Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 14 of 14 for “"sulfur isotopes"”.
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Early evolution of environments and metabolism: insights from nitrogen, selenium and sulfur isotopes
… modified these cycles, in particular the global sulfur cycle. Statistical analyses of sulfur concentrations and isotopic ratios in marine mudrocks support an early Archean origin of microbial sulfate reduction and late Archean enhancement of biological pyrite oxidation on land, leading to …
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Analysis of stable sulfur isotopes and trace cobalt on sulfides from the TAG hydrothermal mound
Stable sulfur isotopes (δ34S) and trace Co are analyzed in sulfide and sulfate minerals from six sample types collected from the TAG active mound, 26°N Mid-Atlantic Ridge. δ34S values range from 2.7 to 2O.9%, with sulfate minerals isotopically indistinguishable from seawater (21%), and sulfide …
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Analysis of stable sulfur isotopes and trace cobalt on sulfides from the TAG hydrothermal mound
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998.
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Carbon and sulfur isotopic constraints on Ediacaran biogeochemical processes, Huqf supergroups, Sultanate of Oman
… 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 …
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Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea
… a subsurface biosphere. In Chapter 5, multiple sulfur isotopes were measured on metal sulfide deposits, So, and fluid H2S to constrain sulfur sources and the isotopic systematics of precipitation in a wide variety of seafloor hydrothermal vents. Areas studied include the eastern Manus Basin and …
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Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea
… fluids worldwide. In Chapter 5, multiple sulfur isotopes were measured on metal sulfide deposits, S0, and fluid H2S to constrain sulfur sources and the isotopic systematics of precipitation in a wide variety of seafloor hydrothermal vents. Areas studied include the eastern Manus Basin and …
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Stratigraphic control and distal hydrothermal footprint of the Ursa Zn-Pb-Ag prospect, Selwyn Basin, Yukon Territory, Canada
… electron microscopy, and the analysis of sulfur isotopes of pyrite, sphalerite and other sulfur-bearing minerals have been used to systematically evaluate the textural, mineralogical, and isotopic characteristics of the weakly altered, reduced, calcareous, and barite-bearing sedimentary …
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Foraging ecology and population structuring of baleen whales in the western South Atlantic and eastern South Pacific
… whale species; and (iii) identify whether sulfur isotopes can be used to infer site fidelity to feeding grounds. In addition, (iv) I combine DNA metabarcoding, population genetics and stable isotope analysis to compare foraging patterns, genetic diversity, and population structure of …
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Sulfur, carbon, and oxygen isotopes of coexisting sulfides and carbonates in gas and oil seeps from the Gulf of Mexico
… reduction (BSR), bacterial disproportionation of sulfur (BDS), and BSR coupled with anaerobic oxidation of methane (BSR-AOM) occur in the Gulf of Mexico (GOM) at sites where hydrocarbon oil and gas seep through conduits to the seafloor. Thus far, no studies have measured the solid-phase sulfides …
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Geochemical investigation of the co-evolution of life and environment in the Neoproterozoic Era
… chert nodules and do not have superheavy sulfur isotopes. For the superheavy pyrite, the models consistently show high confidence levels in identifying its genesis type, and three out of four samples were inferred to be of sedimentary origins. For the pyritic nodule rims, the models …
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Implementing a new method to measure δ³⁴SSO₄ in ice cores to assess sulfate sources in West Antarctica
… Each source can be identified by its unique sulfur isotopic composition of sulfate (δ³⁴SSO₄). However, δ³⁴SSO₄ measurements in Antarctic ice cores are scarce and have poor temporal resolution due to the large sample volume required for isotopic analysis. For this thesis, I established a new …
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A multiproxy investigation of oceanic redox conditions during the Cambrian SPICE event
… large changes to the global cycles of carbon, sulfur, uranium, molybdenum and the overall trace metal content of seawater. Furthermore, the initiation of these changes appears to have been temporally coupled with marine extinctions across several paleocontinents raising the possibility of a …
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Magmatic volatiles at rifts and arcs: Sources and fractionation effects
… additional data (including carbon, oxygen ,and sulfur isotope compositions and assessment of sulfur behaviour in the magma system) from Oldoinyo Lengai that have not been published. Chapter 2 presents the first bulk gas and nitrogen isotope compositions from the Rungwe Volcanic Province, which …
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Trace Elements and Sulfur Isotope Variations in Endowed and Non-Endowed Porphyry Systems of the Dawson Range Mineral Belt, Yukon Territory
… this area, focusing on select trace elements and sulfur isotope analyses to distinguish between endowed deposits and non-endowed occurrences. The remote location, poor access, and extensive glacial deposits complicate exploration efforts. The study analyzed fifty-six samples from eight porphyry …