To see the other types of publications on this topic, follow the link: Sulfur isotopes.
Dissertations / Theses on the topic 'Sulfur isotopes'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Sulfur isotopes.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Pruett, Lee. "Stable Sulfur Isotope Rations from West Antarctica and the Tien Shan Mountains: Sulfur Cycle Characteristics from Two Environmentally Distinct Areas." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/PruettL2003.pdf.
Full text
2
Cousineau, Mélanie L. "Tracing Biogeochemical Processes Using Sulfur Stable Isotopes: Two Novel Applications." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23714.
Full textAbstract:
Abstract Dissimilatory microbial sulfate reduction (MSR) The specific objectives of the study were to provide the first measurements of sulfur isotope fractionation associated with acidophilic sulfate reducing-microorganisms, and to examine whether pH influences sulfur fractionation during MSR. The fractionation associated with the strains investigated was comparable to that of neutrophilic strains with similar metabolisms (4-12‰), but varied with pH. Two fractionation regimes were identified: one regime is consistent with fractionation during exponential growth, while the other – not identified previously - is not linked to active sulfate reduction and may result from internal sulfate accumulation. This would represent the first measurement of sulfur fractionation during sulfate uptake, the first step of MSR. Geological processes at the Cretaceous-Paleogene (KPg) boundary The KPg boundary is associated with one of the largest biological extinctions in the history of our planet. Two major geologic events - the Chicxulub bolide impact with evaporite terrane and the eruption of the Deccan continental flood basalts - coincide with the KPg boundary and have been identified as possible triggers for the extinctions, but their relative timing remains unresolved. The objectives of this study were to identify the contribution of these processes to the sulfur burden in the sedimentary environment of two freshwater KPg sections, and to determine their relative timing. The results demonstrate that the peak of Deccan volcanism post-dates the Chicxulub impact and the associated abrupt KPg mass extinction, thus precluding a direct volcanic causal mechanism, but shedding light on the underlying causes for the delayed recovery of ecosystems in the early Paleogene.
3
Meyer, Amanda Lynn. "Biogeochemistry of Sulfur Isotopes in Crystal Lake, Clark County, West-Central Ohio." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1420911116.
Full text
4
Leavitt, William Davie. "On the mechanisms of sulfur isotope fractionation during microbial sulfate reduction." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11511.
Full textAbstract:
Underlying all applications of sulfur isotope analyses is our understanding of isotope systematics. This dissertation tests some fundamental assumptions and assertions, drawn from equilibrium theory and a diverse body of empirical work on biochemical kinetics, as applied to the multiple sulfur isotope systematics of microbial sulfate reduction. I take a reductionist approach, both in the questions addressed and experimental approaches employed. This allows for a mechanistic, physically consistent interpretation of geological and biological sulfur isotope records. The goal of my work here is to allow interpreters a more biologically, chemically and physically parsimonious framework to decipher the signals coded in modern and ancient sulfur isotope records.Earth and Planetary Sciences
5
Jamieson, John William. "Tracing sulfur sources in an Archean hydrothermal system using sulfur multiple isotopes a case study from the Kidd Creek volcanogenic massive sulfide deposit /." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2697.
Full textAbstract:
Thesis (M.S.) -- University of Maryland, College Park, 2005Thesis research directed by: Geology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
6
Edwards, Cole T. "Carbon, sulfur, and strontium isotope stratigraphy of the Lower-Middle Ordovician, Great Basin, USA: Implications for oxygenation and causes of global biodiversification." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405797089.
Full text
7
Friedman, Carrie T. 1972. "Analysis of stable sulfur isotopes and trace cobalt on sulfides from the TAG hydrothermal mound." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/53034.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998.Includes bibliographical references (leaves 86-90).
by Carrie T. Friedman.
M.S.
8
Sparks, Janine M. "Characterizing Spatial Patterns for Natural and Anthropogenic Atmospheric Sulfur in Terrestrial Biological Systems." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1527606422395088.
Full text
9
Rennie, Victoria Christian Frances. "Carbonate associated sulfate as a proxy for the isotopic composition of Cenozoic seawater sulfate." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708258.
Full text
10
Howard, Bret Harmon. "The hydrodesulfurization of thiophene by Mo/Co treated oxyaluminum pillared montimorillonites." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07122007-103926/.
Full text
11
BONILLA, ALEJANDRA. "GEOCHEMISTRY OF ARSENIC AND SULFUR IN SOUTHWEST OHIO: BEDROCK, OUTWASH DEPOSITS AND GROUNDWATER." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1132088950.
Full text
12
Kitayama, Yumi. "Les quatre isotopes du soufre dans les kimberlites de Sibérie, traceurs du recyclage de croûte océanique et de sédiments Archéens dans le manteau terrestre." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0244.
Full textAbstract:
Héritées de l’atmosphère primitive, des anomalies dans les abondances relatives des isotopes du soufre (32S, 33S, 34S et 36S) sont enregistrées dans les sédiments terrestres d’il y a plus de 2,5 milliards d’années (i.e. archéens). Nous évaluons ici la robustesse des isotopes du soufre à tracer le recyclage précoce de croûte océanique et de sédiments, transférés dans le manteau profond ou stockés dans le manteau lithosphérique depuis la mise en place de la subduction. En Sibérie, le manteau lithosphérique a été naturellement échantillonné par l’éruption de la kimberlite d’Udachnaya-Est. Extrêmement bien préservée, riche en Na, K, Cl, S et contenant des reliques de croûte océanique Archéenne, cette kimberlite nous permet de tester : (1) l’hypothèse du recyclage de soufre atmosphérique Archéen dans le manteau lithosphérique et/ou la source de cette kimberlite ; (2) la cohérences entre les méthodes in situ (SIMS dans les minéraux de sulfure) et bulk (extraction chimique du soufre et spectrométrie de masse à source gazeuse) pour les mesures multi-isotopiques du soufre. Nos résultats, complétés par des mesures isotopiques en Rb-Sr, Sm-Nd et plomb (204Pb, 206Pb, 207Pb, 208Pb), montrent que : (1) les sulfates de la kimberlite et des nodules composés de chlorure-carbonate ont une origine magmatique profonde, non-contaminée par les sédiments encaissants, suggérant la présence de domaines oxydés et riches en sulfates dans le manteau ; (2) les mesures isotopiques du soufre par méthode bulk sont cohérentes avec les populations de sulfures observées in situ ; (3) les sulfures des kimberlites salées sont appauvris en 34S par rapport à la valeur chondritique et enregistrent de faibles anomalies isotopiques en soufre ; (4) les péridotites déformées contiennent d’autres sulfures appauvris en 34S, qui eux préservent des anomalies en 33S et 36S héritées de la surface archéenne, malgré un équilibrage isotopique du chronomètre U-Pb lors de l’éruption de la kimberliteInherited from the early atmosphere, anomalies in the relative abundances of sulfur isotopes (32S, 33S, 34S and 36S) are recorded in sediments older than 2.5 billion year (i.e. Archean). Here we test the robustness of sulfur isotopes to trace the early recycling of oceanic crust and sediments that may have been transferred to the deep mantle or stored in the lithospheric mantle since the onset of subduction. In Siberia, the lithospheric mantle has been naturally sampled by the Udachnaya-East kimberlite while it was erupting. Because it is extremely well preserved, rich in Na, K, Cl, S and contains remnants of oceanic crust recycled during the Archean, this kimberlite enables us to test : (1) the hypothesis of an early recycling of Archean atmospheric sulfur in the lithospheric mantle and/or the deeper source of the kimberlite; (2) the coherence between in situ (SIMS in sulfide minerals) and bulk methods (chemical extraction of sulfur from powdered rocks, followed by gas source mass-spectrometry) for measuring multiple sulfur isotopes. Our results, combined with measurements of Rb-Sr, Sm-Nd and lead (204Pb, 206Pb, 207Pb, 208Pb) isotopes, show that: (1) sulfates from the Udachnaya-East kimberlite and its nodules composed of chloride-carbonate have a deep, magmatic origin, uncontaminated by host sediments, suggesting the presence of sulfate-rich, oxidized domains in the mantle; (2) measurements of sulfur isotopes by bulk methods are consistent with the sulfide populations observed in situ; (3) sulfides from salty kimberlites are depleted in 34S with respect to the chondritic value and record small anomalies in sulfur isotopes ; (4) sheared peridotites contain another population of sulfides that are depleted in 34S and preserve 33S and 36S anomalies inherited from the Archean surface, despite resetting of the U-Pb chronometer during kimberlite eruption
13
Kitayama, Yumi. "Les quatre isotopes du soufre dans les kimberlites de Sibérie, traceurs du recyclage de croûte océanique et de sédiments Archéens dans le manteau terrestre." Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0244.
Full textAbstract:
Héritées de l’atmosphère primitive, des anomalies dans les abondances relatives des isotopes du soufre (32S, 33S, 34S et 36S) sont enregistrées dans les sédiments terrestres d’il y a plus de 2,5 milliards d’années (i.e. archéens). Nous évaluons ici la robustesse des isotopes du soufre à tracer le recyclage précoce de croûte océanique et de sédiments, transférés dans le manteau profond ou stockés dans le manteau lithosphérique depuis la mise en place de la subduction. En Sibérie, le manteau lithosphérique a été naturellement échantillonné par l’éruption de la kimberlite d’Udachnaya-Est. Extrêmement bien préservée, riche en Na, K, Cl, S et contenant des reliques de croûte océanique Archéenne, cette kimberlite nous permet de tester : (1) l’hypothèse du recyclage de soufre atmosphérique Archéen dans le manteau lithosphérique et/ou la source de cette kimberlite ; (2) la cohérences entre les méthodes in situ (SIMS dans les minéraux de sulfure) et bulk (extraction chimique du soufre et spectrométrie de masse à source gazeuse) pour les mesures multi-isotopiques du soufre. Nos résultats, complétés par des mesures isotopiques en Rb-Sr, Sm-Nd et plomb (204Pb, 206Pb, 207Pb, 208Pb), montrent que : (1) les sulfates de la kimberlite et des nodules composés de chlorure-carbonate ont une origine magmatique profonde, non-contaminée par les sédiments encaissants, suggérant la présence de domaines oxydés et riches en sulfates dans le manteau ; (2) les mesures isotopiques du soufre par méthode bulk sont cohérentes avec les populations de sulfures observées in situ ; (3) les sulfures des kimberlites salées sont appauvris en 34S par rapport à la valeur chondritique et enregistrent de faibles anomalies isotopiques en soufre ; (4) les péridotites déformées contiennent d’autres sulfures appauvris en 34S, qui eux préservent des anomalies en 33S et 36S héritées de la surface archéenne, malgré un équilibrage isotopique du chronomètre U-Pb lors de l’éruption de la kimberliteInherited from the early atmosphere, anomalies in the relative abundances of sulfur isotopes (32S, 33S, 34S and 36S) are recorded in sediments older than 2.5 billion year (i.e. Archean). Here we test the robustness of sulfur isotopes to trace the early recycling of oceanic crust and sediments that may have been transferred to the deep mantle or stored in the lithospheric mantle since the onset of subduction. In Siberia, the lithospheric mantle has been naturally sampled by the Udachnaya-East kimberlite while it was erupting. Because it is extremely well preserved, rich in Na, K, Cl, S and contains remnants of oceanic crust recycled during the Archean, this kimberlite enables us to test : (1) the hypothesis of an early recycling of Archean atmospheric sulfur in the lithospheric mantle and/or the deeper source of the kimberlite; (2) the coherence between in situ (SIMS in sulfide minerals) and bulk methods (chemical extraction of sulfur from powdered rocks, followed by gas source mass-spectrometry) for measuring multiple sulfur isotopes. Our results, combined with measurements of Rb-Sr, Sm-Nd and lead (204Pb, 206Pb, 207Pb, 208Pb) isotopes, show that: (1) sulfates from the Udachnaya-East kimberlite and its nodules composed of chloride-carbonate have a deep, magmatic origin, uncontaminated by host sediments, suggesting the presence of sulfate-rich, oxidized domains in the mantle; (2) measurements of sulfur isotopes by bulk methods are consistent with the sulfide populations observed in situ; (3) sulfides from salty kimberlites are depleted in 34S with respect to the chondritic value and record small anomalies in sulfur isotopes ; (4) sheared peridotites contain another population of sulfides that are depleted in 34S and preserve 33S and 36S anomalies inherited from the Archean surface, despite resetting of the U-Pb chronometer during kimberlite eruption
14
Lang, James Robert 1961. "A GEOCHEMICAL STUDY OF ALTERATION AND MINERALIZATION IN THE WALLAPAI MINING DISTRICT, MOHAVE COUNTY, ARIZONA (MINERAL PARK, FLUID INCLUSIONS, SULFUR ISOTOPES)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275536.
Full text
15
Zamotaeva, Valeriya. "High-resolution FTIR spectra analysis of sulfur dioxide isotopologues." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCK053.
Full textAbstract:
Dans cette thèse, nous avons examiné les propriétés spectrales de l’anhydride sulfureux. Les spectres FTIR expérimentaux de nombreux isotopologues du dioxyde de soufre, 32S16O2, 34S16O2, 32S18O2 et 32S16O18O, ont été enregistrés pour la première fois dans les régions des bandes fondamentales, «chaudes», harmoniques et de combinaison. La grande variabilité des conditions expérimentales a permis d’observer et d’identifier pour la première fois des transitions appartenant aux ban¬des ro-vibrationnelles suivantes : 3v2, 3v2 - v2, 2v2 - v2 bandes de 32S16O2 ; 2v2 - v2 bande de 34S16O2 ; v1 + v2, v2 + v3, v1 + v3, 2v1, 2v3 bandes de 32S18O2 ; v1, v3, 2v1, v1 + v3, 2v3 bandes de 32S16O18O. Les problèmes spectroscopiques inverses ont été résolus pour les états étudiés avec une déviation «rms» comparable à l’incertitude expérimentale. Suite à cette analyse, environ 38 000 transitions ro-vibrationnelles appartenant à 17 états vibratoires excités ont été identifiées pour la première fois. Les données très précises obtenues sur tous les isotopologues du dioxyde de soufre ont été utilisées pour corriger les paramètres de la IPFIn this thesis we considered the spectral properties of the sulfur dioxide. The experimental FTIR spectra of numerous sulfur dioxide isotopologues, 32S16O2, 34S16O2, 32S18O2 and 32S16O18O, were first recorded in the regions of fundamental, «hot», combination and overtone bands. The wide variability of the experimental conditions gave possibility to observe and identify for the first time transitions be¬ longing to the following of ro-vibrational bands: 3v2, 3v2 - v2, 2v2 - v2 bands of 32S16O2; 2v2 - v2 band of 34S16O2; v1 + v2, v2 + v3, v1 + v3, 2v1, 2v3 bands of 32S18O2; v1, v3, 2v1, v1 + v3, 2v3 bands of 32S16O18O. The inverse spectroscopic problems were solved for the studied states with the «rms»-deviation comparable to the experimental uncertainty of the spectral line position. As a result of the analysis about 38 000 ro-vibrational transitions belonging to 17 excited vibrational states were identified for the first time. The obtained highly accurate data on all sulfur dioxide isotopologues were used to correct the parameters of the IPF
16
Thibon, Fanny. "Chimie des océans au Paléoprotérozoïque." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN008/document.
Full textAbstract:
Les conditions oxydantes de la surface terrestre actuelle sont dues à la teneur élevée en dioxygène de l’atmosphère. Au début de l’histoire de la Terre il y a 4.54 milliards d'années (Ga), l’oxygène n’était pas stable dans l’atmosphère. Il a fallu deux épisodes d’augmentation brutale de ce gaz atmosphérique pour qu’il atteigne son niveau actuel : l’un vers 2.4 Ga, nommé le Grand Evènement Oxydant (GOE) qui fait l’objet de ce projet, l’autre 2 milliards d’années plus tard, nommé l’Evènement Oxydant Néo-protérozoïque (NOE). Le GOE est vraisemblablement le résultat de l’émersion généralisée de larges continents dont l’érosion libère le phosphate dans l’océan, un nutriment nécessaire à la production biologique, qui a donc permis l’explosion de la photosynthèse oxygénée. Ces deux hausses d’oxygène atmosphérique coïncident avec deux évolutions majeures dans l’histoire de la vie : (i) peu après le GOE, les eucaryotes sont apparus, alors que (ii) le NOE correspond à l’apparition des métazoaires et à l’explosion cambrienne. L’étude de ces phénomènes atmosphériques primitifs peut avoir d’importantes répercussions sur notre compréhension de l’origine et de l’évolution de la vie, qu’on estime principalement marine à cet âge. Les seules archives de ces temps primitifs sur Terre sont les roches sédimentaires. Pour savoir comment l’oxygénation de l’atmosphère a pu être reliée à cette vie marine, il faut tout d’abord comprendre comment l’océan a interagi avec l’atmosphère lors de cet évènement d’oxygénation. Cette question est au coeur de ce projet : comment le GOE a-t-il affecté les cycles biogéochimiques océaniques dont la vie est dépendante ? Nous nous sommes intéressés aux formations ferrifères litées ou BIFs (Banded Iron Formations). La chimie de ces roches marines fait écho à celle de l’océan contemporain à leur formation. Déterminer quantitativement la composition de l’océan à partir de celles des sédiments, même chimiques, est un défi quasiment impossible à relever y compris dans l’océan moderne. C’est pourquoi nous avons proposé de déterminer le temps de résidence d’éléments sensibles aux conditions redox de la surface, le soufre, le fer et le cuivre dans l’océan pré-GOE. Nous avons obtenu, par des séries temporelles, le spectre des fluctuations isotopiques de ces éléments enregistrées dans des carottes de formations ferrifères litées. La limite inférieure du spectre donne le temps de résidence de ces éléments dans l’eau de mer et fournit donc une indication solide sur la teneur de ces éléments dans l’océan à cette période. Nous avons analysé des échantillons protérozoïques proches de la limite Archéen-Protérozoïque du Transvaal (Afrique du Sud) et d’Hamersley (Australie). Des échantillons eoarchéens de Nuvvuagittuq (Canada) ont été récoltés mais n'ont pas pu être analysés faute de tempsThe present-day oxidizing conditions at Earth's surface are due to the high oxygen content of the atmosphere. However, oxygen was not always stable in the terrestrial atmosphere. Two distinct periods during which oxygen increased in a step-like manner were required to reach the current atmospheric oxygen level. The first, at about 2.4 Ga, is known as the Great Oxidation Event (GOE) and is at the core of this Ph.D. thesis. The other, occurring almost two billion years later, is called the Neo-Proterozoic Oxidation Event (NOE). The GOE likely is the result of the beginning widespread emergence of large continental expanses whose subsequent erosion gradually released phosphate into the ocean. Phosphate, a nutrient essential to organic production, in turn allowed the explosion of oxygenated photosynthesis. The GOE and NOE coincide with two major changes in the history of life. Shortly after the GOE, eukaryotes appeared, while the NOE corresponds to the appearance of metazoans and the Cambrian explosion. A better grasp of the GOE hence may have important implications for the understanding of the origin and evolution of life, which is thought to have been mainly marine at this stage in Earth history. The only records of the oxygen level during these ancient times are found in terrestrial sedimentary rocks. To understand how oxygenation of the atmosphere relates to marine life, we must first understand how the ocean was connected to the atmosphere during the GOE and how the GOE affected life-dependent ocean biogeochemical cycles. To this end we focused on banded iron formations (BIF). The chemistry of these sedimentary marine rocks directly reflects the chemistry of the contemporary ocean. Deriving quantitatively the composition of the ocean from a hydrogenous sediment is a challenge almost impossible to meet, even for the modern ocean. This is why we instead determined the residence time of redox-sensitive elements (in this case sulfur, iron, and copper) in the pre-GOE ocean. We specifically targeted the periods of isotopic fluctuations in these elements as recorded in BIF cores. The lower limit of the spectrum provides the residence time of these elements in seawater, hence giving a robust indication of their contents in the pre-GOE ocean. We sampled early Proterozoic BIF near the Archean-Proterozoic boundary in Transvaal (South Africa) and Hamersley (Australia), as well as Archean BIF from Nuvvuagittuq (Canada), though the latter were not analyzed during this thesis due to shortage of time
17
Foley, Derek J. "Analysis of the Point Pleasant/Lexington/Trenton Formations: Sulfides, Mineralogy, and Trace Elements as Geochemical Proxies." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461333436.
Full text
18
Diekrup, David. "Depositional Pathways and the Post-Depositional History of the Neoarchean Algoma-Type BIF in Temagami, ON." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39875.
Full textAbstract:
Algoma-type banded iron formation is common in Neoarchean greenstone belts, and many of its distinctive features such as the banding of iron-rich and silica-rich material and deposition in volcanic terranes have been ascribed to their deposition related to volcanic-hydrothermal activity and cyclic variability in depositional pathways. The work presented in this thesis tests these assumptions and presents a model for the deposition and post-depositional processes now represented by the petrography and geochemistry of a 2.73 Ga type-locality of Algoma-type BIF in Temagami, ON. Adsorption of components onto the surface of Fe-oxyhydroxides forming in the anoxic Neoarchean water column is the most likely process capable of transferring silica, as well as trace quantities of transition metals, rare earth elements, Ge, P, U and other components to the sediment. The petrogenesis of the Temagami BIF lithologies suggests ongoing recrystallization processes and volume loss reactions leading to the formation of magnetite layers, while jasper is identified as the most pristine lithology best representative of the initially deposited Fe-oxyhydroxide-silica gel. Recrystallization and volume loss reactions are controlled by the ongoing dewatering during compaction and diagenesis, without the influence of external hydrothermal or metamorphic fluids. When corrected for the volume loss and small amounts of clastic contamination, little residual variability can be observed in the composition of jasper and magnetite layers, indicative of an originally homogenous primary precipitate instead of sorted and layered material deposited on the seafloor. This model is in stark contrast to previous interpretations of seasonal variability in biologic activity, cyclical seasonal or hydrothermal events responsible for primary layering in BIF. Instead, very little direct input of hydrothermal components is recorded in the chemistry of the Temagami BIF, and elements abundant in high-temperature hydrothermal fluids such as sulfur are instead sourced from atmospheric sources and deposited by bacterial pathways. Lack of primary chemical variability and non-hydrothermally sourced components captured in BIF argue against a genetic link to local hydrothermal venting, but rather an open ocean depositional setting. As such, the Temagami BIF does not represent a marker horizon related to local or regional hydrothermal venting and potential formation of associated massive sulfide deposits but reflects processes and the chemistry of the open Neoarchean ocean.
19
Reed, Alan Thomas. "Decay studies of neutron-rich nuclei." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367175.
Full text
20
Cendón, Sevilla Dionisio Ignacio. "Evolución geoquímica de cuencas evaporíticas terciarias: implicaciones en la composición isotópica disuelto en el océano durante el terciario." Doctoral thesis, Universitat de Barcelona, 1999. http://hdl.handle.net/10803/81705.
Full textAbstract:
Esta memoria trata de la evolución geoquímica de cuencas evaporíticas terciarias y de su utilidad en la reconstrucción de la evolución isotópica (delta(34)S y delta(18)O) del sulfato disuelto en el océano durante el Terciario. Para ello se ha dividido el texto en tres partes principales:
Parte 1. Se tratan los aspectos metodológicos y se describen las técnicas empleadas. El microanálisis de inclusiones fluidas mediante Cryo-SEM-EDS, permite el análisis cuantitativo de los solutos en inclusiones fluidas congeladas de tamaños de hasta 15 delta m. Los electrolitos analizados son los componentes mayoritarios presentes en las salmueras atrapadas. Na, K. Mg, Ca, Cl y SO(4). La precisión del método varia según los casos, pero es inferior al 6% para todos ellos salvo para el Cl (<15%). Con el objeto de ampliar el número de elementos analizados a minoritarios y traza, se han realizado análisis mediante otra técnica, LA-ICP-MS, demostrándose que ambas técnicas son complementarias.
También se describe la metodología empleada en el análisis isotópico, en especial el funcionamiento de las líneas de extracción de gases y la manipulación de las muestras. Otra parte fundamental es la descripción del funcionamiento de las simulaciones numéricas y sus fundamentos teóricos. Todos los datos analíticos obtenidos de forma sistemática a lo largo de las secuencias evaporíticas son comparados con simulaciones numéricas en diferentes escenarios. Estas comparaciones permiten refinar un modelo de evolución de las cuencas evaporiticas durante la precipitación de las evaporitas, en especial de las halitas. De esta forma se obtienen los parámetros fundamentales en la evolución hidrológica de la cuenca: el índice de restricción, que indica lo abierta o cerrada que está la cuenca a los aportes externos, y las proporciones de recarga, que son las proporciones aproximadas de los distintos tipos de aguas que llegan a la cuenca (continentales, marinas, reciclajes, etc.).
Las composiciones isotópicas también están introducidas en los modelos, de forma que una vez determinados el índice de restricción y las proporciones de recarga puede ajustarse la evolución isotópica de las unidades evaporíticas. Al establecerse el carácter marino de la totalidad o de parte de las unidades, éstas pueden ser utilizadas para deducir la composición isotópica de las salmueras y del océano original del que proceden. Los datos de composición isotópica del mar, obtenidos a partir de estas unidades están corregidos de los fraccionamientos provocados por cristalización o por variaciones en el índice de restricción de la cuenca. Por otra parte pueden detectarse otros fenómenos que modifican la composición isotópica, tales como la sulfato-reducción bacteriana o el reciclaje de evaporitas previamente formadas. En el caso del reciclaje puede llegar a cuantificarse de forma aproximada.
Parte II. En esta parte se aplica la metodología descrita a diferentes cuencas evaporíticas.
a) Cuenca surpirenaica (subcuenca navarra). En este caso ya existen trabajos anteriores en los que se aplica la metodología descrita y en los que se muestra el carácter marino de la unidad halítica inferior (UHI) y el carácter continental de la unidad halítica superior (UHS). En esta memoria se aplica de forma complementaria el estudio de inclusiones fluidas al estudio de las zonas estériles en los yacimientos de silvita de Subiza (Navarra). Se determina el carácter primario de la silvita y el origen sinsedimentario de las zonas estériles.
b) Cuenca surpirenaica (subcuenca catalana). Ésta tiene apones fundamentalmente marinos, si bien se pone de manifiesto la importante influencia del reciclaje de los yesos marginales durante la precipitación de la halita. Esta influencia queda registrada en las composiciones isotópicas más pesadas de la subcuenca catalana respecto de la navarra. Ambas subcuencas siguen una evolución paralela, aunque la mayor influencia continental en la subcuenca catalana parece sugerir una menor conexión entre ambas subcuencas. Para ambas subcuencas se deduce la composición isotópica del mar durante el Eoceno superior.
c) Fosa Renana (Cuenca de Mulhouse. Alsacia). La evolución de esta cuenca durante la precipitación de la Sal IV es fundamentalmente continental como indican la evolución de solutos en las inclusiones fluidas, composiciones isotópicas y determinaciones (87)Sr/(86)Sr. Es posible la existencia de una influencia marina en la base de la Sal IV, cerca de la llamada zona fosilífera, si bien no se preserva según evoluciona el medio. En esta cuenca se ponen de manifiesto procesos de mezclas de aguas de diferentes orígenes y en proporciones variables en el tiempo. También se identifican procesos redox con
reequilibración del oxígeno del sulfato con el oxígeno disuelto en la salmuera. Eslos procesos provocan el enriquecimiento de la delta(18)O hasta valores de +/- 22º/ºº y parecen estar relacionados a una mayor actividad bacteriana en la cuenca. Los datos obtenidos no permiten deducir la composición isotópica del mar durante el Oligoceno.
d) Cuenca Precarpática. Se pone de manifiesto la importancia del reciclaje durante la precipitación de toda la unidad halitica. La fuente de solutos es mayoritariamente marina, al principio de la precipitación de halita, y se pone de manifiesto un incremento notable del reciclaje de evaporitas. La composición isotópica de los sulfatos intercalados entre halita y de los yesos marginales es muy semejante. Se plantea el reciclaje de los sulfatos precipitados en el margen activo de la cuenca como posible fuente de solutos. A partir de los datos obtenidos y una vez determinada la influencia del reciclaje, se deduce una composición isotópica para el mar durante el Badeniense.
e) Cuenca de Lorca. Las conclusiones de los estudios preexistentes sobre inclusiones fluidas se ven confirmadas por los nuevos datos isotópicos obtenidos. Se diferencia en la unidad salina un tramo inferior de origen marino, con variaciones en el índice de restricción y apones continentales puntuales que provocan ligeras variaciones isotópicas. Por encima se distingue un tramo superior, de origen continental, con una evolución isotópica que se interpreta por el reciclaje de diferentes proporciones de sulfatos de la propia cuenca y sulfatos de origen Triásico. A partir de los datos de la unidad salina (tramo inferior) se deduce la composición isotópica del mar messiniense.
f) Cuenca de Caltanissetta. Los datos de inclusiones fluidas preexistentes y los realizados para esta memoria diferencian un tramo halltico inferior, de origen marino, y un tramo superior, separado por sulfatos de K y Mg, que muestra su carácter marino, pero con influencias del reciclaje de evaporitas de la propia cuenca. Se ha determinado la evolución isotópica de dos sondeos diferentes, siendo los resultados iguales para ambos, y en concordancia con los resultados de las inclusiones fluidas. A partir del tramo marino se obtiene un rango para la composición isotópica delta(34)S del océano messiniense que coincide con la deducida en la cuenca de Lorca. Las delta(18)O obtenidas son aproximadamente +3 º/ºº más pesadas e incompatibles con las deducidas en Lorca. Se propone la existencia de procesos redox generalizados de forma semejante a como sucede en medios actuales de origen marino.
Parte III. En esta parte se realizan diversas consideraciones sobre la evolución del sulfato disuelto en el océano. A partir de los datos obtenidos en diferentes cuencas evaporíticas, se concluye que el déficit de sulfato (respecto a la evaporación del mar actual), común a muchas cuencas evaporíticas, no se debe a cambios globales en la composición del océano sino a variaciones locales dentro de las propias cuencas evaporíticas. Procesos de dolomitización o la entrada de salmueras ricas en Ca son las responsables del descenso en la concentración de sulfato. Una de las consecuencias directas del déficit de sulfato es la precipitación de silvita como mineral primario a partir de la evaporación de agua marina. En cuanto a la composición isotópica., se insiste en la necesidad de conocer con exactitud el origen marino de las evaporitas empleadas para deducir la evolución isotópica del sulfato disuelto en el océano. La metodología empleada en trabajos anteriores en la que se utilizan evaporitas de orígenes diversos, y en ocasiones desconocidos, provocan la imprecisión de las curvas de evolución isotópica deducidas. La metodología presentada en esta memoria permite el refinamiento de dichas curvas y la obtención de datos precisos sobre la composición isotópica del sulfato disuelto en el océano.The subject of this thesis is the geochemical evolution of tertiary evaporitic basins and their use in reconstructing the isotopic evolution (delta(34)S y delta(18)O) of sulphate dissolved in the ocean during the Tertiary. Part 1: The methodology is discussed and the techniques employed are described. Microanalysis using Cryo-SEM-EDS allows the quantitative analysis of frozen fluid inclusions up lo 15 mili-micres in size. The major solutes analysed from the trapped brine are Na. K, Mg, Ca, CI and SO. To analyse minor and trace elements, diverse analyses have been carried out using another technique, LA-ICP-MS. Thus demonstrating that, these techniques complement each other. The methodology used in isotopic analysis and numerical simulations, how they work and their theoretical bases are also described. The analytical data are compared with numerical simulations that reproduce different scenarios. Thus a model of the evaporitic basins evolution during precipitation can be refined. From these models fundamental parameters in the basins hydrological evolution have been obtained: restriction index and recharge proportions. The isotopic compositions are also introduced into the models so the isotopic evolution of the evaporitic units can be adjusted. Once the marine origin has been established, the model is used to deduce the brine's isotopic composition and that of the original ocean. Part II: In this section the methodology discussed above is applied to various evaporitic basins. - Southpyrenean basin (Navarran sub-basin, Spain) - Southpyrenean basin (Catalonian sub-basin, Spain) - Rhine Graben (Mulhouse basin, Alsace, France) - pre-Carpathian basin (Poland) - Lorca basin (Murcia, Spain) - Caltanissetta basin (Sicily, ltaly) Part III: According to the data obtained from different evaporitic basins it is concluded that the sulphate deficit - in respect to the evaporation of today's seawater - common in many evaporitic basins is not due to global changes in the oceans composition but rather lo local variations within the evaporitic basins. Regarding the isotopic compositions, it is important lo assure the exact marine origin of the evaporates that are used to deduce the isotopic evolution of sulphate dissolved in the ocean. The methodology presented in this thesis allows isotopic curves to be refined.
21
Ullrich, Maria K. [Verfasser], and Britta [Akademischer Betreuer] Planer-Friedrich. "Preservation and analysis of sulfur isotopes in thioarsenates : New methods for the investigation of abiotic and biotic transformation processes / Maria K. Ullrich ; Betreuer: Britta Planer-Friedrich." Bayreuth : Universität Bayreuth, 2017. http://d-nb.info/1143013964/34.
Full text
22
Pasquier, Virgil. "Climate and sea level variations in the Gulf of Lion : coupling stable and radiogenic isotopes proxies." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0094/document.
Full textAbstract:
De par sa position, le Golfe du Lion est un site idéal pour l’investigation des changements paléo-environnementaux et des processus affectant le dépôt sédimentaire. Les travaux antérieurs ont permis de mettre en évidence les impacts de la variabilité climatique et glacioeustatique sur l’organisation stratigraphique de la marge, mais également sur les exports terrestres de matière organique.L’étude isotopique du carbone organique et de l’azote de la matière organique dans les sédiments du forage PRGL1-4 nous a permis de mettre en évidence de forts exports fluviaux lors des interstades survenus au cours des 200 000 derniers milles ans. La mise en regard de cette découverte avec les enregistrements paléo-climatologiques terrestre et marin disponibles dans la région indique que ces forts exports fluviaux résultent d’une augmentation des précipitations le long de la bordure Nord Méditerranéenne. Grâce à la position dePRGL1-4, nous proposons que ces pluies soient le résultat d’une augmentation du passage de dépressions Nord Atlantique dans le bassin Ouest Méditerranéen.Une caractérisation des isotopes du soufre préservés dans la pyrite sédimentaire a été réalisée. Les résultats obtenus ont permis de mettre en évidence une variation isotopique insoupçonnée, l’une des plus grandes observées de nos jours, dont la cyclicité semble indiquer un fort contrôle climatique. Nous proposons deux mécanismes influençant le fractionnement isotopique: une modulation de l’activité bactérienne par le climat, et/ou (ii) une modulation locale liée la nature des sédiments impliqués dans la formation des pyrites en lien avec les variations eustatiquesBy its position, the Gulf of Lion is an ideal location for investigation of past ecological changes and processes affecting the sedimentary deposition. Previous work has highlighted the impacts of climatic and glacio-eustatic changes on the GoL stratigraphic organization, but also on terrestrial exports of organic matter.This isotopic study based on the organic carbon and nitrogen preserved in PRGL1-4 sediments highlights important rivers runoff during warm periods of the last 200 000 years.Regional intercomparison with terrestrial and marine records indicates that these river exports resulting from an increase of precipitation over the North Mediterranean borderland.Using PRGL1-4 location, out of Mediterranean cyclogenetic area, we suggest that these pluvial events occurred in response to enhance passage of North Atlantic atmospheric perturbation into the Western Mediterranean basin.Pyrite sulfur isotopes investigations over the last 500 kyr have also been done. The stratigraphic variations (up to 76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records. Two different mechanisms influencing the isotopic fractionation can explain the observed dataset: a climatic modulation of the bacterial activity, and / or (ii) a local sedimentary modulation involve during early diagenetic formation of pyrite in relation with the eustatic variations
23
Whitehill, Andrew (Andrew Richard). "Mass-independent sulfur isotope fractionation during photochemistry of sulfur dioxide." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97334.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 161-175).
Mass-independent sulfur isotope signatures are observed in Archean and early Paleoproterozoic sedimentary sulfate and sulfide minerals, and provide the most robust constraints on early atmospheric oxygen levels. Smaller mass-independent sulfur isotope anomalies are observed in ice cores and interpreted as a tracer of stratospheric volcanic loading. Photochemistry of sulfur dioxide (SO2) has been implicated as a possible source of the mass-independent sulfur isotope signatures in both the modern stratosphere and on the early earth. However, the mechanisms responsible for the production of mass-independent sulfur isotope fractionation remain poorly constrained. This thesis investigates the multiple sulfur isotope systematics during photochemical reactions of sulfur dioxide as a function of a variety of experimental conditions. Two absorption regions of SO2 are tested - photolysis in the 190 to 220 nm region and photoexcitation in the 250 to 350 nm region. Experimental conditions modified include temperature, SO2 pressure, bath gas pressure, and addition of reactive gases (C2 H2, 02 and CH4). Results of photochemical experiments are compared with isotope systematics predicted from isotopologue-specific absorption cross-sections to identify potential mechanisms for the production of mass-independent fractionation during photochemical reactions. Strong similarity between the isotope systematics of SO2 photolysis and ice core data suggest that SO2 photolysis is responsible for the production of mass-independent sulfur isotope effects in the modern stratosphere. In contrast, significant discrepancies between the isotope signatures from SO2 photochemistry and those in the Archean record suggest that, although SO2 photolysis was likely an important process in the Archean atmosphere, an additional reaction likely contributes to the mass-independent sulfur isotope signatures preserved in the Archean rock record.
by Andrew Richard Whitehill.
Ph. D.
24
El, Kilany Aïda. "Hydrologie et cycles biogéochimiques du soufre dans deux bassins marginaux de Méditerranée pendant la Crise de Salinité Messinienne." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC107/document.
Full textAbstract:
La formation du gypse (CaSO4.2H2O) dans les bassins marginaux méditerranéens au cours du Messinien est contrôlée par la restriction des bassins et par le cycle hydrologique local. La compétition entre l’évaporation et l’apport d’eau douce par les rivières, en association avec des échanges limites avec la Méditerranée, ont permis la mise en place de conditions chimiques favorables à la formation du gypse. La restriction des bassins entraine, de plus, l’augmentation de la consommation de l’oxygène par les microorganismes, l’anoxie, et la mise en place d’un cycle biogéochimique actif du soufre. Au cours de cette étude, j’utilise la composition isotopique stable du gypse en tant que traceur des cycles de l’eau et du soufre dans les bassins marginaux. Le but est de mieux comprendre les conditions hydrologiques et géochimiques qui ont mené à la précipitation du gypse. Ce problème se place dans un débat actuel de la communauté scientifique, particulièrement depuis que de récents travaux proposent qu’une partie du gypse dans les bassins marginaux aurait pu précipiter à partir d’une colonne d’eau à faible salinité (£ 35 PSU) - hypothèse qui peut sembler peu réaliste d’un point de vue géochimique. J’ai mené une analyse isotopique à haute-résolution des couches de gypse qui composent les alternances cycliques gypse-marnes dans les bassins messiniens de Caltanissetta (BC, Sicile) et du Piémont (BP, nord-ouest de l’Italie). Ces alternances gypse-marnes correspondraient à l’expression sédimentaire des cycles astronomiques de précession (~20 ka), pendant lesquels les bassins marginaux ont subi une alternance de conditions climatiques arides et humides. Le cycle hydrologique a été trace grâce aux mesures des compositions isotopiques de l’oxygène et de l’hydrogène de l’eau de cristallisation des gypses ; le cycle biogéochimique du soufre a quant à lui été trace en mesurent les compositions isotopiques du soufre et de l’oxygène des ions sulfates des gypses. J’ai pu observer que : (1) les isotopes de l’eau piégée dans les gypses sont nettement plus légers que ceux théoriquement attendus pour des gypses ayant précipite uniquement à partir d’une eau de mer, et (2) l’eau du BC est caractérisée par un plus fort déficit en deutérium - compare à sa teneur en 18O - que l’eau du BP. Combine a un modèle hydrologique numérique, ces observations impliquent que (1) la précipitation des gypses est réalisée sous l’influence d’un apport d’eau douce fluviatile important, particulièrement au nord du BP, et est donc caractérisée par de très faibles salinités (27-50 psu pour le BC et 10-42 psu dans le BP) ; (2) le contraste de déficit en deutérium entre les deux bassins résultant de la différence de teneur en deutérium des flux évaporais respectifs, est contrôlée par a une différence d’humidité atmosphérique : cela implique que l’atmosphère au-dessus du BC était plus sèche que celle au-dessus du BP. Nous pouvons alors proposer qu’un gradient latitudinal d’humidité relative similaire à l’actuel existait au Messinien, apportant la preuve d’un climat de type méditerranéen dans la région il y a 5.97 Ma. La composition isotopique des ions sulfate suggère globalement une formation de gypse sous influence marine. Cependant, des divergences observées avec la signature marine messinienne mettent en évidence un cycle biogéochimique du soufre actif, contrôlé par la réduction des sulfates et l’oxydation des sulfures. En particulier : (1) les sulfates du BP enrichis en 18O et 34S sont indicateurs d’une sulfato-reduction dans un système géochimique ouvert ou la perte de 32S est liée a la formation de minéraux soufres sédimentaires ; (2) l’enrichissement (BC) ou l’appauvrissement (BP) significatifs en 18O dans les échantillons alors que la teneur en 34S est la même que celle de l’eau de mer indique une reoxydation de sulfure dans un système géochimique ferme d’un bassin marginal soit évaporait (BC) soit dilue (BP)The formation of gypsum (CaSO4.2H2O) in Messinian Mediterranean marginal basins is controlled by basin restriction and the local hydrological cycle. Acting together, evaporation, river input and restricted water exchange with the Mediterranean basin bring about the chemical conditions for gypsum formation. Basin restriction also leads to enhanced microbial oxygen consumption, anoxia, and the triggering of active biogeochemical sulfur cycling. In this work I use the stable isotopic composition of gypsum as a proxy of water and sulphur cycling in the marginal basins. The goal is to better understand the hydrological and geochemical conditions that lead to gypsum precipitation. This is an open question, especially since recent work has proposed that part of the gypsum in marginal basins precipitated from a low-salinity (£ 35 PSU) water column - a hypothesis that seems unrealistic based on simple geochemical considerations. I carried out a high-resolution isotopic study of gypsum layers composing gypsum-marl cycles in the Messinian Caltanissetta (Sicily) and Piedmont (north-western Italy) marginal basins (CB and PB, respectively). These gypsum-marl cycles are thought to be the sedimentary expression of astronomical precession cycles (~20 kyr), during which the marginal basins experienced a succession of arid and wet conditions. The hydrological cycle was tracked by measuring the oxygen and hydrogen isotope composition of the gypsum-bound water molecule; the biogeochemical sulfur cycle was tracked by measuring the sulfur and oxygen isotope composition of the gypsum sulfate ion. I observed that: (1) the isotopes of gypsum-bound water are considerably lighter than those expected for gypsum precipitated via evaporation of seawater, and (2) water in the Caltanissetta basin was characterized by a higher deuterium deficit - compared to its 18O content - than water in the Piedmont basin. In conjunction with a hydrological box-model, these observations imply that (1) gypsum precipitation takes place under the influence of large riverine freshwater fluxes, particularly in the North Piedmont basin, that result in very low salinities (27-50 psu in CB and 10-42 psu in PB) and (2) the contrast in deuterium deficit results from atmospheric humidity-drived difference in the deuterieum content of the evaporative flux, implying that the atmosphere over the CB was drier than that over the PB. Thus, a latitudinal relative humidity gradient similar to the modern one existed in the Messinian, providing evidence for a Mediterranean-like climate in the region 5.97 million years ago. The isotopic composition of the gypsum sulfate ion suggests that it originates from coeval sea water. Deviation from the Messinian marine signature, however, highlights an active biogeochemical sulfur cycle driven by sulfate reduction and sulfide oxidation. In particular, (1) 18O- and 34S-rich sulfate in the Piedmont basin indicates sulfate-reduction in a geochemically open system where 32S is lost to sedimentary sulfide minerals, and (2) significant 18O-enrichment (CB) or 18O-depletion (PB), in samples where the 34S concent is that of seawater, indicates re-oxidation of sulphide in a geochemically closed system of an evaporative (CB) or dilution (PB) marginal basin. A strong relation between the hydrological cycle and the biogeochemical cycle is thus highlighted in marginal Messinian basins
25
Nannan, He. "Compound-specific Sulfur Isotope Study of Petroleum." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/80115.
Full textAbstract:
This PhD project progressed petroleum applications of compound specific sulfur isotope analysis. Standard compounds and high S petroleum samples were studied. New discoveries included an enrichment effect on the ?34S values of organic sulfur compounds during petroleum biodegradation; and preservation of the ?34S of organic sulfur compounds in the asphaltene fraction of oils impacted by thermochemical sulfate reduction. Field studies helped identify the source inputs of mixed oils and S-availability during deposition.
26
Gälman, Veronika. "Varved lake sediments and diagenetic processes." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-5724.
Full textAbstract:
Varved (annually laminated) sediments are of great interest for inference of past environmental conditions, as they provide dated records with high time resolution. After deposition, the sediment varves are affected by diagenesis; i.e., chemical, physical and biological changes that occur within the sediment. An important premise when reconstructing past environmental conditions using lake sediments is that the signal of interest is preserved in the sediment. In this thesis I have used a unique collection of ten stored freeze cores of varved lake sediment from Nylandssjön in northern Sweden, collected from 1979 to 2007. The suite of cores made it possible to follow long-term (up to 27 years) changes in iron (Fe), sulfur (S), carbon (C), nitrogen (N), δ13C and δ15N in the sediment caused by processes that occur in the lake bottom as the sediment ages. The sediment geochemistry and resulting changes were followed in years for which there are surface varves in the core series. Fe and S concentrations analyzed by X-ray fluorescence spectroscopy showed no diagenetic front in the sediment and the data do not suggest a substantial vertical transport of Fe and S in the sediment. A model based on thermodynamic, limnological, and sediment data from the lake, showed that there are pe (redox) ranges within which either FeS (reduced specie) or Fe(OH)3/FeOOH oxidized species) is the only solid phase present and there are pe ranges within which the two solid phases co-exist. This supports the hypothesis that blackish and grey-brownish Fe-layers that occur in the varves were formed at the time of deposition. C and N analyzed with an elemental analyzer showed that within the first five years after deposition the C concentration of the sediment decreased by 20% and N by 30%, and after 27 yr in the sediment, there was a 23% loss of C and 35% loss of N. The C:N ratio increased with increasing age of the sediment; from ~ 10 in the surface varves to ~12 after 27 years of aging. δ13C and δ15N analyzed on a mass spectrometer showed that δ13C increased by 0.4-1.5‰ units during the first five years, after that only minor fluctuations in δ13C were recorded. Another pattern was seen for δ15N, with a gradual decrease of 0.3-0.7‰ units over the entire 27-year-period. The diagenetic changes in the stable isotope values that occur in Nylandssjön are minor, but they are of about the same magnitude as the variation in the isotopic signal in the varves deposited between 1950-2006. My results show that diagenesis does not change the visual appearance of the varves, except for varve thickness; the varves get thinner as the sediment ages. As the color of Fe in the varves likely reflects the environmental conditions at the time of deposition this creates possibilities for deciphering high-temporal-resolution information of past hypolimnetic oxygen conditions from varves. My findings on C, N, δ13C and δ15N will have implications for interpretations of paleolimnological data. The diagenetic effects should be carefully taken into consideration when C, N, δ13C and δ15N in sediment cores are used to study organic matter sources or paleoproductivity, in particular when dealing with relatively small and recent changes. In addition to the significance of diagenetic effects on sediment parameters, a comparison of the varves in Nylandssjön and the adjacent lake Koltjärnen, and the two deep basins of Nylandssjön show that subtle features in the lakes and their catchments affect the appearance of the varves, which make interpretation of varves complicated.
27
Fiege, Adrian [Verfasser]. "Sulfur and sulfur isotope distribution between fluids and silicate melts : an experimental investigation / Adrian Fiege." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2013. http://d-nb.info/1043725067/34.
Full text
28
Unal, Ezgi. "Genetic Investigation And Comparison Of Kartaldag And Madendag Epithermal Gold Mineralization In Canakkale-region, Turkey." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612369/index.pdf.
Full textAbstract:
This thesis study is concerned with the genetic investigation of two epithermal gold deposits (Madendag and Kartaldag) in Çanakkale, NW Turkey. The methodology comprises field and integrated laboratory studies including mineralogic-petrographic, geochemical, isotopic, and fluid inclusion analysis. Kartaldag deposit, hosted by dacite porphyry, is a typical vein deposit associated with four main alteration types: i) propylitic, ii) quartz-kaolin, iii) quartz-alunitepyrophyllite, iv) silicification, the latter being characterized by two distinct quartz generations as early (vuggy) and late (banded, colloform). Primary sulfide minerals are pyrite, covellite and sphalerite. Oxygen and sulfur isotope analyses, performed on quartz (&delta
18O: 7.93- 8.95 &permil
) and pyrite (&delta
34S: -4.8 &permil
) separates, suggest a magmatic source for the fluid. Microthermometric analysis performed on quartz yield a temperature range of 250-285 º
C, and 0-1.7 wt % NaCl eqv. salinity. Madendag deposit, hosted by micaschists, is also vein type associated with two main alteration types: illite and kaolin dominated argillization and silicification, characterized by two distinct quartz phases as early and late. Oxygen isotope analyses on quartz (&delta
18O: 9.55-18.19 &permil
) indicate contribution from a metamorphic source. Microthermometric analysis on quartz yield a temperature range of 235-255 º
C and 0.0-0.7 wt % NaCl eqv. salinity. The presence of alunite, pyrophyllite and kaolinite, vuggy quartz and covellite suggest a high-sulfidation epithermal system for Kartaldag. On the other hand, Madendag is identified as a low- sulfidation type owing to the presence of neutral pH clays and typical low temperature textures (e.g. colloform, comb, banded quartz).
29
Deloule, Etienne. "Analyses isotopiques à l'échelle intra-cristalline : une contribution à l'étude des systèmes géologiques." Vandoeuvre-les-Nancy, INPL, 1991. http://docnum.univ-lorraine.fr/public/INPL_T_1991_DELOULE_E.pdf.
Full textAbstract:
La composition isotopique du Plomb a été mesurée sur des lessivages progressifs des minéraux de sulfures des gisements métallifères de la ceinture archéenne de l'Abitibi (Québec). La signature isotopique des gisements en milieu sédimentaire montre que les métaux proviennent d'une croute continentale antérieure à la ceinture de roches vertes, âgée de 2,7 milliards d'années. Les minéralisations associées au volcanisme résultent d'un mélange entre cette source crustale et une source mantellique. L'analyse isotopique à la sonde ionique du plomb et du soufre des galènes de Tristate et du Viburnum trend (Mississippi Valley) met en évidence des variations à courte échelle (100 micromètres) pour ces deux éléments. L'absence de corrélations entre les deux éléments montre l'existence de plusieurs sources de compositions isotopiques différentes et une croissance épisodique. Ces zonations suggèrent que les solutions hydrothermales à l'origine des gisements ont circule dans des fractures avec des débits importants. La modélisation numérique montre que ce type de circulation joue vraisemblablement un rôle important pour la mise en place des gisements du type de la vallée du Missouri. La calibration de la mesure isotopique de l'hydrogène par sonde ionique permet l'analyse de quelques nanogrammes d'échantillons, avec une précision meilleur que 10 %, quand les méthodes classiques en requièrent des milligrammes. L'analyse d'amphiboles dans des xénolites mantelliques équilibres à haute température et haute pression montre des zonations isotopiques importantes à l'échelle du minéral, jusqu'a 60% sur une échelle intra-millimétrique, pour des parasites d'Hawaii et du massif central. Ceci implique la présence d'hétérogénéités isotopiques importantes dans le manteau et une relation temporelle étroite entre les échanges d'hydrogène minéraux phases fluides et le volcanisme qui entraine les xénolites
30
Sim, Min Sub. "Physiology of multiple sulfur isotope fractionation during microbial sulfate reduction." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77788.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references.
Microbial sulfate reduction (MSR) utilizes sulfate as an electron acceptor and produces sulfide that is depleted in heavy isotopes of sulfur relative to starting sulfate. The fractionation of S-isotopes is commonly used to trace the biogeochemical cycling of sulfur in nature, but a mechanistic understanding of factors that control the range of isotope fractionation is still lacking. This thesis investigates links between the physiology of sulfate reducing bacteria in pure cultures and multiple sulfur isotope (³², ³³, ³⁴34S, and ³⁶S) fractionation during MSR in batch and continuous culture experiments. Experiments address the influence of nutrient and electron donor conditions, including organic carbon, nitrogen, and iron, in cultures of a newly isolated marine sulfate reducing bacterium (DMSS-1). An actively growing culture of DMSS-1 produced sulfide depleted in ³⁴S by 6 to 66%o, depending on the availability and chemistry of organic electron donors. The magnitude of isotope effect correlated well with the cell specific sulfate reduction rate (csSRR), and the largest isotope effects occurred when cultures grew slowly on glucose, a recalcitrant organic substrate. These findings bridge the long-standing discrepancy between the upper limit for S-isotope effect in laboratory cultures and the corresponding observations in nature and indicate that the large (>46 %o) fractionation of S-isotopes does not unambiguously record the oxidative sulfurrecycling. When the availability of iron was limited, the increase in S-isotope fractionation was accompanied by a decrease in the cytochrome c content as well as csSRR. In contrast, growth in nitrogenlimited cultures increased both csSRR and S-isotope fractionation. The influence of individual enzymes and electron carriers involved in sulfate respiration on the fractionation of S-isotopes was also investigated in cultures of mutant strains of Desulfovibrio vulgaris Hildenborough. The mutant lacking Type I tetraheme cytochrome c₃ fractionated ³⁴S/³²S ratio 50% greater relative to the wild type. The increasing S-isotope fractionation accompanied the evolution of H2 in the headspace and the decreasing csSRR. These results further demonstrate that the flow of electrons to terminal reductases imparts the primary control on the magnitude of the fractionation of S-isotopes, suggested by culture experiments using DMSS-1.
by Min Sub Sim.
Ph.D.
31
Hodkiewicz, Paul. "The interplay between physical and chemical processes in the formation of world-class orogenic gold deposits in the Eastern Goldfields Province, Western Australia." University of Western Australia. Centre for Global Metallogeny, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0057.
Full textAbstract:
[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] The formation of world-class Archean orogenic gold deposits in the Eastern Goldfields Province of Western Australia was the result of a critical combination of physical and chemical processes that modified a single and widespread ore-fluid along fluid pathways and at the sites of gold deposition. Increased gold endowment in these deposits is associated with efficient regional-scale fluid focusing mechanisms and the influence of multiple ore-depositional processes at the deposit-scale. Measurement of the complexity of geologic features, as displayed in high-quality geologic maps of uniform data density, can be used to highlight areas that influence regional-scale hydrothermal fluid flow. Useful measurements of geological complexity include fractal dimensions of map patterns, density and orientation of faults and lithologic contacts, and proportions of rock types. Fractal dimensions of map patterns of lithologic contacts and faults highlight complexity gradients. Steep complexity gradients, between domains of high and low fractal dimensions within a greenstone belt, correspond to district-scale regions that have the potential to focus the flow of large volumes of hydrothermal fluid, which is critical for the formation of significant orogenic gold mineralization. Steep complexity gradients commonly occur in greenstone belts where thick sedimentary units overly more complex patterns of lithologic contacts, associated with mafic intrusive and mafic volcanic units. The sedimentary units in these areas potentially acted as seals to the hydrothermal Mineral Systems, which resulted in fluid-pressure gradients and increased fluid flow. The largest gold deposits in the Kalgoorlie Terrane and the Laverton Tectonic Zone occur at steep complexity gradients adjacent to thick sedimentary units, indicating the significance of these structural settings to gold endowment. Complexity gradients, as displayed in surface map patterns, are an indication of three-dimensional connectivity along fluid pathways, between fluid source areas and deposit locations. Systematic changes in the orientation of crustal-scale shear zones are also significant and measurable map features. The largest gold deposits along the Bardoc Tectonic Zone and Boulder-Lefroy Shear Zone, in the Eastern Goldfields Province, occur where there are counter-clockwise changes in shear zone orientation, compared to the average orientation of the shear zone along its entire length. Sinistral movement along these shear zones resulted in the formation of district-scale dilational jogs and focused hydrothermal fluid-flow at the Golden Mile, New Celebration and Victory-Defiance deposits. Faults and lithologic contacts are the dominant fluid pathways in orogenic gold Mineral Systems, and measurements of the density of faults and contacts are also a method of quantifying the complexity of geologic map patterns on high-quality maps. Significantly higher densities of pathways in areas surrounding larger gold deposits are measurable within 20- and 5-kilometer search radii around them. Large variations in the sulfur isotopic composition of ore-related pyrites in orogenic gold deposits in the Eastern Goldfields Province are the result of different golddepositional mechanisms and the in-situ oxidation of a primary ore fluid in specific structural settings. Phase separation and wall-rock carbonation are potentially the most common mechanisms of ore-fluid oxidation and gold precipitation. The influence of multiple gold-depositional mechanisms increases the potential for significant ore-fluid oxidation, and more importantly, provides an effective means of increasing gold endowment. This explains the occurrence of negative δ34S values in ore-related pyrites in some world-class orogenic gold deposits. Sulfur isotopic compositions alone cannot uniquely define potential gold endowment. However, in combination with structural, hydrothermal alteration and fluid inclusion studies that also seek to identify multiple ore-forming processes, they can be a useful indicator. The structural setting of a deposit is also a potentially important factor controlling ore-fluid oxidation and the distribution of δ34S values in ore-related pyrites. At Victory-Defiance, the occurrence of negative δ34S(py) values in gently-dipping dilational structures, compared to more positive δ34S(py) values in steeply-dipping compressional structures, is potentially associated with different gold-depositional mechanisms that developed as a result of fluid-pressure fluctuations during different stages of the fault-valve cycle. During the pre-failure stage, when fluids are discharging from faults, fluid-rock interaction is the dominant gold-depositional mechanism. Phase separation and back-mixing of modified ore-fluid components are dominant during and immediately after faulting. Under appropriate conditions, any, or all, of these three mechanisms can oxidize orogenic gold fluids and cause gold deposition. The influence of multiple gold-depositional mechanisms during fault-valve cycles at dilational jogs, where fluid pressure fluctuations are interpreted to be most severe, can potentially explain both the large gold endowment of the giant to world-class Golden Mile, New Celebration and Victory-Defiance deposits along the Boulder-Lefroy Shear Zone, and the presence of gold-related pyrites with negative δ34S values in these deposits. This study highlights the interplay that exists between physical and chemical processes in orogenic gold Mineral Systems, during the transport of ore fluids in pathways from original fluid reservoirs to deposit sites. Potentially, a single and widespread orogenic ore-fluid could become oxidized, and lead to the formation of ore-related sulfides with variable sulfur isotopic compositions, depending on the nature and orientation of major fluid pathways, the nature of wall-rocks through which it circulates, and the precise ore-depositional processes that develop during fault-valve cycles.
32
Johnston, David T. "Sulfur isotope fractionations in biological systems insight into the Proterozoic biosphere /." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6714.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Geology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
33
Sharman, Elizabeth. "Application of multiple sulfur isotope analysis to Archean ore-forming processes." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104747.
Full textAbstract:
Identification of sulfur sources in an ore-forming system is important as it provides a greater understanding of how a mineral deposit forms and how best to explore for that particular type of deposit. It can also aid in the understanding of the ocean and atmosphere chemistry at the time of formation. Mass independent sulfur isotope fractionation in the Archean atmosphere provides a fingerprint for identifying non-magmatic sources of sulfur. This makes sulfur multiple isotope measurements a powerful tool for deconvolving ore-forming processes in the Archean. This thesis presents three applications of multiple sulfur isotope analysis for investigation of ore forming processes in the Archean. The first study evaluates proposed models for formation of volcanogenic massive sulfide (VMS) deposits during the Neo- and Mesoarchean, which demand little to no contribution of seawater sulfate to the ore-forming system. This is in contrast to Phanerozoic VMS systems where evidence for a seawater sulfate component is clear. We re-evaluate these models in the context of the ~2.7 Ga Noranda Camp of the Abitibi subprovince, Québec, using a combination of multiple sulfur isotope and trace element data. Sulfide samples analysed for this study have Δ33S values between -0.59 and -0.03 ‰. We interpret these negative values to reflect a sulfur component that originated in the seawater sulfate reservoir. Incorporation of this component appears to have increased during the collapse and subsequent evolution of the Noranda caldera. Higher concentrations of Se in samples with Δ33S values close to 0 ‰, and higher Fe/(Fe + Zn) values in sphalerite, are indicative of higher temperatures of formation.The second study is an investigation of sulfur sources that contributed to the formation of Cu- and Au-rich VMS deposits of the ~2.7 Ga Doyon-Bouquet-LaRonde (DBL) mining camp, also within the Abitibi subprovince. This subgroup of deposits has previously been interpreted as having a significant magmatic-hydrothermal source of ore fluids and metals. Multiple sulfur isotope analysis of deposits within the DBL mining camp, with the exception of one minor lens, indicates a very clear igneous-magmatic affinity (Δ33SV-CDT = 0.14 to +0.04 ‰), with little to no contribution from any surficial source of sulfur. In contrast, sulfide that formed at or very near the paleo-seafloor exhibits a distinct component of sulfur from the seawater sulfate reservoir (Δ33SV-CDT = 1.43 to 0.34 ‰). This study highlights the isotopic difference between the Noranda VMS deposits and those of the DBL. In addition, a lack of variation in Δ33S values between ore lenses which exhibit aluminous alteration and those that do not calls into question the characteristics with which to identify those VMS deposits that required dominant contribution of magmatic fluids.The final study examines sulfur sources within the Platreef, the main PGE bearing horizon of the Northern Limb of the Bushveld Igneous Complex (BIC), South Africa. The Platreef has a high percentage of sulfides relative to the analogous Merensky Reef in the eastern and western limbs of the BIC. It is in direct contact with underlying Neoarchean to Paleoproterozoic sediments, which are potential local sources of sulfur. However, Δ33S analysis of the Platreef sulfides identifies heterogeneous crustal sulfur contribution to the system both prior to and post-emplacement throughout the length of the Platreef.This thesis clearly demonstrates that multiple sulfur isotope analysis is a powerful tool for the identification of sulfur sources in ore forming processes of the Archean, and those involving Archean rocks, and can be applied to a range of problems and deposit types. It also highlights important issues for future consideration, including the role of seawater sulfate in the formation of Archean VMS deposits, and the characteristics of the parent magma of the BIC.L'identification des sources de soufre dans la minéralisation est importante car elle permet de comprendre les processus et de définir la meilleure méthode d'exploration. Elle peut aussi aider à la compréhension de la chimie des océans et de l'atmosphère lors de sa formation. Le fractionnement indépendant de la masse des isotopes du soufre dans l'atmosphère de l'Archéen fournit une emprunte unique permettant d'identifier les sources de soufre non magmatiques. La nature chimique conservatrice des signatures du Δ33S en fait un outil puissant pour la déconvolution des processus minéralisateurs Archéen.Cette thèse présente trois applications de l'analyse multiple des isotopes du soufre dans l'investigation des processus de minéralisation à l'Archéen. La première étude teste les modèles de formation des sulfures massifs volcanogènes (SMV) Néo- et Mésoarchéen récemment proposés ne requérant peu ou pas d'apport de sulfate marin par rapport aux systèmes SMV du Phanérozoïque et contemporains où le sulfate marin joue un rôle important. Ces modèles sont réévalués en utilisant le camp de Noranda (~2.7 Ga), sous-province de l'Abitibi, et en combinant l'utilisation de données provenant de l'analyse des isotopes du soufre et des éléments traces.Les sulfures analysés pour cette étude ont des valeurs de δ34SV-CDT entre -14.90 et +2.49 ‰, et des valeurs de Δ33SV-CDT entre -0.59 et -0.03 ‰. Selon notre interprétation, les valeurs négatives de Δ33S sont dues à l'incorporation de soufre provenant de l'eau de mer. La proportion de soufre marin aurait augmenté durant l'affaissement et l'évolution subséquente de la caldera de Noranda. Des concentrations plus élevées de Se combinées à des valeurs près de 0 ‰ et d'un haut ratio Fe/(Fe + Zn) dans les sphalérites indiquent une température de formation élevée.La deuxième étude est une investigation des sources de soufre ayant contribuées à la formation des SMV riches en Cu et en Au du camp minier Doyon-Bousquet-LaRonde (DBL; ~2.7 Ga), aussi dans la sous-province de l'Abitibi. Une source magmatique-hydrothermale de fluides minéralisateurs importante était l'interprétation donnée pour ce sous-groupe. À l'exception d'une lentille mineure, l'analyse isotopique multiple des dépôts du camp minier DBL indiquent clairement une affinité ignée-magmatique (Δ33SV-CDT = 0.14 to +0.04 ‰), avec peu ou pas de contribution de soufre provenant de la surface. Par contre, les sulfures formés sur le plancher océanique ou près de celui-ci exhibe une contribution distinctive des sulfates marins (Δ33SV-CDT = 1.43 to 0.34 ‰). D'un autre côté, l'absence de variation des valeurs du Δ33S entre des lentilles minéralisées avec une altération alumineuse et celles ne démontrant pas cette altération remet en question les l'identification des dépôts de type SMV ayant une contribution importante ou dominante de fluides magmatiques. La dernière étude examine les sources de soufre du Platreef – horizon riche en éléments du groupe platine (EGP) du flanc nord du Complexe Igné Bushveld (CIB) en Afrique du Sud. Le Platreef contient un haut pourcentage de sulfures par rapport au dépôt analogue Merensky Reef des flancs est et ouest du CIB. Il est en contact direct avec les sédiments Néoarchéens à Paléoprotérozoïques qui sont une source potentielle de soufre locale. D'un autre côté, les analyses du Δ33S des sulfures du Platreef permettent d'identifier une contribution de soufre hétérogène provenant de la croûte terrestre, avant et après la mise en place du gisement.Cette étude démontre clairement que l'analyse multiple des isotopes du soufre est un outil puissant dans l'identification des sources de soufre des processus minéralisateurs de l'Archéen, ainsi que ceux impliquant des roches archéennes, et cette approche peut être appliquée à un éventail de problèmes et types de dépôt. Aussi, elle soulève des questions importantes sur le rôle du sulfate marin dans la formation des dépôts SMV de l'Archéen et les caractéristiques du magma du CIB.
34
Fuentes, A. Fernandez. "FTIR determination of sulphur isotope ratios." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334712.
Full textAbstract:
A new method for the determination of sulphur isotopic ratios by FTIR measuring the area or absorbance of individual lines, has been developed. The project could be divided into three parts: (i) In part one the infrared spectra of four sulphur gases SCO, H2S, SF6 and SO2, were collected and studied to evaluate which one would be the most appropriate to determine sulphur isotopic ratios. The synthesis of these gases was also assessed and performed in those cases where the means to carry them out were available. This part was designed to test the viability of these compounds as a means of extracting sulphur from natural samples. (ii) In part two, the methodology for the determination of sulphur isotopic ratios using the infrared spectrum of sulphur dioxide, gas chosen for this project, was performed. Different factors affecting the precision of the method, such as resolution, number of scans, etc., were evaluated and optimized. The UV/Vis spectrum of this gas was collected and the viability of using the L(1)-bound overdetermined Gaussian elimination method for assessing sulphur isotopic ratios over data obtained from this spectrum as well as from its infrared spectrum, was also tested. Both methods, integration of individual lines in the infrared spectrum of SO2, and use of the L(1)-bound overdetermined Gaussian elimination method over data also obtained from the infrared spectrum of sulphur dioxide, proved to be applicable when determining isotopic ratios in enriched samples. (iii) In part three, levels of sulphur-34 and nitrogen-15 in the biomass of four arable Scottish soils were determined. A slight enrichment in both isotopes was detected for one of the soils, being the first time such a measurement has been carried out. Sulphur and nitrogen deficiency in this soil are given as a possible explanation although the lack of sufficient number of data do not allow us to establish with certainty its cause.
35
Díaz, Ramos Rut Amélia. "Geoquímica inorgânica, orgânica e isotópica do enxofre em sedimentos holocênicos do sistema de ressurgência de Cabo Frio (RJ)." Niterói, 2017. https://app.uff.br/riuff/handle/1/3816.
Full textAbstract:
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-06-07T18:11:24Z
No. of bitstreams: 1
Tese Rut Díaz.pdf: 2159528 bytes, checksum: 159d73b33fae80ff4ee36bea4366ea74 (MD5)Made available in DSpace on 2017-06-07T18:11:24Z (GMT). No. of bitstreams: 1 Tese Rut Díaz.pdf: 2159528 bytes, checksum: 159d73b33fae80ff4ee36bea4366ea74 (MD5)
Fundação de Amparo a Pesquisa do Rio de Janeiro
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Petrobras/CENPES
Agência Nacional do Petróleo
Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ
O presente estudo utiliza a geoquímica inorgânica das espécies reduzidas do enxofre, operacionalmente definidas como acid - volatile sulfufide (AVS) e chromium -reducible sulfur (CRS),a composição isotópica ( δ 34 S) do sulfat o da água intersticial, do CRS, e das frações orgânicas (ácidos húmicos, ácid os fúlvicos e resíduo orgânico) para avaliar a diagênese do enxofre ao longo do Holoceno (últimos 12.000 anos cal AP) no Sistema de Ressurgência de Cabo Frio (SRCF) . Também foi usada a morfologia da pirita, considerando a distribuição de tamanho dos frambóides através de microscopia eletrônica de varredura (MEV), com o objetivo de inferir o estado de oxidação do ambiente de formação. Foram coletados quatro perfis sedimentares cur tos (b ox - cores ) e três longos ( kullembers ) em um gradiente “cross - shelf” na plataforma continental de Cabo Frio. A razão C/N e o a composição isotópica ( δ 13 C) da matéria orgânica reflete uma fonte marinha durante a diagênese recente. As diferentes caracter ísticas morfológicas, como as superfícies de oxidação nos microcristais, os processos de crescimento secundário e os poliframboides encontrados nas análises morfológicas da pirita, assim como também a variabilidade na distribuição dos diâmetros dos frambói des evidenciaram uma formação sob condição redox altamente dinâmica. A razão COT/CRS indica que o fator limitante para a formação da pirita é o enxofre , devido as condições de deposição do ambiente as quais favorecem a re - oxidação do sulfeto de hidrogênio. A composição isotópica do sulfato ao longo dos perfis apresenta um valor médio de +23‰, e não foi observado um fracionamento isotópico com respeito ao sulfato da água do mar (+ 21‰), indicando a diagênese do sulfato em um sistema aberto e baixas taxas de sulfato redução. No entanto, a composição isotópica do CRS apresentou sinais altamente empobrecidos em 34 S ( - 45‰ até - 25 ‰), indicando reações de re - oxidação no ciclo do enxofre. A composição isotópica das espécies orgânicas do enxofre apresenta um enrique cimento em 32 S quando comprados com o sulfato da água intersticial , e isotopicamente pesadas comparadas com a pirita. O incremento na razão S/C dos ácidos húmicos e o empobrecimento do sinal isotópico em 34 S com o avanço da profundidade indicam a captura d o enxofre de origem diagenético pela matéria orgânica. Um balanço de massa isotópico indica a predominância de uma fonte biossintética nos ácidos húmicos e diagenética nos ácidos fúlvicos, estes resultados guardam relação com a reatividade da matéria orgân ica em cada fração. No gradiente “cross - shelf” as frações orgânicas da plataforma média apresentam os menores conteúdo de enxofre biossíntetico, indicando a presença de matéria orgânica mais reativa. Estes resultados indicam que a sulfurização da matéria o rgânica e a cumulação de pirita em Cabo Frio foi favorecida pelo ciclo re - oxidativo do enxofre devido a intensas condições óxicas na coluna de água. O processo de diagênese do enxofre ao longo do Holoceno não guarda relação aparente com as mudanças oceanog ráficas registrada na área de estudo, assim sendo, adinâmica do enxofre esteve relacionada com a intensidade dos processos de diagênese
Four box-corer and tree kullemberg were collected in a cross - shelf gradient in the continental shelf of Cabo Frio. The box-corer were used to evaluated the sulfurization of the organic matter during the early diagenesis and also, study the pyrite morphology and size distribution of framboids by scanning electron microscopy (SEM) to infer the oxidation state of the environment during the early diagenesis. This study uses the inorganic geochemistry of reduced sulfur species operationally defined as acid-volatile sulfufide (AVS) and chromium - reducible sulfur (CRS), the isotopic composition ( δ 34 S) of pore water sulfate, CRS, and the isotopic composition of difference organic fraction (humic acids, fulvic acids and organic residue to evaluated the sulfur diagenesis during the Holocene (last 12000 years cal AP) in the upwelling system of Cabo Frio. Carbon stable isotopes signatures and C/N ratios of total organic matter evidence a marine source during the early diagenesis. The observed increase in the atomic S/C ratios and t he 34 S depletion in humic acids with increasing depth evidence the diagenetic uptake of reduced sulfur species by organic matter during the early diagenesis. The different morphological characteristics observed, such as surface oxidation in the microcrysta ls, the processes of secondary growth and poliframboides found, as well as the variability in the framboids diameters distribution, show the formation under highly dyna mic redox condition. In the sedi m e nts from the Holocene the COT/CRS ratio indicates that the limiting factor for the pyrite formation is the sulfur. The isotopic composition of sulfate is around +23 ‰ , and without fractionation of sulfate with respect to sea water (21 + ‰) indicating a sulfur diagenesis in a open system and a low net sulfate r eductions. The isotopic composition of the CRS is highly depleted ( - 45 ‰ to - 35‰), indicating oxida tion reactions in the cycle of sulfur . The stable sulfur isotope composition of the organic fractions ( humic acids, fulvics acids and organic res idue ) was sub stantially enriched in 32 S when compared to bottom and pore water sulfate (δ 34 S SO4 2 - ~ +23‰), but isotopically heavier than the co - existing pyrite ( δ 34 S CRS = - 45‰ to - 35‰). The 34 S depletion in humic acids, fulvis acids and in the organic residue with increasing depth evidence the diagenetic uptake of reduced sulfur species by organic matter. A sulfur isotope mass balance indicated a predominance of biogenic sulfur in humic acids and in the organic residue, while the fulvic acids has a predominance of d iagenetic sulfur. In cross - shelf gradient, the organic fractions from the middle shlelf have the lower proportion on biosynthetic sulfur, indicating the presence of more reactive matter. The results evidenced that the sulfurization of organic matter and th e p yrite accumulation in the Cabo F rio sediments was favored by the sulfur re - oxidative cycling due to the intense oxic water conditions . The diageneses process in the sulfur cycle during the Holocene in sediments from the continental shelf don’t have rela tion with the changes in the oceanography conditions. The process of diagenesis of sulfur seem to be a continuous process
36
Allen, Linda Mathilda 1965. "Boron and Sulfur Isotopic Fractionation in the Coal Combustion System." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/192073.
Full textAbstract:
The boron and sulfur isotopic ratios of four coal samples and corresponding fly ash leachates provide explanations for boron and sulfur incorporation into coal and behavior during combustion. Fractionation processes occur during coal formation and during the combustion of coal as some of the boron and sulfur is concentrated on the ash, and some escapes into the atmosphere as flue gas. Water-soluble boron in coal is extracted using a modified soil technique. Boron is isolated from solution using Amberlite IRA-743 resin and concentrated by methyl borate distillation with no isotopic fractionation observed. The forms of sulfur in coal are extracted sequentially using the lithium aluminum hydride (LAH) method. The isotopic content of samples from a coal-fired power-plant are used to determine if waste water has impacted a shallow aquifer system. No indication of mixing between waste water and ground water was observed.
37
Gill, Benjamin Charles. "High-resolution sulfur isotope records of the Paleozoic and a detailed geochemical study of the late Cambrian SPICE event utilizing sulfur isotope stratigraphy, metal chemistry and numerial modeling." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=78&did=1871861801&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270232379&clientId=48051.
Full text
38
Wieser, Michael Eugene. "Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0012/NQ31081.pdf.
Full text
39
DeYoung, Susan. "A sulfur isotope study of granitic plutons in the Great Basin, Western USA : implications for magma-crust interaction and crustal architecture /." abstract and full text PDF (UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446793.
Full textAbstract:
Thesis (M.S.)--University of Nevada, Reno, 2007."May, 2007." Includes bibliographical references (leaves 76-81). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
40
Harris, Eliza [Verfasser]. "Using sulfur isotope fractionation to understand the atmospheric oxidation of SO 2 / Eliza Harris." Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/1024640310/34.
Full text
41
Shen, Bing. "Contributions to the Neoproterozoic Geobiology." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29979.
Full textAbstract:
This thesis makes several contributions to improve our understanding of the Neoproterozoic Paleobiology. In chapter 1, a comprehensive quantitative analysis of the Ediacara fossils indicates that the oldest Ediacara assemblageâ the Avalon assemblageâ already encompassed the full range of Ediacara morphospace. A comparable morphospace range was occupied by the subsequent White Sea and Nama assemblages, although it was populated differently. In contrast, taxonomic richness increased in the White Sea assemblage and declined in the Nama assemblage. The Avalon morphospace expansion mirrors the Cambrian explosion, and both may reflect similar underlying mechanisms.
Chapter 2 describes problematic macrofossils collected from the Neoproterozoic slate of the upper Zhengmuguan Formation in North China and sandstone of the Zhoujieshan Formation in Chaidam. Some of these fossils were previously interpreted as animal traces. Our study of these fossils recognizes four genera and five species. None of these taxa can be interpreted as animal traces. Instead, they are problematic body fossils of unresolved phylogenetic affinities.
Chapter 3 reports stable isotopes of the Zhamoketi cap dolostone atop the Tereeken diamictite in the Quruqtagh area, eastern Chinese Tianshan. Our new data indicate that carbonate associated sulfate (CAS) abundance decreases rapidly in the basal cap dolostone and δ34SCAS composition varies between +9⠰ and +15⠰ in the lower 2.5 m. In the overlying interval, CAS abundance remains low while δ34SCAS rises ~5⠰ and varies more widely between +10⠰ and +21⠰. δ34Spy is typically greater than δ34SCAS measured from the same samples. We propose that CAS and pyrite were derived from two isotopically distinct reservoirs in a chemically stratified basin.
Chapter 4 studies δ13C, δ18O, δ34SCAS, and δ34Spy of the Zhoujieshan cap carbonate that overlies the Ediacaran Hongtiegou glaciation. The Zhoujieshan cap dolostone shows positive δ13C values (0 â 1.7â °). δ34SCAS shows rapid stratigraphic variations from +13.9 to +24.1â °, probably due to relatively low oceanic sulfate concentrations. δ34Spy shows a steady stratigraphic trend. Thus, the δ34SCAS and δ34Spy trends are decoupled from each other. The decoupling of δ34SCAS and δ34Spy trends suggests that CAS and pyrite were derived from different sulfur pools, which were probably due to the postglacial basin stratification.Ph. D.
42
McArdle, Nicola Clare. "The use of stable sulphur isotopes to distinguish between natural and anthropogenic sulphur in the atmosphere." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335422.
Full text
43
Thomas, Cyril. "Etude de la dissociation du dihydrogène et du sulfure de dihydrogène sur catalyseurs d'hydrotraitement par échange isotopique (1H-2H)." Poitiers, 1997. http://www.theses.fr/1997POIT2284.
Full textAbstract:
L'hydrotraitement est un procede du raffinage du petrole qui s'opere sous forte pression d'h#2 et ne presence d'h#2s. Le but principal de ce procede est d'eliminer les heteroatomes comme le soufre (hydrodesulfuration : hds) et l'azote (hydrodesazotation : hdn) des coupes petrolieres. L'objectif principal de l'etude est de determiner le mode de dissociation du dihydrogene sur les catalyseurs d'hydrotraitement a base de sulfures de metaux supportes. Les reactions d'echange isotopique h-d entre h#2 et d#2, h#2s et d#2 et enfin h#2 et d#2s sont realisees a 80c sous une pression totale de deux atmospheres dans un reacteur a recirculation. L'analyse du melange isotopique de l'hydrogene est effectuee par chromatographie en phase gazeuse. L'existence d'un echange d'atomes d'hydrogene (ou de deuterium) entre h#2 et h#2s montre que les atomes de soufre de surface sont impliques dans la dissociation du dihydrogene. De plus, on peut conclure que la dissociation du dihydrogene se produit au moins partiellement de maniere heterolytique sur des sites catalytiques mixtes (probablement une lacune associee a un atome de soufre voisin). L'effet inhibiteur d'h#2s sur la reaction d'echange h#2-d#2 confirme qu'h#2 et h#2s s'adsorbent sur les memes sites. La quantite d'hydrogene preadsorbe sur les catalyseurs peut etre determinee a l'aide de la reaction d'echange h#2-d#2. L'utilisateur de differentes formules catalytiques et conditions de pretraitement montre que l'hydrogene preadsorbe provient en grande partie du support et notamment du sulfure de dihydrogene adsorbe a sa surface dans le cas des catalyseurs supportes sur alumine. Toutefois, l'hydrogene retenu par le support n'est echangeable avec celui de la phase gazeuse que par l'intermediaire de la phase active. Il n'existe pas d'effet de synergie entre le molybdene et le nickel pour ce qui concerne les reactions d'echange et la quantite d'hydrogene adsorbe a la surface du catalyseur. Ceci indique que le phenomene de synergie observe pour les reactions d'hydrotraitement n'est pas lie a l'activation de l'hidrogene ou a la quantite d'hydrogene adsorbe sur le catalyseur.
44
Ogliore, Ryan Christopher Stone Edward Stone Edward. "The sulfur, argon, and calcium isotopic composition of the galactic cosmic ray source /." Diss., Pasadena, Calif. : California Institute of Technology, 2007. http://resolver.caltech.edu/CaltechETD:etd-02082007-175902.
Full text
45
Young, Steven E. "Crystal chemical control on intra-structural copper isotope fractionation in natural copper-iron-sulfur minerals." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289914.
Full textAbstract:
The nature of Cu isotope fractionation in natural Cu-Fe-S minerals was investigated through acid ferric sulfate leaching of copper ore from Morenci, Arizona. Copper isotope composition of the derived solutions varies from δ⁶⁵Cu = 0.47‰ to 5.21‰ over the course of progressive copper extraction. High δ⁶⁵Cu values characterize solutions collected in the first half of the leach, while the solutions collected between 35% and 45% copper recovery exhibit lower δ⁶⁵Cu values. This general pattern was observed for both bacterially-mediated and abiotic leaching. Sulfate solutions derived from dissolving pure djurleite show variable Cu isotope compositions as well, although the range is protracted from δ⁶⁵Cu = 0.01‰ to 1.21‰. As the Cu:S ratio of the remaining sulfide decreases, crystal structure parameters change as mineralogy passes through a series of nonstoichiometric copper sulfides. Mineralogy converges to yarrowite near 44% copper dissolution. Crystal chemical studies show that distribution of the two copper-sulfur bond coordination geometries, triangular planar and tetrahedral, in the copper sulfides, approximately corresponds to changes in δ⁶⁵Cu of the leachates. In particular, the proportion of CuS3 relative to CuS4 groups decreases from Cu/S = 2.00 (chalcocite) to 1.40 (geerite). Between Cu/S = 1.40 to 1.00 (covellite), the relative proportion of CuS3 groups increases slightly. Connection between coordination number and Cu isotope fractionation implies affinity of CuS₃ groups for the heavier, ⁶⁵Cu, isotope. This can be justified through bond length-bond strength arguments. Solutions from bornite dissolution vary from δ⁶⁵Cu = -0.79‰ to 1.14‰, with the largest values associated with solutions from early stage of reaction (up to 15% copper removal). Around 25% dissolution, δ⁶⁵Cu of the solution approaches that of the original bornite (δ⁶⁵Cu = 0.02‰). This is explained by disappearance of all remaining CuS₃ groups. Sulfur isotope compositions of solutions and sulfides derived from djurleite leaching were determined to investigate the possibility of intra-mineral fractionation. Very soon after reaction initiation, δ³⁴S of both sulfur reservoirs reach a steady-state with sulfate solutions about 2‰ enriched in ³⁴S relative to residual sulfide. Unlike the case of Cu isotopes, the main partitioning affecting S isotopes is exchange between sulfate and sulfide.
46
FURUSAWA, HELIO A. "Razão isotópica de enxofre em material atmosférico por ICPMS de alta resolução." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11632.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:54:07Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:09:24Z (GMT). No. of bitstreams: 1 12435.pdf: 4820144 bytes, checksum: 0d8279d9b23571886f63adee62a8b6f4 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
47
Fike, David Andrew. "Carbon and sulfur isotopic constraints on Ediacaran biogeochemical processes, Huqf supergroups, Sultanate of Oman." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42278.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, September 2007."August 2007."
Includes bibliographical references.
The link between environmental and evolutionary change is investigated in the Ediacaran Period (- 635 - 541 million years ago (Ma), an interval where we see the emergence of macroscopic animals along with large perturbations to the carbon and sulfur cycles. Paleoenvironmental reconstruction used the carbon and sulfur isotopic composition of sedimentary minerals and organic matter, supplemented by geochemical and molecular biomarker proxies, of strata from the Huqf Supergroup, Sultanate of Oman. Within Ediacaran strata, three successive stages of geochemical oxidation are observed and correlated to episodes of biological evolution. The second stage corresponds to the large Shuram 613Ccarb excursion and is identified with the oxidation of an organic carbon reservoir. An extreme enrichment in sulfur isotopes occurs in the overlying strata spanning the Ediacaran-Cambrian (E-C) boundary. This interval is characterized using paired sulfate and pyrite sulfur isotopes to quantify pyrite burial and the isotopic composition of sulfur entering the ocean, which leads to a reinterpretation of existing Phanerozoic data. These strata contain sulfates in two forms (carbonate-associated sulfate: CAS, and anhydrite), providing an opportunity to investigate isotopic offsets reported between these seawater sulfate proxies. The results indicate that changing basin restriction can significantly alter the isotopic composition of gypsum/anhydrite and suggest that CAS is the most reliable proxy for the reconstruction of the marine sulfur cycle. A combination of geochemical and biomarker proxies were used to investigate the biological and environmental changes across the Ediacaran- Cambrian boundary.
(cont.) In the Huqf strata, a crash in the photic zone primary production is observed immediately before the geochemical evidence for anoxia that is typically associated with the extinction of the Ediacaran organisms at the E-C boundary. All of these studies rely on interpretations made from geochemical data, which depend on how representative of depositional conditions (local, regional, or global) a given dataset is. Carbon and sulfur isotopes are characterized from replicate sections of the Huqf Supergroup strata to assess the basin-scale (-1,000km) reproducibility of these signals. The trends in the sulfur isotopic record were reproducible across the basin and serve to correlate sections lacking distinctive carbon isotopes or lithologies.
by David Andrew Fike.
Ph.D.
48
Graham, Kathleen. "An experimental study of sulphur isotope fractionation during magmatic degassing." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66980.
Full textAbstract:
The sulphur isotopic evolution of basaltic melts degassed under disequilibrium conditions was investigated experimentally at temperatures of 1225 oC and oxygen fugacities between 0.5 and 1.9 log10 units above that defined by the Ni-NiO buffer. Melts were equilibrated at a pressure of 550 MPa in a piston-cylinder apparatus and degassed at ~490 to 0 MPa. Water concentrations in the experimental glasses varied from 1.5-10 wt %. Extents of degassing were quantified by comparing sulphur concentrations in the experimentally degassed (DG) glasses to those in isobarically quenched (IQ) glasses, and ranged from 0 to ~40%. Degassed glasses were systematically more enriched in 34S than IQ glasses, and the degree of enrichment correlated positively with the extent of degassing. Predicted fractionation factors between the gas and the melt (34αg-m) for open-system degassing under conditions of local gas-melt equilibrium ranged from 0.9986 to 0.9996. Our empirical fractionation factor was found to be 0.9987, which lies near the low end of the predicted range, suggesting that another process is contributing to S isotope fractionation. Modelling results indicate that a possible explanation for this behaviour is the diffusion of S during bubble growth; however consideration of the mechanistic details of bubble growth show that more sophisticated models than those employed in this study are needed to fully quantify this effect.Une investigation de l'evolution isotopique du soufre dans les liquides basaltiques a été effectuée à une temperature de 1225 °C et à une fugacité d'oxygène entre 0.5 et 1.9 unités log10 au-dessus du tampon Ni-NiO. Les matières fondues ont été équilibrées à une pression de 550 MPa dans un appareil piston-cylindre et dégazées de ~490 à 0 MPa. Les concentrations de l'eau dans des verres expérimentaux ont varié entre 1.5 et 10 % (en masse). Le taux de dégazage (variable de 0 à ~40 %) a été quantifié en comparant les concentrations de soufre dans les verres dégazés experimentalement (DG) à celles de verres trempés de façon isobarique (IQ). Les verres DG étaient systématiquement plus enrichis en 34S que les verres IQ, et cet enrichissement montrait une corrélation positive avec le degré de dégazage observé. Les facteurs de fractionation théoriques entre la phase gazeuse et la phase fondue (34αg-m) pour dégazage d'un système ouvert sous conditions d'équilibre localisé (phase gazeuse-phase fondue) ont varié entre 0.9986 to 0.9996. Notre facteur de fractionation empirique était de 0.9987, vers le bas de la gamme prédite, ce qui suggère qu'un processus additionel contribue à la fractionation isotopique de soufre. Nos résultats de modélisation suggèrent la diffusion du soufre pendant la croissance de bulles de gaz comme possible explication; néanmoins, la prise en compte des détails mécanistiques de la croissance des bulles montre que des modèles plus complexes que ceux utilisés ici sont nécessaires pour une quantification complète de cet effet.
49
Feast, Nicholas A. "Application of nitrogen and sulphur isotope hydrochemistry in groundwater studies." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309939.
Full text
50
John, Eleanor Heulwen. "Strontium and sulphur isotopes and the origin of Mid-Late Palaeozoic mass extinctions." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493302.
Full textAbstract:
This project focuses on two Palaeozoic mass extinction events: the Frasnian-Famennian crisis of the Late Devonian and the end-Guadalupian event of the Permian for which similar extinction mechanisms have been proposed. These have been evaluated by examining the nature of the Sr and S isotopic systems during these intervals. Proposed extinction mechanisms for the Late Devonian event include extraterrestrial impacts, rapid sea-level fluctuations, climate change eutrophication and the spread of anoxia in bottom waters. Many models invoke changes in nutrient fluxes related to proposed increases in continental weathering or hydrothermal/volcanic fluxes but these theories have not been tested on a global scale. This study attempted to address this by compiling high resolution 87Sr/86Sr ratio curves for an interval spanning the FrasnianFamennian boundary based on measurements in well-preserved conodont apatite from sections in Poland and Iowa.