The geochemistry of quartz-hosted melt (MI) and fluid inclusions (FI) in quartz syenite from Terceira, Azores was investigated to provide insight into late-stage evolution of peralkaline melts and the behaviour of high field strength (HFSE) and rare-earth elements (REE) at the magmatic-hydrothermal transition. Crystalline and hydrous MI analyzed by laser ablation-inductively-coupled plasma mass-spectrometry (LA-ICP-MS) show extreme magmatic enrichment of HFSE and REE. Sanidine crystallization resulted in enrichment of the melt in HFSE, REE and volatiles. Halite-saturated FI analyzed by LA-ICP-MS show lower total REE abundances than melts, and a general enrichment in HREE. Comparison of REE distribution patterns of MI and miarolitic zircon and monazite suggest late-stage melt evolution by monazite, then zircon and pyrochlore fractionation. Microthermometry of FI suggests maximum trapping conditions of 675°C, 120 MPa. The residual evolved to very volatile-rich compositions and initially exsolved a hydrosaline melt that was diluted to lower salinities by aqueous-fluid exsolution on cooling.

The geochemistry of quartz-hosted melt (MI) and fluid inclusions (FI) in quartz syenite from Terceira, Azores was investigated to provide insight into late-stage evolution of peralkaline melts and the behaviour of high field strength (HFSE) and rare-earth elements (REE) at the magmatic-hydrothermal transition. Crystalline and hydrous MI analyzed by laser ablation-inductively-coupled plasma mass-spectrometry (LA-ICP-MS) show extreme magmatic enrichment of HFSE and REE. Sanidine crystallization resulted in enrichment of the melt in HFSE, REE and volatiles. Halite-saturated FI analyzed by LA-ICP-MS show lower total REE abundances than melts, and a general enrichment in HREE. Comparison of REE distribution patterns of MI and miarolitic zircon and monazite suggest late-stage melt evolution by monazite, then zircon and pyrochlore fractionation. Microthermometry of FI suggests maximum trapping conditions of 675°C, 120 MPa. The residual evolved to very volatile-rich compositions and initially exsolved a hydrosaline melt that was diluted to lower salinities by aqueous-fluid exsolution on cooling.

The Kawerau hydrothermal system lies at the northern end of the Taupo Volcanic Zone, on the some 20 km south of the Bay of Plenty. The system, which is thought to have been active for at least 200,000 years, is situated over an area which has been volcanically active through time. Relatively recent local magmatism is found in the 800 m high, 3000-10,000 year old Mt. Edgecumbe dacite massif and the 200 m high Onepu Dome complex which lie adjacent to and within, respectively, the present day resistivity anomaly. Shallow reservoir fluids show evidence of steam heating as expressed by elevated bicarbonate and/or sulphate contents and mildly to strongly acidic pH, whereas the deep fluids are dominantly alkaline at their respective temperatures. The calculated base fluid composition is comprised of 2.5 wt% CO$/sb2$ and ca. 890 mg/kg Cl at 310$/sp/circ$C. Fluid inclusion studies show a largely stable, boiling point thermal regime through time, whereas oxygen stable isotope studies on hydrothermal carbonates prove the existence of one or more pulses of isotopically heavy fluids into the reservoir at some time(s) in the past. Hydrothermal alteration associated with these isotopic anomalies indicate strongly oxidising conditions relative to both alteration elsewhere in the reservoir and the present day reservoir redox conditions. Collectively, the data suggest a magmatic source for these transient, isotopically heavy fluids. The present day system is ore forming, as evident from both metal rich scales formed in the production silencers of the geothermal wells and open fracture reservoir mineralogy. Stockwork environments in the deep reservoir are host to both base and precious metals, and evidence indicates that boiling is the main depositional mechanism for these ore phases. / Subscription resource available via Digital Dissertations only.

The Kawerau hydrothermal system lies at the northern end of the Taupo Volcanic Zone, on the some 20 km south of the Bay of Plenty. The system, which is thought to have been active for at least 200,000 years, is situated over an area which has been volcanically active through time. Relatively recent local magmatism is found in the 800 m high, 3000-10,000 year old Mt. Edgecumbe dacite massif and the 200 m high Onepu Dome complex which lie adjacent to and within, respectively, the present day resistivity anomaly. Shallow reservoir fluids show evidence of steam heating as expressed by elevated bicarbonate and/or sulphate contents and mildly to strongly acidic pH, whereas the deep fluids are dominantly alkaline at their respective temperatures. The calculated base fluid composition is comprised of 2.5 wt% CO$/sb2$ and ca. 890 mg/kg Cl at 310$/sp/circ$C. Fluid inclusion studies show a largely stable, boiling point thermal regime through time, whereas oxygen stable isotope studies on hydrothermal carbonates prove the existence of one or more pulses of isotopically heavy fluids into the reservoir at some time(s) in the past. Hydrothermal alteration associated with these isotopic anomalies indicate strongly oxidising conditions relative to both alteration elsewhere in the reservoir and the present day reservoir redox conditions. Collectively, the data suggest a magmatic source for these transient, isotopically heavy fluids. The present day system is ore forming, as evident from both metal rich scales formed in the production silencers of the geothermal wells and open fracture reservoir mineralogy. Stockwork environments in the deep reservoir are host to both base and precious metals, and evidence indicates that boiling is the main depositional mechanism for these ore phases. / Subscription resource available via Digital Dissertations only.

The Kawerau hydrothermal system lies at the northern end of the Taupo Volcanic Zone, on the some 20 km south of the Bay of Plenty. The system, which is thought to have been active for at least 200,000 years, is situated over an area which has been volcanically active through time. Relatively recent local magmatism is found in the 800 m high, 3000-10,000 year old Mt. Edgecumbe dacite massif and the 200 m high Onepu Dome complex which lie adjacent to and within, respectively, the present day resistivity anomaly. Shallow reservoir fluids show evidence of steam heating as expressed by elevated bicarbonate and/or sulphate contents and mildly to strongly acidic pH, whereas the deep fluids are dominantly alkaline at their respective temperatures. The calculated base fluid composition is comprised of 2.5 wt% CO$/sb2$ and ca. 890 mg/kg Cl at 310$/sp/circ$C. Fluid inclusion studies show a largely stable, boiling point thermal regime through time, whereas oxygen stable isotope studies on hydrothermal carbonates prove the existence of one or more pulses of isotopically heavy fluids into the reservoir at some time(s) in the past. Hydrothermal alteration associated with these isotopic anomalies indicate strongly oxidising conditions relative to both alteration elsewhere in the reservoir and the present day reservoir redox conditions. Collectively, the data suggest a magmatic source for these transient, isotopically heavy fluids. The present day system is ore forming, as evident from both metal rich scales formed in the production silencers of the geothermal wells and open fracture reservoir mineralogy. Stockwork environments in the deep reservoir are host to both base and precious metals, and evidence indicates that boiling is the main depositional mechanism for these ore phases. / Subscription resource available via Digital Dissertations only.

The Kawerau hydrothermal system lies at the northern end of the Taupo Volcanic Zone, on the some 20 km south of the Bay of Plenty. The system, which is thought to have been active for at least 200,000 years, is situated over an area which has been volcanically active through time. Relatively recent local magmatism is found in the 800 m high, 3000-10,000 year old Mt. Edgecumbe dacite massif and the 200 m high Onepu Dome complex which lie adjacent to and within, respectively, the present day resistivity anomaly. Shallow reservoir fluids show evidence of steam heating as expressed by elevated bicarbonate and/or sulphate contents and mildly to strongly acidic pH, whereas the deep fluids are dominantly alkaline at their respective temperatures. The calculated base fluid composition is comprised of 2.5 wt% CO$/sb2$ and ca. 890 mg/kg Cl at 310$/sp/circ$C. Fluid inclusion studies show a largely stable, boiling point thermal regime through time, whereas oxygen stable isotope studies on hydrothermal carbonates prove the existence of one or more pulses of isotopically heavy fluids into the reservoir at some time(s) in the past. Hydrothermal alteration associated with these isotopic anomalies indicate strongly oxidising conditions relative to both alteration elsewhere in the reservoir and the present day reservoir redox conditions. Collectively, the data suggest a magmatic source for these transient, isotopically heavy fluids. The present day system is ore forming, as evident from both metal rich scales formed in the production silencers of the geothermal wells and open fracture reservoir mineralogy. Stockwork environments in the deep reservoir are host to both base and precious metals, and evidence indicates that boiling is the main depositional mechanism for these ore phases. / Subscription resource available via Digital Dissertations only.

The Kawerau hydrothermal system lies at the northern end of the Taupo Volcanic Zone, on the some 20 km south of the Bay of Plenty. The system, which is thought to have been active for at least 200,000 years, is situated over an area which has been volcanically active through time. Relatively recent local magmatism is found in the 800 m high, 3000-10,000 year old Mt. Edgecumbe dacite massif and the 200 m high Onepu Dome complex which lie adjacent to and within, respectively, the present day resistivity anomaly. Shallow reservoir fluids show evidence of steam heating as expressed by elevated bicarbonate and/or sulphate contents and mildly to strongly acidic pH, whereas the deep fluids are dominantly alkaline at their respective temperatures. The calculated base fluid composition is comprised of 2.5 wt% CO$/sb2$ and ca. 890 mg/kg Cl at 310$/sp/circ$C. Fluid inclusion studies show a largely stable, boiling point thermal regime through time, whereas oxygen stable isotope studies on hydrothermal carbonates prove the existence of one or more pulses of isotopically heavy fluids into the reservoir at some time(s) in the past. Hydrothermal alteration associated with these isotopic anomalies indicate strongly oxidising conditions relative to both alteration elsewhere in the reservoir and the present day reservoir redox conditions. Collectively, the data suggest a magmatic source for these transient, isotopically heavy fluids. The present day system is ore forming, as evident from both metal rich scales formed in the production silencers of the geothermal wells and open fracture reservoir mineralogy. Stockwork environments in the deep reservoir are host to both base and precious metals, and evidence indicates that boiling is the main depositional mechanism for these ore phases. / Subscription resource available via Digital Dissertations only.

Mass-independent fractionation (MIF) of Hg isotopes has the potential to track the environmental transport and fate of Hg. Herein we demonstrate that reducing both the frequency and intensity of light have a large effect on the expression and magnitude of MIF. This strongly supports the magnetic isotope effect as the mechanism behind MIF observed during aqueous photo-reduction of Hg(II) and MeHg. The ratios of MIF, KapDelta199Hg/KapDelta201Hg, were 1.00 ± 0.04 (2SE) for Hg(II) and 1.35 ± 0.16 (2SE) for MeHg respectively and did not change as incident radiation energy and magnitude of MIF diminished, suggesting the respective MIF pathways remained constant regardless of experimental conditions. Comparable amounts of total photo-reduction were shown to coincide with different magnitudes of MIF depending the wavelength light available for photo-reduction. This confirms there are multiple pathways for photo-reduction in freshwater reservoirs and indicates that quantitatively relating photo-reduction and MIF will be challenging.

Mass-independent fractionation (MIF) of Hg isotopes has the potential to track the environmental transport and fate of Hg. Herein we demonstrate that reducing both the frequency and intensity of light have a large effect on the expression and magnitude of MIF. This strongly supports the magnetic isotope effect as the mechanism behind MIF observed during aqueous photo-reduction of Hg(II) and MeHg. The ratios of MIF, KapDelta199Hg/KapDelta201Hg, were 1.00 ± 0.04 (2SE) for Hg(II) and 1.35 ± 0.16 (2SE) for MeHg respectively and did not change as incident radiation energy and magnitude of MIF diminished, suggesting the respective MIF pathways remained constant regardless of experimental conditions. Comparable amounts of total photo-reduction were shown to coincide with different magnitudes of MIF depending the wavelength light available for photo-reduction. This confirms there are multiple pathways for photo-reduction in freshwater reservoirs and indicates that quantitatively relating photo-reduction and MIF will be challenging.

Master of Science / Department of Geology / Matthew W. Totten / The source of the hydrocarbons in western Kansas has been an ongoing debate for many years. The highly organic-rich Anadarko basin, directly south of western Kansas, has been a very prolific producer for many years. This basin is the most widely accepted source of the oil in Kansas, as it is very deep and thermally mature. The main source rock in this area is the Woodford Shale, a very thick, very organic-rich unit which has been proven to produce many hydrocarbons. Several studies have been done on the oils that are presently in Kansas, suggesting that they can be traced back to the source of the Woodford Shale. The hydrocarbons in the Anadarko basin would have traveled several hundred miles, which would require that the migration mechanism be unusually efficient. An alternate explanation could be that one of the many organic black shales in western Kansas may have sourced this oil. This study examines formations of Cambrian to Permian ages which include organic shales interbedded with several known producing formations. Shales of these ages in other areas have produced thermally mature hydrocarbons, which indicate relatively high temperatures and pressures. Several models suggest that thermal maturity may be reached even with lower temperatures if burial times are longer. The shales in western Kansas were deposited in marine seas, and upon TOC testing, proved to be very organic-rich. Two sets of data were analyzed in this study, with the first from northwestern Kansas, and the second from southwestern Kansas. These two sets were analyzed for TOC, whole-rock analysis, and vitrinite reflectance. The shales analyzed from the first set proved to be thermally immature. Had they been subjected to higher temperatures, then they would have made excellent source rocks. The second set of shales analyzed also proved to be thermally immature with the exception of a few deeper shales, which are closer to being mature source rocks. These shales may have contributed to some of the hydrocarbons currently within Kansas.