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- Seismology (2)
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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Single-Crystal Elasticity Of Earth’S Mantle Transition Zone Minerals And High Pressure-Temperature Phase Equilibrium Experiments On Martian Basalts, Wenyi Zhou
Earth and Planetary Sciences ETDs
Wadsleyite and ringwoodite are major minerals in the Earth’s Mantle Transition Zone. Global and local seismic studies have detected strong lateral variations in seismic velocity and anisotropy in the Mantle Transition Zone, reflecting temperature and possible composition variations. Interpretation of these seismic observations requires knowledge of thermoelastic properties of wadsleyite and ringwoodite with different compositions (water and Fe contents) under high pressure-temperature conditions. In this dissertation, we have measured single-crystal elastic properties of wadsleyite and ringwoodite under high pressure-temperature conditions by Brillouin spectroscopy. Based on our measurements and previous experimental results, we further model the effects of water and Fe …
Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow
Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow
Earth and Planetary Sciences ETDs
Natural processes like mantle convection and plate tectonics dominate Earth’s seismic structure. Recently human activities have increasingly influenced the deformation of the shallow crust. In this dissertation, passive source seismology was used to constrain seismic discontinuities in the mantle transition zone and seismogenic structures in induced earthquake settings. Using a novel sampling method and uniform processing approach, I found the 410-km discontinuity is thermally and compositionally variable. Using a machine- learning approach, I found the three main zones of seismicity in the Raton Basin consist of short faults or fault segments with variable orientations. The zone that hosted a Mw …
A Rapid High-Precision Analytical Method For Triple Oxygen Isotope Analysis Of Co2 Gas Using Tunable Infrared Laser Direct Absorption Spectroscopy, Nathan Perdue, Zachary Sharp, David Nelson Jr., Rick Wehr, Christoph Dyroff
A Rapid High-Precision Analytical Method For Triple Oxygen Isotope Analysis Of Co2 Gas Using Tunable Infrared Laser Direct Absorption Spectroscopy, Nathan Perdue, Zachary Sharp, David Nelson Jr., Rick Wehr, Christoph Dyroff
Earth and Planetary Sciences ETDs
Rationale
The simultaneous analysis of the three stable isotopes of oxygen – triple oxygen isotope analysis – has become an important analytical technique in natural sciences. Determination of the abundance of the rare 17O isotope in CO2 gas using magnetic sector isotope ratio mass spectrometry is complicated by the isobaric interference of 17O by 13C (13C16O16O and 12C16O17O both have mass 45 amu). A number of analytical techniques have been used to measure the 17O/16O ratio of CO2 gas. They …
Observational Constraints On The 520 Km Mantle Discontinuity, Mantle Transition Zone Anisotropy, And Local Seismicity At Mount St. Helens, Han Zhang
Earth and Planetary Sciences ETDs
Seismology provides valuable observational constraints to thermal and compositional states at inaccessible depths via understanding how elastic wave propagating through them. While many of fundament questions regarding solid Earth structures have been addressed during its more than 100 years history, some details remain unfilled and carefully designed approaches are needed to complete the pictures. This dissertation contributes observational constraints on three topics with newly developed methods. 1) We detected a controversial mantle discontinuity at about 520 km and concluded a mean mantle composition close to the Pyrolite model based on its seismic properties. 2) We isolated anisotropic effects in mantle …
Tree Ring Isotopic Reconstruction Of Hurricane Dolores, Jonathan Kane
Tree Ring Isotopic Reconstruction Of Hurricane Dolores, Jonathan Kane
Earth and Planetary Sciences ETDs
Tree rings contain high-resolution climate proxies of temperature and precipitation (Hughes et al., 1982; Fritts 2012; Scuderi 1993). The objective of this study was to use tree ring cellulose, specifically measuring δ18O - the oxygen-18 to oxygen-16 stable isotope ratio- to investigate the impact of Hurricane Dolores, a tropical cyclone that produced heavy precipitation in the Sierra Nevada in July 2015. Prior studies (Berkelhammer and Stott, 2008, 2009) have shown that conifer forests in California record the influence of varying precipitation regimes in their ring alpha-cellulose. Hurricane Dolores produced an intense precipitation event that inundated parts of the Mojave Desert …
Using Triple Oxygen Isotopes To Reveal The Origin And Evolution Of Mantle Eclogite, Catherine Mary Peshek
Using Triple Oxygen Isotopes To Reveal The Origin And Evolution Of Mantle Eclogite, Catherine Mary Peshek
Earth and Planetary Sciences ETDs
Triple oxygen isotope (TOI) measurements of mantle eclogite from the Orapa kimberlite pipe have reconstructed bulk rock '18O values from 4.587 to 9.542‰ (vs. VSMOW) and '17O from -0.075 to -0.044‰ (vs. VSMOW, ~0.528). TOI values show increasing '18O with decreasing '17O, overlapping with modern measured altered oceanic crust. Orapa eclogite xenoliths with alkali enrichments show variable mantle-like and heavy 18O, consistent with subduction of seafloor altered basalt. Na# (Na/Na+Ca) in clinopyroxene for some xenoliths pairs with mantle-like oxygen, variable and extreme LREE enrichment, elevated Mg# and lower jadeite contents. These samples preserve records of eclogite melting, mantle interaction …