Geological Sciences Theses and Dissertations

Permanent URI for this collection

https://hdl.handle.net/1794/6057

Browse

Browsing Geological Sciences Theses and Dissertations by Author "Bindeman, Ilya"

Now showing 1 - 6 of 6
  • Thumbnail Image
    ItemOpen Access
    Experimental Investigation of Rates and Mechanisms of Isotope Exchange (O,H) Between Volcanic Ash and Isotopically-Labeled Water
    (University of Oregon, 2012) Nolan, Gary; Nolan, Gary; Bindeman, Ilya
    The hydrogen and oxygen isotope ratios in hydrous minerals and volcanic glass are used as paleo-proxies to infer isotopic values of meteoric waters and thus paleo-climate conditions. Long-term exposure experiments with Mt Mazama ash reacted with isotopically labeled water (+650#8240; #948;
  • Thumbnail Image
    ItemOpen Access
    H and O Isotope Systematics in Volcanic Glass: Hydration Experiments and their Application to Volcanic and Hydrothermal Processes
    (University of Oregon, 2021-11-23) Hudak, Michael; Bindeman, Ilya
    The goal of my dissertation is to expand the application of H2O, δD, and δ18O in silicic volcanic glass to a greater diversity of pyroclast cooling, degassing, and rehydration histories. All pyroclasts must cool from magmatic temperatures and those at Earth’s surface, which can affect the distribution of H2O and its constituent isotopes in glass. Vapor hydration experiments of silicic glass constrain H2O solubility and diffusivity in glass between 175°C and 375°C. Modeling of the experimental data demonstrates that H2O diffusivities approximate extrapolations of high temperature relationships, but H2O solubility in glass is at least 1.5 wt% higher than predicted by extrapolating H2O solubilities in melts. Next, I evaluate the time evolution of δD in experimental glasses with an isotope reaction-diffusion model. Below 250°C, the δD fractionation between glass and H2O vapor (103lnαg-v) is between −25‰ and −33‰, overlapping with low temperature D/H 103lnαglass-H2O values. The boundary composition of the model controls the bulk glass composition rather than reactions of H2Om to OH− internal to the glass during hydration. These results enable interpretation of H2O, δD, and δ18O in natural samples over a large range of temperature conditions, which I first apply to cooling ignimbrites from the 7700 BP Mt. Mazama eruption and the 1912 Novarupta eruption. This work also highlights that glass hydration of pumaceous can occur rapidly over days to months and lock in a δD value that records local meteoric waters as a paleoclimate proxy. Finally, I show that glass rehydration can occur even more rapidly on the timescales in eruptive volcanic plumes with meteoric water sources using H2O–δD compositions in a suite of tephras from the 2009 eruption of Redoubt volcano. Waning influence of a summit glacier has no effect on tephra compositions, suggesting moist air entrainment is the rehydration source. Furthermore, H2O diffusion modeling illustrates that the temperatures at which erupted material comes into contact with an H2O is more important than the quench rate of the pyroclast as rehydration can occur at the fastest quench rates if H2O is available. Tephra H2O–δD compositions therefore record water-glass interactions in multiple volcanic environments.
  • Thumbnail Image
    ItemOpen Access
    An Isotopic, Trace Element, and Volatile Investigation of Large-Volume Rhyolite Generation at the Picabo Volcanic Field of the Yellowstone Hotspot Track
    (University of Oregon, 2014-06-17) Drew, Dana; Bindeman, Ilya
    Rhyolites of the Picabo volcanic field (10.4-6.6 Ma) of the Yellowstone hotspot in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain. This study presents new O and Hf isotope data and U-Pb geochronology from individual zircons, O isotope data from major phenocrysts, whole rock Sr and Nd isotope data, whole rock geochemistry, and trace element and volatile analyses of quartz-hosted melt inclusions, which were used to characterize the evolution of rhyolite generation through the eruptive sequence. The chemical composition of the first eruption of the caldera complex, the Tuff of Arbon Valley, suggests magma generation through repeated magma injection into the crust, remelting, crystallization, mixing, and crustal assimilation. Subsequent eruptions have diverse and low δ18O signatures indicating rhyolite generation through the remelting of variably hydrothermally altered volcanics, followed by rapid batch assembly. This thesis includes co-authored material previously published.
  • Thumbnail Image
    ItemOpen Access
    Oxygen and hydrogen investigation of volcanic rocks: Petrogenesis to paleoclimate
    (University of Oregon, 2016-10-27) Seligman, Angela; Bindeman, Ilya
    Knowledge of the isotopic evolution of volcanic eruptions is essential to volcanologists, geochemists, and paleoclimatologists. I isotopically evaluate the evolution of magmas from their initial formation, to eruption, and then to their alteration during the diffusion of environmental waters into volcanic glass. I focus first on the formation and evolution of large, caldera-forming eruptions from both Gorely volcano in Kamchatka, Russia and 30–40 Ma caldera forming eruptions through Oregon in the United States of America. I utilize oxygen (δ18O), hafnium (εHf), strontium (87Sr/86Sr), and neodymium (143Nd/144Nd) isotopes to document the creation of caldera-forming eruptions at these eruptive centers through the melting of surrounding crust. I also use U-Pb and 40Ar/39Ar to document the timescales of the formation of these large-volume silicic eruptions. Following eruption, the volcanic glass in tephra and ash can slowly take in environmental water. It is thought that the hydrogen isotopic ratio (δD) of these waters can be used to determine paleoenvironments from the time that the volcanic glass was deposited. The latter portion of my dissertation focuses on the use of hydrogen isotopes of environmentally hydrated volcanic glass to determine paleoenvironments, and the calibration of the TCEA to analyze oxygen isotopes of hydrated volcanic glass. I first focus on the rate of diffusion of water at ambient temperature to better understand the time frame necessary to hydrate volcanic glass for use as a paleoenvironmental indicator. I also document the hydrogen isotopic ratios that result from the diffusion of water into volcanic glass, which is documented as a decrease in δD with an increase in secondary hydration in all regions worldwide except equatorial. Finally, I focus on the earliest stages of diffusion of water into volcanic glass by analyzing tephra deposits that were collected within days of the 1980 eruptions of Mount St. Helens as well as tephra deposits recently collected in 2015 to identify changes in water concentration and hydrogen isotopic ratios over an ~35 year period.
  • Thumbnail Image
    ItemOpen Access
    Triple Oxygen Isotope in High-Temperature Hydrothermally Altered Rocks: A Record of Paleoclimate and Ancient Hydrosphere-Rock Interactions
    (University of Oregon, 2020-02-27) Zakharov, David; Bindeman, Ilya
    In this dissertation, I use isotopes of H, O and Sr to trace interaction between meteoric waters, seawater and rocks in modern and extinct areas of high-temperature hydrothermal alteration. The ancient hydrothermal systems are used here as a tool to investigating paleoclimate, paleogeography, and the long-term evolution of global isotope budget of hydrosphere. The dissertation begins with exploring triple oxygen isotopes to trace local fluids in modern geothermal systems of Iceland (Krafla, Reykjanes), where seawater and meteoric waters participate in reaction with mid-ocean ridge basalts at high temperatures (> 250 °C). Next, I present results of the triple oxygen and hydrogen isotope study of the 2.43-2.41 Ga altered basalts from the Vetreny belt, Russia to constrain the isotope composition of contemporaneous seawater. I find that the δD, δ18O and Δ17O values of the early Paleoproterozoic seawater were similar to that of Cenozoic seawater values. This study is supported by demonstrating the combined strontium and oxygen isotope exchange between Precambrian seawater and basalt with implications for the effects of low marine sulfate levels. Further, I explore the low δ18O signature of the Belomorian belt, Russia that was likely generated during subglacial rifting and magmatism at low latitudes in the early Paleoproterozoic. Using Δ17O approach, I reconstruct the δ18O values of the low latitude precipitation to ca. -40 ± 5 ‰. This value is evident of an active hydrologic cycle facilitated through evaporation of seawater and precipitation at extremely low temperatures (between -45 and -40 °C) during the Paleoproterozoic snowball Earth glaciations. Using high-precision U-Pb zircon dating, I constrain the timing of subglacial magmatism to 2.44-2.41 Ga and 2.29 Ga. The triple oxygen isotope approach is also applied to the low δ18O 2.42-2.38 Ga Scourie dikes of the Lewisian complex, Scotland to test for assimilation or/and recycling of very low δ18O component, similar to the rocks from the Belomorian belt. This dissertation includes previously published and unpublished co-authored material. This dissertation is accompanied by electronic supplemental file that contains U-Pb geochronology data.
  • Thumbnail Image
    ItemOpen Access
    Understanding the Origins of Yellowstone Hot Spot Magmas Through Isotope Geochemistry, High-Precision Geochronology, and Magmatic-Thermomechanical Computer Modeling
    (University of Oregon, 2018-09-06) Colon, Dylan; Bindeman, Ilya
    The last several years have seen renewed interest in the origin of silicic magmas thanks to the developments of new microanalytical techniques allowing the measurement of the isotopic and trace element compositions of erupted magmas on sub-crystal length scales. Concurrently, there has been rapid improvement in the sophistication of computer modeling of igneous systems. This dissertation is an interdisciplinary study of the rhyolites of the Yellowstone hotspot track using both techniques. Chapters II-IV, which have all been published in existing journals, are a detailed study of the O and Hf isotopic compositions of zircon phenocrysts from large rhyolitic eruptions in the central Snake River Plain, and from rhyolites which erupted in Oregon, Idaho, and Nevada coeval with the Columbia River flood basalts. They show that rhyolites are derived from combinations of fractionates of mantle-derived basalts and of different crustal end-members which are identifiable by their distinct isotopic end-member compositions. In the Snake River Plain and Yellowstone, they recognize a common trend where early erupted rhyolites have a strong signature of melting of ancient Precambrian crust, whereas later erupted rhyolites more closely resemble the mantle in their radiogenic isotopes and are more likely to be depleted in oxygen isotopes. Diversity in zircon grain compositions also documents a batch mixing process in which multiple compositionally distinct magma bodies are assembled into a larger common magma body prior to eruption. In Chapters V and VI, the former of which has been published with the latter in preparation, a new series of magmatic-thermomechanical models is presented which assume that melts rising through the crust are arrested by strong rheological contrasts. The strongest such contrast occurs at the brittle-ductile transition at 5-10 km depth, leading to the formation of a 10-15 km thick mafic mid-crustal sill, which separates upper and lower-crustal zones of partial melt, corroborating previous geophysical imaging studies. In Chapter VI, the above isotopic trends are replicated in the modeling scheme, which shows that the source depth of crustal melts tends to shallow with time through a combination of crustal heating and repeated caldera collapses. This dissertation includes both previously published co-authored material.