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Full-Text Articles in Physical Sciences and Mathematics

Formation And Alteration Of Basaltic Soils On Mars, Ian Oliver Mcglynn Aug 2012

Formation And Alteration Of Basaltic Soils On Mars, Ian Oliver Mcglynn

Doctoral Dissertations

The current surface of Mars is an arid inhospitable environment, dominated by aeolian processes, composed of largely volcanic rocks that have little apparent indication of pervasive aqueous chemical weathering, and blanketed by dust. Rocks are composed of basalts and the “soil” sediments appear to be largely basaltic-derived, and are chemically similar on a global scale. If the climate was once warmer and wetter during the Noachian period, with environmental conditions favorable to the development of life, physically weathered remnants, such as large quantities of phyllosilicate minerals, should remain. Basaltic soils provide a crucial constraint on chemical and physical weathering processes, …


Characterizing Phyllosilicate Distribution, Abundance, And Origin On Mars, Christina Elizabeth Viviano May 2012

Characterizing Phyllosilicate Distribution, Abundance, And Origin On Mars, Christina Elizabeth Viviano

Doctoral Dissertations

Secondary phyllosilicates are hydrated minerals formed in the presence of liquid water. On Earth, their formation is often indicative of a neutral, water-rich environment, capable of supporting and preserving organic matter. Different phyllosilicate species may be produced in different pH levels and water-to-rock ratios. The identification of mineralogically diverse phyllosilicates in small, localized exposures on Mars provides a complex record of their formation processes. While discrete outcrops of phyllosilicates have been previously identified in high-resolution visible/near-infrared images of Mars, regional coverage of these phyllosilicate-rich areas at better resolution is limited. Furthermore, spectra of minerals in this wavelength range do not …


From The Mantle To The Moon: Studies Of Kimberlitic Ilmenites, Meteorite Fusion-Crusts, And The Moscoviense Basin On The Moon, Kevin Glenn Thaisen May 2012

From The Mantle To The Moon: Studies Of Kimberlitic Ilmenites, Meteorite Fusion-Crusts, And The Moscoviense Basin On The Moon, Kevin Glenn Thaisen

Doctoral Dissertations

I have explored a variety of geologic problems in the course of the chapters contained within this dissertation. These include a study relating to the fusion crusts on meteorites, an impact basin of the Moon, and Siberian kimberlitic ilmenites. The first chapter explores two assumptions commonly employed in meteorite analysis; that fusion crust compositions represent the bulk-rock chemistry of the entire meteorite and that the vesicles within the fusion crust result from the release of implanted solar-wind volatiles. Neither of these assumptions was found to hold true in that study. The second chapter explores the unusual nature of the Moscoviense …


Mantle Flow And Lithosphere-Asthenosphere Coupling Beneath The Southwestern Edge Of The North American Craton: Constraints From Shear-Wave Splitting Measurements, Hesham A. Refayee Jan 2012

Mantle Flow And Lithosphere-Asthenosphere Coupling Beneath The Southwestern Edge Of The North American Craton: Constraints From Shear-Wave Splitting Measurements, Hesham A. Refayee

Doctoral Dissertations

"High-quality broadband seismic data recorded by the USArray and other stations in the southwestern United States provide a unique opportunity to test different models of anisotropy-forming mechanisms in the vicinity of a cratonic edge. Systematic spatial variations of anisotropic characteristics are revealed by 3027 pairs of splitting parameters measured at 547 broadband seismic stations. The western and southern edges of the North American craton show edge-parallel fast directions with larger-than-normal splitting times, and the continental interior is characterized by smaller splitting times spatially consistent fast directions that are mostly parallel to the absolute plate motion direction of North America. Except …


Plate Kinematics Of The Afro-Arabian Rift System With An Emphasis On The Afar Depression, Helen Carrie Bottenberg Jan 2012

Plate Kinematics Of The Afro-Arabian Rift System With An Emphasis On The Afar Depression, Helen Carrie Bottenberg

Doctoral Dissertations

This work utilizes the Four-Dimensional Plates (4DPlates) software, and Differential Interferometric Synthetic Aperture Radar (DInSAR) to examine plate-scale, regional-scale and local-scale kinematics of the Afro-Arabian Rift System with emphasis on the Afar Depression in Ethiopia. First, the 4DPlates is used to restore the Red Sea, the Gulf of Aden, the Afar Depression and the Main Ethiopian Rift to development of a new model that adopts two poles of rotation for Arabia. Second, the 4DPlates is used to model regional-scale and local-scale kinematics within the Afar Depression. Most plate reconstruction models of the Afro-Arabian Rift System relies on considering the Afar …