superiore. Dal punto di vista paleogeografico, la sezione ha una paleoprofondità di 600-1000 m ed è parte del bacino di Belluno, entro la Tetide centro occidentale; la seconda sezione di studio è stata recuperata nell’IODP Site 1333 durante l’Exp.320 svoltasi nel Pacifico Equatoriale. La paleoprofondità stimata per questo Site è di 3800 m, mentre la profondità attuale è ca. 4800 m. La terza sezione di studio è stata recuperata dal Leg ODP 171B nell’area del Blake Nose (Atlantico nord occidentale) ed ha paleoprofondità stimata di ca. 1500 m. Il primo obiettivo di questo studio è verificare se c’è un cambiamento unico e globale nelle associazioni a nannofossili calcarei in risposta al MECO. Un ampio spettro di setting paleodeposizionali e aree diverse (sezione di Alano, Site 1051A and U1333C) è stato analizzato durante questa fase paleoclimatica estrema e sono state fornite ricostruzioni paleoambientali basate su modificazioni osservate nelle associazioni a nannofossili calcarei. Il secondo obiettivo di questo studio è centrato sulla biostratigrafia e biocronologia dell’intervallo Eocene medio a Oligocene inferiore, con particolare attenzione al MECO. Biorizzonti standard e addizionali sono stati testati e confrontati con dati precedenti presenti in letteratura, fornendo stime del grado di affidabilità dei bioeventi considerati e delle loro calibrazioni. Il primo capitolo della tesi è una breve presentazione generale dell’evoluzione paleoclimatica del Paleogene inferiore, seguita dalla descrizione dei materiali di studio e dei metodi e strategie adottate in questo lavoro. Nel secondo capitolo di questa tesi viene presentato uno studio sui nannofossili calcarei ad alta risoluzione attraverso il MECO. I nostri dati dalla sezione medio batiale di Alano indicano che l’intervallo riguardante il MECO sembra coincidere con cambiamenti significativi nelle associazioni a nannofossili calcarei. Taxa che preferiscono acque eutrofiche/fredde e forme rimaneggiati mostrano un aumento nelle abbondanze durante l’evento ipertermale. Al contrario, taxa con preferenze per acque oligotrofiche/calde mostrano un trend peculiare anticovariante rispetto ai taxa meso-eutrofici, diminuendo in modo significativo durante gli intervalli del MECO e post-MECO. Questi risultati possono essere interpretati come un arricchimento temporaneo dei nutrienti disciolti nelle acque più calde superficiali, e suggeriscono che la aumentata disponibilità di nutrienti nella colonna d’acqua ricopre un’importanza maggiore rispetto ad altri fattori ambientali nel determinare l costituzione dell’associazione a nannofossili calcarei. Inoltre il maggior rimaneggiamento è coerente con un aumentato input di terrigeno, probabilmente dovuto all’accelerato weathering (alterazione) chimico, scatenato dall’aumentato ciclo idrologico. Nel terzo capitolo di questa tesi, fornisco i risultati dei sedimenti recuperati dall’IODP Site 1333 durante l’Exp.320 nel Pacifico Equatoriale, in un intervallo di tempo compreso tra l’Eocene medio e l’Oligocene inferiore. Questi dati evidenziano un importante cambiamento nello stato di preservazione, con il numero di individui contati entro un’area specifica (1 mm2) che si avvicinano allo zero durante il MECO. Nello stesso intervallo abbiamo osservato modifiche nelle associazioni a nannofossili calcarei coerenti con un evento di intensa dissoluzione. Oltre alla evidente forte diminuzione di individui/mm2 già citata, un argomento ancora più forte a favore di condizioni di dissoluzione pervasiva è basato sul fatto che, se consideriamo l’abbondanza relativa (%), Discoaster, il genere più resistente, aumenta considerevolmente, come atteso nel caso in cui l’associazione originaria sia alterata da dissoluzione preferenziale. Al Site U1333C, il MECO si può considerare un intervallo semi sterile, quindi nessuna interpretazione paleoambientale è possibile. Per questo motivo ho deciso di focalizzarmi su un intervallo più lungo, con l’obiettivo di ottenere dati biostratigrafici e biocronologici da una delle rare successioni carbonatiche disponibili dall’Eocene medio all’Oligocene inferiore nel Pacifico equatoriale. Abbiamo usato questo modello per analizzare il modo e tempo dell’evoluzione di alcuni taxa di nannofossili calcarei (i.e., sfenoliti e Dictycoccites). Il quarto capitolo della tesi fornisce una serie di dati ad alta risoluzione del MECO, ottenuti dal Site 1051A (Atlantico nordoccidentale). I nostri risultati evidenziano cambiamenti nelle associazioni a nannofossili calcarei durante questo episodio transitorio di riscaldamento globale coerenti con un aumento nella disponibilità di nutrienti. I reticulofenestridi di piccole dimensioni, che tipicamente prosperano in ambienti eutrofici e in condizioni di stress, mostrano un aumento graduale di lunga durata nelle loro abbondanze relative, suggerendo quindi una aumentata disponibilità di nutrienti nelle acque superficiali dell’ODP Site 1051A. Un andamento simile si registra anche nei Dictyococcites di grandi dimensioni, eutrofici, che aumentano bruscamente in abbondanza allo stesso livello stratigrafico (LCO), fornendo una ulteriore evidenza di uno shift verso condizioni più eutrofiche. Questo scenario è supportato anche dal lieve declino che si evidenza in Sphenolithus e Discoaster. Questi generi sono considerati taxa di acque calde ed oligotrofiche, K-specialisti, e la loro diminuzione in abbondanza durante una fase di graduale riscaldamento è chiaramente correlabile ad un aumento dei nutrienti disponibili. Infine, entrando all’interno del genere Sphenolithus, si è osservata una profonda riorganizzazione, S. furcatolithoides si estingue, S. predistentus e S. obtusus fanno la loro prima comparsa, e molte delle altre specie subiscono aumenti o diminuzioni temporanee delle loro abbondanze. Nel complesso, i dati provenienti dal Site ODP 1051A indicano che i cambiamenti nelle associazioni a nannofossili calcarei sono iniziati molto dopo l’inizio del MECO e prima del picco di riscaldamento, presentando due diversi andamenti: un primo tipo può essere definito brusco (ad es. la LCO di Dictyococcites, la HO di S. furcatolithoides), mentre un secondo tipo è graduale (ad es. l’aumento delle Reticulofenestra di piccole dimensioni).
Russo, F. "CALCAREOUS NANNOFOSSIL REVISED BIOSTRATIGRAPHY OF THE LATEST ALBIAN-EARLIEST CAMPANIAN TIME INTERVAL (LATE CRETACEOUS)." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/231575.
Full textOzkan, Sevinc. "Calcareous nannofossil and calpionellid biostratigraphy of the Upper Jurrassic-Lower Cretaceous in Northwest Anatolia, Turkey." Thesis, University College London (University of London), 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508109.
Full textStarkie, Stephen Patrick. "Calcareous nannofossil biostratigraphy and depositional history of the late Cretaceous to early Miocene sequence of Iraq." Thesis, University College London (University of London), 1994. http://discovery.ucl.ac.uk/1317864/.
Full textMINIATI, FRANCESCO. "CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY AND PALEOECOLOGY OF THE LATE TURONIAN TO EARLY CAMPANIAN INTERVAL AND OF OCEANIC ANOXIC EVENT 3." Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/826218.
Full textThe Late Cretaceous was punctuated by several periods of global perturbations of the climate-ocean system that lead to widespread organic carbon-rich marine black shale deposition, termed Oceanic Anoxic Events (OAEs). The OAE3 represents the last episode of anoxia dated as Coniacian-Santonian. Compared to previous anoxic events, OAE3 has a regional extension, rather than a global significance, since it is confined to the equatorial-south Atlantic Ocean and adjacent basins (e.g. Caribbean Basin, Western Interior Basin). Another major difference of OAE3 relative to previous OAEs resides in the absence of a prominent δ13C anomaly, but the occurrence of several minor positive and negative excursions in the Coniacian-Santonian interval. Moreover, the deposition of organic carbon-rich sediments (black shales) seems to be diachronous even in the central-south Atlantic Ocean. This PhD project focused on calcareous nannofossil biostratigraphy and paleoceanography of the Late Turonian to Early Campanian time interval (Late Cretaceous), and specifically of the Coniacian-Santonian. Nannofossil assemblages were investigated semiquantitatively and quantitatively to obtain a detailed biostratigraphic framework for assessing the paleoenvironmental changes across OAE3. The study was performed on Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sites and on-land sections, situated in the equatorial and south Atlantic Ocean, the Indian Ocean and the Anglo-Paris Basin. The results of my investigation were integrated with data from literature in order to achieve a solid framework of events for the Coniacian-Santonian time interval and provide a paleoceanographic characterization of OAE3. A detailed revision of the taxonomy was accomplished for solving a few taxonomic incongruities and obtain a unified updated nomenclature. This was the basis for the coherent high-resolution biostratigraphy of the selected sites, in order to establish dating and correlations at supra-regional scale. The four standards biozonation schemes available for the Upper Cretaceous were applied to attain the maximum resolution and test their individual applicability in different oceanic basins and oceanographic settings. The major objective of this PhD thesis was the reconstruction of presumed paleoceanographic changes across OAE3 as recorded by abundance and composition of calcareous nannofossil assemblages. Quantitative analyses of calcareous nannofossil assemblages allowed the characterization of paleotemperature and nutrient changes prior, during and after OAE3. Nannofossil-based paleotemperature obtained in this study and documented in the literature do not show significant changes in the studied successions, perhaps due to unresolved unambiguous temperature-related taxa in the Late Cretaceous and/or minor (subtle) temperature changes across OAE3. As far as paleofertility isconcerned, the nannofossil taxa indicative of higher nutrient content display very different patterns at the various sites, suggesting that OAE3 was not characterized by a global fertilization episode. Indeed, fertility remained globally low with the exception of upwelling areas characterized by meso-eutrophic conditions also in the intervals preceding and following OAE3. The quantitative analyses conducted in this study pointed out relatively large fluctuations in abundance of genera Micula and Marthasterites in the Coniacian-Santonian interval. These abundance peaks could be correlated with analogous events described in the literature, even if with different values of abundance at the various sites/sections. Two Marthasterites (M. furcatus) abundance peaks and five Micula (M. staurophora) abundance peaks were distinguished across OAE3. The paleoecological affinity of Micula, and specifically M. staurophora, as well as that of genus Marthasterites remains unexplained, so the causes of their abundance peaks continue to be elusive. However, the distinctive fluctuations in nannofossil assemblages indicate profound paleoceanographic changes during the Coniacian-Santonian. The onset of OAE3 coincides with a major increase in abundance (and locally dominance) of M. furcatus suggesting the rapid establishment of new and peculiar paleoceanographic conditions at widespread to global scale. The most altered paleoceanographic conditions were reached in the core of OAE3 with the synchronous maximum abundance (climax) of M. staurophora at global scale. In addition to their value for paleoenvironmental reconstructions, the identified Micula and Marthasterites abundance peaks turned out to be extremely useful for complementing/implementing the biostratigraphic characterization of the Turonian/Coniacian, Coniacian/Santonian and Santonian/Campanian boundaries and might be introduced as additional events in future nannofossil zonations for the Late Cretaceous.
VISENTIN, STEFANO. "CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY AND TAXONOMY ACROSS THE EARLY TOARCIAN OCEANIC ANOXIC EVENT: A COMPARISON BETWEEN TETHYAN AND BOREAL SECTIONS." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/701592.
Full textAbstract The Early Toarcian Oceanic Anoxic Event (T-OAE), in the Early Jurassic Period, was associated with one of the largest perturbations of the carbon cycle in the past 250 Ma. This dramatic episode of ecosystem adjustments, global warming, oceanic anoxia and altered chemistry occurred during a crucial time for calcareous nannoplankton diversification as a major speciation episode took place in the Late Pliensbachian – Early Toarcian time interval. New genera and species appeared and quickly evolved allowing a high-resolution biostratigraphy of the onset and the termination of the T-OAE based on first and last occurrences. Moreover, drastic drops in abundance of some taxa are associated to the paleoenvironmental perturbations recorded across the T-OAE. In this PhD thesis I present a high-resolution calcareous nannofossil biostratigraphy of three cores drilled in the Lombardy Basin (Sogno Core) and in the Lower Saxony Basin (L1 and Schandelah Cores), covering the lithological expression of the T-OAE in the Tethyan and Boreal realms. Events recognized across the Sogno Core allow the detection of three biozones (NJT5a, NJT5b and NJT6) whereas those recognized in the L1 and Schandelah Cores result in the identification of three zone/subzones (NJ5b, NJ6 and NJ7). These results are integrated with data from literature in order to derive a solid framework of primary and secondary events characterizing the upper Pliensbachian/lower Toarcian interval with a special focus on the Pliensbachian/Toarcian boundary and the characterization of the T-OAE in the Tethyan and Boreal realms. For the Tethyan sections (Italy, South-East Spain, South France, Greece and Hungary) the primary events include the FOs of Lotharingius sigillatus, Carinolithus poulnabronei, Lotharingius crucicentralis, Carinolithus superbus sceptrum, Watznaueria sp. 1, Discorhabdus striatus, Schizosphaerella crisis and LO of Mitrolithus jansae while the FOs of Lotharingius velatus and Discorhabdus ignotus are considered within the secondary ones. Likewise, for the Boreal Realm (sections in Central-North France, England and Germany), my synthesis resulted in the separation of primary events including the FOs of Crepidolithus impontus, L. sigillatus, C. superbus sceptrum, D. striatus and LOs of Crucirhabdus primulus and Biscutum finchii from the secondary ones comprising the FOs of L. crucicentralis, L. velatus, D. ignotus, C. poulnabronei, Watznaueria sp. 1, Schizosphaerella crisis and LOs of Crepidolithus granulatus, Parhabdolithus liasicus and Biscutum grandis. My study revealed that the FO of C. superbus sceptrum is the only event reproducible at a supraregional level and confirmed that the Pliensbachian/Toarcian boundary is approximated by the FOs of L. sigillatus (slightly below) and C. poulnabronei (slightly above) in the Tethyan Realm and by the LO of C. primulus in the Boreal. At lower latitudes (sections in Italy, South-East Spain, South France, Greece and Hungary), my study revealed that the T-OAE is well constrained by the FOs of C. superbus sceptrum and the “Schizosphaerella crisis” at the onset and by the LO of M. jansae at its termination. These events are reproducible in Portugal, with the addition of the FCO of D. ignotus marking the termination of the event. At higher latitudes (sections in Central-North France, North Spain, England and Germany) my study confirms that the onset of the T-OAE is constrained by the FO of C. superbus sceptrum. Secondary events, not reproducible in North Spain, are the “Schizosphaerella crisis” at the onset of the T-OAE and the LOs of C. granulatus, B. finchii, P. liasicus and B. grandis within the carbon isotope excursion characterizing the T-OAE. Morphometric analyses conducted on Carinolithus superbus and Carinolithus magharensis specimens allow to clarify taxonomic discrepancies regarding the two taxa. Qualitative investigations performed on Carinolithus cantaluppii revealed that this taxon is a diagenetic artefact of the genus and, therefore, that this species must be rejected. Implications for biostratigraphy and evolutionary trends are discussed.
Campbell, Robert John. "Calcareous nannofossil and foraminiferal analysis of the middle to upper cretaceous Bathurst Island Group, Northern Bonaparte Basin and Darwin Shelf, Northern Australia." University of Western Australia. School of Earth and Geographical Sciences, 2003. http://theses.library.uwa.edu.au/adt-WU2003.0025.
Full textCasellato, C. E. "Causes and consequences of calcareous nannoplankton evolution in the Late Jurassic : implications for biogeochronology, biocalcification and ocean chemistry." Doctoral thesis, Università degli Studi di Milano, 2009. http://hdl.handle.net/2434/50615.
Full textWalsworth-Bell, Edward Benedict. "Jurassic calcareous nannofossils and environmental cycles." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251594.
Full textBaky, Alaaeldin Mohamed Abdel. "Maastrichtian to early Eocene calcareous nannofossils from Egypt." Thesis, University College London (University of London), 1988. http://discovery.ucl.ac.uk/1317747/.
Full textPeleo-Alampay, Alyssa M. "Miocene and oligocene calcareous nannofossils : biochronology and paleoceanography /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9823695.
Full textShafik, Samir. "Late Cretaceous, early Tertiary calcareous nannofossils from Australia." Title page, contents and summary only, 1989. http://hdl.handle.net/2440/19212.
Full textKenjo, Samer. "Biostratigraphie intégrée à nannofossiles calcaires et ammonoïdes : développement et implications pour la définition et la valorisation des stratotypes d’unité et de limite. L’exemple des étages Berriasien et Valanginien et de leur limite (~140 Millions d’années)." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10156.
Full textThe integrated biostratigraphic study of ammonites and calcareous nannofossils in three sections from SE France (Vergol, Courchons, and Berrias) allowed a solid new biozonation scheme to be proposed here. This study should enable us to strengthen the proposition of the Vergol section as GSSP for the lower boundary of Valanginian. Concerning ammonites, an intensive exploitation bed by bed coupled to a taxonomic revision of all groups have shown a faunal renewal and brought to the proposal of a new zonal scheme. The Upper Berriasian is characterized in its upper part by a new zone, the Alpillensis zone, which replaces the upper part of the Boisseri zone sensu Le Hégarat. The Alpillensis zone is subdivided into two subzones, Alpillensis and Otopeta. For the Lower Valanginian, the Pertransiens (with the introduction of two new subzones, Premolicus and Salinarium) and Neocomiensiformis zones have been recognized. Concerning calcareous nannofossils, many events are recorded across the Berriasian/Valanginian boundary, underlying a major change in the assemblages as indicated by Principal Component Analysis. These changes are very likely linked to sea level changes. In fact, a major regression occurred in the Alpillensis zone, followed by a transgression in the Petransiens zone. Unitary Associations resulted in an UA 1 whose topmost part occurs just above the first occurrences of the nannofossil C. oblongata and of the ammonite « Thurmanniceras » pertransiens. The stratigraphic succession of these three events (namely, the FOs of « T. » pertransiens and of C. oblongata and the top of UA 1) allow us to identify the boundary between the Berriasian and Valanginian in this work with the FO of « T. » pertransiens
Ferreira, Jorge. "Palaeoenvironmental and palaeoceanographic changes during the Lower to Middle Jurassic ( Toarcian-Aalenian, ~183-171 Ma) : new evidences from calcareous nannofossils of the Lusitanian Basin." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1033/document.
Full textAt ~183 Ma when large amounts of organic matter was dumped onto the ocean beds (known as the Toarcian Oceanic Anoxic Event, T-OAE), the Early Toarcian marine biota experienced one of the most important biological crises in Earth history. Calcareous nannoplankton was deeply affected and started only to recover from the end of the Early Toarcian. After the T-OAE, as phytoplankton communities dwelling the oceans photic layer recover from the previous disturbing conditions, the ecological niches once occupied by calcareous nannoplankton are again replenished. Located in the westernmost part of the Tethyan ocean, the Lusitanian Basin acted as a seaway between the NW Tethys and the Mediterranean Tethys provinces, therefore been actively influenced by these two different water masses. Hence such a region stands as the perfect spot to study the calcareous nannoplankton community, as its fossil remains bears species typical of both provinces. In order to appraise the nannoplankton demise and subsequent recovery, absolute and relative abundances of nannofossils were determined from pelagic marl-limestone couplets from three sections of the Lusitanian Basin. Also brachiopods shells were investigated for stable carbon and oxygen isotopes analysis. In order to independently assess the morphologic evolution of Lotharingius coccoliths, a Toarcian section from south France was studied. Different statistic methodologies were used throughout this work, in order to screen for robust and significant information from the numerous datasets that were built
Há cerca de 183 milhões de anos atrás, a biota marinha sofreu uma das mais importantes crises biológicas na história do planeta, quando grandes quantidades de matéria orgânica foram depositadas nos fundos oceânicos. Este episódio que teve lugar durante o Toarciano, resultou de um Evento Anóxico Oceânico (T-OAE), e afectou os mares epicontinentais à escala global. O nanoplâncton calcário, um grupo de organismos extremamente sensível às variações nas condições ambientais que têm lugar na camada superficial das massas de água, foi profundamente afectado. Foi somente no final do Toarciano Inferior que a sua recuperação se iniciou. Apesar de já muito se ter escrito sobre o T-OAE, a previsível recuperação deste grupo nunca foi sistemática nem detalhadamente estudada. Até hoje, não se sabia ainda se esta recuperação teria sido relativamente rápida, ou resultado de um processo lento e gradual que teria durado milhões de anos. Durante o Toarciano Inferior, quando as condições ambientais eram extremamente instáveis, ocorreram importantes e drásticas oscilações na temperatura e no nível médio dos oceanos. Após o T-OAE e durante todo o Toarciano e Aaleniano Inferior, as oscilações do nível médio dos oceanos e de temperatura são bastante mais suaves. À medida que a comunidade fitoplanctónica instalada na zona fótica recupera das condições extremas anteriores, os nichos ecológicos antes ocupados por nanoplâncton calcário, começam novamente a ser preenchidos. Apesar das prolongadas e suaves variações abióticas, é num ambiente então mais estável, que melhor se pode observar a evolução deste grupo, e de que forma as suas relações sinecológicas se alteraram ao longo de aproximadamente 10 milhões de anos. Apesar de ser considerado como um período onde a comunidade nanoplanctónica sofreu importantes alterações, nada se sabe em concreto que alterações foram essas que tiveram lugar após o TOAE num local tão estratégico como a Bacia Lusitânica. Situada na extremidade Oeste do Tétis e fazendo parte de um rift originado pela abertura do Atlântico, a Bacia Lusitânica actuou como um corredor que ligava livremente as massas de água das províncias mediterrânica e NW do Tétis, sendo por estas, activamente influenciada. Por essa razão, tal situação geográfica constitui um local excepcional para se estudar a comunidade de nanoplâncton calcário, uma vez que o seu registo fóssil compreende espécies típicas destas duas províncias do Tétis
Rutledge, David Charles. "Calcareous nannofossils of the Boreal Lower Cretaceous : applications in biostratigraphy and palaeoceanography." Thesis, University College London (University of London), 1994. http://discovery.ucl.ac.uk/1360347/.
Full textBurnett, Jacqueline Anne. "North-west European late cretaceous calcareous nannofossils : biostratigraphy and selected evolutionary lineages." Thesis, University College London (University of London), 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295154.
Full textLübke, Nathalie [Verfasser], Jörg [Gutachter] Mutterlose, and Elisabetta [Gutachter] Erba. "Size evolution of Cretaceous calcareous nannofossils / Nathalie Lübke ; Gutachter: Jörg Mutterlose, Elisabetta Erba." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1137380160/34.
Full textYoung, Jeremy R. "Neogene calcareous nannofossils from the Makran region of Pakistan and the Indian Ocean." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46920.
Full textFinch, Edward Maurice. "Tertiary calcareous nannofossils : biostratigraphy and global correlation with special reference to the Sphenolithaceae (Deflandre)." Thesis, Kingston University, 1989. http://eprints.kingston.ac.uk/20524/.
Full textGallagher, Liam Thomas. "Tertiary calcareous nannofossils from the central and southern North Sea Basins, and their biostratigraphical application." Thesis, University College London (University of London), 1988. http://discovery.ucl.ac.uk/1381826/.
Full textMorse, Trevor John. "Biostratigraphical constraints (calcareous nannofossils) on the Late Cretaceous to Late Miocene evolution of S.W. Cyprus." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/1565/.
Full textSuchéras-Marx, Baptiste. "Émergence de la production carbonatée pélagique au Jurassique moyen (180-160 Ma) : la conquête des océans par les coccolithophoridés du genre Watznaueria." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10024.
Full textCoccolithophorids are photosynthetic and planktonic marine algae that produce micrometric calcium carbonate (CaCO3) platelets called coccoliths. These algae appeared about 210 Ma ago and produce today most of the CaCO3 in the modern oceans, hence playing a major role in the carbon cycle. Nevertheless, the onset of oceanic CaCO3 production by these organisms during the Jurassic and its impact on carbon cycling remain poorly understood. This study therefore focused on the Middle Jurassic interval (Early Bajocian, -170 Ma) which records the diversification of Watznaueria, an evolutionary important coccolith genus that subsequently dominated oceanic CaCO3 production for more than 80 Myr. The analysis of coccolith assemblages from the Middle Jurassic of southern France and Portugal, based on an automaticcoccolith recognition device used for the first time on Jurassic coccoliths, allowed quantifying the impact of this diversification on CaCO3 production. In addition, the duration of this key interval has been revaluated by the cyclostratigraphic analysis of sedimentary strata from southern France. The reconstructed changes in CaCO3 production were compared to carbon cycle perturbations recorded by carbon isotope ratios and indicate a probable link with a marked increase of ocean fertility. Besides, paleontological analyses show that this diversification episode correspond to the successive appearance of different, probably opportunistic Watznaueria species. The obtained fluxes of pelagic CaCO3 production, by far lower than those recorded in modern oceans, seems too low to have significantly impacted theMiddle Jurassic carbon cycle
Alqudah, Mohammad Verfasser], Jörg [Gutachter] [Mutterlose, and Olaf Günther [Gutachter] Podlaha. "Calcareous nannofossils from Late Cretaceous - Paleogene oil shales of Jordan / Mohammad Alqudah ; Gutachter: Jörg Mutterlose, Olaf Günther Podlaha." Bochum : Ruhr-Universität Bochum, 2014. http://d-nb.info/1133361439/34.
Full textBlaj, Teodora. "Late Eocene through Oligocene calcareous nannofossils from the paleo-equatorial Pacific Ocean – taxonomy, preservation history, biochronology and evolution." Doctoral thesis, Stockholm : Department of geology and geochemistry, Stockholm university, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-27600.
Full textFaucher, G. "RESPONSE OF CALCAREOUS NANNOPLANKTON MORPHOLOGY TO ENVIRONMENTAL PERTURBATIONS: THE LATEST CENOMANIAN OCEANIC ANOXIC EVENT 2 AND LAB SIMULATIONS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/260348.
Full textFerrarese, Heliane Bevervanso. "Variações de produtividade da porção oeste do Atlântico Sul ao longo dos últimos 15 mil anos a partir de estudo quantitativo de nanofósseis calcários." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/21/21133/tde-03082011-154253/.
Full textThe aim of this study consisted in estimate possible changes on southwestern Atlantic Ocean surface water productivity for the last 15.000 years, contributing to a better understanding of oceanographic changes that occurred along this time. Quantitative calcareous nannofossils analyses were carried out on a Santos Basin core using the random settling technique. Bulk carbon and oxygen stable isotopes and calcium carbonate content were also used for paleoproductivity interpretation. Primary productivity of surface waters presented variation along the last 15.000 years. Variations in continental contribution and thermocline/nutricline depth must have influenced the surface water conditions and therefore coccolithophorids productivity. Upper photic zone productivity was estimated and seems to have diminished since early Holocene. Prior to this time, a major continent contribution would have provided more favorable conditions for the development of the coccolithophorids that inhabit the upper layers of the ocean.
Krammer, Regina. "Calcareous nannofossils in the S-Atlantic during the middle to late Miocene Coccolithophorid carbonate budgets, fine-fraction stable isotopes and their paleoceanographic implications /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979757770.
Full textTamagnini, P. "Calcareous nannofossils as tracers of paleoceanographic changes associated to Oceanic Anoxic Event 2: records from the Tethys and Atlantic Oceans. di Paola TAMAGNINI." Doctoral thesis, Università degli Studi di Milano, 2008. http://hdl.handle.net/2434/49827.
Full textBarbarin, Nicolas. "La reconnaissance automatisée des nannofossiles calcaires du Cénozoïque." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4318.
Full textSYRACO 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
Antiqueira, Antonio Henrique Bender. "Nanofósseis calcários do DSDP Leg 40, Poços 361 e 364. Bioestratigrafia e implicações paleoceanográficas do Período Cretáceo na Margem Africana, Oceano Atlântico Sul." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/21/21136/tde-20032018-155424/.
Full textBiostratigraphic studies, based on calcareous nanofossils samples from DSDP, Leg 40, sites 364 and 361 (Angola - Cuanza and Cabo - Orange Basins, African Margin), allowed the taxonomic refinement for the Cretaceous period (145.5 - 65.5 M.a.), between Aptian and Turonian (125 - 89.3 M.a.). The Leg 40 data obtained from the 1970\'s DSDP reports were based in a controversial literature using biozones from distinct regions of the South Atlantic Ocean. In site 364, 89% of the samples contained nanofossil material, counting 168 slides useful to obtain biostratigraphic information. 78 taxa of calcareous nanofossils were identified, 66 at specific level and 12 at generic level. In site 361, 67% of the samples were sterile, thus, 64 slides were made, where 18 taxa were identified, 9 at the specific level, 6 at generic level and 3 at family level. The biostratigraphic refinement allowed to divide the Cretaceous section sampled on five ages in site 364: Turonian (93.5 - 89.3 Ma), Cenomanian (99.6 - 93.5 Ma), Albian (112 - 99.6 Ma), Aptian (125 - 112 Ma) and one generally identified as Lower Cretaceous (125 M.a. down). At site 361, the division of the Cretaceous level sampled occurred in three ages: Albian (112 - 99.6 M.a.), Aptian (125 - 112 M.a.) and a Cretaceous generic (125 M.a. down). With the biostratigraphic data obtained in the two sites, it was possible to generate a correlation between both sites, integrating the Albian (112 - 99.6 M.a.) and Aptian (125 - 112 M.a.) ages. This correlation made it possible to interpret the influence of waters from the north (Angola - Cuanza Basin) and the South (Cape Basin - Orange), divided by the structural high represented by the Walvis Ridge.
Joachim, Christian [Verfasser], Jörg [Gutachter] Mutterlose, Adrian [Gutachter] Immenhauser, and Christophe [Gutachter] Pascal. "The late Paleocene and early Eocene hyperthermal events : evidenced by calcareous nannofossils and geochemistry / Christian Joachim ; Gutachter: Jörg Mutterlose, Adrian Immenhauser, Christophe Pascal ; Fakultät für Geowissenschaften." Bochum : Ruhr-Universität Bochum, 2013. http://d-nb.info/122468172X/34.
Full textKanungo, Sudeep. "Biostratigraphy and palaeoceanography of mid-Cretaceous calcareous nannofossils : studies from the Cauvery Basin, SE India; the Anglo-Paris Basin, SE England; the North Atlantic and Pacific Oceans." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1445720/.
Full textQuadros, Juliana Pereira de. "Nanofósseis calcários da margem continental nordeste do Brasil: uma contribuição à paleoceanografia do Atlântico Sul nos últimos 25.000 anos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/21/21133/tde-06112007-112950/.
Full textThis study focuses on changes in calcareous nannofossil assemblages as an evidence of paleoceanographic variability during the last 25,000 years in two deep sea piston cores from the northeastern Brazilian continental margin. To support reconstructing ancient marine environment others proxies have been applied along with the calcareous nannofossil analysis: 1) oxygen isotopic data from planktonic and benthic foraminifers\' tests; 2) temperature and nutrient indices; 3) paleoproductivity equation and 4) multivariate analysis. For the first time the temperature and nutrient indices were employed to Quaternary calcareous nannofossil from the South Atlantic Ocean. According to presented results major oceanographic features were stable in the last 25,000 years, although instable environmental conditions were recorded in the Last Glacial Maximum - Holocene boundary. During the Last Glacial Maximum the western tropical Atlantic seems to have experienced slight temperature changes and served as a heat and salt reservoir. Nutricline and thermocline depth variation was considered the most important response to climate changes largely related to Trade Winds strength oscillation.
Püttmann, Tobias [Verfasser], Jörg [Gutachter] Mutterlose, Adrian [Gutachter] Immenhauser, and Carsten [Gutachter] Jürgens. "Exceptionally well-preserved calcareous nannofossils from a late cretaceous nearshore setting : implications for stratigraphy and paleoecology / Tobias Püttmann ; Gutachter: Jörg Mutterlose, Adrian Immenhauser, Carsten Jürgens ; Fakultät für Geowissenschaften." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1229694730/34.
Full textLinnert, Christian [Verfasser], Jörg [Gutachter] Mutterlose, Adrian [Gutachter] Immenhauser, and Wolfgang [Gutachter] Friederich. "Case studies of Late Cretaceous calcareous nannofossils : implications for the Cenomanian-Maastrichtian palaeoceanography of the proto-North Atlantic / Christian Linnert ; Gutachter: Jörg Mutterlose, Adrian Immenhauser, Wolfgang Friederich ; Fakultät für Geowissenschaften." Bochum : Ruhr-Universität Bochum, 2011. http://d-nb.info/1240475888/34.
Full textGuerra, Rodrigo do Monte. "Nanofósseis calcários do cretáceo na Bacia de Pelotas, RS : infêrencias bioestratigráficas e paleoecológicas." Universidade do Vale do Rio dos Sinos, 2011. http://www.repositorio.jesuita.org.br/handle/UNISINOS/3494.
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Este estudo apresenta inferências bioestratigráficas e paleoecológicas baseadas na distribuição de nanofósseis calcários em três poços perfurados na plataforma continental da Bacia de Pelotas, sul do Brasil. Estudos bioestratigráficos na bacia foram realizados no final da década de 1980, porém nos últimos trinta anos o arcabouço bioestratigráfico com nanofósseis calcários para as bacias marginais brasileiras obteve um refinamento significativo, justificando a elaboração de um novo estudo. A sucessão é composta principalmente por rochas siliciclásticas provenientes de amostras de calha com pequenos intervalos de testemunhos. Foram reconhecidas onze biozonas atingindo a seção Albiano superior/Maastrichtiano, o resultado das análises bioestratigráficas produziram uma melhor resolução principalmente para o Turoniano e o Campaniano da bacia. Abundâncias relativas e absolutas de espécies do Cretáceo foram utilizadas para a determinação de inferências paleoecológicas, as primeiras com base em nanofósseis calcários para a Bacia de Pelotas. Estes dados sugerem o predomínio de condições de águas quentes com alguns eventos de esfriamento da água durante o Turoniano superior, Turoniano superior/Coniaciano inferior, Coniaciano superior e Santoniano superior/Campaniano inferior.
This study reports biostratigraphic and paleoecologic inferences based on the distribution of calcareous nannofossils in three wells drilled in Pelotas Basin continental shelf, southern Brazil. The first biostratigraphic study in the basin comes from late 1980s, however the Brazilian nannoplankton biostratigraphic framework reached a higher resolution in the last thirty years, justifying the development of a new study. The successions are composed mainly by siliciclastic rocks coming from cutting samples and short intervals of cored samples. Eleven biozones were recognized, within the upper Albian and Maastrichtian interval, the biostratigraphic analyses provided a higher resolution mainly for Turonian and Campanian strata in the basin. Absolute and relative abundances of some Cretaceous calcareous nannofossils species provided paleoecological proxies, pioneer in Pelotas Basin using this fossil group. The results suggest a prevalence of warm-water condition, with cooling events during the upper Turonian, upper Turonian/lower Coniacian, upper Coniacian and upper Santonian/lower Campanian.
Guerra, Rodrigo do Monte. "Nanofósseis calcários do Campaniano e Maastrichtiano no Atlântico Sul: bioestratigrafia, paleoceanografia e paleobiogeografia." Universidade do Vale do Rio dos Sinos, 2016. http://www.repositorio.jesuita.org.br/handle/UNISINOS/5721.
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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.
Bornemann, André [Verfasser]. "Case studies of Mesozoic calcareous nannofossils : implications for palaeoecology, calcareous nannofossil morphology and carbonate accumulation / vorgelegt von André Bornemann." 2004. http://d-nb.info/970713509/34.
Full textWang, Sheng-Tzung, and 王聖宗. "Calcareous nannofossil biostratigraphy of the Kutingkeng formation in the Yanchao,Kaohsiung." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/96447008235727409500.
Full textChuang, Chih-Kai, and 莊智凱. "Upper Pliocene-Pleistocene calcareous nannofossil biostratigraphy of ODP1115B in the Solomon Sea, western equatorial Pacific." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/71015919626976590607.
Full text國立臺灣大學
地質科學研究所
96
The Western Pacific Warm Pool (WPWP) is the largest source of heat and moisture on the Earth surface. For its importance the paleoceanographic studies of the WPWP have increased dramatically during the past decade. In an attempt to improve the resolution and accuracy of chronology of the stratigraphic records in the WPWP for the last 3 million years, the current study establishes calcareous nannofossil biostratigraphy of ODP site 1115B (9o11.382’S, 151 o 34.437’E, water depth 1149 m) in the Solomon Sea with a newly modified magnetostratigraphy of the Upper Pliocene-Pleistocene. The existing, unpublished oxygen isotope stratigraphy (Ke, 2008) provides a stratigraphic framework in which the chronological significances of the 14 recognized bioevents were evaluated against published results of other sites. Semi-quantitative estimations of relative abundances of environmentally-sensitive nannofossil taxa are used to infer paleoceanographic changes. The nannofossils in samples of the upper 216.43 mbsf of ODP1115B were identified under a light microscope at 1250X magnification augmented with additional scanning electronic microscopy when necessary. Among the 14 recognized bioevents, seven are of good correlation markers because of their global synchroniety. They are the first occurrence (FO) of Emiliania huxleyi, the last occurrence (LO) of Pseudoemiliania lacunosa, LO Reticulofenestra asanoi, LO large Gephyrocapsa, FO large Gephyrocapsa, LO Calcidiscus macintyrei and LO Discoaster brouweri. Seven of the bioevents are considered to be diachronous, including the reentrance (reen) of medium Gephyrocapsa, FO Reticulofenestra asanoi, LO Helicosphaera sellii, FO medium Gephyrocapsa, LO Discoaster pentaradiatus, LO D. surculus and LO D. tamalis. The reason of reen medium Gephyrocapsa being diachronous is that the medium-sized Gephyrocapsa omega (= G. parallela) favored warm water conditions and thereby shows a latitudinal heterogeneity of their first occurrence during marine oxygen isotope stages (MIS) 25-29. Changes in nannofossil assemblage composition signify several major climatic changes during the past 3 million years. The abundance of Discoaster spp. is used as an indicator of warm conditions. The major drops of Discoaster abundance during 2.8-2.6 Ma and 2.5-2.4 Ma are indicative of decrease of sea-surface temperature as resulted from the onset of northern Hemisphere glaciation and its subsequent major ice-sheet expansion. The relative abundance of Florisphaera profunda may indicate the strength of upwelling and therefore change in thermocline depth. The extinction of Reticulofenestra asanoi and the dramatic reduction of Gephyrocapsa omega at about 0.9 Ma related to the mid-Pleistocene revolution when the dominant periodicity of global climatic variation changes from 41 ka to 100 ka, as well as a major step-wise increase of global ice volume took place.
Chang, Jing, and 張靖. "The Calcareous Nannofossil Biostratigraphy Along Both Sides of Tamayhsi Fault In Hengchun Peninsula,Southern Taiwan." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/90826941446953260455.
Full text國立成功大學
地球科學系碩博士班
91
Tamayhsi Fault was one of dominant geological structure in Hengchun Peninsula, southern Taiwan, but character of the fault wasn’t fully appreciate yet. Some species of calcareous nannofossil with short life span, which called “zoonal marker” could be used as a indicator of geological epoch. Calcareous nannofoaais samples which be collected from the Miocene Mutan Formation in Hengchun Peninsula were observed by microscopy. As the result, the biozone of the stratum along the west side of the Tamaychi Fault can be assigned to the NN5 or NN6 Zone , and NN11 or NN12 zone on the other side along the 199 highway, discontinuity of biozone was found in Mutan Formation along the both sides of Tamayhsi Fault. In southern part of study area, similar discontinuty between west and east side was also found along Tamayhsi Fault. Early or middle Miocene sedimentary stratum of Central ranges was the implicative sediment source of Hengchun Peninsula, due to secondary fossil which could be assign to the NN1~NN5 appear in late Miocene stratum here.
Lin, Ho-Ya, and 林荷雅. "Upper Miocene-lower Pleistocene calcareous nannofossil biostratigraphy of ODP 1210, northwestern Pacific and some application." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/37578740971710550469.
Full text國立臺灣大學
地質科學研究所
100
The conventional nannofossil standard zonations of Martini (1971) and Okada & Bukry (1980) have been prime standards for biostratigraphic correlation of Neogene sediments. Advance in biochronology in the last four decades has further calibrated the first and last occurrences of index species in those schemes. However, these two zonations were mainly based upon low-latitudes stratigraphic sections of marine sediments. The diachroniety of each bioevent needs to be evaluated when such standard schemes are employed in middle latitudes. Particularly, the first and last occurrences of warm-water Discoaster spp. tend to be diachronous between low- and mid-latitudes. This study analyzed the upper Miocene-lower Pleistocene calcareous nannofossil assemblages from a mid-latitude ODP site in the northern Pacific to address the fore-mentioned issues. The studied site is ODP 1210 (32°13N, 158°15E; water depth of 2574 m) which located on the Shatsky Rise. This study examined the samples at 50 cm intervals with semi-quantitative abundance of nannofossils, and prepared all slides with processed standard techniques.All slides were analyzed under the light microscope at ×1600 magnification. Moreover, the bioevents were determined by higher resolution which was 10 cm sampling interval and counting the key fossil number within a total as 500 specimens. The age of 11 nannofossil datums is estimated by interpolation between magnetic reversals. They are: LCO of Discoaster brouweri at 1.96 Ma, LO of D. pentaradiatus at 2.51 Ma, LO of D. surculus at 2.52 Ma, LO of D. asymmetricus at 2.81 Ma, LO of D. tamalis at 2.85 Ma, LCO of Reticulofenestra pseudoumbilica at 3.82 Ma, FO of D. tamalis at 3.98 Ma, LO of Amaurolithus spp. at 4.00 Ma, FO of D. asymmetricus at 4.12 Ma, FO of Ceratolithus spp. at 5.00 Ma, LO of D. quinqueramus at 5.86 Ma. Three bioevents are evaluated to be diachronous, including LO of D. surculus, LO of D. tamalis, and LO of D. quinqueramus. 3.84 Ma for the FO of Pseudoemiliania lacunosa recorded slightly below the LCO of R. pseudoumbilica. Amaurolithus spp.and Ceratolithus spp. are presented in rare numbers, hence the LO of A. tricorniculatus and the FO of C. rugosus are unavailable in ODP 1210. Especially, that the LCOs of R. gelida and R. pseudoumbilica at 3.82 Ma are identical suggested the fates of both morphotypes were controlled by the same factor. Reticulofenestra gelida may represented a winter morphovariant of R. pseudoumbilica. The absence of a warm-water species Sphenolithus abies implies that the water masses throughout the late Miocene-early Pliocene at this location were too cold for Sphenolithus abies to live, but still warm enough for various Discoaster species.
Chen, Liling, and 陳俐陵. "Upper Pliocene-Pleistocene Calcareous Nannofossil Biostratigraphy of DSDP 594 and ODP 1125 in the Middle Latitudes of Southwest Pacific." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/16691871938127616756.
Full text國立臺灣大學
地質科學研究所
89
In order to establish an adequate biochronological framework for the transitional mid-latitudes in the southwest Pacific, the calcareous nannofossils of Sites DSDP594 and ODP1125 were investigated. Both sites are furnished with low-quality magnetostratigraphy as an independent calibration aid. Based upon correlation with other lower-latitude sites in the warm subtropical region (DSDP593, 590, and 588), the synchroniety and usefulness of eight commonly used nannofossil datum levels were evaluated. These bioevents are: (1) the first occurrence (FO) of Emiliania huxleyi, (2) the last occurrence (LO) of Pseudoemiliania lacunosa, (3) the LO of Calcidiscus macintyrei, (4) the FO of medium-sized Gephyrocapsa spp., (5) the LO of Discoaster brouweri, (6) the LO of Discoaster surculus, (7) the FO of P. lacunosa and (8) the LO of Reticulofenestra pseudoumbilica. As a result, a mid-latitude, transitional nannofossil biozonation was established with an adequate correlation with the low-latitude biozones. Due to the paucity of some age-diagnostic species, the newly erected biozonation is less resolved than the conventional low-latitude biozonation. Nevertheless, these biozones are useful for correlating sites in the warm and cool subtropics separated by the Subtropical Convergence.
Browning, Emily. "Calcareous nannofossil records of Miocene sea level at the Marion Plateau (Northeastern Australia); and Pliocene-Pleistocene formation of cold water carbonate mounds (Northeastern Atlantic Continental Margin)." 2012. https://scholarworks.umass.edu/dissertations/AAI3518214.
Full textShafik, Samir. "Late cretaceous - early tertiary calcareous nannofossils from Australia." Thesis, 1989. http://hdl.handle.net/2440/19212.
Full textJiang, Shijun. "Applications of calcareous nannofossils and stable isotopes to Cenozoic paleoceanography examples from the Eastern Equatorial Pacific, Western Equatorial Atlantic and Southern Indian Oceans /." 2007. http://etd.lib.fsu.edu/theses/available/etd-07262007-144559.
Full textAdvisor: Sherwood W. Wise, Jr., Florida State University, College of Arts and Sciences, Dept. of Geological Sciences. Title and description from dissertation home page (viewed Mar. 26, 2008). Document formatted into pages; contains xvi, 173 pages. Includes bibliographical references.
Chen, Miaw-Zen, and 陳妙珍. "Late Miocene to late Pliocene calcareous nannofossils paleobiogeography and paleoceanography of Ocean Drilling Program (ODP) Leg 184,Site 1146, northern South China Sea." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/38959309545543346431.
Full text國立臺灣大學
海洋研究所
88
Late Miocene to Late Pliocene (~6-2 Ma) calcareous nannofossils at Ocean Drilling Program Site 1146 were analyzed. Q-mode factor analysis of nannofossil assemblages and biometric study of Reticulofenestra were conducted to provide a better understanding of their implications to paleoceanography. Site 1146 is located at the north slope of the South China Sea (19o27.40’N, 116o16.37’E) under 2091 m of water. Q-mode factor analysis of Pliocene nannofossils from 65 Deep Sea Drilling Project sites in the Indo-Western Pacific region obtain 3 varimax factors which explain 92.8% of the total variance. The loadings of the 3 factors are clearly related to distinct geographical zones. Factor 1 is dominated by Discoaster and controls most part of the low to mid-latitude, warm marine environments, reflecting strong influence of warm water masses. Factor 2 is dominated by Reticulofenestra and Calcidiscus. It controls the high latitude oceans and is influenced mainly by cold water masses. Factor 3 is dominated by Helicosphaera and controls the low latitude Indian and western Pacific Oceans. It is most likely affected by the Monsoons. Factor scores of Site 1146 nannofossil assemblages indicates a gradual cooling of the northern South China Sea from 3.6 Ma to 2.6 Ma and an accelerated cooling stage after 2.6 Ma. Correlation of Factor 1 and δ18O indicates 3 relatively warmer stages in the late Miocene and Pliocene: 6-5.5 Ma, 4.6-4.2 Ma, and 3.4-2.7 Ma. Biometric study indicates that the maximum diameter (length) of Reticulofenestra changes systematically during the latest Miocene and Pliocene. Larger Reticulofenetra are more abundant in warmer stages while smaller Reticulofenestra spp. are more abundant during the colder stages.