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• 1. [Article] Magmatic volatile contents and explosive cinder cone eruptions in the High Cascades: Recent volcanism in Central Oregon and Northern California

  xvi, 182 p. : col. ill.

  Citation × Citation Citation Abstract Copy Title: Magmatic volatile contents and explosive cinder cone eruptions in the High Cascades: Recent volcanism in Central Oregon and Northern California Author: Ruscitto, Daniel M., 1981- Year: 2011 xvi, 182 p. : col. ill. Title: Magmatic volatile contents and explosive cinder cone eruptions in the High Cascades: Recent volcanism in Central Oregon and Northern California Author: Ruscitto, Daniel M., 1981- Year: 2011 xvi, 182 p. : col. ill. Close

• 2. [Article] NWA 8614: The Least Heated Winonaite

  Northwest Africa 8614 is classified as a winonaite on the basis of oxygen isotope ratios, mineralogy, and highly reduced chemistry. Unlike other winonaites, it contains numerous and readily apparent chondrules. ...

  Citation × Citation Citation Abstract Copy Title: NWA 8614: The Least Heated Winonaite Author: Farley, Karla, Ruzicka, Alexander M., Armstrong, Katherine Year: 2015 Northwest Africa 8614 is classified as a winonaite on the basis of oxygen isotope ratios, mineralogy, and highly reduced chemistry. Unlike other winonaites, it contains numerous and readily apparent chondrules. Here we discuss various features of NWA 8614 and the possible significance of the meteorite. Petrological and chemical analyses were performed using optical microscopy with a DM2500 Leica petrographic microscope and a Zeiss Sigma VP-FEG scanning electron microscope (SEM) with a high-efficiency energy dispersive spectrometer (EDS). Oxygen isotopes were analyzed by Karen Ziegler at the University of New Mexico on acid-washed samples to remove terrestrial weathering products. Owing to the abundance of chondrules, NWA 8641 may be one of the least heated winonaites, and therefore may provide clues to the chondritic protolith of the winonaite parent body. Overall textures are similar to those found in type 6 chondrites that escaped significant melting. Despite similar geothermometer temperatures for various mineral pairs, NWA 8614 apparently did not attain Fe-Mg equilibrium between olivine and pyroxene. Like other winonaites, NWA 8614 has olivine compositions that are too magnesian for equilibrium relative to low-Ca pyroxene. Among winonaites as a whole, there is no evidence for a curved trend between Fa and Fs compositions as would be expected for FeO-reduction during metamorphism [Benedix, et al 1998], nor for mineral compositions that correlate with geothermometry temperatures. This argues against a single metamorphic FeO-reduction trend from a common chondritic precursor. Instead, protoliths for different winonaites may have varied slightly in composition. Title: NWA 8614: The Least Heated Winonaite Author: Farley, Karla, Ruzicka, Alexander M., Armstrong, Katherine Year: 2015 Northwest Africa 8614 is classified as a winonaite on the basis of oxygen isotope ratios, mineralogy, and highly reduced chemistry. Unlike other winonaites, it contains numerous and readily apparent chondrules. Here we discuss various features of NWA 8614 and the possible significance of the meteorite. Petrological and chemical analyses were performed using optical microscopy with a DM2500 Leica petrographic microscope and a Zeiss Sigma VP-FEG scanning electron microscope (SEM) with a high-efficiency energy dispersive spectrometer (EDS). Oxygen isotopes were analyzed by Karen Ziegler at the University of New Mexico on acid-washed samples to remove terrestrial weathering products. Owing to the abundance of chondrules, NWA 8641 may be one of the least heated winonaites, and therefore may provide clues to the chondritic protolith of the winonaite parent body. Overall textures are similar to those found in type 6 chondrites that escaped significant melting. Despite similar geothermometer temperatures for various mineral pairs, NWA 8614 apparently did not attain Fe-Mg equilibrium between olivine and pyroxene. Like other winonaites, NWA 8614 has olivine compositions that are too magnesian for equilibrium relative to low-Ca pyroxene. Among winonaites as a whole, there is no evidence for a curved trend between Fa and Fs compositions as would be expected for FeO-reduction during metamorphism [Benedix, et al 1998], nor for mineral compositions that correlate with geothermometry temperatures. This argues against a single metamorphic FeO-reduction trend from a common chondritic precursor. Instead, protoliths for different winonaites may have varied slightly in composition. Close

• 3. [Article] Quantification of the temperature, pressure and compositional dependence of trace element partitioning : an experimental and theoretical study

  The thermodynamic history of the Earth is preserved in the trace element record created through igneous processes. The ability to interpret that record depends on the accuracy and precision of numerical ...

  Citation × Citation Citation Abstract Copy Title: Quantification of the temperature, pressure and compositional dependence of trace element partitioning : an experimental and theoretical study Author: Cunningham, Jennifer Lynn The thermodynamic history of the Earth is preserved in the trace element record created through igneous processes. The ability to interpret that record depends on the accuracy and precision of numerical models that connect igneous processes with their geochemical consequences. This project answers three major questions concerning the relationship between trace element partitioning and the processes that influence it. One: using a common igneous mineral, clinopyroxene, as a base, how complete is the dataset on which our understanding of this relationship relies? Two: what are the dangers involved with basing models on experiments that contain higher than natural concentrations of trace elements? Three: how accurate and precise is the current numerical model that describes this relationship, and can it be improved? This project determined that the data contain gaps at high pressures and temperatures, are limited for felsic rock compositions, and are lacking for hydrous conditions. A set of experiments conducted on plagioclase feldspar crystallization from a base MORB composition containing various levels of dopants at below wt% levels reveals the presence of non-Henry's Law partitioning behavior through the disruption of the phase equilibria of the system. Lastly, the current clinopyroxene/melt rare earth element partitioning model (Wood and Blundy, 2003) is shown to reasonably, though less than ideally, describe the relationship between igneous processes and their trace-element partitioning results using the thermodynamics of the system. The accuracy was improved through adding a regression, which is based on the major element concentrations of the clinopyroxene and melt to the original numerical expressions. Title: Quantification of the temperature, pressure and compositional dependence of trace element partitioning : an experimental and theoretical study Author: Cunningham, Jennifer Lynn The thermodynamic history of the Earth is preserved in the trace element record created through igneous processes. The ability to interpret that record depends on the accuracy and precision of numerical models that connect igneous processes with their geochemical consequences. This project answers three major questions concerning the relationship between trace element partitioning and the processes that influence it. One: using a common igneous mineral, clinopyroxene, as a base, how complete is the dataset on which our understanding of this relationship relies? Two: what are the dangers involved with basing models on experiments that contain higher than natural concentrations of trace elements? Three: how accurate and precise is the current numerical model that describes this relationship, and can it be improved? This project determined that the data contain gaps at high pressures and temperatures, are limited for felsic rock compositions, and are lacking for hydrous conditions. A set of experiments conducted on plagioclase feldspar crystallization from a base MORB composition containing various levels of dopants at below wt% levels reveals the presence of non-Henry's Law partitioning behavior through the disruption of the phase equilibria of the system. Lastly, the current clinopyroxene/melt rare earth element partitioning model (Wood and Blundy, 2003) is shown to reasonably, though less than ideally, describe the relationship between igneous processes and their trace-element partitioning results using the thermodynamics of the system. The accuracy was improved through adding a regression, which is based on the major element concentrations of the clinopyroxene and melt to the original numerical expressions. Close

• 4. [Article] Mineralogical indicators of magmatic and hydrothermal processes in continental arc crust

  xviii, 177 p. : ill., maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.

  Citation × Citation Citation Abstract Copy Title: Mineralogical indicators of magmatic and hydrothermal processes in continental arc crust Author: Mercer, Celestine Nicole, 1979- Year: 2010, 2009 xviii, 177 p. : ill., maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. Title: Mineralogical indicators of magmatic and hydrothermal processes in continental arc crust Author: Mercer, Celestine Nicole, 1979- Year: 2010, 2009 xviii, 177 p. : ill., maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. Close

• 5. [Article] Large-volume rhyolite genesis in caldera complexes of the Snake River Plain

  xix, 189 p. : ill. (some col.), maps (some col.)

  Citation × Citation Citation Abstract Copy Title: Large-volume rhyolite genesis in caldera complexes of the Snake River Plain Author: Watts, Kathryn Erin, 1983- Year: 2011 xix, 189 p. : ill. (some col.), maps (some col.) Title: Large-volume rhyolite genesis in caldera complexes of the Snake River Plain Author: Watts, Kathryn Erin, 1983- Year: 2011 xix, 189 p. : ill. (some col.), maps (some col.) Close