Geology Commons^™

Investigation Of Shocked Basalts From Vargeão Dome And Vista Alegre: Implications For The Search For Life On Mars, Nikol Posnov

Electronic Thesis and Dissertation Repository

Impact craters represent excellent astrobiological targets for planetary exploration missions to Mars. The impact of an asteroid or comet into a crystalline, H₂O-bearing target may result in development of a hydrothermal system and increase the habitability of the substrate for the colonization of endolithic microorganisms. Given that Mars’ surface is covered by cratered basaltic rock, this study investigated target rocks and impact breccias from Vargeão Dome and Vista Alegre impact structures that formed in basalt in the Paraná Basin of Brazil.

Utilizing petrography and micro-X-ray diffraction (μXRD), the degree of shock metamorphism in plagioclase was quantitively determined. Measuring …

Creating Calibration Curves Using In Situ X-Ray Diffraction To Determine The Shock Pressure Experienced By Clinopyroxene, Laura Jenkins

Electronic Thesis and Dissertation Repository

This work extends on two quantitative methods for evaluating shock metamorphism to include clinopyroxene using X-ray diffraction (XRD). Clinopyroxene samples experimentally shocked to known shock pressures were studied with XRD. Lattice strain (ε) and strain-related mosaicity (SRM) were measured for each sample and plotted against their known shock pressures, creating a ε versus shock pressure calibration curve and an SRM versus shock pressure calibration curve. These calibration curves were applied to three meteorites: Nakhla, Zagami, and ALHA 77005. The SRM calibration curve gave peak shock pressures of 12±8 GPa for Nakhla, 44±8 GPa for Zagami, and 68±8 GPa for ALHA …

Understanding New Trends On Gold Mineralization At The Yellowknife City Gold Project, Northwest Territories, Using Synchrotron X-Ray Spectroscopy, Ramjay Jude L. Botor

Electronic Thesis and Dissertation Repository

The Yellowknife City Gold Project (YCGP) currently encompasses 780 sq. km of contiguous land north, south and east of the city of Yellowknife. The project lies in the prolific Archean north-south trending Yellowknife Greenstone Belt, a suite of mafic and felsic volcanics and greywacke turbidites overlying a gneissic basement. Exploration and drilling efforts have been focused along 70 km of strike length on the southern and northern extensions of the mineralized shear zones and quartz veins associated with the past-producing high-grade Con (6.1 Moz @ 16.1 g/t Au) and Giant (8.1 Moz @ 16.0 g/t Au) gold mines.

Synchrotron X-ray …

P-T-X Constraints On Ilmenite Unit Cell And Relationship To Kimberlitic And Non-Kimberlitic Sources, Mitchell R. Galarneau

Electronic Thesis and Dissertation Repository

This research investigates the mineral ilmenite, focusing on the relationship between crystal structure and geochemical and/or pressure data. Ilmenites were obtained from diamond-rich and diamond-poor kimberlites and non-kimberlitic localities, to discriminate between these populations. Crystallographic results showed a delineation between kimberlitic and non-kimberlitic ilmenites at a c-axis value of 14.02 (±0.01) Å. Adding geochemistry and pressure enhances the separation of kimberlitic and non-kimberlitic samples; however, this isn’t the case for diamond-rich versus diamond-poor kimberlites, even with three-dimensional and cluster analyses. A subset of kimberlitic ilmenites (manganese rich) were found with c-axis values and geochemical concentrations similar to non-kimberlitic ilmenites.

By …

Strength Study Of Zircon Under High Pressure, Ievgeniia Morozova

Electronic Thesis and Dissertation Repository

Zircon (ZrSiO₄) is a strong accessory mineral that can retain U, Th and Hf within its structure. This makes zircon an important material in geochemical and geochronological studies. In addition, the strong thermal shock resistance of zircon allows for dating the formations of melt and impact events and to separate shocked and potentially shocked country rocks. However, the deformation mechanism and microstructure behavior of zircon at high pressure is poorly understood. Therefore, this work aims to study the deformation and texture of zircon in situ at high pressure and room temperature, and also to examine the microstructure of …