The thesis area consists of 33 square miles in the south-central Pueblo Mountains of Humboldt County, Nevada and Harney County, Oregon. The Pueblo Mountains are tilted fault block mountains found in the extreme northwestern part of the Basin and Range province and were produced during Early Tertiary Basin and Range orogeny. Northwest and northeast trending faults of Late Tertiary time have since cut the entire stratigraphic sequence. The oldest rocks exposed are metamorphosed Permian to Triassic eugeosynclinal sedimentary rocks. The metamorphic sequence is intruded by several granitic plutons of Late Jurassic to Middle Cretaceous age. A thick sequence of Miocene basalt flows unconformably overlies the pre- Tertiary rocks. A slight angular unconformity separates the basalt sequence from overlying Miocene tuffaceous sedimentary rocks, sillar flows, and welded tuffs. Unconsolidated deposits of Quaternary alluvium include alluvial fan and lacustrine sediments. Mineralization within the area includes several gold prospects, a mercury prospect, and a possible copper deposit. The copper prospect consists of a large gossan (6, 000 feet by 3, 000 feet). Mineralization and alteration from a Cretaceous porphyritic quartz monzonite intrusion has produced potassic and quartz sericite hydrothermal alteration in the host. Oxidation and weathering has removed the sulfides from the surface leaving goethite, hematite, and limonite residues. / Graduation date: 1971

published_or_final_version / Earth Sciences / Master / Master of Philosophy

Extensive studies have been undertaking in exploring the tectonic evolution of the Himalayan Orogen. Various tectonic models were developed to explain and constraint spatially and temporally critical events including the collision of Indian Plate with the Eurasia Plate, crustal thickening in association with the indentation, crustal spreading of the Tibetan Plateau. Recent study by King et al., 2011 identified two distinct leucogranite suites which were formed by contrasting tectonic actions at Sakya. They are Equigranular Anastomosing Leucogranite (AEG) formed under prograde fluidpresent condition while the Discrete Porphyritic Pluton Leucogranite (DPP) formed with retro-grade fluid-absent environment. Based on the characteristics of AEG and DPP, this study started with the acquisition of geochemistry data of rock samples collected for researches at various locations of the Himalaya Orogen. The two leucogranite suites were characterized through the study of their geochemistry comprised major elements, trace elements and rare earth elements models. Results of the studies concluded the existence of AEGs and DPPs distributed over the eastern area of the Himalaya Orogen beyond longitude 85 degree East. DPPs are also found at the far West location of the orogen. AEGs are typically formed from around 38Ma to 23Ma, while DPPs are of young age from 23Ma to 15Ma. Based on the observation of missing, or paucity in data for AEG and DPPs available to the west of longitude 85 degree East, it is hypothesized that recent collision of the Arabia plate to the Iran Domain inhibited the northward indentation movement of the Indian plate that not only caused the anticlockwise rotation of the Indian plate but also decreased the rate of tectonic movement of the Indian plate in the West relative to Eurasia plate. The slow rate of tectonic movement may result in insufficient thickening/energy developed within the crustal layer to cause any melting. Further studies to examine and development of the hypothesis is recommended. / published_or_final_version / Applied Geosciences / Master / Master of Science

The San Andres and Grayburg Formations are important stratigraphic units for constructing correlation frameworks of the Guadalupe Mountains because these strata record the transition between the ramp profiles of the San Andres along the Algerita Escarpment and the reef-rimmed platforms of the Capitan Formation of the southern Guadalupe Mountains (Franseen et al. 1989). Sarg et al. (1999) and Kerans and Tinker (1999) have published significantly different models of shelf-to-basin correlations within this stratigraphic interval. Central to the debate is the correlation of mixed carbonate-siliciclastic strata exposed at Plowman Ridge in the Brokeoff Mountains to the better-constrained strata along the Shattuck Escarpment in the Guadalupe Mountains. This study applies high-resolution cyclostratigraphy, inorganic carbon isotope geochemistry, and sequence stratigraphic concepts to test the hypothesis that the strata exposed at Plowman Ridge are equivalent to Grayburg strata exposed at the Shattuck Escarpment in the southern Guadalupe Mountains (Kerans and Nance 1991, Kerans and Kempter 2002). The shelf-to-basin cyclostratigraphic framework of the Grayburg Formation used in this study was established at the Shattuck Escarpment with data compiled from nine detailed measured sections, high-resolution photopans, and petrographic analysis. Based on one- and two-dimensional cycle stacking analysis, the Grayburg Formation was divided into three high-frequency sequences (HFSs). The high-frequency sequences contain transgressive systems tracts separated by maximum flooding surfaces from the highstand systems tracts. The Grayburg high-frequency sequences are composed of between 6 and 20 high-frequency cycles (HFCs), which were identified and classified into vertical facies successions. The Grayburg succession at Shattuck section 7 (32.09ᵒ, -104.81ᵒ) was selected as the reference section from the Guadalupe Mountains for comparison with Plowman section PR1 (32.03ᵒ, -104.89ᵒ) in the Brokeoff Mountains. Correlation between sections is documented at the 3rd-order composite sequence, high-frequency sequence, and when feasible, high-frequency cycle scale. Three high-frequency sequences recognized at Plowman Ridge section PR1 are equivalent to the G10, G11, and G12 Grayburg sequences described at Shattuck section 7. Correlation of the Grayburg G10-G12 high-frequency sequences with the three sequences at Plowman Ridge is based on comparison of overall thicknesses, facies proportions, cycle number, vertical facies succession, stratigraphic position of diagnostic units, and excursions within the inorganic carbon isotope profiles taken from both sections. Establishing the links between Grayburg strata on the Shattuck wall with strata on Plowman Ridge corroborates the framework/correlation scheme of Kerans and Tinker (1999) in lieu of other published correlation frameworks. / text

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published_or_final_version / abstract / toc / Earth Sciences / Doctoral / Doctor of Philosophy

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