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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee
Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee
Earth and Planetary Sciences ETDs
Volatiles (N2, CO2, and He) are released by volcanism and hydrothermal activity during continental rifting and subduction processes. Analyses of volatile components have been conducted to obtain gas contents (CO2, SO2, H2S, N2, Ar, He, and so on), stable isotope compositions (δ13C, δ15N, and so on), and noble gas isotopes (3He/4He, 40Ar/36Ar, and so on). This dissertation includes four chapters to report new nitrogen isotope fractionation factors of bubbling gases during gas-water transfer at various water temperatures (Chapter 1), first measurements of massive amounts of CO2 released by incipient continental rifting in the Magadi and Natron Basin, East African Rift …
Observed Changes In Climate And Streamflow In The Upper Rio Grande Basin, Shaleene Chavarria
Observed Changes In Climate And Streamflow In The Upper Rio Grande Basin, Shaleene Chavarria
Earth and Planetary Sciences ETDs
Observed streamflow and climate data are used to test the hypothesis that climate change is already affecting the streamflow volume derived from snow accumulation in ways consistent with climate model-based projections of 21st century streamflow. Annual and monthly changes in streamflow volume and surface climate variables on the upper Rio Grande (URG) near its headwaters in southern Colorado are assessed for water years 1958-2015. Trends in discharge are examined together with variations in snow water equivalent and surface climate variables. Results indicate that temperatures in the basin have increased significantly primarily in the winter and spring seasons, April 1 snow …
Oxygen Isotope Composition Of Water In Martian Meteorites, Oleg Vitalivich Maltsev
Oxygen Isotope Composition Of Water In Martian Meteorites, Oleg Vitalivich Maltsev
Earth and Planetary Sciences ETDs
The oxygen isotope composition of water extracted from Martian meteorites appears not to be in isotopic equilibrium with the silicate portion of the meteorites. This disequilibrium suggests the existence of multiple distinct oxygen isotope reservoirs on planet Mars. Here we present oxygen isotope measurements of waters extracted from Martian shergottites Tissint, Zagami and NWA-7042 and from nakhlite NWA-10153. These waters were extracted by stepwise heating to preserve segregation between low temperature adsorbed waters, intermediate temperature mineral waters and the high temperature mineral structural OH groups. The results of our study, analyzed cooperatively with previous work by Karlsson et al., (1992) …
Modeling Atmosphere-Mountain Interactions: Implications For Stable Isotope-Based Paleoaltimetry, Lauren B. Wheeler
Modeling Atmosphere-Mountain Interactions: Implications For Stable Isotope-Based Paleoaltimetry, Lauren B. Wheeler
Earth and Planetary Sciences ETDs
The measure of surface uplift can provide an important constraint on the behavior of continental lithosphere and the underlying upper mantle. Isotope-based paleoaltimetry aims to quantitatively estimate the magnitude and timing of surface uplift from records of the isotopic composition of precipitation in order to provide constraints on the tectonic processes driving mountain building. As the surface of a topographic barrier increases in height, along the windward side, δ-values of precipitation should get progressively more negative, and on the leeside, δ-values of precipitation should also get progressively more negative based on the presence and development of a topographically-induced rain shadow. …
Insights On Magmatic Addition Beneath The Mid-Atlantic Coastal Plain From Crustal Seismic Refraction Data, Thomas W. Luckie
Insights On Magmatic Addition Beneath The Mid-Atlantic Coastal Plain From Crustal Seismic Refraction Data, Thomas W. Luckie
Earth and Planetary Sciences ETDs
Magmatic addition can lead to intraplate crustal growth through plume-generated voluminous underplating of mafic material, particularly during early syn-rift processes. In addition, magmatism facilitates crustal growth and rift development by assisting extensional tectonic forces. Therefore, understanding the relationship between magmatism and rifting may help explain both these processes. In the summer of 2015 the GeoPRISMS Eastern North American Margin (ENAM) Community Seismic Experiment collected two margin-dip active source seismic refraction profiles in eastern North Carolina and southeastern Virginia using five onshore explosive shots on a northern profile and six on a southern profile (see figure). Analysis of these data resulted …
Magmatic Hydrothermal Alteration And Secondary Post-Shock Features In Martian Olivine-Phyric Basalt Northwest Africa 10416; Petrology And Geochemistry Of Primitive Achondrite Northwest Africa 11042, Zoltan Vaci
Earth and Planetary Sciences ETDs
The Martian olivine-phyric basalt Northwest Africa (NWA) 10416 contains large olivine xenocrysts whose cores have been stained brown by hydrothermal alteration and whose rims are composed of pristine olivine overgrowths. Microanalysis of these olivine cores reveals various degrees of amorphization, some of which have been overprinted by terrestrial weathering, evident as part of a weathering rind along the exposed surface of the meteorite. Studies of a completely unweathered terrestrial analogue basalt from southern Colorado reveal similar features and indicate that both basalts were altered in a supersolidus magma chamber setting. The alteration features in NWA 10416 thus imply the presence …
Classifying Microseismicty At Mount St. Helens Using A Large-N Array, Margaret E. Glasgow
Classifying Microseismicty At Mount St. Helens Using A Large-N Array, Margaret E. Glasgow
Earth and Planetary Sciences ETDs
A dense array of ~1,000 continuously recording, short-period geophones was deployed in the summer of 2014 within ~15 km of Mount St. Helens. Two earthquake catalogs created using reverse time imaging and template detection techniques, increase the detection rate and completeness of the earthquake catalog when compared to the permanent network, Pacific Northwest Seismic Network, catalog. An investigation into event type for ~200 of the earthquake detections leads to the discrimination of two major classification groups, volcano-tectonic and long period. Previous to this study, long period earthquakes had not been identified in the upper crust during a volcanically inactive period …
A Multi-Proxy Stalagmite Reconstruction Of The Climate Of Southwestern North America From The Middle To Late Holocene, Christine Allen
A Multi-Proxy Stalagmite Reconstruction Of The Climate Of Southwestern North America From The Middle To Late Holocene, Christine Allen
Earth and Planetary Sciences ETDs
The seasonal balance of moisture has a significant effect on natural ecosystems and culture in southwestern North America (SWNA), and it thus is necessary to understand the cause of this moisture variability in order to better predict the scope of potential future changes. Studies of modern SWNA climate indicate that most of the annual moisture at this site comes from monsoonal summer precipitation and a lesser amount of Pacific winter moisture. The climate of the Holocene is of particular interest for constraining natural variability of interglacial climates prior to any anthropogenic influence. An overall transition to a wetter Late Holocene …
The Dynamic Geomorphic Setting Of The Late Pleistocene Hartley Mammoth Site: Burial And Skeletal Preservation In A Slump-Block Depression Near Abiquiu, New Mexico, Jennifer K. Muus
The Dynamic Geomorphic Setting Of The Late Pleistocene Hartley Mammoth Site: Burial And Skeletal Preservation In A Slump-Block Depression Near Abiquiu, New Mexico, Jennifer K. Muus
Earth and Planetary Sciences ETDs
Near Abiquiu in northern New Mexico, the skeletal remains of two mammoths were discovered in the summer of 2014 in the near-surface deposits of a very small alluvial channel. The channel occupies a depression on the backtilted top of a Toreva slump block, a highly unusual setting for a mammoth burial. Geomorphological investigation of the site has provided insight into processes leading to burial and preservation of the remains, as well as local environmental change. Field mapping of sediment sources and LiDAR scans of the contributing slope basin and slump bench provided a map of geomorphic features and surficial geologic …