Thesis (doctoral)--Université Pierre et Marie Curie, 1978. / Cover title. Includes bibliographical references (leaves 223-231).

Issued also as thesis, Paris. / Issued in portfolio with an album of 43 plates (part col.) Album has title: Foraminifères planctoniques de Grèce occidentale du Paléogène supérieur au Néogène. Errata slip inserted. Bibliography: p. 117-133.

Thesis (M.S.)--University of Delaware, 2005. / Principal faculty advisor: Katharina Billups, Dept. of Marine and Earth Studies . Includes bibliographical references.

A series of modern sediment samples from seven sites and five sediment cores collected in central and southern Biscayne Bay were analyzed for benthic foraminifers. The goal of the research was to determine important foraminiferal assemblages in the modern environment, and use these data to assess the distributions of marine ecosystems over the past 100-400 years. Two of the cores are from localities in the mid-bay, whereas three represent near-shore sites. The latter cores were collected under the supposition that near-shore sites may be more sensitive to recent ecosystem change that may not be so readily apparent at the mid-bay sites. Seven assemblages were identified from these data that appear robust enough to be recognized at the regional level in Biscayne Bay. The assemblages identify a range of haline environments in Biscayne Bay both presently and in the recent past. None of the assemblages is typical of a continental shelf assemblage after Rose and Lidz (1977), but the conditions within Biscayne Bay include assemblages indicative of polyhaline-euhaline restricted circulation environments and mesohaline brackish environments. The near-shore cores reveal a pattern of assemblages indicative of increasing salinity. There is clearly a natural component of the ongoing Holocene marine transgression. However, there are key data which show sudden increases in salinity via rapid changes to the benthic foraminiferal assemblages. At Middle Key, salinity increases at the time of construction of the Key West Extension of the Florida East Coast Railway. Increased marine species at the top of the core corroborate the findings of Ishman et al. (1998) from a core in Manatee Bay. The foraminiferal assemblages near the top of the cores at Black Point North and at Chicken Key show a shift toward higher salinity conditions. Ostracode and mollusk data in Wingard et al. (2004) reveal an increase of genera that are tolerant of wide ranges of salinity. This manner of salinity fluctuations is not correlative to any patterns observed historically in any of the cores from Biscayne Bay. Recent changes to the marine ecosystems in Biscayne Bay reflect both natural and anthropogenic changes. It is necessary to determine appropriate restoration of natural sheet and groundwater flows to Biscayne Bay as part of the ongoing Everglades restoration to reduce the high stress of salinity fluctuations that are a recent alteration to the natural ecosystems in Biscayne Bay.

The late Neogene represents an exceptionally dynamic period in Earth history during which the Northern Hemisphere has transitioned from a warmer, more equable climate to a cooler, more transient state characterized by waxing and waning continental ice sheets. While geographical distal, the tropical ocean has played a significant role in shaping the evolution of the climate system, as the opening and closing of low latitude (LL) ocean gateways and reorganization of oceanic and atmospheric circulation structure have helped shape the climate system into its present form. This study provides a reconstruction of sea surface temperature (SST), ocean circulation, and thermal structure of the LL eastern Pacific and North Atlantic based upon the compilation of proxy data derived from planktic foraminifer assemblages and geochemical techniques. This research begins with a paleoceanographic reconstruction of the eastern tropical Pacific (ETP) and subtropical Northwest Atlantic (NWA) during the early stages of uplift of the Central American Isthmus and associated shoaling of the Central American Seaway (CAS). In the subtropical NWA (DSDP 103 and ODP 1006), the 5.2 to 5.1 Ma interval is characterized by an increase in SST and sea surface salinity, indicating a strengthening of the Florida Current (FC) and Gulf Stream (GS). Sea surface temperature in the ETP Warm Pool (DSDP Site 84) remained relatively stable between 6.9 and 5.1 Ma, during which El Niño-like conditions persisted. A slight cooling is observed after this interval (with synchronous warming in the NWA), followed by the onset of major cooling at ~3.2 Ma, both of which are preceded by a shallowing of the thermocline. Stepwise cooling is attributed to enhanced Atlantic meridional overturn circulation (AMOC), which caused a shoaling of the main tropical thermocline, thereby strengthening the Walker Circulation and weakening the Pacific North Equatorial Counter Current. During the mid-Piacenzian warm period (MPWP; ~3.3-3.0 Ma), SST in the Panama Basin was ~0.8°C cooler than today, while the subtropical NWA was only ~1.1°C warmer. This corroborates evidence for reduced meridional SST gradients during the mid-Pliocene as well as the hypothesis that more vigorous ocean circulation--particularly in the NWA--was critical during this period. The timing of SST changes in the ETP and NWA (~5.1 Ma) suggest that the termination of permanent El Niño and enhanced AMOC did not contribute significantly to the onset of major Northern Hemisphere glaciation (NHG), as both of these events occur well before the beginning of the glacial cycles. However, these processes may have contributed to the development of the small ice sheets of the late Miocene and early Pliocene, but were most likely only preconditioning factors for the onset of major NHG. In contrast, changes in SST and relative thermocline position suggest that high latitude (HL) processes and global cooling may have influenced thermal structure in the ETP. The SST estimates provided indicate that even in its early stages, the shoaling of the CAS had significant implications for low-latitude ocean circulation and thermal structure, as well as for some of the most significant global climate events of the late Neogene, including the MPWP. During the MPWP, mean global surface temperatures were similar to those predicted for the next century (2-3˚ C warmer) while atmospheric CO2 concentrations, paleogeography, and paleobiology were similar to today. As such, the MPWP has been studied in detail as a potential (albeit imperfect) analog for future climate change and has provided a natural and unique test-bed for the integration of proxy data and general circulation models. Central to this research effort is the Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) project, an iterative paleoenvironmental reconstruction of the MP focused on increasing our understanding of warm-period climate forcings, dynamics, and feedbacks by providing three-dimensional data sets for general circulation models. A mainstay of the PRISM project has been the development of a global sea surface temperature (SST) data set based primarily upon quantitative analyses of planktic foraminifer assemblages, supplemented with geochemical SST estimates wherever possible. In order to improve spatial coverage of the PRISM faunal and SST data sets in the LL North Atlantic, this study provides a description of the MP planktic foraminifer assemblage and multiproxy SST estimates from five Ocean Drilling Program sites (951, 958, 1006, 1062, and 1063) in the North Atlantic subtropical gyre (NASG), a region critical to Atlantic Ocean circulation and tropical heat advection. Assemblages from each core provide evidence for a temperature- and circulation-driven 5-10° northward displacement of MP faunal provinces, as well as regional shifts in planktic foraminifer populations linked to species ecology and interactions. General biogeographic trends also indicate that, relative to modern conditions, gyre circulation was stronger (particularly the Gulf Stream, North Atlantic Current, and North Equatorial Current) and meridionally broader. Overall, SST estimates suggest that surface waters in this region were not significantly warmer (1-2˚ C) than today and that mean annual SSTs along LL western boundary currents were indistinguishable from modern. Multiproxy SST data also provide evidence for enhanced northward transport of warm, salty, oligotrophic surface waters via a vigorous western boundary current system with warmer (cooler) cold-season (warm-season) temperatures. Collectively, this reconstruction of SST and ocean circulation provides support for a model of an enhanced Atlantic meridional overturn circulation (AMOC) system, with particularly vigorous LL western boundary currents and thus, more efficient northward heat transport. These trends therefore suggest that more vigorous thermohaline circulation, in conjunction with elevated atmospheric CO2 concentrations, played a significant role in shaping the global surface temperature distribution during the MPWP. A strengthening of the AMOC under warmer-than-modern conditions has significant implications for future climate change. The current generation of climate models suggests that HL warming and associated ice-sheet melting will induce a freshening of the North Atlantic and thus, to a reduction in the strength of the AMOC, thereby buffering surface temperature increases in the Northern Hemisphere. However, if after this transient period of climate system adjustment, Earth returns to a more Pliocene-like climate state the AMOC system may strengthen, thereby exacerbating the HL warmth caused by elevated atmospheric CO2 concentrations. Thus, through the reconstruction of warm-period SST and ocean circulation, this research provides insight into the potential operation of the LL North Atlantic and its associated impact on broad-scale Northern Hemisphere climate.

This study used Jumbo Piston Core 126, collected from the Nathaniel B. Palmer during cruise NBP10-01, to investigate environmental variability in Barilari Bay, western Antarctic Peninsula as part of the LARsen Ice Shelf System, Antarctica (LARISSA) project. A total of 107 samples were collected every 20cm from a 21.42m sediment core. Benthic foraminiferal data from Jumbo Piston Core 126 was analyzed using Principal Component (PC), Canonical Correspondence Analysis (CCA), and cluster analyses to assist in the Holocene oceanographic and climatic interpretation of Barilari Bay. The first three principal components explain 79.5% of the variance in the foraminiferal abundance data. PC1 comprises 49.6% of the variance and represents the Bulimina aculeata assemblage. PC2 and PC3 explain 16.3% and 13.6% of the variance and characterize the Fursenkoina fusiformis and Pseudobolivina antarctica assemblages, respectively. F. fusiformis assemblage represents the presence of a less saline water mass associated with ice shelf decay. The agglutinated P. antarctica assemblage is indicative of Hyper Saline Shelf Water (HSSW). TheB. aculeata assemblage is associated with Upper Circumpolar Deep Water (UCDW) (Ishman and Domack, 1994) Sediments from ~1100-950 calibrated years Before Present (cal. yr BP) are characterized by theB. aculeata assemblage, indicating the presence of UCDW. At ~950 cal. yr BP the UCDW receded coincident with glacial conditions observed during what is interpreted as the Little Ice Age. The ~950-350 cal. yr BP interval represents glacial conditions interpreted from the high PC scores of the P. antarctica assemblage and low foraminiferal abundances due to HSSW and a high sedimentation rate from glacial runoff. Intermittent pulses of UCDW are observed in the 950-350 cal. yr BP interval, expressed by the PC peaks in the B. aculeata assemblage. Between ~300 and 100 cal. yr BP the middle of the fjord was dominated by the F. fusiformis assemblage, suggesting ice shelf decay and open marine conditions. At ~50 cal. yr BP UCDW progressed back into Barilari Bay and is currently the dominant water mass.

60 leaves, 7 leaves of plates : ill. ; 28 cm Thesis (M.A.)--University of Oregon, 1943 Bibliography: leaves [51]-53

Quatre coupes ont été étudiées dans les séries marno-calcaires de talus et de bassin profond de la "fosse vocontienne" au Cénomanien. Le travail effectué à partir de plus de 800 échantillons dans lesquels les associations de foraminifères planctoniques et benthiques ont été étudiées a montré des particularités biostratigraphiques, et paléogéographiques. En effet, il existe un diachronisme dans l’extension verticale de Thalmanninella reicheli et dans l’apparition du marqueur de la base du Cénomanien supérieur (Rotalipora cushmani). T. reicheli a une extension verticale courte, mais située dans le Cénomanien inférieur peu élevé d’après les faunes d’ ammonites associées; R. cushmaniapparait avant les ammonites marquant le Cénomanien moyen (Acanthoceras). Les chutes du niveau marin relatif enregistrées par des discontinuités lithologiques dans la coupe de la marge du talus au Cénomanien basal, dans la partie moyenne du Cénomanien, et au passage Cénomanien-Turonien sont également repérées par la dominance des assemblages de foraminifères benthiques opportunistes, d’abord dans les coupes de marge et de plate-forme méridionale, ensuite dans les coupes de bassin profond. Ces passages correspondent aussi à des évènements dysoxiques, liés à l’anomalie du δ13C. L’évolution des foraminifères benthiques s’avère très sensible à profondeur de l’eau et à la dysoxie,leur réponse étant plus rapide que la variation du δ13C. La régression forcée au passage Cénomanien-Turonien correspond à des dépôts de black shales dans la coupe du bassin le plus profond, traduisant l’événement anoxique OAE2. La fin de l’ extension de Rotalipora cushmani, définit le sommet de l’étage dans les 4 coupes. / A detailed lithologic and biostratigraphic framework was determined for 4 Cenomanian sections, allowing correlations from the boarder of the upper slope to the platform and the lower slope of the vocontian basin. Over 800 samples provided planktonic and benthic foraminifera associations for a biostratigraphic and paleogeographic succession. There was a diachronisme between the ammonites and the foraminifera biozonation. Indeed, Thalmanninella reicheli, the marker of the middle Cenomanian substage had a short extension,overlapping with the Mantelliceras mantelli, ammonite of the Inferior Cenomanian. Moreover Rotalipora cushmani, the foraminifer marker for the Upper Cenomanian,appeared before Acanthoceras, an ammonite of the Middle Cenomanian. Basal Cenomanian, Middle Cenomanian, and CTB were registered by local lithologic discontinuities resulting from the lowering of the relative sea level in the boarder of the upper slope section. Correlated with the lithologic events, the benthic opportunist foraminifera dominated the associations from the Inferior Cenomanian of the upper slope and platform sections, and from the middle part of the Upper Cenomanian of the deep sea sections. Dysoxic periods (Albian-Cenomanian boundary, MCE, and OAE2) as detected by δ13C anomalies, also corresponded to the regression levels. Benthic Foraminifera responsiveness to sea water depth and anoxia was faster than δ13C variations. CTBE was lithologically registered by black shakes deposits in the deep sea section, but the end of the Rotalipora extension was the marking event in all sections.

The Cretaceous–Paleogene (K/Pg) boundary marks one of the major crises in the history of life on Earth. The cause is widely regarded as a large bolide impact at Chicxulub, Mexico, coincident with a major series of volcanic eruptions on the Deccan Plateau, India. Fieldwork in the Brazos River area of Texas has involved an investigation of the sections on the Brazos River and its tributaries. A previously overlooked K/Pg section (RBS) on the Brazos River was found and contains the most accessible and complete K/Pg boundary succession in the area. The RBS succession provides a clear exposure of the various lithological units within the Paleocene and was used to correlate to the successions in the nearby creeks. The K/Pg boundary is also well-exposed and records an erosional relief of ~1 m, cut into the Maastrichtian mudstone succession, creating a mounded topography. The overlying ‘Event Bed’, containing reworked impact spherules at its base, is shown to infill troughs on this irregular surface. The same features were recorded in tributary creeks, with all previous descriptions of these locations clearly failing to recognise the various sedimentary relationships. Distinct, thin, yellow clay horizons within the uppermost Maastrichtian mudstones are present in some sections. Geochemical analysis and radiometric dating have confirmed these as volcanic ashes, with extracted zircons giving a date of 65.95+0.04 Ma. These ash bands are located in Maastrichtian mudstones just below the K/Pg boundary and the recorded date is, within error, that of the K/Pg boundary. This identification of this latest Maastrichtian volcanic ash negates the suggestion of a pre-K/Pg boundary impact, a pre-extinction impact or multiple impacts. The benthic foraminiferal data generated indicates significant changes in palaeoecology of the benthic foraminifera across the K/Pg boundary. The benthic foraminifera do not experience a mass extinction, unlike the planktic foraminifera, which were significantly affected by the end-Maastrichtian extinction event. The benthic foraminferal assemblage appears to only experience transient, short-lived changes with pulses of agglutinated, elongate and large species in the early Paleocene. Mono-specific samples of Lenticulina rotulata have been analysed for stable isotopes and the data may indicate the presence cyclicity across the K/Pg boundary interval. In the earliest Paleocene significant negative δ18O excursions near the Pα/P1a and NP1/NP2 boundary represents a potential hyperthermal event that may be coeval with the DAN-C2 and Lower C29n events respectively recorded at Gubbio, and in the Atlantic Ocean. A sequence stratigraphy package is determined based on the micropaleontology and sedimentology in the Brazos River area. The latest Maastrichtian is marked by a sealevel rise immediately before the K/Pg boundary. Immediately after the K/Pg event, sealevel fell and is recorded as a change from mid to inner shelf. The condensed unit of the Middle Sandstone Bed (MSB) represents a Transgressive systems tract, with increasing diversity and abundance of benthic foraminifera to the top of the MSB, where maximum abundance and diversity is marks a Maximum Flooding Surface. The interval above indicates sea-level continuing to rise to a mid to outer-shelf setting. These sealevel changes are also recorded at the same stratigraphic level in Alabama, and at more distal K/Pg boundary sections (e.g., Denmark and Tunisia) suggesting that these sealevel changes are eustatically controlled.

Ocean acidification may cause biodiversity loss, alter ecosystems and impact food security, yet uncertainty over ecological responses to ocean acidification remains considerable. Most work on the impact of ocean acidification on foraminifera has been short-term laboratory experiments on single species. To expand this, benthic foraminiferal assemblages were examined across shallow water CO2 gradients in the Gulf of California, off the islands of Ischia and Vulcano in Italy and off Papua New Guinea. Living assemblages from the Gulf of California did not appear to show a response across a pH range of 7.55 – 7.88, although the species assemblage was impoverished in all locations and the dead assemblage was less diverse at the lowest pH sites where there was evidence of post mortem dissolution. At Vulcano, the small macroalga, Padina pavonica, did not protect calcareous foraminifera from the adverse effects of ocean acidification. Calcareous taxa disappeared from the assemblage and were replaced by agglutinated foraminifera as mean pH reduced from 8.19 to 7.71. Settlement of benthic foraminifera onto artificial collectors off Vulcano was adversely affected in the acidified water, with few species as pCO2 increased and evidence of post-mortem dissolution. The foraminiferal tests, collected off Papua New Guinea, had lower δ11B as mean pH decreased from 7.99 – 7.82 for small (250 – 500 µm) Amphistegina lessonii, but not for A. lessonii or Calcarina spengleri >500 µm. In the larger foraminifera, photosynthetic activity by symbionts may begin to dominate the boron isotopic signature. Overall, the responses of foraminiferal assemblages to ocean acidification are complex, but there was an overall reduction in species diversity in infaunal, epifaunal and epiphytic assemblages as pCO2 increased. This raises serious concerns for the survival of shallow water calcareous benthic foraminifera as the oceans continue to acidify, with implications for benthic ecosystems and inorganic carbon cycling.