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- Keyword
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- Moon (3)
- Adsorption (2)
- Diagenesis (2)
- Mars (2)
- Photometry (2)
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- Sulfur isotopes (2)
- Trace metals (2)
- APXS (1)
- Alkanes (1)
- Anoxygenic photosynthesis (1)
- Antarctica (1)
- Apollo (1)
- Apollo 12 (1)
- Aquatic systems, iron oxide transformation, methane, trace metal speciation, wetland (1)
- Arc magmatism (1)
- Arrokoth (1)
- Asteroid Vesta (1)
- Astrobiology (1)
- Backarc spreading (1)
- Box Modeling (1)
- Bronze production, Geochemical analysis, Paleo-environmental pollution, Public health, Shang Dynasty, Yinxu Anyang (1)
- Bulk Silicate Earth (1)
- CPO evolution (1)
- Calcite, feldspar, micropillar deformation, nanoindentation, olivine, quartz (1)
- Calvin-Benson-Bassham Cycle (1)
- Carbon Cycle (1)
- Carbon isotope (1)
- Carbonate-associated sulfate (1)
- Caves (1)
- Ceres (1)
Articles 1 - 30 of 35
Full-Text Articles in Physical Sciences and Mathematics
The Isotropic And Anisotropic Structure Of Antarctica From Seismic Inversion, Zhengyang Zhou
The Isotropic And Anisotropic Structure Of Antarctica From Seismic Inversion, Zhengyang Zhou
Arts & Sciences Electronic Theses and Dissertations
This dissertation utilizes multiple techniques of earthquake tomography to investigate the seismic structure of the crust and mantle beneath Antarctica. The isotropic structure of the Antarctic crust and upper mantle is now constrained by several seismic studies, but until now few studies have investigated the anisotropic structure. Therefore, in this study, I focus on the anisotropic structure, which is crucial information to understanding current or historic deformation and flow patterns, as well as the organic process of Antarctica. I use the data from the seismic stations deployed on the Antarctica continent during the past 20 years, as well as other …
A Synthesis-Based Approach To The Study Of Fe(Ii) Oxidation In Smectites, Robert Joe Kupper Ii
A Synthesis-Based Approach To The Study Of Fe(Ii) Oxidation In Smectites, Robert Joe Kupper Ii
Arts & Sciences Electronic Theses and Dissertations
Smectite clay minerals are present in diverse environments on Earth as a major product of silicate weathering. Although smectites are compositionally varied, they almost always incorporate iron. Iron-bearing smectites are an important component of the biogeochemical iron cycle, serving as a major iron fraction in many soils and altered rocks as well as participating in redox reactions within the surrounding environment. Iron incorporates into smectites in the ferric [Fe(III)] form at the modern, oxygenated surface of Earth but clays forming in anoxic settings instead incorporate ferrous iron [Fe(II)]. Owing to their ubiquity at the surface of the modern Earth, the …
Low-Temperature Plasticity Of Rock-Forming Minerals, Michael Keith Sly
Low-Temperature Plasticity Of Rock-Forming Minerals, Michael Keith Sly
Arts & Sciences Electronic Theses and Dissertations
The rheology of the Earth’s crust and mantle is in part governed by the physical and mechanical properties of feldspar, quartz, calcite, and olivine. Over the past several decades a significant number of experimental studies have been performed on these minerals. Conventional experiments are generally performed at elevated temperatures because much of the viscoplastic deformation of these minerals is accommodated by high-temperature mechanisms. There is, however, evidence of viscoplastic deformation at lower temperatures (T ≤ 0.3Tm) in the uppermost mantle and throughout the crust. Micromechanical experimental techniques, including nanoindentation and micropillar deformation, can be used to achieve plastic deformation at …
Trace Metal Speciation And Impacts On Iron Oxide Transformations And Biogeochemical Cycling, Jinshu Yan
Trace Metal Speciation And Impacts On Iron Oxide Transformations And Biogeochemical Cycling, Jinshu Yan
Arts & Sciences Electronic Theses and Dissertations
Trace metals in anoxic aquatic systems are of great importance for iron oxide transformations and biogeochemical cycling. The presence of trace metal can alter iron oxide transformations under anoxic conditions. Trace metals are also essential for microbially-mediated biogeochemical processes occurring in anoxic wetland soils and stream bed sediments, but low availability of these elements may inhibit anaerobic element cycling and transformations. Trace metal speciation is also vital for understanding the environmental control on nutrients and contaminants. Three projects were conducted to explore trace metal speciation and its associated effect on iron oxide transformations and biogeochemical cycling. First, the Fe(II)-promoted conversion …
Paleo-Environmental Pollution Of The Bronze Production During The Shang Period At Anyang, Henan Province, China, Yi-Ling Lin
Paleo-Environmental Pollution Of The Bronze Production During The Shang Period At Anyang, Henan Province, China, Yi-Ling Lin
Arts & Sciences Electronic Theses and Dissertations
Paleo-environmental pollution is invested in both identifying anthropogenic activities and evaluating the environmental condition and its impact on humans to understand human-environment relationships and the human experience of the past. This project first investigates the environmental and health consequences of bronze production during the Shang period at Anyang. As a contribution to the growing scholarship in paleo-environmental and archaeological studies, this dissertation uses Shang bronze production in Anyang as a case study into how paleo- environmental pollution study can inform us about the on environmental and health conditions of lives in the Bronze Age China. Through geochemical analysis (ICP-MS, ICP-OES) …
Petrology, Geochemistry, And Experimental Studies Of Mafic Enclaves And Amphibole At Shiveluch Volcano, Kamchatka, Andrea Elizabeth Goltz
Petrology, Geochemistry, And Experimental Studies Of Mafic Enclaves And Amphibole At Shiveluch Volcano, Kamchatka, Andrea Elizabeth Goltz
Arts & Sciences Electronic Theses and Dissertations
This thesis connects mineralogical, chemical, and physical observables in quenched mafic inclusions from Shiveluch Volcano in Kamchatka and high pressure and temperature experiments to elucidate the water content of primitive magmas at Shiveluch, the timing of magmatic recharge events relative to eruption, and the petrogenetic history of andesites erupted at Shiveluch. Using the petrology of basaltic andesite mafic inclusions erupted from Shiveluch, in Chapter 2, the water content of primitive magmas at Shiveluch is found to be 8-10 wt%, which is two to three times higher than the global average determined by other methods, and the temperature of primitive magmas …
Potassium Isotope Cosmochemistry, Zhen Tian
Potassium Isotope Cosmochemistry, Zhen Tian
Arts & Sciences Electronic Theses and Dissertations
In Chapter 1, I review the geochemical and cosmochemical properties of potassium (K). Classified as a moderately volatile element, K serves as a robust proxy for understanding the key processes during nebular/planetary evaporation events. I review different mechanisms of volatile depletion among various planetary materials: mass-dependent variations in “nebular” processes; mass-independent variations among different nucleosynthetic sources; or planetary-scale volatile depletion processes. Furthermore, I provide an optimized K purification procedure via ion-exchange chromatography and a high-precision K isotope analysis technique using Neptune plus Multiple Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS) in both “cold plasma” and “dry plasma” methods. I also …
Iron And Manganese Oxidation By Oxyhalogen Species: Implications For Paleoenvironmental Reconstruction On Mars, Kaushik Mitra
Iron And Manganese Oxidation By Oxyhalogen Species: Implications For Paleoenvironmental Reconstruction On Mars, Kaushik Mitra
Arts & Sciences Electronic Theses and Dissertations
As the nearest planetary neighbor with potential earlier habitable conditions, Mars is replete with minerals that hold clues to its past chemistry and evolution of the aqueous systems. Oxidized iron (Fe) and manganese (Mn) minerals on Mars are geochemical markers of such environments in which they formed and record past pH, redox conditions, and intensity of water-rock interaction. Fe and Mn oxides can therefore be used to reconstruct past Martian environmental conditions from settings where aqueous fluids were active. Various processes that form Fe and Mn oxide minerals on Mars have been previously proposed, including chemical oxidation using molecular oxygen …
Landscape Evolution At Endeavour And Gale Craters On Mars, And How Terrain Characteristics Correlate With Mineralogy On Lower Mount Sharp, Gale Crater, Madison Nicole Hughes
Landscape Evolution At Endeavour And Gale Craters On Mars, And How Terrain Characteristics Correlate With Mineralogy On Lower Mount Sharp, Gale Crater, Madison Nicole Hughes
Arts & Sciences Electronic Theses and Dissertations
The geomorphic expression of terrain provides information such as the underlying lithologic properties and the dominant surface processes. By examining the surface morphology of two impact craters on Mars that have been explored by rovers, we can synergistically combine orbital and ground observations to obtain a deeper insight into the geologic history. In this dissertation, we analyze the landscape evolution of Endeavour and Gale craters, which have been explored by the Opportunity and Curiosity rovers, respectively. This is accomplished largely by analyzing the topography on a larger scale using images from Mars orbiters and their associated Digital Elevation Models, combined …
Experimental Constraints On Igneous Iron Isotopic Fractionation And Diffusion, Kelsey Brianne Prissel
Experimental Constraints On Igneous Iron Isotopic Fractionation And Diffusion, Kelsey Brianne Prissel
Arts & Sciences Electronic Theses and Dissertations
The chapters of this dissertation detail experimental studies that have been conducted in order to determine the diffusivity of iron in the mineral ilmenite (FeTiO3) and the high-temperature behavior of iron isotopes during magma crystallization. The experimental study in Chapter 2 is the first to quantify the rates of cation diffusion in ilmenite. Integrating experimentally determined Fe-Mg and Fe-Mn interdiffusivities with disequilibrium preserved in ilmenite grains from natural volcanic samples, this work has established a new geospeedometry tool with which to estimate the time between magmatic perturbation and eruption on the timescale of hours to months. Chapter 3 investigates the …
Seismicity And Shallow Structure At The Mariana Subduction Zone, Melody Eimer
Seismicity And Shallow Structure At The Mariana Subduction Zone, Melody Eimer
Arts & Sciences Electronic Theses and Dissertations
This dissertation examines the incoming Pacific plate and the overriding forearc at the Mariana Subduction Zone using passive and active source seismology. The incoming plate, with water bound in the plate sediment, crust and mantle, is of interest to help constrain the global water cycle. The seismogenic zone at Mariana is noted for being an aseismic end-member, while extensional faults and active serpentine mud volcanoes characterize the forearc. I use an ocean bottom seismograph (OBS) deployment spanning both the incoming Pacific Plate and the forearc to study the seismicity and shallow structure. The passive source component of the deployment consists …
Internal Structures And Spin Evolutions Of Small Bodies In The Solar System And Their Geophysical Implications: A Case Study On Ceres, Vesta, And Arrokoth, Xiaochen Mao
Arts & Sciences Electronic Theses and Dissertations
Asteroids and Kuiper belt objects are for the most part the remnant planetesimals that have not been able to form into planets. These small bodies’ evolutionary pathways encode information from the early days of the Solar System. Recent space missions such as Dawn and New Horizons have now made detailed geological investigations of small bodies (i. e. , Ceres, Vesta, and Arrokoth) possible. In this thesis, I use geophysical modeling to study small body internal structure and to investigate spin history under the influence of impacts. I analyze the gravity and shape data obtained by Dawn of Ceres and make …
Protean Caves And Cyrenean Grottos: The Subterranean World Of Vergil's Fourth Georgic, Kirby Schoephoerster
Protean Caves And Cyrenean Grottos: The Subterranean World Of Vergil's Fourth Georgic, Kirby Schoephoerster
Arts & Sciences Electronic Theses and Dissertations
Using the studies and methodologies spearheaded by the burgeoning field of geomythology, this project aims to reevaluate one of the most famous works of ancient literature, the Georgics of Vergil, within the context of karst geology. In other words, I plan to critically investigate the famous myth of Aristaeus using a geomythological lens that focuses on how Vergil treats caves and cave systems as related to (his) myth. The didactic poem as a whole, and much less so the myth of Aristaeus, has been assessed relatively little by archaeologists, and by geomythologists not at all. Yet, book four contains an …
Understanding The Physiology Of Extracellular Electron Uptake In Purple Nonsulfur Bacteria, Michael Singh Guzman
Understanding The Physiology Of Extracellular Electron Uptake In Purple Nonsulfur Bacteria, Michael Singh Guzman
Arts & Sciences Electronic Theses and Dissertations
Microbially catalyzed oxidation-reduction reactions drive nutrient cycling and energy flux on Earth. Photoautotrophs, which include the cyanobacteria (oxygenic) and purple and green sulfur bacteria (anoxygenic), transform light energy into chemical energy and are responsible for substantial global primary productivity. Anoxygenic phototrophs, in particular, play a crucial role in biogeochemical cycling in anoxic illuminated environments because of their ability to oxidize an array of inorganic compounds for CO2 fixation. Electron donors include molecular hydrogen, nitrite, and reduced sulfur compounds. Recent evidence has also suggested that solid-phase conductive substances (SPCSs), including rust (mixed-valent iron minerals) and their proxies (poised electrodes), can serve …
Investigation And Classification Of Planetary Materials And Surfaces Using Novel Methods To Analyze Large Compositional Datasets: Quantitative X-Ray Compositional Mapping And Lunar Reconnaissance Orbiter Narrow Angle Camera Photometric Analysis, Timothy Michael Hahn
Arts & Sciences Electronic Theses and Dissertations
Our understanding of planetary bodies and their surfaces originates from measurements made by spacecraft instruments and laboratory analysis of extraterrestrial materials. Integration of these datasets can significantly advance the fields of planetary geology and geochemistry. The goal of my dissertation research has been to develop novel methods for interrogating extraterrestrial samples and planetary regoliths, with an emphasis on integrating these complementary datasets. Additionally, my research has focused on utilizing ‘big data’ within the geoscience and planetary science communities, whether that data be geospatial or geochemical in nature. My dissertation research involves two separate, but related projects: (1) coupling Apollo 17 …
The Effect Of Depositional Environment And Early Marine Diagenesis On Carbonate-Associated Sulfate, Jocelyn Ann Richardson
The Effect Of Depositional Environment And Early Marine Diagenesis On Carbonate-Associated Sulfate, Jocelyn Ann Richardson
Arts & Sciences Electronic Theses and Dissertations
The long-term redox state of Earth’s surface environments is governed by the relative burial proportions of redox-sensitive carbon and sulfur species throughout geologic time. The sulfur isotopic signature of seawater sulfate (δ34SSO4) traces the relative proportions of sulfur buried as sulfide (commonly pyrite) and sulfate (as evaporites, barite or carbonate-associated sulfate) and weathering source to the ocean. Thus, δ34SSO4 is a powerful tool to understand the evolution of redox conditions and the marine biogeochemical sulfur cycle. Due to the spatial and temporal extent of carbonates in the rock record, carbonate-associated sulfate (δ34SCAS) is a common proxy for the isotopic composition …
Local Environmental Controls On Sulfur Isotope Ratios In Marine Sedimentary Iron Sulfide Minerals, Roger Nicholas Bryant
Local Environmental Controls On Sulfur Isotope Ratios In Marine Sedimentary Iron Sulfide Minerals, Roger Nicholas Bryant
Arts & Sciences Electronic Theses and Dissertations
The controls on the bulk sulfur isotopic composition of marine sedimentary iron sulfides (often referred to simply as pyrite; δ34Spyr) are poorly understood. Nevertheless, many have employed δ34Spyr in efforts to reconstruct the past operation of the biogeochemical sulfur cycle, from the planetary scale down to individual microbial metabolisms. This practice has been thrown into doubt by a growing body of evidence that suggests δ34Spyr is strongly controlled by local environmental conditions. This dissertation describes efforts to determine the mechanisms responsible for the link between local environmental conditions and δ34Spyr. In order to do this, we developed novel laboratory procedures …
Quantifying Lithochemical Diversity Of Martian Materials Using Hierarchical Clustering And A Similarity Index For Classification, Michael Conner Bouchard
Quantifying Lithochemical Diversity Of Martian Materials Using Hierarchical Clustering And A Similarity Index For Classification, Michael Conner Bouchard
Arts & Sciences Electronic Theses and Dissertations
We are currently living in the golden age of robotic exploration of Mars, with a continued robotic presence there since 1997. Next to Earth, Mars is the planet about which we have gathered the most geologic information. Unlike Earth, Mars does not appear to have plate tectonics, and the planet’s primary and secondary crust is dominated by basalts. Understanding the compositional diversity of the materials that make up the martian crust will give us a better insight into the geologic processes that formed the planet and its subsequent evolution. One large and growing source of martian surface compositions is the …
Understanding The Meaning Of Microbialites As Geobiological Archives, Scott Randall Beeler
Understanding The Meaning Of Microbialites As Geobiological Archives, Scott Randall Beeler
Arts & Sciences Electronic Theses and Dissertations
Microbialites, sedimentary structures formed from the interaction of microorganisms with their environment, provide one of the oldest and most complete records of life on Earth, making them an invaluable tool in the field of geobiology. However, much of the information that could be gained from microbialites remains obscured due to our incomplete understanding of how variability in the microbial, geochemical, and physical processes driving their formation affect their morphological and geochemical characteristics. Modern environments of active microbialite formation provide the opportunity to study the relationship between variability in these environmental processes and the resultant mineral product and can act as …
Fundamental Controls On The Reactivity Of Aluminum Oxide And Hydroxide Surfaces: Contributions Of Surface Site Coordination States And Interfacial Water Structure, Tingying Xu
Arts & Sciences Electronic Theses and Dissertations
Chemical reactions at mineral-water interfaces are of great importance in many geological and environmental processes. Essential to many of these is adsorption because it directly controls contaminant fate and nutrient availability, promotes the nucleation and growth of minerals, initiates surface redox reactions, and plays a crucial role in carbon cycling and sequestration. These reactions occur at mineral surface sites having multiple possible coordination states that interact with both adsorbates and water. While general ion adsorption mechanisms and surface charging behaviors are well established, the roles of individual surface functional group types and water in affecting the structure and reactivity of …
Spectral And Stratigraphic Mapping Of Layered Sulfate Deposits On Mars Using Advanced Crism Data Processing Techniques, Kathryn Elizabeth Powell
Spectral And Stratigraphic Mapping Of Layered Sulfate Deposits On Mars Using Advanced Crism Data Processing Techniques, Kathryn Elizabeth Powell
Arts & Sciences Electronic Theses and Dissertations
We apply orbital remote sensing of Mars to analyze the mineralogy and geologic setting of two areas near rover landing sites. We use the Compact Reconnaissance Orbiter for Mars (CRISM) observations, modeled to single scattering albedo, to identify and map hydrated sulfates in layered sedimentary sequences in these two locations. In Meridiani Planum, the Opportunity rover has characterized a ~10 m section of sulfate-bearing deposits known as the Burns formation. At our study area in ~20 km to the south at Iazu Crater, we found that the crater walls have strong spectral signatures of polyhydrated sulfate, strongly correlated with a …
Seismic Structure Near The Mariana Trench And Deep Earthquake Triggering In The Tonga Flat Slab, Chen Cai
Seismic Structure Near The Mariana Trench And Deep Earthquake Triggering In The Tonga Flat Slab, Chen Cai
Arts & Sciences Electronic Theses and Dissertations
This dissertation utilizes multiple techniques of earthquake location and seismic tomography to investigate deep seismicity in the Tonga flat slab region and the upper mantle structure of the Mariana subduction zone. I study the rupture property and aftershock distributions of the largest earthquake ever recorded in the Tonga flat slab region, defined by scattered seismicity and velocity anomalies. These, along with background seismicity, regional 3-D seismic velocity model and tectonic reconstructions of relict Vitiaz subduction zone, suggest the earthquakes are occurring in the final portion of the slab subducted at the now inactive Vitiaz trench. The associated Coulomb stress change …
The Impact Of Small Organic Acids On Iron And Manganese Mineral Transformations And The Fate Of Trace Metals, Elaine Denise Flynn
The Impact Of Small Organic Acids On Iron And Manganese Mineral Transformations And The Fate Of Trace Metals, Elaine Denise Flynn
Arts & Sciences Electronic Theses and Dissertations
Iron and manganese oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals through adsorption and coprecipitation. At redox interfaces, biogeochemical processes generate conditions with coexisting dissolved Fe(II) and solid-phase Fe(III). In such systems, Fe(II) induces the recrystallization of iron oxides through coupled mineral growth and dissolution due to electron transfer as oxidative adsorption of Fe(II) and reductive dissolution of Fe(III) occur. Aqueous Mn(II) adsorption onto Mn(III/IV) oxides also likely involves oxidation although likely through different mechanisms than that of the Fe system because of the potential for …
Genetic And Biological Studies On Solanum Plants: Insights Into The Leaf Wax Alkane Paleoclimate Proxy, Amanda Lorraine Dorothy Bender
Genetic And Biological Studies On Solanum Plants: Insights Into The Leaf Wax Alkane Paleoclimate Proxy, Amanda Lorraine Dorothy Bender
Arts & Sciences Electronic Theses and Dissertations
The hydrogen isotopic composition (δ2H) of precipitation records fluxes of water in the hydrological cycle, and can reflect climatic variables such as temperature and humidity. Leaf wax n-alkanes can record δ2H of precipitation; consequently, n-alkanes extracted from sedimentary archives are commonly used as proxies for paleoenvironmental reconstruction. However, the utility of the leaf wax paleoclimate proxy is modulated by uncertainty about how physiological processes affect hydrogen isotopic compositions during alkane biosynthesis. This work aims to improve our understanding of the leaf wax paleoclimate proxy by examining biological and environmental sources of variability on cuticular leaf waxes. We used Solanum (tomato) …
Effects Of Regolith Properties On Uv/Vis Spectra And Implications For Lunar Remote Sensing, Ecaterina Ioana Coman
Effects Of Regolith Properties On Uv/Vis Spectra And Implications For Lunar Remote Sensing, Ecaterina Ioana Coman
Arts & Sciences Electronic Theses and Dissertations
Lunar regolith chemistry, mineralogy, various maturation factors, and grain size dominate the reflectance of the lunar surface at ultraviolet (UV) to visible (VIS) wavelengths. These regolith properties leave unique fingerprints on reflectance spectra in the form of varied spectral shapes, reflectance intensity values, and absorption bands. With the addition of returned lunar soils from the Apollo and Luna missions as ground truth, these spectral fingerprints can be used to derive maps of global lunar chemistry or mineralogy to analyze the range of basalt types on the Moon, their spatial distribution, and source regions for clues to lunar formation history and …
Evolution Of Olivine Crystallographic Preferred Orientation In The Upper Mantle -- Implications For The Interpretation Of Seismic Anisotropy, Yuval Boneh
Arts & Sciences Electronic Theses and Dissertations
Earth’s plate tectonics is the outermost manifestation of mantle convection. Understanding plate tectonics at the global scale requires understanding of regional processes near plate boundaries. Flow patterns in the upper mantle are generally inferred from observations of anisotropy of seismic wave speed. In plate interiors, where flow patterns are assumed to be simple, interpretation of seismic anisotropy is straightforward. However, near plate boundaries, where flow patterns are complex, different strategies for interpreting seismic anisotropy may be required. This dissertation examines, using experimental and numerical tools, the effects of complex flow patterns on the evolution of olivine crystallographic preferred orientation (CPO). …
The Evolution Of Igneous Rocks On The Moon: Insights From Lunar Meteorites And Apollo 12, Sarah Valencia
The Evolution Of Igneous Rocks On The Moon: Insights From Lunar Meteorites And Apollo 12, Sarah Valencia
Arts & Sciences Electronic Theses and Dissertations
Lunar samples are the “ground truth” that anchor our knowledge of lunar geology. Lunar rocks present many challenges in that they are often brecciated (composed of multiple rock types), and their location of formation on the Moon is not always known. The brecciated nature of lunar samples also has advantages – multiple lithologies that have a related petrogenetic history can occur in the same sample, allowing us to trace the petrogenetic history of evolving magmatic systems. In this dissertation, I examine two evolved magmatic systems, using samples from the Northwest Africa (NWA) 773 clan of lunar meteorites and Apollo 12 …
Plate Tectonics Initiation On Earth-Like Planets: Insights From Numerical And Theoretical Analysis Of Convection-Induced Lithospheric Failure, Teresa Wong
Arts & Sciences Electronic Theses and Dissertations
Plate tectonics is central to many aspects of the geology and evolution of terrestrial planets, yet it is only observed on the Earth while all other known planets are covered with a stagnant lithosphere. Plate motions on the Earth are mostly driven by the pull of subducting slabs, therefore understanding the initiation of subduction is crucial to understanding plate tectonics initiation. On a one-plate planet which lacks the forces due to plate motions, some other mechanisms will have to cause the first episode of subduction to mobilize the surface. Sublithospheric convection has been proposed as a possible mechanism that induce …
Seismic Array Studies Of Antarctica And Madagascar, Martin James Pratt
Seismic Array Studies Of Antarctica And Madagascar, Martin James Pratt
Arts & Sciences Electronic Theses and Dissertations
The scope of this dissertation is broad, involving seismic array studies from Antarctica and Madagascar, and includes aspects of glaciology and oceanography as well as solid Earth geophysics. Chapter 2 focuses on the study of stickslip motion of the Whillans Ice Stream, West Antarctica. It includes methods combining seismic array and GPS time series, from ice stream based-sensors, to determine source dynamics in the framework of an earthquake source. The source characteristics are then analyzed to explain far-field seismic observations of ice stream- sourced surface waves detected throughout West Antarctica. Locations of asperities, or sticky- spots, that cause the Whillans …
Seismic Studies Of The Tonga Subduction Zone And The Lau Back-Arc Basin, Songqiao Wei
Seismic Studies Of The Tonga Subduction Zone And The Lau Back-Arc Basin, Songqiao Wei
Arts & Sciences Electronic Theses and Dissertations
This dissertation utilizes multiple techniques of seismic tomography and earthquake location to investigate the upper mantle structure and intermediate-depth seismicity of the Tonga subduction zone, the Lau back-arc basin, and adjacent regions. Data for these studies consist of broadband records from 49 ocean bottom seismographs and 17 island-based seismic stations deployed for one year in 2009-2010, as well as more limited earlier datasets. I conducted tomographic studies of Rayleigh wave velocity and body wave attenuation to examine the thermal variations and the distribution of partial melt in the mantle wedge. The shear-wave velocity structure is first determined using only teleseismic …