Masters of Science / Located on the western offshore on the Atlantic Ocean margin of Southern Africa, the Orange Basin is the youngest and largest of the South Africa’s seven sedimentary basins. This passive margin basin in known for its hydrocarbon potential and therefore is the focus of attraction of several oil exploration companies. The study area lies near the continental margin in which four exploratory wells were drilled. An attempt has been made in this work to understand the depositional settings of these reservoirs and their biostratigraphy. Distribution of important planktonic index foraminifera helps in dating the reservoir sections. Paleoecological studies of benthic foraminifera were used for understanding the prevailing environment during the Cretaceous period. The study indicates that most of the reservoirs are distributed in the Albian (Early Cretaceous) and a few in the Cenomanian age sediments. Relatively shallow shelf sedimentation prevailed in the Late Aptian to middle part of Albian with deposition of arenaceous units. There were periodic localised deepening as well as very shallow depositional condition leading to exposure (diastem) as indicated by lithology and faunal composition. Gradual rise in sea level started in Late Albian and the entire area was under bathyal environment till the end of Cenomanian stage. This is indicated by deposition of claystone rich units and the associated fossil benthics indicates deposition in slope area. The few relatively minor argillaceous sandstone and siltstone units are with poor reservoir quality.

Accurate reconstruction of natural climate variability over the past millennium is critical for predicting responses to future climate change. In order to improve on current understanding of climate variability in the sub-tropical North Atlantic region over the past millennium, a rigorous study of Gulf of Mexico (GOM) sea surface temperature (SST) variability was conducted using both inorganic (foraminiferal Mg/Ca) and molecular organic (TEX86) geochemical proxies. In addition to generating multiple high-resolution climate records, the uncertainties of the SST proxies are rigorously assessed. There are 3 major research questions addressed: (1) What was the magnitude of GOM SST variability during the past 1,000 years, particularly during large-scale climate events such as the Little Ice Age (LIA) and the Medieval Warm Period (MWP). (2) Is the SST signal reproducible within the same sediment core, among different northern GOM basins, and using different geochemical SST proxies? (3) What are the ecological controls on the paleothermometers used to reconstruct SST variability in the GOM? Can differences in the ecology (i.e. seasonal distribution, depth habitat, etc.) of distinct paleothermometers be exploited to gain insight into changes in upper water column structure or seasonality in the GOM during the LIA and MWP? The major findings include: (1) The magnitude of temperature variability in the GOM over the past millennium is much larger than that estimated from Northern Hemisphere temperature reconstructions. The MWP (1400-900 yrs BP) was characterized by SSTs in the GOM that were similar to the modern SST, while the LIA (400-150 yrs BP) was marked by a series of multidecadal intervals that were 2-2.5°C cooler than modern. (2) This LIA cooling was replicated in the Mg/Ca-SST records from three different well-dated northern GOM basins (Pigmy, Garrison and Fisk Basins), as well as in two different geochemical proxies. (3) It is determined that foraminiferal test size has a significant effect on shell geochemistry. Using core-top calibration, discrepancies in the seasonal/depth habitats between different planktonic Foraminifera, and between Foraminifera and Crenarchaeota are inferred. Downcore differences are used to make inferences about changes in GOM mixed layer depth and seasonality over the past millennium.

>Magister Scientiae - MSc / Durban Basin located on the eastern coast of South Africa has been a focus of interest for Petroleum Exploration for the last few decades. Only four exploratory wells have been drilled in this offshore basin without success. During the initial stage of its creation, the basin suffered major tectonic disturbance as evident from the presence extensional faults followed by intense igneous activities. This was followed by marine sedimentation in the late Mesozoic (late Jurassic-early Cretaceous). An attempt has been made in this work to understand the distribution of the rock in space and time for the early Cretaceous sediments considered most prospective for hydrocarbon exploration in Southern Africa. Temporal distribution of planktonic foraminifera helps in identification of the three early Cretaceous (Barremian to Albian) stages within the drilled intervals. Foraminiferal biostratigraphic studies integrated with sedimentology, log motif analysis and seismic data analysis helps to predict paleodepth and depositional environment during early Cretaceous in this research. The integrated analysis reveals that during the Barremian-early Aptian stages graben filled sediments were deposited in a marine shelf in the northern part of the studied area (site Jc-D1) whereas, in the central and southern part finer clastics were deposited in middle slope (site Jc-B1 and Jc-C1). The thick claystone section and presence of minor limestone lenses and their benthic foraminifera assemblage in late Aptian-Albian stage in the northern area indicates possibility of submarine fan. Overlying succession dated between late Aptian to Albian and early part of Cenomanian interval in the three studied exploratory wells shows serrated log signatures. The dominant claystone lithology with intermittent siltstone/sandstone units and the benthic foraminifera indicates fluctuating distal marine slope environment with periodic shallowness in the entire area.

This thesis deals with the use of geochemical proxies on foraminifera for paleoceanographical, paleoecological and paleoenvironmental interpretations in the fossil epicontinental sea - the Central Paratethys during the Langhian. It discusses the used methodologies and approaches that were specially chosen to fit the problematic of the studied area such as the single test analysis of carbon and oxygen stable isotopes on foraminifera. Other geochemical methods were represented by Mg/Ca based paleothermomethry and by several organic geochemistry proxies on whole rock samples (n-alkane indices, δ13 Corg, and carbon ratios - TOC/TIC/TC). These were further combined with foraminiferal paleoecological data, which allowed identification of particular water masses in the studied region as well as the prevailing circulation patterns/regimes during the studied interval in the Paratethyan marine realm. Additionally, there were interpreted various regional paleoenvironmental and paleoecological consequences. The Paratethys had similar hydrography of surficial waters with the Mediterranean, conversely to the bottom waters that were different, probably of a regional origin with their own evolution during the studied time interval. The anti-estuarine circulation regime, which was probably linked with the closure...

This PhD thesis is a commentary to the attached publications. The thesis deals with two microfossil groups Ostracoda and Foraminifera in the Upper Cretaceous of the Bohemian Cretaceous Basin. Contribution of these microfossils for biostratigraphy and application in palaeoenvironmental reconstruction with the modern approach is the main goal of this work. Basic ecology, biogeography and previous work in the Bohemian Cretaceous Basin is included. Studied fossil sites, methods, microfossil preservation and data evaluation are described below. Obtained palaeontological, geochemical and lithological data are interpreted in the context with available data from studied fossil sites. Ostracoda assemblage from Úpohlavy fossil site is correlated with the Ostracoda assemblage from Great Britain. The similarity of the Ostracoda taxa suggests a possible communication of compared areas. Thanks to this work, biostratigraphy occurrence of six Ostracoda species (Cythereloidea stricta, Nemoceratina (Pariceratina) montuosa, Cythereis ornatissima ornatissima, Phodeucythere cuneiformis, Pterygocythereis robusta a Bairdoppilata litorea) is extended to Upper Turonian. Taxonomical changes in studied ostracoda assemblage expressed by PSH hypothesis (Platycopid Signal Hypothesis) support previous palaeoenvironmental...

Thesis (M.S.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1988. / Includes bibliographical references (leaves 82-85). / The sulfur content of planktonic and benthic foraminifera was measured in specimens recovered from deep-sea sediment cores and individuals grown in culture. A new method for measuring sulfur in foraminiferal calcium carbonate was developed, employing a high-resolution inductively coupled plasma-mass spectrometer. The sulfur measurements, expressed as sulfur-to-calcium (S/Ca) ratios in the foraminiferal shells, ranged from 0.26 to 6.0 mmol/mol. Most analyses fell in the range of 0.7 to 2.5 mmol/mol. Culturing experiments were conducted in the planktonic foraminifer G. sacculifer to test the hypothesis that S/Ca ratios in the foraminifer are inversely proportional to the carbonate ion concentration in the seawater in which they grow, and hence proportional to the pH of the seawater. The slope of the relationship between cultured G. sacculifer S/Ca and the pH of the seawater medium was -1.92 mmol mol-1/pH unit with a least squares linear correlation coefficient, r2=0.927. The S/Ca ratios of planktonic and benthic foraminifera from Holocene and last glacial period sediments were measured in an effort to use the established relationship of S/Ca and pH to calculate the ocean pH gradient between Holocene and glacial time. The results indicate the pH of global ocean deepwater was 0.10 to 0.15 pH units higher during glacial time than today. Smaller pH gradients were seen for some cores which may have been caused by circulation-induced water mass changes. Surface ocean changes in pH over the Holocene-glacial interval seem to vary from region to region, with up to an 0.2 pH unit increase at the Sierra Leone Rise in glacial time. Benthic foraminifera from coretops in the thermocline of the Little Bahama Bank were analyzed for S/Ca to examine the effects of hydrographic variables on S/Ca. The relationship of S/Ca to pH and [CO3=] has a positive slope, at odds with the expected negative slope from the previous results. The S/Ca results do correlate well with salinity, suggesting that salinity or other hydrographic parameters may also influence foraminiferal S/Ca ratios. / by Jeffrey Nicholas Berry. / M.S.

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Tropical latitudes play an important role in global climate as they export moisture and energy pole-ward. Recent tests of predictive climate models against Holocene paleoclimate data show discrepancies between predicted and observed values in Tropical regions. Terrestrial paleoclimate records could help resolve these discrepancies by all allowing for better understand of the sensitive ocean-atmosphere climate dynamics in the tropics and by providing additional information from a diverse source of proxies. The Caribbean is an ideal location for study as its climate is influenced by both the Atlantic and Pacific Oceans. However, there are relatively few sources of paleoclimate proxies in this region due to its archipelagic nature. If Caribbean climate is to be thoroughly investigated, additional environments and climate proxies need to be investigated. As coastal systems are ubiquitous throughout the Caribbean, they are ideal for investigation of Holocene paleoclimate in this region. However, they can be ephemeral on millennial timescales making them challenging to use in paleoclimate analysis. This dissertation discusses new methods and basins that facilitate the study of these systems. Several important contributions have been made by this thesis. (1) Core scanning XRF data, when examined with additional proxies such as foraminifera, can be used to infer shifts in regional precipitation patterns in a coastal setting. Though these methods have been used before in deep basins, this represents the first use of core scanning XRF in a littoral setting. (2) The evolution of sinkhole sedimentation is reliant on both the morphology of the sinkhole and water level within the feature. This thesis shows that coastal systems are a viable source of paleoclimate information and which can hold valuable information for reconstructing climate. / Thesis / Master of Science (MSc)

Foraminifera are a diverse clade of mostly shell-building single-celled organisms. Estimation of foraminiferal diversity is critical for understanding past and present climatic conditions, as they are highly sensitive to environmental perturbations. Biodiversity estimates of foraminifera began with the counting of test (i.e., shell) microfossils composed of calcium carbonate, as they are well preserved in sediment samples. However, this view has changed with molecular biodiversity estimates, which suggest that early-diverging single-chamber (i.e., "monothalamid") species that lack preservation ability are more diverse than anticipated. Although biodiversity estimates of foraminifera at the molecular level have changed our perceptions, they possess various challenges, especially with metabarcoding approaches. The metabarcoding approach is challenging in foraminifera because small subunit ribosomal (SSU) rRNA gene does not PCR amplify "universal" eukaryotic primers due to the presence of large insertions. Therefore, studies of foraminiferal diversity require targeted primers. Similarly, the pair-wise sequence similarity approach to taxonomic resolution can be problematic for Foraminifera, as fewer matching reference database exists for “monothalamids”- this requires the use of a more robust phylogeny-informed taxonomy, which provides a taxonomic identification for each sequence. Also, the appropriateness of recently developed metabarcoding tools still needs validation and comparison with clustering approaches for foraminiferal biodiversity estimation. This chapter introduces the current state of knowledge of foraminiferal biodiversity while also describing the knowledge gaps addressed in this thesis.

My dissertation addresses two aspects of eukaryotic evolution, 1) the organization of eukaryotic diversity and 2) genomic variation in Foraminifera. The bulk of eukaryotic diversity is microbial with plants and animals representing just two of the estimated 75 lineages of eukaryotes. Among these microbial lineages, there are many examples of dynamic genome processes. Elucidating the origin and evolution of genome features requires a robust phylogenetic framework for eukaryotes. Taxon-rich molecular analyses provide a mechanism to test hypothesized evolutionary relationships and enable placement of diverse taxa on the tree of life. These analyses result in a well-resolved eukaryotic tree of life. Relaxed molecular clock analyses of this taxon-rich dataset place the origin on eukaryotes in the Paleoproterozoic, and suggest that all of the major lineages of eukaryotes diverged before the Neoproterozoic. This robust scaffold of the tree of eukaryotes is also used to elucidate common themes in genome evolution across eukaryotes. Mapping dynamic genome features onto this tree demonstrates that they are widespread in eukaryotes, and suggests that a common mechanism underlies genome plasticity. Foraminifera, a diverse lineage of marine amoebae, provide a good model system for investigating genome dynamics because they amplify portions of their genome and go through ploidy cycles during their life cycle. Assessment of nuclear dynamics in one species of Foraminifera, Allogromia laticollaris strain CSH, reveals that genome content varies according the life cycle stage and food source, which may differentially impact organismal fitness. The inclusion of diverse microbial eukaryotes enables better resolution of eukaryotic relationships and improves our understanding the dynamic nature of eukaryotic genomes.