Foraminiferal faunas across the early to middle Eocene transition (EMET) were studied from three locations in the western Caribbean: Calle G section in Cuba, ODP site 998 B the Cayman Rise, and ODP site 999 B the Colombian basin. There were three primary objectives of this project 1) to observe changes in physical and biological paleoceanographic parameters in the Western Caribbean, more directly in the Cayman Ridge and the Colombian Basin, by the use of planktonic foraminifera data, 2) determine the cause of an oxygen isotope anomaly seen in Cuba by Fluegeman (2007) and that is expected to be present in the Western Caribbean, and 3) determine if the anomaly is a local or a more widespread regional event. The Calle G section in northwestern Cuba consists of early to middle Eocene age foraminiferal chalks. The planktonic foraminiferal fauna at this section is characterized by subbotinids and acarininids but does not contain morozovellids. Oxygen isotopes were obtained across the EMET from the planktonic foraminiferan Acarinina collactea. The resultant curve shows widely fluctuating values during the early portion of the EMET with more stable values occurring in the middle Eocene. The foraminiferal paleoecologic index tau curve at the Calle G section produced is similar to the oxygen isotope curve. ODP site 998 B, Cayman Rise, contains a series of foraminiferal limestones across the EMET. Unlike the Calle G section, this interval contains an abundant planktonic foraminifera fauna including Morozovella. The Morozovella:Acarinina ratio studied at ODP site 998 shows high, fluctuating values in the early part of the EMET with low, stable values during the middle Eocene.ODP site 999 B in the Colombian Basin consists of a series of foraminiferal chalks throughout the EMET. Similar to ODP site 998 this location also has an abundant assemblage of planktonic foraminifera including Morozovella. Evidence supporting turbidities have been observed at this locale as layers of shell hash and large benthic foraminifera. The Morozovella:Acarinina ratio studied at ODP site 999 is similar to that of ODP site 998 showing a high fluctuating values in the early part of the EMET with low, stable values in the middle Eocene. The presence of fluctuating values of oxygen isotopes, tau, and the Morozovella:Acarinina ratio followed by stable values across the EMET may be related to a change in circulation patterns through the Caribbean caused by a developing oceanic gateway. The widely fluctuating oxygen isotope values in the latest Ypresian may also be related to an influx of freshwater in the North Atlantic associated with the coeval Azolla event in the Arctic Ocean. / Department of Geological Sciences

Implementing oxygen isotopes (H218O, H216O) in coupled climate models provides both an important test of the individual model's hydrological cycle, and a powerful tool to mechanistically explore past climate changes while producing results directly comparable to isotope proxy records. The addition of oxygen isotopes in the University of Victoria Earth System Climate Model (UVic ESCM) is described. Equilibrium simulations are performed for preindustrial and Last Glacial Maximum (LGM) conditions. The oxygen isotope content in the model's preindustrial climate is compared against observations for precipitation and seawater. The distribution of oxygen isotopes during the LGM is compared against available paleo-reconstructions. Records of temporal variability in the oxygen isotopic composition of biogenic carbonates from ocean sediment cores inform our understanding of past continental ice volume and ocean temperatures. Interpretation of biogenic carbonate d18O variability typically neglects changes due to factors other than ice volume and temperature, equivalent to assuming constant local seawater isotopic composition. This investigation focuses on whether sea ice, which fractionates seawater during its formation, could shift the isotopic value of seawater during distinct climates. Glacial and interglacial states are simulated with the isotope-enabled UVic ESCM, and a global analysis is performed. Results indicate that interglacial-glacial sea ice variability produces as much as a 0.13 permil shift in local seawater, which corresponds to a potential error in local paleotemperature reconstruction of approximately 0.5 C. Isotopic shifts due to sea ice variability are concentrated in the Northern Hemisphere, specifically in the Labrador Sea and northeastern North Atlantic. / Graduate

This thesis describes an attempt to develop a pioneering method for the analysis of oxygen isotopes in metamorphic rocks. This technique is then applied to a suite of metapelites from Massachusetts, U.S.A. with the aim of investigating metamorphic history. The study of oxygen isotopes is a rapid and efficient way of deciphering the reaction history of a metamorphic rock, and they are particularly useful for quantifying the role of fluids during metamorphism. Technological advances have given the opportunity to develop a new laser fluorination facility capable of in-situ oxygen isotope analysis on the 100μm scale. The use of UV laser ablation coupled with helium carrier flow and isotope ratio mass spectrometry gives the potential for liberation, transfer and analysis of nanomoles of oxygen. This analytical technique is developed herein, and applied to garnets from high alumina metapelites of the Hoosac Schist of Western Massachusetts. These large garnets contain concentric unconformity textures which are attributed to at least two metamorphic events. Core-rim zoning profiles from three Hoosac garnets has been accomplished. Metamorphic modelling in the complex chemical system Na₂O-CaO-MnO-K₂O-FeO-MgO-Al₂O₃- SiO₂-H₂O has yielded P-T estimates for garnet cores of 520°C and 8.5 kbar, and rims at 590°C and 8-10kbar. Within this framework, a new approach enables calculation of oxygen isotope shifts with reaction progress in the presence of a non-equilibrium fluid. Fitted profiles from the Hoosac garnets imply prograde core growth during inflow of external low-δ¹⁸O fluid, and calculations suggest a minimum time integrated fluid flux for the first garnet growth event of the order of 0.2 cm³/cm², some four to five orders of magnitude less than other New England studies.

Ecosystem metabolism is an important indicator of aquatic ecosystem function. This thesis concerns ecosystem metabolism as recorded by daily variation in dissolved oxygen (DO) and δ18O-DO in an impacted temperate river network, the Grand River, Ontario, Canada, and specifically addresses the effects of stream size and human disturbance including agriculture, deforestation, and wastewater treatment plants (WWTPs). A suite of 14 sites in the Grand River network was selected with stream sizes varying from 2nd to 7th order. A transient model of river ecosystem oxygen metabolism, ROM-TM, was developed in order to calculate river ecosystem metabolic rates and reaeration rates from field observation of changes in DO and δ18O-DO. ROM-TM is an inverse modeling approach programmed using MATLAB. Key parameters describing the main metabolic processes, gas exchange, and isotopic fractionation, such as maximum photosynthetic rate (Pm), photosynthetic efficiency (a), respiration rate at 20℃ (R20), gas exchange coefficient (k), respiration isotopic fractionation factor (aR), and photorespiration coefficient (βR), can be obtained by matching of model predictions with field data. Besides being capable of teasing apart metabolic processes and gas exchange to provide daily average estimates of metabolic parameters at the ecosystem level, ROM-TM can be used to address issues related to light including light saturation phenomena at the ecosystem level, the effect of cloud cover on metabolic balance and photorespiration. Primary production responses to light along a longitudinal gradient in the Grand River network were described by means of P-I curves. Both light-limited and light-saturated conditions were observed. Production parameters Pm and Ik in the Grand River network exhibited an increase with stream order, while a was independent of stream size. However, a did vary among and within sites. Higher light availability in small and middle-sized streams without riparian trees was associated with high Pm, Ik and Ec, but low a. Ecosystem-level Pm in both small periphyton-dominated streams and large macrophyte-dominated rivers in the Grand River basin were generally less than community-level Pm values from the literature. However, two Grand River sites had comparable Pm to literature-derived Pm due to the prolific growth of macrophytes supported by high nutrient effluents from upstream WWTPs. Ecosystem-level a in my study streams were also less than those at the community level, indicating there was a declining trend of this parameter with scale, from individual, community to ecosystem. Derived parameters (e.g., Ik, Ec, and saturation point) increased from the individual level to the community level, and then to the ecosystem level. From May to early October, metabolic rates in the Grand River network (gross primary production, GPP = 0.4 to 20 and ecosystem respiration, ER = 2 to 33 g O2 m-2 day-1) were within the broad range of metabolic rates occurring in the temperate region, regardless of stream size. The Grand River network is a net heterotrophic system. The total GPP and ER for whole basin was 3.3e+08 and 4.2e+08 g O2 day-1, respectively. Reach geomorphology controls the spatial patterns of stream metabolism in the Grand River network, although the spatial patterns may be modified by effects of human disturbance on riparian vegetation, nutrients and other factors. Stream order and channel width, as measures of stream size, are good predictors of metabolic rates and ratios of GPP: ER from small streams to the central Grand River. Ecosystem metabolic rates and ratios generally increase with stream size, but with site-specific variation. The Grand River network is experiencing effects of human disturbance, mostly downstream of the urban areas and least in small streams with remaining riparian forest. The small and middle-sized streams (2nd to 4th order) without riparian trees in agriculture regions in the Grand River basin did not exhibit significantly different GPP and ER than their counterparts with riparian trees. The stimulative effect of increased light availability due to open canopy on GPP in non-shaded streams may be offset by shading from stream banks and riparian grasses, and unstable sediments resulting from agricultural activities. Large river sites impacted by WWTPs had significantly increased metabolic rates, both GPP and ER, compared to two upstream sites impacted by agriculture only. This result suggests that urban areas cause impacts on the Grand River that are superimposed on the impacts of agriculture. Three aspects of metabolism of the Grand River differ from the general pattern for the temperate regions: (1) a increase trend of GPP: ER ratios with stream size from 2nd to 7th order; (2) overall, human activities in the Grand River watershed have stronger positive effects on the GPP than on the ER; (3) the middle-sized to large river sites (5th-7th order) had greater influence than small to middle-sized streams (2nd-5th order) in the Grand River on overall GPP and ER. The general trend of GPP: ER ratio in tropical, subtropical, temperate, and global data approximately conforms to the predictions of the River Continuum Concept (RCC). However, the maximum ratio of GPP: ER in mid-reaches of river networks is not usually >1 as proposed in the RCC. There is a latitude and stream size shift phenomenon regarding where the peak ratio of GPP: ER occurs in each climate zone. The maximum GPP: ER ratio is higher at higher latitudes and occurs at higher order streams. The study of stream ecosystem metabolism can benefit from the addition of the second oxygen budget, δ18O-DO, in four ways: (1) it is better to use both DO and δ18O-DO budgets, rather than DO only, in sampling protocols with low temporal frequency but high spatial frequency; (2) the δ18O-DO time series data can provide relatively independent constraints on parameter estimation; (3) the addition of δ18O-DO in using two oxygen budgets to quantify metabolic rates provides a way, the cross-plot of δ18O-DO against fraction of DO saturation, to indicate trophic status of an aquatic ecosystem; and (4) the addition of δ18O-DO can provide an estimate of aR at the ecosystem level that can be used to understand factors affecting respiration.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1977. / Bibliography: leaves 138-146. / Microfiche. / x, 146 leaves ill

The reef corals Pocillopora damicornis and Montipora verrucosa were cultured under various controlled temperatures and light conditions at Ulupau Head Microcosm facility. The skeletal carbonate deposited under different experimental regimes was analyzed for 13C and 18O. Coral skeletal 013C values varied with light dose and correlated with changes in zooxanthellar pigment. The o13C value of skeletal aragonite seems to be controlled by oxidation of photosynthetically produced organic matter. Functionally significant relationships between coral skeletal o18O values and temperature have been determined. The temperature coefficients of the o18O values (-4.20) are the same as the first order coefficient in the equilibrium paleotemperature equation, but the o18O values have species-specific offsets from equilibrium. These offsets may be attributed to the activity of the coral's zooxanthellae. Based upon the results of this study a model of coral skeletal isotopic incorporation is presented. / Typescript. Thesis (M. S.)--University of Hawaii at Manoa, 1979. Bibliography: leaves 94-102.

No verão de 2004 – 2005 foi realizada uma travessia do manto de gelo da Antártica Ocidental organizada pelo governo chileno em parceria com pesquisadores brasileiros como parte do ITASE (International Trans-Antarctic Scientific Expedition). A travessia partiu da base chilena Tenente Parodi em Patriot Hills (80°18'S; 81°22'W, altitude 720 m) e seguiu até o Polo Sul geográfico (90°S, altitude 2.840 m), voltando pelo mesmo caminho. Ao longo da travessia foram coletadas amostras de neve superficial (< 0,3 m de profundidade) a cada 10 km, a cada 220 km foi obtida a temperatura média anual local (medida a uma profundidade entre 10 e 15 m). As amostras foram analisadas utilizando espectrometria de massa com fonte de gás (GSMS - Gas Source Mass Spectrometry), no Climate Change Institute, Universidade do Maine, Orono, EUA. As razões isotópicas de oxigênio foram medidas com um dispositivo Micromass Multiprep acoplado a um espectrômetro de massa com precisão de 0,05‰. Os dados são apresentados em delta (δ), notação relativa ao padrão das águas oceânicas (VSMOW – Vienna Standard Mean Ocean Water). Os resultados estão de acordo com observações pretéritas, apresentando redução dos valores com a distância da costa (- 0,0323‰/ km) com exceção de uma área anômala no transecto, no qual em menos de 20 quilômetros (entre as latitudes 87°30' e 86°44'S) há um aumento da razão isotópica de -45,0‰ para -34,5‰, sendo que aproximadamente 100 quilômetros adiante o 18O retorna para a tendência de decréscimo inicial da razão isotópica. Trajetórias das parcelas de ar chegadas em 6 pontos escolhidos ao longo da travessia foram calculadas usando o modelo HYSPLIT para derivar informações sobre a anomalia encontrada, atribuída inicialmente ao efeito orográfico das montanhas transantárticas. Posteriormente se constatou que a anomalia poderia ser causada pela sublimação decorrente do vento ou pela ablação parcial do pacote de neve anual, sendo assim um efeito pós-deposicional. / In the summer of 2004 – 2005, the Chilean government along with Brazilian researchers carried out a traverse in the Antarctic ice sheet as part of the ITASE (International Trans- Antarctic Scientific Expedition) program. The traverse, a return trip to the Geographic South Pole (90°S, altitude 2.840 m), started at Tenente Parodi Chilean station at Patriot Hills (80°18'S; 81°22'W, altitude 720 m). Along the route, we collected snow samples at every 10 km, 0.3 m deep. The average local annual temperature was determined at 6 points spaced approximately 220 km apart, at a depth between 10 and 15 m. Samples were analyzed by mass spectrometry with gas source (GSMS - Gas Source Mass Spectrometry) at the Climate Change Institute, University of Maine, Orono, USA. A Micromass Multiprep device coupled to the spectrometer with 0.05‰ precision measured the isotopic ratio. Data are presented in delta (δ), relative to SMOW – Vienna Standard Mean Ocean Water. Results agree with previous works, which show an isotope ratio decrease with distance from the coast (- 0,0323‰/ km), except for an anomalous area, where in less than 20 km (from 87°30' S and 86°44'S) the isotopic ratio increases rapidly from -45 to -34.5‰, and then, after about 100 km, goes back to the general decreasing trend. HYSPLIT air trajectory models were run to examine if an orographic effect caused by the Transantarctic Mountains could be the cause of the anomalous area. After further examination, this anomaly is attributed to postdepositional processes, such as wind-driven sublimation.

No verão de 2004 – 2005 foi realizada uma travessia do manto de gelo da Antártica Ocidental organizada pelo governo chileno em parceria com pesquisadores brasileiros como parte do ITASE (International Trans-Antarctic Scientific Expedition). A travessia partiu da base chilena Tenente Parodi em Patriot Hills (80°18'S; 81°22'W, altitude 720 m) e seguiu até o Polo Sul geográfico (90°S, altitude 2.840 m), voltando pelo mesmo caminho. Ao longo da travessia foram coletadas amostras de neve superficial (< 0,3 m de profundidade) a cada 10 km, a cada 220 km foi obtida a temperatura média anual local (medida a uma profundidade entre 10 e 15 m). As amostras foram analisadas utilizando espectrometria de massa com fonte de gás (GSMS - Gas Source Mass Spectrometry), no Climate Change Institute, Universidade do Maine, Orono, EUA. As razões isotópicas de oxigênio foram medidas com um dispositivo Micromass Multiprep acoplado a um espectrômetro de massa com precisão de 0,05‰. Os dados são apresentados em delta (δ), notação relativa ao padrão das águas oceânicas (VSMOW – Vienna Standard Mean Ocean Water). Os resultados estão de acordo com observações pretéritas, apresentando redução dos valores com a distância da costa (- 0,0323‰/ km) com exceção de uma área anômala no transecto, no qual em menos de 20 quilômetros (entre as latitudes 87°30' e 86°44'S) há um aumento da razão isotópica de -45,0‰ para -34,5‰, sendo que aproximadamente 100 quilômetros adiante o 18O retorna para a tendência de decréscimo inicial da razão isotópica. Trajetórias das parcelas de ar chegadas em 6 pontos escolhidos ao longo da travessia foram calculadas usando o modelo HYSPLIT para derivar informações sobre a anomalia encontrada, atribuída inicialmente ao efeito orográfico das montanhas transantárticas. Posteriormente se constatou que a anomalia poderia ser causada pela sublimação decorrente do vento ou pela ablação parcial do pacote de neve anual, sendo assim um efeito pós-deposicional. / In the summer of 2004 – 2005, the Chilean government along with Brazilian researchers carried out a traverse in the Antarctic ice sheet as part of the ITASE (International Trans- Antarctic Scientific Expedition) program. The traverse, a return trip to the Geographic South Pole (90°S, altitude 2.840 m), started at Tenente Parodi Chilean station at Patriot Hills (80°18'S; 81°22'W, altitude 720 m). Along the route, we collected snow samples at every 10 km, 0.3 m deep. The average local annual temperature was determined at 6 points spaced approximately 220 km apart, at a depth between 10 and 15 m. Samples were analyzed by mass spectrometry with gas source (GSMS - Gas Source Mass Spectrometry) at the Climate Change Institute, University of Maine, Orono, USA. A Micromass Multiprep device coupled to the spectrometer with 0.05‰ precision measured the isotopic ratio. Data are presented in delta (δ), relative to SMOW – Vienna Standard Mean Ocean Water. Results agree with previous works, which show an isotope ratio decrease with distance from the coast (- 0,0323‰/ km), except for an anomalous area, where in less than 20 km (from 87°30' S and 86°44'S) the isotopic ratio increases rapidly from -45 to -34.5‰, and then, after about 100 km, goes back to the general decreasing trend. HYSPLIT air trajectory models were run to examine if an orographic effect caused by the Transantarctic Mountains could be the cause of the anomalous area. After further examination, this anomaly is attributed to postdepositional processes, such as wind-driven sublimation.

No verão de 2004 – 2005 foi realizada uma travessia do manto de gelo da Antártica Ocidental organizada pelo governo chileno em parceria com pesquisadores brasileiros como parte do ITASE (International Trans-Antarctic Scientific Expedition). A travessia partiu da base chilena Tenente Parodi em Patriot Hills (80°18'S; 81°22'W, altitude 720 m) e seguiu até o Polo Sul geográfico (90°S, altitude 2.840 m), voltando pelo mesmo caminho. Ao longo da travessia foram coletadas amostras de neve superficial (< 0,3 m de profundidade) a cada 10 km, a cada 220 km foi obtida a temperatura média anual local (medida a uma profundidade entre 10 e 15 m). As amostras foram analisadas utilizando espectrometria de massa com fonte de gás (GSMS - Gas Source Mass Spectrometry), no Climate Change Institute, Universidade do Maine, Orono, EUA. As razões isotópicas de oxigênio foram medidas com um dispositivo Micromass Multiprep acoplado a um espectrômetro de massa com precisão de 0,05‰. Os dados são apresentados em delta (δ), notação relativa ao padrão das águas oceânicas (VSMOW – Vienna Standard Mean Ocean Water). Os resultados estão de acordo com observações pretéritas, apresentando redução dos valores com a distância da costa (- 0,0323‰/ km) com exceção de uma área anômala no transecto, no qual em menos de 20 quilômetros (entre as latitudes 87°30' e 86°44'S) há um aumento da razão isotópica de -45,0‰ para -34,5‰, sendo que aproximadamente 100 quilômetros adiante o 18O retorna para a tendência de decréscimo inicial da razão isotópica. Trajetórias das parcelas de ar chegadas em 6 pontos escolhidos ao longo da travessia foram calculadas usando o modelo HYSPLIT para derivar informações sobre a anomalia encontrada, atribuída inicialmente ao efeito orográfico das montanhas transantárticas. Posteriormente se constatou que a anomalia poderia ser causada pela sublimação decorrente do vento ou pela ablação parcial do pacote de neve anual, sendo assim um efeito pós-deposicional. / In the summer of 2004 – 2005, the Chilean government along with Brazilian researchers carried out a traverse in the Antarctic ice sheet as part of the ITASE (International Trans- Antarctic Scientific Expedition) program. The traverse, a return trip to the Geographic South Pole (90°S, altitude 2.840 m), started at Tenente Parodi Chilean station at Patriot Hills (80°18'S; 81°22'W, altitude 720 m). Along the route, we collected snow samples at every 10 km, 0.3 m deep. The average local annual temperature was determined at 6 points spaced approximately 220 km apart, at a depth between 10 and 15 m. Samples were analyzed by mass spectrometry with gas source (GSMS - Gas Source Mass Spectrometry) at the Climate Change Institute, University of Maine, Orono, USA. A Micromass Multiprep device coupled to the spectrometer with 0.05‰ precision measured the isotopic ratio. Data are presented in delta (δ), relative to SMOW – Vienna Standard Mean Ocean Water. Results agree with previous works, which show an isotope ratio decrease with distance from the coast (- 0,0323‰/ km), except for an anomalous area, where in less than 20 km (from 87°30' S and 86°44'S) the isotopic ratio increases rapidly from -45 to -34.5‰, and then, after about 100 km, goes back to the general decreasing trend. HYSPLIT air trajectory models were run to examine if an orographic effect caused by the Transantarctic Mountains could be the cause of the anomalous area. After further examination, this anomaly is attributed to postdepositional processes, such as wind-driven sublimation.

Abstract Amorphous Calcium Carbonate (ACC) is a naturally occurring amorphous form of the widely distributed mineral calcium carbonate (CaCO3). ACC has been found increasingly as a precursor phase, calcium storage site, or strengthening structural phase in a wide array of different biomineralizing organisms. An accurate understanding of the widely used classic carbonate-water paleothermometry relies on formation of CaCO3 minerals and associated oxygen isotope effects. Moreover, ACC has oft been pointed to as a possible reason for non-equilibrium isotope effects, also called vital effects, in biogenic carbonates. It is, therefore, vital to understand whether ACC can reach equilibrium with its surrounding solution, as well as the role of ACC precursors in the isotopic composition and evolution of the final crystalline phase they transform into. This study is designed to answer these questions through the precipitation of stable ACC by two methods, the alkaline method (AM) which utilizes high pH to precipitate ACC, and the silica method (SM) which envelopes precipitating ACC particles in silica vesicles to prevent crystallization. These differently precipitated ACCs are then subjected to several different experimental treatments. This is achieved by monitoring the crystallization by X-ray Diffraction (XRD), and isotopic evolution of the ACC precipitates by Isotope Ratio Mass Spectrometry (IRMS) as they age and concurrently crystallize in parent solution, or in 18O enriched re-equilibration solution. This research indicated a marked difference in the crystallization behaviour, isotopic composition, and isotopic evolution of ACC produced by these two precipitation methods. With the AM method, ACC precipitates (AM-ACC) crystallized more predictably to calcite and maintained δ18O signatures that were slightly lower than the equilibrium CO32- and resisted further isotopic exchange with surrounding solution. We propose that the former is mostly due to an incomplete DIC-water oxygen isotope equilibrium prior to the AM-ACC precipitation and the latter is a result of the high pH of the precipitating solution decreasing the solubility of the precipitated ACC phase, disallowing isotope exchange, and favouring crystallization by solid-state transformation. Conversely, while ACC precipitated using the SM (SM-ACC) yielded much more variable results, both in terms of mineralogical identity upon crystallization, and δ18O values. Isotopic results were much closer to the expected equilibrium δ18O value for calcite, hinting at an expedited oxygen isotope exchange between SM-ACC and parent solution. Furthermore, SM-ACC was capable of isotopic exchange with the 18O enriched re-equilibration solution, a feat corresponding AM-ACC was incapable of. Overall, our experimental results gleaned here that precipitation method or precipitation environment play a critical role in the isotopic evolution of precursor ACC to crystalline CaCO3, suggesting ACC as an important source of the vital effect. / Thesis / Master of Science (MSc)