published_or_final_version / Earth Sciences / Master / Master of Philosophy

No description available.

xvi, 121 p. : ill. (some col.), maps (some col.) Also includes two large-scale maps in two separate pdf files. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Deformation across plate boundaries often occurs over broad zones with relative motions between plates typically accommodated by faults of different styles acting together in a complex system. Collision of the Yakutat microplate within the Alaskan portion of the Pacific-North America plate boundary drives deformation over 600 km away where the Denali fault divides predominantly rigid crustal block motions of southern Alaska from distributed deformation in central Alaska. Quaternary geologic mapping along the Nenana River valley and the Japan Hills of the northern foothills of the Alaska Range defines zones of Quaternary thrust faulting recorded in the progressive deformation of Pleistocene fluvial terraces. I use topographic profiles of these terraces and paleoseismic trenching of fault scarps to characterize the Quaternary activity and constrain the subsurface geometry of these faults. Radiocarbon and cosmogenic exposure dating methods provide age control on the stratigraphy in the trenches and landforms offset by these faults. These observations define a 1-1.5 mm/yr slip rate for the Gold King fault which changes laterally from a north-vergent thrust into a north and south vergent thrust wedge that uplifts the Japan Hills. Along the Nenana River valley, the progressive deformation of Pleistocene surfaces defines a north-vergent critically-tapered thrust wedge. The geometry of progressive uplift and folding requires a near planar, south-dipping basal thrust fault with two major north-dipping backthrusts. All three faults were active simultaneously on a scale of 10 4 yrs with slip rates of 0.25-1 mm/yr, until the late Pleistocene when we infer the retreat of glacial ice from the main axis of the Alaska Range caused a change in thrust wedge dynamics. I use the orientation of Quaternary deformation north of the Denali fault to show that strain is highly partitioned and establish geologic constraints on the regional horizontal stress orientation. North of the Denali fault, fault-normal principal shortening accommodates 3-5 mm/yr of strain transfer across the Denali fault system. Two appendices contain additional results of paleoseismic trenching and neotectonic investigations across 4 active faults near the Nenana River. This dissertation includes previously unpublished co-authored material. / Committee in charge: Ray Weldon, Chairperson, Geological Sciences; Joshua Roering, Member, Geological Sciences; David Schmidt, Member, Geological Sciences; Douglas Kennett, Outside Member, Anthropology

xv, 372 p. / In my dissertation I argue that because the European Union and the United States of America have been largely treated as unique or at least special cases, both the literature on American-state building and that on European market integration have missed how close comparison alters both our descriptive views and social-scientific explanations of the shape of each polity. In particular, scholars have not sufficiently recognized that the European Union has gone further than the United States in many elements of the creation of a centralized, liberalized single market, nor have they produced explanations that account well for this development. This study challenges the dominant assumption that the United States is generally more hierarchical and centralized than the European Union and more of a single free market in the sense of fewer allowable trade barriers. By analyzing the rules of market integration in services (over 70% of GDP), public procurement (15 - 20% GDP) and the regulated goods markets (goods like elevators with their own regulatory regimes), I demonstrate that in all these major cases the European Union has adopted rules that open exchange to competition more than the United States. While the actual integration of flows on the ground is still generally less across European states than American ones, the political rules are more - and more liberally - integrated in Europe. I offer an institutional and ideational argument to explain these differences, with two main parts. First, there is no American parallel to the institution of the European Commission, which is mandated to continually push liberalization forward. My research shows that Commission leadership has been critical to each of the examined cases. Second, broader norms of legitimate governance favor centralized authority - including liberalizing central authority - more in the European Union than in the United States. Despite all the criticism we hear of the European Union, the basic notion of federal governance of market integration is far more strongly accepted across Europe at both elite and mass levels than in the United States. As interview evidence in this study displays, many Americans consistently object to any role for the federal government. / Committee in charge: Dr. Craig Parsons, Chairperson; Dr. Gerald Berk, Member; Dr. Lars Skålnes, Member; Dr. Alexander B. Murphy, Outside Member

In the Upington region, there are three major- tectonic crustal provinces; namely the Kaapvaal Craton, Kheis and Namaqua tectonic provinces. The Eburnian-aged (early Proterozoic) Kheis Province developed along the western flank of the Archaean Kaapvaal Craton while the Kibaran-aged (middle Proterozoic) Namaqua Metamorphic Province, superimposed on the Eburnian-aged basement, developed to the east of the Kheis Province. The Namaqua Metamorphic Province is divided into the Gordonia and Bushmanland Subprovinces, the former being further subdivided into various tectonostratigraphic terranes. These are termed, from west to east, the Kakamas, Areachap, and Upington Terranes. The Upington Terrane includes fault bounded grabens with accompanied bimodal volcanism and sedimentation of the Wilgenhoutsdrif and Koras Groups. The Areachap Terrane consists predominantly of amphibolites generated in an island arc environment while the Kakamas Terrane is characterised by volcano-sedimentary sequences which have been extensively intruded by syn to late-tectonic predominantly I-type Keimoes Suite granitoids. The main styles of mineralisation correlate well with the various tectonostratigraphic terranes. Sedimentary exhalative massive sulphide deposits are characteristic of the Bushmanland Subprovince and are thought to be associated with the deposits at Aggeneys and Putsberg to the west of the area under investigation. These deposits are considered to have been deposited in an east-west-elongated intracontinental basin. The Kakamas Terrane is typified by granite-related mineralisation. In the eastern portion of the Kakamas Terrane, Sn-Wand base metal-bearing veins occur while pegmatites are developed in the western portion. These two styles of granite-related mineralisation is considered to reflect differing depths of formation due mainly to varying degrees of thrusting. The Areachap Terrane consists of volcanogenic massive sulphide deposits of the Besshi-type and is considered to have formed in a back-arc environment. In the Upington Terrane, the Wilgenhoutsdrif and Koras Groups consists essentially of minor Cu occurrences mainly disseminated within basalts and in structural trap sites. The possibility for sediment-hosted Cu deposits is not ruled out. More recent surface processes have led to uranium and gypsum deposits in pans, river beds and calcretes. Eburnian aged tectonic setting remains enigmatic. Kibaran-aged tectonics which best fits the metallogeny of the area under investigation is considered to be of a subduction zone from west to east formed by the collision of the Bushmanland "microcontinent" against the Kaapvaal Craton. Subduction fbrmed an island arc setting in which the massive sulphide deposits were formed in the Areachap Terrane while the Wilgenhoutsdrif Groups developed in a marginal basin. Further convergence led to collision of the two continents and underriding of the Bushmanland "microcontinent" which generated predominantly I-type granitoids represented by the Keimoes Suite. The level of emplacement of these granitoids is a reflection of the degree of foreland thrusting and produced shallower level Sn-W and base metal vein-type mineralisation closer to the suture zone and deeper level pegmatites further from the suture zone to the west. The final period of deformation is represented by northward lateral movement which created "pull apart" fault-bounded basins into which the Koras Group was deposited.

M.Sc. (Geology) / Please refer to full text to view abstract

The modern plate tectonic paradigm provides a predictive model to understand what mediates dynamic processes at both plate margins and intraplate settings. At some locations on the Earth, the geological record provides evidence of apparent violations of this theoretical framework. In this dissertation, I examine a region on the rifted continental margin of Eastern North America, where at least four distinct episodes of magmatism occurred (in the Late Triassic, Early Jurassic, Early Cretaceous) since the onset of rifting and ultimate breakup of the supercontinent Pangea. It also coincides with a present-day low seismic velocity anomaly in the upper mantle. No other region on the Eastern North American Margin has a record of such anomalous dynamic processes occurring and persisting for more than 200 Myr. In this dissertation, I primarily use zircon U-Pb geochronology to establish the basic chronological framework in which magmatic and magmatic-hydrothermal systems in this region existed and persisted, establishing the temporal parameter space in which it will be possible to test geodynamic mechanisms for their formation. In Chapter 2, I use ultra-high precision zircon U-Pb geochronology via Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to test whether the onset of magmatism in the largest igneous body in this region (the White Mountain Batholith) is linked to the eruption of the vast flood basalts within the Central Atlantic Magmatic Province (CAMP) and whether its apparent duration is indeed > 50 Myr, as previous workers using whole rock K-Ar and mineral Ar-Ar geochronologic methods suggest. My work uncovered a previously unknown episode of rift-related magmatism in the region that precedes the both the CAMP and the emplacement of the White Mountain Batholith by 3 – 5 Myr. In Chapter 3, I use a combination of high-precision zircon U-Pb geochronology and absolute plate motion models to test whether the Cretaceous igneous province in this region resulted from hot spot magmatism as North America moved over the purported Great Meteor Hotspot. These results cannot falsify the hotspot hypothesis and the new zircon U-Pb ages therefore provide the best available chronological constraints for one of the longest-lived hot spot tracks on the Earth. In Chapter 4, motivated by the confirmation of age discrepancies between low- and intermediate-temperature chronometers and the zircon U-Pb ages presented in Chapter 2, I use a combination of both CA-ID-TIMS and LA-ICP-MS zircon U-Pb geochronologic techniques to place constraints on the timing and duration of magmatism for the Late Triassic-Early Jurassic province. The results of this chapter demonstrate that the magmatism of the White Mountain Magma Series occurs in discrete pulses through much of the Jurassic. Together with zircon Hf isotopic analyses from select samples, I synthesize these age results and construct a hypothesis testing framework in which it will be possible for future investigators to unravel the geodynamic complexities in this region. I provide recommendations for future work and emphasize the need for unified approaches coupling geochronology, geochemistry, and geophysics, to test the range of possible mechanisms responsible for these episodes of anomalous tectono-magmatic activity.

No description available.

Increasingly, teachers are encouraged to use data resources in their classrooms, which are becoming more widely available on the web through organizations such as Digital Library for Earth System Education, National Science Digital Library, Project Kaleidoscope, and the National Science Teachers Association. As "real" data becomes readily accessible, studies are needed to assess and describe how to effectively use data to convey both content material and the nature of scientific inquiry and discovery. In this study, we created two introductory undergraduate physical geology lab modules for calculating plate motion. One engages students with a model-driven approach using contrived data. Students are taught a descriptive model and work with a set of contrived data that supports the model. The other lab exercise uses a data-driven approach with real data. Students are given the real data and are asked to make sense of it. They must use the data to create a descriptive model. Student content knowledge and understanding of the nature of science were assessed in a pretest-posttest experimental design using a survey containing 11 Likert-like scale questions covering the nature of science and 9 modified true/false format questions covering content knowledge. Survey results indicated that students gained content knowledge and increased their understanding of the nature of science with both approaches. Lab observations and written interviews indicate these gains resulted from students experiencing different pedagogical approaches used in each of the two labs. / Master of Science

Master of Science / Geology / Joel Q. Spencer / Optically stimulated luminescence (OSL) dating is a relatively new dating method, tangibly introduced in 1985 when Huntley et al. demonstrated the ability to use light-sensitive traps to measure radiation exposure and determine the age of sediment. Quartz and feldspar grains are commonly used for the method, with quartz receiving significantly more attention than feldspars until the past decade. Recent research has improved the practicality of using feldspars as a reliable dosimeter –an appealing notion as the intrinsic properties of feldspars allow them to date older sediment that may lie beyond the reliable range of quartz dosimetry. This work explores and utilizes the contemporary feldspar technique termed post-infrared, high-temperature infrared stimulated luminescence (pIRIR) dating to add to the existing knowledge base of this method, particularly by testing different preheat and measurement temperature combinations. Analysis of the each pIRIR method indicates that the pIRIR signal stimulated at 225°C is more appropriate for dating than the pIRIR signal stimulated at 290°C. Techniques and protocols developed in this work are done so via their application to a marine terrace that is displaced by the San Andreas Fault. Corals from the terrace along the Pacific plate, dated with U-series by Muhs et al. (2002), offer an age estimate. Comparison of the pIRIR ages to the U-series ages yield an underestimation, suggesting the pIRIR method may be more useful as a means of correlating terraces across the fault, than for providing ages of terrace formation.